compression ratio vs boost psi

[myztery]

ok this might have been covered, but i couldnt find anything.

Here we go:

1. higher compression ratio vs low boost
or
2. Lower compression ratio vs high boost

advantages and disadvantages?, reliability?, engine handling?
and keep it around these grounds

i was told low boost, high comp gets rid of turbo lag???

[VTi_b0i]

well as ive said before, IF you LOWER your compression then youll lose power on your motor and have to try and make that up before u actually see gains which is rather silly....
Better to run ur motor as honda intended it to be but then run a little less boost... ull experience less lag and have a more fun car to drive

[Q_ball]

Not so much lag, but running a higher compression motor/setup allows for better response.

[myztery]

so in other words, say i raised the comp to 12:1 instead of 10.2:1 ill get a better response?
but run less boost?
would this then affect dyno out put, max kw???

[VTi_b0i]

LOL but that also isnt a good idea because that would put ALOT of stress on the motor...
what im saying is... what the motor was made for... keep it at that then boost lol
a little bit more is ok... im running 11.4... but any more then that and its a little bit too much... who knows how long itll last

[delsol9000rpms]

stock comp or high comp and lower boost..

[votek]

but what turbo size are you guys talking about

11.1 compression
7psi on a t28bb will make ~150
7psi on a gt30r will make ~200

what one has more response?

[myztery]

t2871r

[FastFwd]

In my experience Stock compression didnt work. I was running it at 7psi with stock compression and i blew the motor with my old gt30 in less than 6 months. The bottom end bearings just fell apart and the motor only had 30,000k's on it from japan.

i think its just luck or the tune when your running psi on the stock motor. Some people have no problems at all and there engines have had 150,000km's+

but i must say stock compression on boost did feel better than my 9.3 or whatever im running now with my lower comp eagle pistons.

[gReY-oNe]

Ive been running stock compression for over a yr on a motor that has 14X,XXX on about 9-10psi and everything seems fine. I enjoy it, though mine still lags a fair bit so most times im driving off boost.

[FastFwd]

Yer exactly, its just luck i guess. some people can run perfectly fine some just blow. Although your laggyness might just be your turbo. Not the compression

[DLO01]

Luck is like hoping it won't blow up. If thats the case why boost it if your going to worry all the time.

There are heaps of variables, but luck is not a factor at all.

[FastFwd]

Well your right, there are many variable. Motor condition, Tune, etc etc but it depends on every turbo setup your running.

But it didnt bother me that i blew my motor anyways cos i knew "ahh if i blow it im gonna be rebuilding the motor anyways"

[nigs]

lol, sounds like you'd love a rotary.

[Q_ball]

Luck is like hoping it won't blow up. If thats the case why boost it if your going to worry all the time.

There are heaps of variables, but luck is not a factor at all.

Touche... its all in the tune baby... all in the tune.

[Lukezen27]

I'm running high comp I'd say after two head shaves with 11PSI on stock internals :p

http://fjdistributors.com/index.php now make custom rods to raise the comp close to stock with low comp forged pistons

[spardikis]

Luck is like hoping it won't blow up. If thats the case why boost it if your going to worry all the time.

There are heaps of variables, but luck is not a factor at all.




he just said it for me...

keep compression on the higher side. better response, less lag, less boost for same power.

good luck

[A-man]

yeh u cant build a highly modified car and not expect something to go wrong... if u r worried and if u dont wana fix stuff then go buy a xbox and forza motorsport and sell ur car and buy a jazz or something...

i think tune has alot to do with it aswell as maintance...

[votek]

keep compression on the higher side. better response, less lag, less boost for same power.


is that the same results for the same turbo?

[dsp26]

http://www.ozhonda.com/forum/showthread.php?t=44592&highlight=compression+ratio

[DLO01]

keep compression on the higher side. better response, less lag, less boost for same power.


is that the same results for the same turbo?

Given the same engine specs. You will get more power out of a larger, higher flowing turbo. Same with boost pressure. At the same pressure (10psi or whatever), you get more out of a larger, higher flowing turbo. Pressure and Flow are 2 different things.

[Limbo]

all comes down to the fuel and tuning.
The higher compression needs better fuel and more accurate tuning, or it can detonate easliy. Its one of the drawbacks of hi-comp, that i don't think everyone explains

On a lower comp car there is less issue when it comes to fuel & detonation.

True you will make slightly less power & lag abit more, but people generally up boost to compensate.

[anjin]

I did an exercise on engine cycles a while ago, and one of the things that really made sense was the interelationship between compression ratio (however achieved) and timing. The maximum pressure developed in the cylinder should occur about 14/15 degrees after tdc - at that point the force developed will force the piston and rod around the crankshaft. Any earlier and you are trying to force the rod through the crankshaft. Any later and you are past the optimum leverage point as the mixture expands and the piston accelerates away down the bore.
Now in order to get maximum pressure at that point you have to start the fuel air mixture burning much earlier -before tdc. That is why you have a static ignition point at say 16 degrees BTDC and it advances to even earlier at higher revolutions - the fuel-air mixture burns at the same pace at 1000 prm as 8000 prm.
But it burns faster at higher compression ratios. So to get maximum cylinder pressure at 14 degrees atdc with high compression ratios than stock you actually have to retard the timing.
That is where a lot of the tuning skill for engine longevity comes in when you boost engines.

[FastFwd]

I did an exercise on engine cycles a while ago, and one of the things that really made sense was the interelationship between compression ratio (however achieved) and timing. The maximum pressure developed in the cylinder should occur about 14/15 degrees after tdc - at that point the force developed will force the piston and rod around the crankshaft. Any earlier and you are trying to force the rod through the crankshaft. Any later and you are past the optimum leverage point as the mixture expands and the piston accelerates away down the bore.
Now in order to get maximum pressure at that point you have to start the fuel air mixture burning much earlier -before tdc. That is why you have a static ignition point at say 16 degrees BTDC and it advances to even earlier at higher revolutions - the fuel-air mixture burns at the same pace at 1000 prm as 8000 prm.
But it burns faster at higher compression ratios. So to get maximum cylinder pressure at 14 degrees atdc with high compression ratios than stock you actually have to retard the timing.
That is where a lot of the tuning skill for engine longevity comes in when you boost engines.

NS dude?

where u learn that man u sound fairly knowledgeable.

[IsItQik??]

I agree with a lot of what's being said, yet it is worth noting that if it's to be more than a theoretical discussion a desired outcome should be initially decided upon. If a smallish turbo is to be used, with a modest power figure in mind, than retaining a higher comp ratio would certainly be advantageous. Although if a larger turbo was to be used it then would be reasonable to reduce the compression, run higher boost and achieve your power goals. Even with only 9psi through a gt30 on a properly built motor 200+fwkw is available.
Of course lag is not purely a function of comp ratio; turbo size and design, manifold design, pipe diameter(bigger is not always better), pipe length, engine displacement and tune all play important roles in minimising lag. I also feel that with a high rev limit a big turbo on a built motor will give you a far greater power band, as it will not run out of puff higher in the rev range.
All of this means nothing without a good tune, if you go for small turbo/ hi-comp set up or large turbo/built motor neither will live a happy or long life without the right tune.
Yes you can put a large turbo on a hi-comp motor, it's just that it's like gambling. You may win in the short term but chances are you'll lose in the long run.
So save money and do it properly once.

[DLO01]

If you have a decent setup and a tuner that knows what he is doing you, will have no problems at what so ever, weather your running high compression and/or a large or small turbo.

Even with stock internals you can acheive over 200kw @ wheels, B and K series and no reliability problems. Lasts for a long time. :thumbsup:

[anjin]

NS dude?

where u learn that man u sound fairly knowledgeable.

I belong to a local club were we do technical sessions on various topics. So if you're presenting you do a lot of homework. The information like this is available in various places - its a matter of finding and assimilating it. Plus I have rebuilt engines, assisted with other rebuilds, done engine swaps, and so on.

To expand on the topic a bit, the maximum cylinder pressure in an NA car varies between 900 and about 1400 psi. Boost it or up the compression ratios and you start looking at 2000 psi. Thats why getting that point correct is important - 2000 psi at tdc means you bust the bearings pretty quickly. Get it too late and you waste the effort. Arranging things to get it correct is the tuner's art.
Get pre-ignition (knock) and you start seeing 3000 psi plus spikes which busts pistons and rods.

Re the more general discussion on small or large turbo and starting cr, everything I see agrees with isitqik and DL001- its the total package and how its put together that determines a lot of what you get. Talk to the people who have experience with your motor, know what your goals are and where you will use the motor, and go with 'that' package.
And then don't go a change it up without getting it retuned!

[FastFwd]

I belong to a local club were we do technical sessions on various topics. So if you're presenting you do a lot of homework. The information like this is available in various places - its a matter of finding and assimilating it. Plus I have rebuilt engines, assisted with other rebuilds, done engine swaps, and so on.

To expand on the topic a bit, the maximum cylinder pressure in an NA car varies between 900 and about 1400 psi. Boost it or up the compression ratios and you start looking at 2000 psi. Thats why getting that point correct is important - 2000 psi at tdc means you bust the bearings pretty quickly. Get it too late and you waste the effort. Arranging things to get it correct is the tuner's art.
Get pre-ignition (knock) and you start seeing 3000 psi plus spikes which busts pistons and rods.

Re the more general discussion on small or large turbo and starting cr, everything I see agrees with isitqik and DL001- its the total package and how its put together that determines a lot of what you get. Talk to the people who have experience with your motor, know what your goals are and where you will use the motor, and go with 'that' package.
And then don't go a change it up without getting it retuned!

Im nor agreeing or disagreeing im just saying it sounds like you know what your talking about. I'm not close to a mechanic but ive done everything myself over the years ive had my civic/s15 and i've learnt everything i know. I've gone for the engine build myself as the high comp didnt work out so well for me in the past but i think that was cos the tuner made a mess of it.

[anjin]

It does help that a close mate is a mechanical engineer who does similar builds and who corrects me when I get off beam, but yes its about learning and doing yourself. A necessity for me with a 1983 model crx - try fixing that at the Honda dealer workshop. I've had everything in and out of that car and a previous one, so nothing much bothers me anymore.

[A-man]

they still fix old hondas in the dealer workshops...

there is a point where to small of a turbo is a waste of time it becomes a bottle neck of the engine...

its like having 2inch pipes on the exhaust manifold but only run 1inch exhaust

[s2kadl]

I agree that its almost all in the tune. Im running 15psi with a greddy T518z in an s2000 on stock compression. Should be looking at a ECR of around 21-22. The car runs great thanks to the boys at Willall racing.

[FastFwd]

wow s2000's can run 15psi on stock compression. I didnt know that, thats awesome.

What's the stock comp?

[votek]

shouldnt it start knocking at 14 ecr

[A-man]

if u sort out the timing and the fuel... it should b fine

[s2kadl]

Stock compression is 11:1.

Yeah my tuner is really good, plus Im running on E85 fuel allowing me to run slightly more boost as per 98.

[nd55]

> plus Im running on E85 fuel

I think this has a LOT to do with it.

> say i raised the comp to 12:1 instead of 10.2:1 ill get a better response

I think on a Honda the compression ratio's you'd be considering are in the range of 8 to high 10's : 1.

The 12:1 ratios and higher are specific to highly tuned pushrod V8's turning really high RPM.

I think NASCAR V8's topped out at about 16:1 some time ago, but racing rules have been introduced to limit this with a view to moderating costs.

Higher ratio's are often used when turning really big RPM's and the cylinder VE isn't the best. By squashing a cylinder with an 80% VE with very high CR the cylinder pressure is the same as a 100% VE with less compression.

Not as application on a street engine with an 7000rpm redline.

Any form of alcohol changes this a lot.

Nick.

[s2kadl]

Yes, there is no way I could run 15psi on stock compression without the cooling and octane properties of E85, well safely anyway.

[Weq]

[with respect to building engines]

WIth high compression, all it takes is a bad batch of fuel for a new motor to be had.

On the street, if u want power on pump fuel, low compression is the way to go. Low compression is forgiving. And in the real world, if u daily drive ur beast, this is the difference between life and death (of ur motor).

E85 isnt pump fuel here, yet...

[s2kadl]

From memory some of the LS1 LS2 turbo guys in NSW are running E85, I reckon there are 4 or 5 servos that carry E85 over in NSW. From memory some Enhance petroleum and United petrolroleum.

[Weq]

From memory some of the LS1 LS2 turbo guys in NSW are running E85, I reckon there are 4 or 5 servos that carry E85 over in NSW. From memory some Enhance petroleum and United petrolroleum.

Like i said, it isnt exactly pump fuel. Unless your a weekend warrior that doesnt venture 200kms (E85 runs at 9:1 stoich, double the fuel) from there home, then its not viable yet.

I just did 2400km round trip with my Z, boosting hard after 10hrs running, stopping off at remote servo's for fillups. Unless you can do that, you might as well be running C16.

[s2kadl]

You are right, its definitely not an option for those who daily drive high kms. My S is just a weekend car and so far Im using about 30% more fuel compared to when I was at 12psi on ULT98. C16 was an option but costing 6-7 times that of E85($1.22/L) made it unviable for me. The extra 3 psi on E85 netted me an additional 38 rwkw.

[IEVAQ8]

I don’t understand how some of u people with no experience can comment about a high compression boosted Honda on pump fuel is no good for a daily driver………

Please give me some reasons or experience to back your negativity…………on high comp with low boost on a big turbo……

as my daily dc2r with stock compression (11.1) and gt30 on 7.5psi is making a healthy 239.8kw and hasn’t missed a beat yet (almost a year)………it gets driven every day and on the weekends (rain, hail, shine, 45degrees or 10degrees), also goes to the drag strip when I can……………..
anything regarding boost/higher compression is all in the tune and the quality of the parts u decide to use……………

[votek]

the tune is everything... what variables you have. its all about the tune!!!

[Limbo]

i agree i drive mine all the time without fail no probs at all


I don’t understand how some of u people with no experience can comment about a high compression boosted Honda on pump fuel is no good for a daily driver………

Please give me some reasons or experience to back your negativity…………on high comp with low boost on a big turbo……

as my daily dc2r with stock compression (11.1) and gt30 on 7.5psi is making a healthy 239.8kw and hasn’t missed a beat yet (almost a year)………it gets driven every day and on the weekends (rain, hail, shine, 45degrees or 10degrees), also goes to the drag strip when I can……………..
anything regarding boost/higher compression is all in the tune and the quality of the parts u decide to use……………

[nd55]

There's a David Vizard article floating around the net which lists rough power differences across a range of CR's for a NA motor. .

I think it was in the range of 10-15% improvement for a 8-12:1 CR range.

This using pushrod V8's.

... and this link comparing 9:1 & 10:1 from elsewhere on this site:

http://www.evans-tuning.com/dynocomp_9vs10to1.html
Nick.

[votek]

Yes, there is no way I could run 15psi on stock compression without the cooling and octane properties of E85, well safely anyway.

anyone ever run 15psi on a stock bseries motor? rod gone?

[DLO01]

Yes its been done before. Think it was a B16A2. No problems. Depends how you drive it. On the street, on/off boost, no problems.

[Sexc86]

I Did look into High compression + boost with an engine builder a while back. They basically said there is a Happy/medium level to be found betweeen timing and CR. Higher compression = less timing (assumeing useing pump fuel). Timing is what makes you power.

[IEVAQ8]

again, im not dissing ur tuiner/builder..............

but with the correct fuel and a tuner that knows our hondas well, u can run very high timing in a honda with high comp and low boost and still have that drivability (very little lag) and big power.....

[ZeForce]

Higher compression = less timing (assumeing useing pump fuel). Timing is what makes you power.

I cannot agree with this statement..... when you advance the ignition timing you are making the engine compress a burning (rapidly expanding) mixture and hence it is actually doing NEGATIVE work. Of course, you will always need to ignite the mixture before TDC to ensure maximum amount of the fuel/air is combusted before the piston reaches BDC however more timing isnt always better. Im sure everyone will have their 2cents to say about it, but producing more power from less timing is ideal in my books.

[Sexc86]

A tuner is a tuner ... not a miricle worker. Not matter how good they are they cant stop the physics of premature ignition.

Zeforce - Cylinder pressure and power output dont go hand in hand.

[Blue]

Its been said but in summary

low CR & higher boost = you keep your motor for longer but your car drives a lil bit more like a pig off boost, but hey if you spend the money you can run big boost numbers intermittently if you so wish to save fuel.

hi CR low boost = Your car drives fine off boost, then you get greedy and end up feeding too much boost through the motor and you blowing something through either winding the wick or bad batch of fuel which lets face it is the luck of the draw in most cases.

[FastFwd]

Either way if you want to go low CR and higher boost in the long run just do what i did. Run it hi CR and low boost for as long as you can and then if some thing happens then rebuild it.

Personally for street use in my opinion Hi CR and low boost is much nicer.

[Blue]

yeah but some dont have the cash, this is a big thing left out of discussion, (for obvious reasons)

it always comes down to your budget and your power figure goal, this will ultimately determine which way you go,

unless you have neither and are just squeezing your engine hoping nothing breaks LOL

[FastFwd]

Well if your strapped for the cash then personally you do it right the first time or you dont do it at all.

Having a turbo car that was originally NA isnt as easy and jamming a turbo setup on, tuning it and on ya go. It puts alot of stress on the motor and little things start to break aspecially when the car is 10+ years already things prematurely fail which means money and if you dont have it then Its not something to start playing around with.

[Blue]

says the wise man - look this is going off topic so I will not argue,

Regards,

[FastFwd]

all smiles here :) :)

[Blue]

:) here too

[IEVAQ8]

Either way if you want to go low CR and higher boost in the long run just do what i did. Run it hi CR and low boost for as long as you can and then if some thing happens then rebuild it.

Personally for street use in my opinion Hi CR and low boost is much nicer.

i agree with u completely.........

and if people dont have the cash to do it properly the first time or to budget for breakages, then they shouldnt be doing any mods at all.........

[FastFwd]

i agree with u completely.........

and if people dont have the cash to do it properly the first time or to budget for breakages, then they shouldnt be doing any mods at all.........

Yup...stick with your safe Bolt-on NA mods if you have a little cash to play with but if your not prepared for a random rebuild then dont go boost.

Random Rebuilds seam to come more often than i would like :(

[Blue]

yes they are not allowed....

[Lukezen27]

BAH

I just throw my turbo kits on :p

[FastFwd]

hahhaha i did that...failed hard tho 6 months later i was rebuilding :(

[Lukezen27]

hahhaha i did that...failed hard tho 6 months later i was rebuilding :(

Bad tune...?

As long as you buy good hardware it can only be the tune or incorrect install!!

[FastFwd]

yeh it was bad tune. But how are you supposed to know the car felt ok? you put trust in the tuner to do a good job but then it ends up costing ya.

brought it to Hyperdrive and he was like "wtf is up with your last tune, this is shocking"

[FastFwd]

Ohh wait no...the first build was fine, it was High CR low boost tho. I just pushed it to hard one day..maybe bad fuel. Plus my turbo setup wasnt that flash. It was ok but ive refinded it 100 times since then.

[Lukezen27]

Ohh wait no...the first build was fine, it was High CR low boost tho. I just pushed it to hard one day..maybe bad fuel. Plus my turbo setup wasnt that flash. It was ok but ive refinded it 100 times since then.

Yeah once you start playing round with internals then I don't know..

I'm only talking about 10psi stock motor setups

[FastFwd]

Yeah once you start playing round with internals then I don't know..

I'm only talking about 10psi stock motor setups

well to be honest its much more stable running a lower CR with higher boost setup. atm i feel like i can just Thrash the crap out of my car and not have to worry. I blew my car on 7psi when i was running stock Compression. Engine only had 30,000kms on it imported from JAP-AN. (over night parts from JAP AN)

but i like the feel of higher Compression with lower boost setup..much nicer daily driver.

[Lukezen27]

well to be honest its much more stable running a lower CR with higher boost setup. atm i feel like i can just Thrash the crap out of my car and not have to worry. I blew my car on 7psi when i was running stock Compression. Engine only had 30,000kms on it imported from JAP-AN. (over night parts from JAP AN)

but i like the feel of higher Compression with lower boost setup..much nicer daily driver.

Shit 7psi and she blow WTF?

What setup did that happen with?

Small turbo or cheap I'm gessing?

[FastFwd]

nah massive turbo...t04e.

stock b16a2 motor, with aftermarket fly, clutch, 3inch zorst turbo back. Not a massive front mount but decent enough. tial 38mm gate, screamer, power FC ECU, etc etc.

[Lukezen27]

nah massive turbo...t04e.

stock b16a2 motor, with aftermarket fly, clutch, 3inch zorst turbo back. Not a massive front mount but decent enough. tial 38mm gate, screamer, power FC ECU, etc etc.

So what went wrong?

[FastFwd]

dunno..bad fuel maybe. Tune was ok.

few others have had similar things happen. Its just what happens, im sure it would have been something but i dunno what it was in the end. Since then my whole turbo setup and engine build is completely different.

[FastFwd]

Thats why i went lower RC and higher psi. Safer to thrash, less variables to worry about.

[B16]

Wouldn't lowering the compression compromise drivability off boost, and upping the boost will only mean it will take longer to come on to boost, therefore compounding the situation?

I'm going low blow (8psi) on stock with stock internals. This will retain the B's drivability and give cracking performance anything aver 4k rpm. As far as I have found, this is what most people do, as opposed to lowering their comp.

[Lukezen27]

Thats why i went lower RC and higher psi. Safer to thrash, less variables to worry about.

Gess wi'll see as I have to high comp version B16A2 10.4 lol

[FastFwd]

Wouldn't lowering the compression compromise drivability off boost, and upping the boost will only mean it will take longer to come on to boost, therefore compounding the situation?

I'm going low blow (8psi) on stock with stock internals. This will retain the B's drivability and give cracking performance anything aver 4k rpm. As far as I have found, this is what most people do, as opposed to lowering their comp.

B16 your correcting in saying that lowering the compression will compromise drive-ability. But its not a massive ammount..well not in my case. I think stock compression is 10.4 or 10.1 mines 9.1 you can also go 8.1 in some cases that wanna run upto 30psi lol.

But when you say this:
"upping the boost will only mean it will take longer to come on to boost, therefore compounding the situation?"

I think you might be confusing yourself. Upping the boost wont slow down the spool process it will just take longer to hit maximum psi. But thats why you see alot of conversations on here about the correct turbo to buy because its hard to get the exact spool time compared to Power you desire. Also exhaust manifolds, and wastegates come into play with this also.

Personally though i do think that higher CR setups on boost feel much better to drive daily but you wont get the safety or those massive HP numbers unless you go Lower CR and higher boost setups. Not everyone goes the High CR and low boost setups on here. Alot of guys have fully build motors.

[destrukshn]

i have dropped my comp ratio to 9.0:1 approx, but only using a baby 2871r for now i guess.
making 245kw on 16psi.
and 200kw on 10psi.
yes it laggier, yes it isn't as reponsive as when it was 10:1.
but hell, i want it to last, safely, and not risk such as a bad batch of fuel and boom.

[ZeForce]

Thought this might be relative to the thread...

http://www.evans-tuning.com/dynocomp_9vs10to1.html

[FastFwd]

Destrukshn you running b16 or 18?

im running 9:1 with 2871r, similar setup. im going for around 20psi max and 10 psi daily with boost controller after i finish my rings and bearings rebuild. 245kw...nice my aim was anything above 300hp atw's.

[Limbo]

he's got a built b18

[FastFwd]

ahh k...yup so i will need to push it to like 19-20 psi to get the same amount of power..as his on 16psi roughly.

[DLO01]

It also depends on how you drop compression, by pushing the head away using a thicker head gasket or keeping the head close to the deck and using lower comp pistons.

[ZeForce]

It also depends on how you drop compression, by pushing the head away using a thicker head gasket or keeping the head close to the deck and using lower comp pistons.

This is a very good point, a lot of people are assuming 10:1 comp is the same no matter how it is a achieved.... the fact is combustion chamber shape does play a big part in burn efficiency and detonation resistance.

[Lukezen27]

So you guys think my JAP spec B16A2 10.4 Comp on 10psi will blowup :o

We'll see soon I guess :p

[ZeForce]

Should be fine....

[FastFwd]

Nahh fek a thinker head gasket. No chance i would go dropping my compression by doing it that way. I've got forged 9:1 pistons, i want reliablity and thats what ive paid for. :| hopefully.

But i guess for people trying to squeeze as much as they can out of there stock motors and dont mind if they blow it for a rebuild then i probably would chuck a thicker head gasket on it.

Mind you dropping your comp to 9:1 with a thicker head gasket will need to be fairly large and the gasket will possibly be unstable itself. Cant win :(

[Limbo]

yeah but he's not looking at making that much power.
at about 180kws should be ok still

Now it will just depend on the tune

[VTi_b0i]

id be looking at running forgies at about 10:1 if i ever rebuild... i dont wana go lower then that as youll be loosing power before u gain it...

[FastFwd]

id be looking at running forgies at about 10:1 if i ever rebuild... i dont wana go lower then that as youll be loosing power before u gain it...

I mean correct in saying that but i personally think i havent loost that much. It deffinatly is different to stock compression while driving off boost but its not a huge difference in 9:1.

[EGBOY]

stock comp + turbo:thumbsup:

no difference in performance than standard model off boost yet the addition/power of extra air when it comes on boost... great streetability!

[FastFwd]

great streetability - bad stablitliy

[EGBOY]

bad stability? in what way do you mean?

[FastFwd]

i wont get into this anymore cos i think i've already said it in this thread before...

its great to have high comp and boost aswell but something will give eventually and it did for me motor blew after 6 months of a high comp boost setup at 7psi. Had a drag with this R32 and i was making him eat my vtec but then bamm it gave way and i needed a full rebuild.

[ZeForce]

hmmm I plan to run 6-7psi with 10:1 compression on my weak sleeved B20

[Lukezen27]

i wont get into this anymore cos i think i've already said it in this thread before...

its great to have high comp and boost aswell but something will give eventually and it did for me motor blew after 6 months of a high comp boost setup at 7psi. Had a drag with this R32 and i was making him eat my vtec but then bamm it gave way and i needed a full rebuild.

Man I got'a say I disagree with this...
There’s a lot of boosted Stock B16’s getting round without problems and I hope I’m one of them..
Adrian from TODA who dose my tuning doesn’t seem to think I’ll have any problems and he also said I’d blow my boosted D16 and he was right lol

[FastFwd]

I think if you have a superb build and a smaller turbo then it could run upto a year with no probs...

I think the main factor with mine was i had a t04e which was solid boost from 4500-9000+ rpm and that night i was giving it hurt shifting around 8400 and that solid boost prolly not a great combo.....

where a gt28 etc on a high comp build will die out around 6000-7000rpm soo it will make it a little safer to push to higher rpms etc.

I think thats really the only thing that could have caused my issue.

[FastFwd]

I'm not saying its not possible...im just saying everyone knows theres greater risks in high comp turbo setups. and thats why i said "great streetability - bad stablitliy".

Since ive gone lower comp i've trashed the crap out of my car and ive never had one thing happen.

[Lukezen27]

hhmm boost fade-off is bad for motors, well that's my understanding..

My EBC holds boost to red line no matter what.

Smooth boost delivery is better, someone correct me if I'm wrong

[Limbo]

what Fastfwd is saying is true.
With a high comp motor there is less margin for error.
Low comp motors have a larger margin for error, thus greater reliability.

All comes down to how well the motor has been tuned & how well its been taken care of.

[FastFwd]

what Fastfwd is saying is true.
With a high comp motor there is less margin for error.
Low comp motors have a larger margin for error, thus greater reliability.

All comes down to how well the motor has been tuned & how well its been taken care of.


Yep most defiantly....

[Lukezen27]

what Fastfwd is saying is true.
With a high comp motor there is less margin for error.
Low comp motors have a larger margin for error, thus greater reliability.

All comes down to how well the motor has been tuned & how well its been taken care of.

That’s wasn’t really my point as we all know low comp motors are safer for boost… that’s just a fact.
My point was boosting a stock B16 shouldn’t be a problem… for longevity
I ran my stock D16 on 11psi for close to two years redlining all day every day before she blow… and D16 con rods are like little twigs.
Blowing a B16 on only 7psi sounds strange to me as most people consider 10psi on a stock B16’s as safe.

Were they stock unopened B16s that blow at 7psi FastFwd?

[FastFwd]

I ran my stock D16 on 11psi for close to two years redlining all day every day before she blow… and D16 con rods are like little twigs.

Were they stock unopened B16s that blow at 7psi FastFwd?

Yeh mine was stock...engine had low k's also.

Remember a motor doesnt have to break from the rods snapping. The usual case is the crank bearings failing causing a mess of the pistons hitting the head and the bearings shredding the crank shaft.

[Lukezen27]

Yeh mine was stock...engine had low k's also.

Remember a motor doesnt have to break from the rods snapping. The usual case is the crank bearings failing causing a mess of the pistons hitting the head and the bearings shredding the crank shaft.

bugger!

[Limbo]

depends on the turbo being used also.
a TD04e is actually very large, so 7psi is actually more than 10PSI on a T28.

since most people use a T28, they naturally say 10PSI is fine......
abit of oversimplification


That’s wasn’t really my point as we all know low comp motors are safer for boost… that’s just a fact.
My point was boosting a stock B16 shouldn’t be a problem… for longevity
I ran my stock D16 on 11psi for close to two years redlining all day every day before she blow… and D16 con rods are like little twigs.
Blowing a B16 on only 7psi sounds strange to me as most people consider 10psi on a stock B16’s as safe.

Were they stock unopened B16s that blow at 7psi FastFwd?

[FastFwd]

depends on the turbo being used also.
a TD04e is actually very large, so 7psi is actually more than 10PSI on a T28.

since most people use a T28, they naturally say 10PSI is fine......
abit of oversimplification


Yeah i've been trying to find a reason why my motor blew that night and so far thats what ive come to also. My t04e is a massive turbo, very laggy but when boost came on it was solid. So solid in fact that it might have bee just to much to handle...where others have run gt28 setups all day long and have not had a problem.

I overcompensated :( ahh oh well it was a long time ago and ive learnt from it. :) just cant wait till im hitting 20psi in a couple weeks. I've never heard a honda spool over 10psi.

[Lukezen27]

Yeah i've been trying to find a reason why my motor blew that night and so far thats what ive come to also. My t04e is a massive turbo, very laggy but when boost came on it was solid. So solid in fact that it might have bee just to much to handle...where others have run gt28 setups all day long and have not had a problem.

I overcompensated :( ahh oh well it was a long time ago and ive learnt from it. :) just cant wait till im hitting 20psi in a couple weeks. I've never heard a honda spool over 10psi.

Yeah 20psi going to be fully sick :thumbsup:

[destrukshn]

Yeah 20psi going to be fully sick :thumbsup:
wheel spin galore my friend.
lol
i can break traction in 4th on cold days/nights, on 16psi.
on toyo t1s tyres.
that's a b18 though. still.
quite useless.
hahaha.

[FastFwd]

im running stretched 235's on the front. I can put 265 semi slicks if needed but i wont be running 20psi daily drive no chance...will be around 10

[votek]

i ran 20+ psi on my setup :P

[Sexc86]

Fstfwd.

It sounds like your motor failed from either 2 situations either..

A - bad tuning.. premature ignition

B - your tuning was fine but simply the internals could not handel the power you were producing (due to running a large turbo even at low boost)

7psi of boost is 7psi of boost.. but weather you are makeing 150whp or 300whp.. thats what can break your motor.


Just off topic.. i know D16s standard rods are only good for 200whp. Eg car a could run a T25 on 7psi and make 150whp tuned mildly... and another identical car could run a
Gt35R on 7psi and make 250whp tuned mildly.. and Boom! throw a rod out the block (similar to lukezen)

[Sexc86]

Anyway way! back on topic.

I vote

Lower CR = more boost & more timing = and thats the shit that makes real power

Either Thicker head gasket or low compression pistions (dished)

[Limbo]

again its a choice of what you want.

But more power generally lower compression


Anyway way! back on topic.

I vote

Lower CR = more boost & more timing = and thats the shit that makes real power

Either Thicker head gasket or low compression pistions (dished)

[FastFwd]

Fstfwd.

It sounds like your motor failed from either 2 situations either..

A - bad tuning.. premature ignition

B - your tuning was fine but simply the internals could not handel the power you were producing (due to running a large turbo even at low boost)

7psi of boost is 7psi of boost.. but weather you are makeing 150whp or 300whp.. thats what can break your motor.


Just off topic.. i know D16s standard rods are only good for 200whp. Eg car a could run a T25 on 7psi and make 150whp tuned mildly... and another identical car could run a
Gt35R on 7psi and make 250whp tuned mildly.. and Boom! throw a rod out the block (similar to lukezen)

Yeah the tune was fine and the engine only had like 40-50 thou on it...twas fairly virgin. Could be a range of things that could of caused the issue. I just think it was a combination of a t04e with solid boost and high rpm and possibly slight premature ignition and thats all it needs really and things can all go south very fast.

But i dont regret doing 9:1 compression now at all. Once i have it fully boosted to 20psi and i hear it wind up im seriously going to jizz in my pants "like at the end of sixth sence was bruice willis was dead, i Jizzed in my pants"

[hotdc2]

dude howcome earlier in the thread you said the engine had 30k on it then here you said 40k-50k and in another thread its 60k?

not stirring or anything just thouhgt it was a bit odd.

[IEVAQ8]

i see fastfwd point and understand from his experience where he is coming from..........

but like i have said before.................there is nothing better than driving ur stock internal high comp honda all day every day.....and once u open the throttle and reach 4000-4500rpm............ur on boost and the gate is screaming away...........

my setup has been going strong for almost a year now, and it gets driven daily............

no compromise on drivability for daily duties with high comp off boost, and the thrill, exciting pull when on boost (7.5psi) and the stock high comp b18cr.......

like many people have said, an engine can fail at any given time for a number of reasons.............it could be tune, it could be oil pressure, it could be 'its time is up'

in ur case fastfwd, i think it was badluck, as if it was tune, im pretty sure it would have shit itself a lot earlier than 6 months down the track...............

[Limbo]

could even be a bad batch of fuel......

[FastFwd]

Yeah tru tru but we all learn from our experiences and im just sharing/venting mine. Just chatting with this guy on another thread and he was running 16psi on stock internals/compression and i couldnt believe him and still dont really but he seams to have this other guy backing him.

http://www.ozhonda.com/forum/showthread.php?t=111075&page=8

IEVAQ8 you just commented on it also, i wasnt saying its not possible to make that power on a stock motor i was saying that its not possible to be pushing 16psi on a stock motor with stock compression.

fairly insain if its tru.

[Lukezen27]

Yeah tru tru but we all learn from our experiences and im just sharing/venting mine. Just chatting with this guy on another thread and he was running 16psi on stock internals/compression and i couldnt believe him and still dont really but he seams to have this other guy backing him.

http://www.ozhonda.com/forum/showthread.php?t=111075&page=8

IEVAQ8 you just commented on it also, i wasnt saying its not possible to make that power on a stock motor i was saying that its not possible to be pushing 16psi on a stock motor with stock compression.

fairly insain if its tru.

I too have heard of people running 15psi on stock internals hence why I think 10psi would be completely safe

[FastFwd]

Thats crazy hey...awesome!

[DLO01]

IEVAQ8 you just commented on it also, i wasnt saying its not possible to make that power on a stock motor i was saying that its not possible to be pushing 16psi on a stock motor with stock compression.

fairly insain if its tru.

Of course it is true. You can run 20psi and more on a stock motor if you want. You'll have awsome power for a whole 5 seconds flat out. Or you can run 15 psi for 20 seconds flat out. Or 8 psi flat our for a minute. (made up figures)

Its not the Psi that kills a motor its 'how you drive it' and how its tuned. If your running high boost on the street, giving it a spurt here and there so often, you'll never have any problems. If your going to be flat out on the track its gonna blow eventually. That goes for any motor, if your thermal management is not up to scratch it will eventually blow. As always its a lot of things to consider, not Psi.

[FastFwd]

Of course it is true. You can run 20psi and more on a stock motor if you want. You'll have awsome power for a whole 5 seconds flat out. Or you can run 15 psi for 20 seconds flat out. Or 8 psi flat our for a minute. (made up figures)

Its not the Psi that kills a motor its 'how you drive it' and how its tuned. If your running high boost on the street, giving it a spurt here and there so often, you'll never have any problems. If your going to be flat out on the track its gonna blow eventually. That goes for any motor, if your thermal management is not up to scratch it will eventually blow. As always its a lot of things to consider, not Psi.

Yeh in the thread i said this "anyone can get a stock b series with stock compression and boost it upto 16psi for 2 minutes on one dyno run and cross your fingers that nothing gives way just so you can get a dyno sheet that has 268kw"

it just seams like there dyno junkies.

[Blue]

geez, same thing said a million diff ways, 8 pages later...

Anyway, one thing that was touched on was the EBC, size of the turbo, those IMO are things to look at, and to those running past 14PSI - Did yall use aftermarket ECU's?

[Lukezen27]

geez, same thing said a million diff ways, 8 pages later...

Anyway, one thing that was touched on was the EBC, size of the turbo, those IMO are things to look at, and to those running past 14PSI - Did yall use aftermarket ECU's?

Dude we are all using aftermarket ECU's its the going way!

[Blue]

Nah man, u might find people using stock ECU and chip to comepnsate or maybe a piggy back - most dont have the dosh for full ECU i.e. Motec Haltech Autronic

[FastFwd]

Nah man, u might find people using stock ECU and chip to comepnsate or maybe a piggy back - most dont have the dosh for full ECU i.e. Motec Haltech Autronic

Ok first of all thats usually the case in the US. Alot of people use Apexi Vafc Piggy back ECU's and run there cars upto 7psi or so. But here in the Aus this is not how its generally done. Motec/heltech/autronic's are something that is rarely seen here also. Maybe haltech but alot of guys here run Hondata or other Ecu's like Apexi power FC, thats what im running.

[Limbo]

yeah its called the 'hack', not really recommended if your running decent power. That's the cheap & nasty way. If your thinking that, don't even bother, its going to be a headache in the long run


Nah man, u might find people using stock ECU and chip to comepnsate or maybe a piggy back - most dont have the dosh for full ECU i.e. Motec Haltech Autronic

[Lukezen27]

Yeah I'm running Hondata

[Blue]

Well this Hack is doing well in my car and many others like it - Apexi isnt a full ECU - thats jus a piggy back - i odntknow about a Hondata though - anyone care to explain if its a full ECU or just a piggyback

[Lukezen27]

Well this Hack is doing well in my car and many others like it - Apexi isnt a full ECU - thats jus a piggy back - i odntknow about a Hondata though - anyone care to explain if its a full ECU or just a piggyback

Hondate is a full ECU and it allows complete access to Honda’s real maps and so on… close to the best you can get

Coze its the standard ECU moded

[Limbo]

Apexi PFC is a full ECU.

Difference is a piggyback only intercepts signals & gives different readings. Usually has limited points. When it gets to big setups & features the piggyback is crap

A full ECU is able to be fully programable with all fuel, igntition, timing etc....

[lookingforboost]

the SAFC etc you are talking about only give small tuning parameters.... i belive its every 500rpm or so, and they only allow tuning off the a/f ratio buy hacking in and tricking the factory computer.

a full ecu like above mentioned have tuning parameters down to every (subjective between different ecu's) 50rpm point or even less and allow full ajustment of a/f ratios and ignition timing at every point across the rpm range these are whats called stand alone although these can be run in a piggy back style arrangement where they factory ecu controlls creture comfort accessorys and ide cold start etc but the other ecu controlls all the engine functions and sensors.

as for motor blowing if you reach the breaking point of an engine component then dosent matter how good the tune is then it will fail eventually for example a D series head bottom end will take large amounts of boost but the connecting rods only withstand about 200-220 hp and they will fail at this point ..... hey luke :P

[delsol9000rpms]

FastFwd that 268kw on 16psi was did on race fuel.

Definately believable.

Check the first post on this page.

http://www.ozhonda.com/forum/showthread.php?t=111075&page=8

[FastFwd]

FastFwd that 268kw on 16psi was did on race fuel.

Definately believable.

Check the first post on this page.

http://www.ozhonda.com/forum/showthread.php?t=111075&page=8

As ive said before i believe that someone can make 268kw on a stock block but running 16psi for anything but a "2 minute cross your fingures hope nothing die's Dyno run" is unbelievable. it would last less than 5 mins on a track.

[Sexc86]

as for motor blowing if you reach the breaking point of an engine component then dosent matter how good the tune is then it will fail eventually for example a D series head bottom end will take large amounts of boost but the connecting rods only withstand about 200-220 hp and they will fail at this point ..... hey luke :P



lol cmon mate i made thate point 2 pages back :P

[lookingforboost]

lol cmon mate i made thate point 2 pages back :P

to lazy to read that far back :p

[Blue]

story of this thread...

[myztery]

story of this thread...

if its better for a high comp/low boost or low comp/high boost
it was an application towards my motor, to make the most of my motor, or any motor in that app....

so the thread was bought out there...into what degree is high comp???

[Blue]

my comment more so was that ppl just repeat - cus theyre too lazy to read "that far back"

[woznaldo]

It's probably worth mentioning what CR OEM turbo cars run for reference. I know that VAG 1.8T 20v engines ran 9:1 or 9.5:1 from the factory depending on what car it was going in but, that would obviously be the OEM compromise on a mass produced turbo engine between reliability and drivability.

These engines a capable of reasonable power on std internals 400bhp+

I've got 1988 Renault 5 GT Turbo running a std carb blow through set up. The engine design is getting on for 50 yrs old now and that runs a std CR of 7.9:1 on it's 8v OHV non crossflow head.

The difference between the VAG engine and my old skool Renault lump is the advances in EFI technology and it's control, predominantly, ignition timing. The obvious other differences in head design have little to with a reliable CR.

Food for thought;)

[EK4R]

bringing old thread back

what fuel you guys running???

also is greddy ultimate e-mannager considered a piggy?

[Lukezen27]

bringing old thread back

what fuel you guys running???

also is greddy ultimate e-mannager considered a piggy?

BP 98 here

Yes ultimate e-mannager is a piggy back 100%

[IEVAQ8]

bp ultimate ftw.

and s300 all the way

[WATAJK]

bp ultimate ftw.

and s300 all the way

Mobil 8000
or no good?

[ZeForce]

Mobil 8000
or no good?

BP ultimate and synergy 8000 both good fuels

[EK4R]

was using shell before in the dc5 which wasn't turbo'ed

seemed ok. but dont want to run a batch of bad oil. think il stick to BP like before.

[crx_boy7]

more comp less boost = not much power potential
less comp more boost = good power
very low comp, extreme boost = will give insane power

the amount of power your engine makes is limited to its flow characteristics and how much it can take before pinging,

higher compression will result in a more responsive and fuel efficient engine

but boost is also limited to how much fuel you dump into the engine

1 of hondas F1 engines has 6:1 compression with something like 60psi to make over 700hp from a 1.5L

[IEVAQ8]

more comp less boost = not much power potential
less comp more boost = good power
very low comp, extreme boost = will give insane power


not sure where ur theory comes from, czn u back it up???............excluding the F1 stuff that has millions of dollars spent on research and developement???

[WATAJK]

BP ultimate and synergy 8000 both good fuels

thank god, there the only 2 ill use :)

[crx_boy7]

not sure where ur theory comes from, czn u back it up???............excluding the F1 stuff that has millions of dollars spent on research and developement???

im not sure either, do some research and if you can proove it wrong pls post :):honda:

to get past this problem there is a way to cheat out compression, volvo and a few other manufacturers are duing this, volvos system incorporates a variable height deck, than can lift the head along with the sleeves to increase/decrease compression

[DLO01]

1 of hondas F1 engines has 6:1 compression with something like 60psi to make over 700hp from a 1.5L

That was with old 80's technology.......

Now, higher compression, more responsiveness, better reliabilty you'll acheive the same figure. So therefore, more compression the less boost you need to run to acheive the same figure.

[ZeForce]

Also, an engine like that designed purely for racing application would be useless on the street

[VTi_b0i]

That was with old 80's technology.......

Now, higher compression, more responsiveness, better reliabilty you'll acheive the same figure. So therefore, more compression the less boost you need to run to acheive the same figure.

exactly! i dont know about anyone else but id much rather make for instance 200kw atw on say 7psi then the same figure on like 15psi? its a no brainer... my compression is at 11.4-1 only running 7.5psi daily and occasionally 9psi and its great.

[IEVAQ8]

im not sure either, do some research and if you can proove it wrong pls post :):honda:


the best proof i can give u is in my own ITR.............

stock b18c7 with a gt30, full race mani, 7.5psi making a healthy and very respectful 239.8kw daily driven, and after a whole year of daily driving, 3or 4 1/4mile drag nights/days and plenty of street thrashing/racing, it still made a healthy 240.5kw on the same dyno as it was tuned.........

it made it a very responsive and very fun to drive, and due to the high stock compression, it could be driven as if it was na under 4500rpm on light throttle and no one would know the difference.........

[Lukezen27]

the best proof i can give u is in my own ITR.............

stock b18c7 with a gt30, full race mani, 7.5psi making a healthy and very respectful 239.8kw daily driven, and after a whole year of daily driving, 3or 4 1/4mile drag nights/days and plenty of street thrashing/racing, it still made a healthy 240.5kw on the same dyno as it was tuned.........

it made it a very responsive and very fun to drive, and due to the high stock compression, it could be driven as if it was na under 4500rpm on light throttle and no one would know the difference.........

I think that's also a very good example of just how difference buying quality parts and planning your intended power out-put can be.

Man I can't believe some A-hole sole your car!

[Limbo]

high comp is good, but the reason why people go lower comp is so they can run more boost and make more power reliabily without race fuel.
Reason is our fuel is not up to scratch. If you could get consistent race fuel all the time, a high comp motor with high boost is fine. The low comp motors compensate for the occasional crap fuel without killing the motor completely.

[IEVAQ8]

I think that's also a very good example of just how difference buying quality parts and planning your intended power out-put can be.

Man I can't believe some A-hole sole your car!

thanks luke........

and i still sook about it not being here in my posetion in my garage to be taken for a drive when ever i want.............. it sucks hard............

[Sexc86]

This is a little Off topic. But seriously i cant believe i havnt seen anyone on here run one.

Water / Meth injection kit. I believe increases the fuels octane by up to 10 points. So combine water meth injection with 98 octane is like running on race fuel .. Also drastically cools intake temperatures. Only down side is its something you have to refill.

Good to setup with your boost controller if you want to go to 30psi though !

[Chr1s]

I've seen people say bye bye to their intercooler setup with h20/meth injection.

[Sexc86]

how so?

[crx_boy7]

ok so no one has proven me wrong, i had a friend back mabe 10 years with a b18, typrR head rand 350kw on 9:1 cr,, think it was a gt35 also theres another angle to it, you can run more boost on exactly the same engine by adding extra fuel and retarding the timing, obviously,
anyway, idk why you are quoting me if yur not saying im wrong, you can quote yur dyno figures without posting my name at the top yu know, and yes that engine is old ect, not sure why that was mentioned either

water injection works great , the downside is , the engine becomes a grenade if yur water runs dry or the thing malfunctions
the best way to take advantage of this system is directly inject it into the engine, next to injectors, this method cools the pistons directly, (as they are the hottest part of the intake run, it will take away the most temperature here), as well as allowing you to run alot leaner, and saving you fuel while at the same time adding power, and yess somehow it can damage intercoolers, as well as build up water at the base of them, so while it seems like a great place to place it, its not, after the intercooler is the optimal place for a single nozzle
and i realise someone will say yur valves rust ect, while this isnt a major problem with turbo ect, as the intake is full of oil half the time, there called stailes steel valves..

[Limbo]

been thinking about getting the meth/water system. But dunno, not enough people here have it at the moment.

[crx_boy7]

been thinking about getting the meth/water system. But dunno, not enough people here have it at the moment.

man this system has been around since the hotrod guys, theres tons of guys using this in hondas,mitsubushis, v8s ect, its more popular in the us,

the main reason its not so popular here is
a) the people using it wanto keep there secret to themselvs, or dont think mentioning it is relevant, and
B) the car guys on this forum dont have it for 2 reasons.. 1 there cars are built by shops who dont put it in as it will cause problems wen the inexperienced ouner forgets to add water, or mixes water meth wrongly
or they see it as an anoying extra to fill the canister, or think its voodoo much like the misunderstood N20 cars

[Sexc86]

Quoted from the web page

BOOST SAFE!

All AEM Water/Methanol controllers include a Boost Safe feature. This feature allows users to retard timing or reduce boost via a ground output if the system runs out of fluid or detects a controller error, ensuring fail-safe operation of the engine whether the system is engaged or not. Critical safety features are integrated into the system to virtually eliminate any chance of failure, including an integral fluid level sensor in the reservoir, internal controller diagnostics and an LED dash light to warn of low fluid level or error codes (including short circuits.


Anyway im getting a little off topic.

[97EK1]

i may not be 100% correct but this is what i have found whilst doing hours of reading and research and this is just the jyst i have come up with.
There is nothing wrong with boosting a High Compression motor and running low boost IF you have a good tuner. (i think ievaq8 and DL01 can attest?)
Lowering the Compression and upping the pressure instead does make power too, yes! (and lag) and now the car wont detonate as soon and the tuner will have more margin for error, hence less blow-up-ability.

[spardikis]

i may not be 100% correct but this is what i have found whilst doing hours of reading and research and this is just the jyst i have come up with.
There is nothing wrong with boosting a High Compression motor and running low boost IF you have a good tuner. (i think ievaq8 and DL01 can attest?)
Lowering the Compression and upping the pressure instead does make power too, yes! (and lag) and now the car wont detonate as soon and the tuner will have more margin for error, hence less blow-up-ability.



couldnt agree more!!!!
I had a really "old school mechanic" machine a head and linish a crank for me once, he asked what compression i was going to run my b18c at and freaked out when i told him it was for high boost and high compression...

he sugested i dont run over 8.2:1 or something with a turbo and lots of boost....

I laughed. then laughed some more ;)

[lookingforboost]

speaking of comp ratios whats a stock integra VTiR comp ratio?

[ZeForce]

speaking of comp ratios whats a stock integra vtir comp ratio?

10.0:1

[Sexc86]

Im pretty sure thought. All factors equal.

Both High comp and low comp tuned to the same point before premature detonation. High comp will never have as much timing... & Timing makes the powa!

[ZeForce]

Im pretty sure thought. All factors equal.

Both High comp and low comp tuned to the same point before premature detonation. High comp will never have as much timing... & Timing makes the powa!

I disagree with that, the more you advance the timing the more the engine is working against itself

[Sexc86]

only after a certain point will you increase timing so far that you wont net any futher power... you will only increase combustion pressure. So Yes and No to your opinion. Everything has to be treated on a case by case basis imo

[Punisha00]

I dont think this will ever be agreed on, as i just read all 15 pages and for the whole lot all the ppl with high comp engines say its the best idea because you dont get as much lag but all the low comp say yes bit more lag but safe.

I think its always goin to come down to what you want from your car,(my thoughts) if you want more of a N/A car with boost and dont care abt big numbers then high comp.
but if u like to boast abt ur car how it runs 1,000,000 psi and u have a turbo that resembles a black hole on your car and want massive numbers and dont care abt lag then low comp.

I personally am goin low comp as I have ERL building me a b16 race short block that is rated to 800hp and 40psi with 9:1comp and my logic is if you want response stay with N/A and that a honda engine has a massive rev range so unless your dragging off the lights or at the strip, just down shift.

[DLO01]

I wouldn't class 9.1 as 'low compression'.

[Limbo]

i have high comp and i still have lag.
Its just depends on how much of it you have

[markoJEK1]

Of coarse youre going to have lag, its turbo'd and lag varies on its size and the engine capacity, what people are saying is that NA Honda motors and their high comp, dont have that piggish feeling down low like motors which are built for high psi and are low comp, causing them to be nearly useless off boost / down low.

High comp = more driveable / repsonive off boost

So for a daily / fun car, high comp low boost, you get best of both worlds, (ie: VW making their TSI (turbo superchatged injection) Polo, got the benefit of supercharger down low and turbo up high, to eliminate any 'flat' spots in its driveability.

Low comp = sluggish / boring imo off boost
Not as ideal for daily / will make big numbers

Thats the main thing you need to convey from all of this imo , alot of factors playing a role of how a car will be if turboed.

[lookingforboost]

but which one off the two produce the most torque in specific to hondas?

[Sexc86]

Boost produces torque.

Low comp, More timing, more torque, more hp, more lag

[lookingforboost]

hmmm its a real trade off really....