Just wondering how those with a compression ratio around 12.0:1 to 12.5:1 go with daily driving and more so,how you deal with our pump fuel ?
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Just wondering how those with a compression ratio around 12.0:1 to 12.5:1 go with daily driving and more so,how you deal with our pump fuel ?
just to be somewhat helpful... anything above 12:1 needs a decent tune... and many here have proven that Honda's are tune dependent.
On another note, I know of SR20s that run between 12:1-12.5:1 untuned on 98ron sweet BUT with big cams in the vicinity of 275-290* duration.... just remember that dynamic compression ratio changes with longer duration camshafts and overlap. you will also want to run a tad richer as a safety margin... but again from a few things i've read from the internet (yes intarweb is full of varying info so beware) in regards to the s2k motor, it's fairly detonation resistant due to head design so again thats something to consider.
How do you plan on achieving this compression raise? but no matter what get it tuned and you'll be fine and reap the benefits of additional torque
I agree though that this thread should either be in the All motor or S2k forum as i'm pretty sure flow dynamics of the F series is vastly different from the more common K/B/D series motors that people work here.
Quote:
Originally Posted by aaronng
WTF does that even mean?? English isnt ure first langauge is it?
I wanted to hear from ppl who have built engines with high compression. Usually turbo set ups run low comp. so i figured all motor was a given,but hey this is Ozhonda. :(
Thanks for the input dsp26. I'll be running about 12.4:1 with oversized TODA pistons and a different head gasket. Obviously a tune is in order. Just wanted hear from some of the engine builders that post in all motor.
also ok-ish but you should not depend on the knock sensor as it is an electrical device that retards WHEN it detects ping... what a tuner/builder should achieve is the prevention.Quote:
Originally Posted by EG5[KRT]
same as a rev limiter... it is electrical based when you reach a certain rev... but what happens if you redlined 5th and shift to 1st/2nd... revs will exceed beyond the electrical disabler being the rev limiter and blow your engine anyway as the revs had no way to climb to that threshhold, but rather start somewhere where it already exceeded the point of the limiter
Piston design is crucial since the piston forms the bottom of the combustion chamber, I have heard of B series engines in the states running 13.5+ static compression with well designed pistons on pump fuel.
dsp26 is correct, cam size also plays a big part, at the end of the day it's the dynamic compression which actually matters. It is possible for an engine with 13:1 static compression and an overly large cam to have the same dynamic compression as an engine with static compression of 10:1
Just wondering how those with a compression ratio around 12.0:1 to 12.5:1 go with daily driving and more so,how you deal with our pump fuel ?
Lets read that again shall we.......
Im asking about comp. ratio in the low 12's in an ALL MOTOR section on a honda fourm. To my knowledge no hondas run that stock. I have a car that comes stock at 11.4:1. I was aiming the question at ppl who would already have prior knowldege of this,(hoping to get a helpful response)Hence i originally posted in all motor. For those who know that the s2000 comes out of the box at 11.4,im obviously enquiring about RAISED compression, and that i would have no avid interest in how a standard car with a similar compression ratio, deals with pump fuel. Obviously there would be no issue as it would severely cripple the car manufacture's sales, if a standard car had knocking and detonation problems. We could then go into themes including loss of revenue, GDP and econimical issues, jobless factory workers and so forth ....
Many All motor b18's and k20's etc.. run high compression so..... I posted this question in All Motor, where we see alot of engines running ratios like this. I intentionally did not specify engine model, and posted in all motor,as i wanted numerous answers. I also did not specify engine model or post in the s2000 section,as no one here with an s2000 is running a ratio that high. All Motor is also known to have engine builders themselves post there, their input would have been valued.
My intention was to enquire how members find it,to frequently run modified engines with high compression ratios that are subsequently, higher than standard. This is realised by other ppl who have posted in this thread, whether it be words to the effect of "good luck getting an answer amongst a bunch of dumb shits" or actually contributing with an answer. It seems the only ppl having trouble understanding my question are u and ure buddy. But hey.....this is ozhonda. I posted the same question on s2ki and guess what?? No trouble getting an answer there,but all the memebers there have opposable thumbs,might be a contributing factor?.
I wanted input from actual ppl who have RAISED compression to this level. I didnt want a slinging match with linguistically challenged moderators.
So for the record,to be clear and concise, anybody that has RAISED the compression ratio of their engine to around 12.0:1-12.5:1, your contribution would be appreciated in leaving comments regarding the grade of fuel available at the pump,or any other issues realsied, regarding detonation or knocking. :)
Ahh, much better. :thumbsup:Quote:
Originally Posted by WhiteAP1
Moving to All Motor. :)
You should be fine running that comp on 98 provided the tune is good. I used to run a Pug 205GTi on 98 which had 12:1 comp and it was an old 8v SOHC engine with a poor chamber design. Admittedly I had a big cam (296deg duration) and quad throttles.
On a far superior engine running the same comp or more shouldn't be a worry if the tune is right. Not so sure about doing it with standards cams though. That may push the boundaries a little. You may need some cam to reduce the dynamic compression as was mentioned in a previous post.
its not the COMPRESSION ratio that changes a cars drive ability - its the parts that are needed for higher compression that change it.
IE bigger cams etc.
i think u will be fine just make sure u have a great tune and quality gear to support it, i'm looking at running a k20 frank 12.5 maybe 13 on pump gas for a future project, one of my worries is the fuel being consistent and actually 98. Check out some us forums heaps of info there, quite a few run this comp on street engines and pump gas. Prolly also good to talk to dyno dave and yonas will have an idea from his experience too.
Its not the parts im worried about, the engines built for 12.4,both head and block have been upgraded accordingly. The quality of fuel, or lack there of, was my concern.
I just wanted to hear from others, to pretty much confirm what i thought already. Spent plenty of time on the US forums, and yeah they run higher ratios on pump fuel also,even with their quality of fuel. Its the AU grade of fuel i was curious about.
Rating-wise, our 98 is the same as their 93. A large proportion of their pump fuel has at least 10% of ethanol in it. So in that respect, our 98 octane is better than theirs. Sulfur-wise, they get their fuel from the same souce as we do.
Hey John,
My car had around 12ish CR runs fine. Just get a good tuner (Y)
Yeah ive actually read that somewhere.Quote:
Originally Posted by aaronng
Man i loved that car. Had so much fun comming down black spur with ya that day. Yeah definitely gonna get it tuned.Quote:
Originally Posted by weezer
if it helps you we have run 13.1 on optimax, but u need a fair bit of work done to the support systems and a full system like autronic, motec and EFitechnologies to make it happen.
My car running in the "high 12" to 1 compression. It run fine dude :). U just need a good tune :).
I recommend dynodave if u can get him to tune it. Though his a busy man these days.
Regards,
David
What exactly been done to run 13:1?Quote:
Originally Posted by pornstar
Bigger injectors? Fuel pump? Standalone ecu?
Great thread but I want to read more from the internet tuners before I comment on this subject and I really would like EFiOZ to join in as his knowledge is worth listening to on this subject.Quote:
Originally Posted by WhiteAP1
Regards Dyno Dave
I think my CR would be around 12:1 wouldn't it Dave?
So it seems the fuel quality itself is fine, the key elements are really engine set up and tune.
Too easy
Ok here's my turn to get flamed. (i was bored at work)
From my memory of combustion, the reason for higher octane fuel is to stop pre detonation of fuel on higher compression engines.
Thus a good tuner should be able to tune it to ensure that your timing is adjusted enough to prevent predetonation.
I know on my 20v with the head shaved it increased the compression, but i dunno how much. It was then tuned and it was fine running 98 ron. Just make sure you get the fuel from a reputable place to ensure consistent fuel. I was told that most engines are built with a tolerance and a few mm and upping the compression slightly with a good tune was fine. The engine lasted ABIT, but i wore my piston rings pretty quick, but then i was revving to 9krpm alot without upgraded internals.
Comon Dyno Dave give us the answer now.
Its not just timing that ur worried about limbo, in effect ur limited as u have mentioned by the fuel your using and the system around it in controlling predetonation. Timing is only one element u need to keep in check, predetonation isnt caused solely by timing.
For example, Pat (efiOZ)and myself have used in excess of 16:1 CRs on racing fuels, but the racing fuel alone isnt the sole reason that we can run 16:1, its the combination of the parts that we use that allow us to use 16:1. If we were to put normal street fuel into that thing, it would literally blow the thing up. If we changed another factor for example the restrictor size, but kept the 16:1 Cr and race fuel, the engine would still grenade itself.
to run a high compression what are you planning on running as in what supporting mods are you planning on doing like sleeved block, ur bore size, rod lengths, head work etc....
The blocks been sleeved with Darton sleeves, Oversized TODA pistons (which is mostly responsible for the CR rise),and the bore is around the 88mm mark. A thinner head gasket from Cometic, a set of F22C valve retainers from the US that are heavier and stronger and a set of TODA valve springs with a slightly shorter coil. OEM rods are forged and pretty decent no real need to change them unless i was going to stroke it, and theres not much advantage to gain with aftermarket cams compared to stock (For my current setup anyway)
subscribed
Ok, time for my 5c worth on that,Quote:
Originally Posted by WhiteAP1
The largest F20C piston comercially available through TODA is 87.50mm.
Darton sleeves are not required unless the bores are beyond reconditioning limit.
Further, the factory gasket is very vary good. 0.6mm (0.0236) & should be use together with TODA pistons in the F20C engine.
The cometic gasket is actually thicker at 0.76mm (0.030")
Further the bore of the Cometic gasket is 89mm.
This difference in gasket to bore can cause problems in high compression engine combinations, the larger the difference, the greater the liklihood that you've get either detonation or areas of unburnt fuel.
Regarding F22C valve spring retainers, if these are actually heavier then this is the wrong way to go, regardless of perceved increase in strength.
Use the original retainers with TODA valve springs (Or a quality ti ret)
Regarding Darton sleeves & the F20C
The F20C piston protrudes from the block already, add any machining to the cylinder block surface which is almost guaranteed using the sleeves, if it's just a very light skim, it's all good. If a significant amount of material needs to be removed, unfortunatly you've now started to created a problem that can't be solved without resorting to custom pistons with an alternative installed height.
Regarding OEM rod,
You'll need to change the small end bush to use a forged piston on these.
Press fitting a floating pin will eventually result in engine failure.
Regarding changing cams...
Drop in a set of Spec A2's & you see an extra 10kw at the wheels...
For an F20C, that's an exellent gain.
(std bottom end & std ECU - more with VAFC II)
With higher compression you'll get more with larger cams.
(& an ECU + tuning)
Cheers
Adrian
this is my only input:
http://www.ngk-sparkplugs.jp/english.../iriseries.gif
hope it helps :)
The largest F20C piston comercially available through TODA is 87.50mm.
Darton sleeves are not required unless the bores are beyond reconditioning limit.
Hey Adrian, U propbably dont remember, but i spoke to you a few weeks ago, I was having trouble getting the compression ratio down to a reasonable rate. Thats been fixed now, thanks again for ure advice. Yeah the sleeves are only in because there was some serious cylinder scoring too deep to be honned. The pistons are 87.5mm spec,sorry if i threw anyone.
Further, the factory gasket is very vary good. 0.6mm (0.0236) & should be use together with TODA pistons in the F20C engine.
The cometic gasket is actually thicker at 0.76mm (0.030")
Further the bore of the Cometic gasket is 89mm.
Ive got nothing against the OEM gasket, the Cometic gasket comes with the sleeve kit and is recommended for use. Searching on the net,i also was under the impression cometic gasket came 89mm. I brought this up with my builder and he assured me there were a few specs and only an appropriate size will be used.
Regarding F22C valve spring retainers, if these are actually heavier then this is the wrong way to go, regardless of perceved increase in strength.
Use the original retainers with TODA valve springs (Or a quality ti ret)
Too many cases of AP1 retainers cracking (due to bad driving or poor adjustment or whatever) The F22 retainers fit perfectly, and i came across many well documented builds form credible sources, with improvment and longevity with F22 retainers in F20s. So far no one with the F22 retainers has seen them crack in an F20.
Regarding Darton sleeves & the F20C
The F20C piston protrudes from the block already, add any machining to the cylinder block surface which is almost guaranteed using the sleeves, if it's just a very light skim, it's all good. If a significant amount of material needs to be removed, unfortunatly you've now started to created a problem that can't be solved without resorting to custom pistons with an alternative installed height.
Heights fine, all tests have come back good, there was no excessive surface machining.
Regarding OEM rod,
You'll need to change the small end bush to use a forged piston on these.
Press fitting a floating pin will eventually result in engine failure.
I'll look into that, but arent the OEM pistons forged???
Regarding changing cams...
Drop in a set of Spec A2's & you see an extra 10kw at the wheels...
For an F20C, that's an exellent gain.
(std bottom end & std ECU - more with VAFC II)
With higher compression you'll get more with larger cams.
(& an ECU + tuning)
Ive heard too many mixed reports. Most Ppl with the product state is a waste of money, and those selling it say its an excellent mod. I guess i cant believe everything i read. Im sure poor instillation of the product could be a factor, or a bad tune, but ultimatley i'll have to see for myself.
True, true...Quote:
Originally Posted by WhiteAP1
erl superdeck block and endyn head FTW... very interesting thread...
It's likley the cracking retainer is more to do with assembly error or setting than the product itself.
More so,most failures occur due to over reving and the like. Even though they've cracked(mainly hairline cracks), most still drive without realising. With some u cant even tell untill the valve cover is off and they're closley inspected.
The OEM piston is forged, however it uses a press pin. (Std with most Honda OEM pistons)The TODA pin is a floating pin, hense the need to bush the small end of the rod.
And of course this bush doesnt come in the TODA piston kit does it...lol If u could point me in the right direction to grab hold of a set, that would be great.
Or DART tall deck B20 - we just recived ours for an engine in the pipeline.Quote:
Originally Posted by EGB18CT
It's just sexual chocolate ha ha... :p
Ok, fair enough. The cracking in this case would be caused by the exhaust valves touching the pistons whenthe engine is over reved on a down shift & the valves float.Quote:
Originally Posted by WhiteAP1
Find out if the cracking only occurs on the exhaust side, this would confirm this thought.
(It's hard to imagine any other way to cause such a failure)
LOL, no it's not included...Quote:
Originally Posted by WhiteAP1
Your machinist should have no problem sorting this out for you, the going rate is around $250 for a set of 4 rods. If you get stuck, we can get this sorted out for you.
Im a little confused. $250 for a set of rods or a set of bushes to attatch to the rods?
LOL, sorry no, my bad, that's done, ready to use.Quote:
Originally Posted by WhiteAP1
(Rod small ends bored out, bushes fitted & honed to size.)
Oh i see. lol
On the retainers,from what i read it seems the intake side are the problem. The exhaust retainers don't crack, because the valves would hit the piston first. Also, the exhaust valves don't float at the same RPM as the intake because of their weight.
heres a bit more reading
http://www.s2ki.com/forums/index.php?showtopic=483032&hl=cracked%20retainers& st=0
http://www.s2ki.com/forums/index.php...etainers&st=25
http://www.s2ki.com/forums/index.php...retainers&st=0
Hmmm, interesting read,
That's an odd problem that we've not yet encountered.
Looks like valve clearance issue combined with a loose nut between the steering wheel & the seat.
I'd be quite interested to find out if Honda have had any genuine warranty claims on this one.
i run higher compression than 12.5 in my b20b + JUN stage 3 CAMS.. on shell v-power ... my verdict.. LOVE it...
i have done it and it's fine.. no detonation on my engine..
still drive my car out everyday to work... (dont tell the cops that) :)
also with valve hitting the pistons.. there are so many ways to get around it...
so it isnt a problem if you know what you are doing..
valve hitting a piston is an amatuer problem. so should not happen if you bring it to a proper engine building shop..
and also if your valve hits the piston ... trust me it will not be hairline cracks..at high revs you will know... for sure...
it goes boom, boo, bo, bzzz..
yeh they just replace the flux capicitor...:pQuote:
Originally Posted by TODA AU
New flux capacitor = 1.21 jigawatts at the wheels