what compression would you run on a b18c2?

[dzyn3]

i just want to know the peoples opinions, and experiences with people running after market pistons in their b-series Hondas, which are boosted.
mainly a b18c2.
9:1
10:1
even, 10.5:1

which one would you pick and why.
running approximately 16psi of boost, daily driven.

[INTEG]

i just want to know the peoples opinions, and experiences with people running after market pistons in their b-series Hondas, which are boosted.
mainly a b18c2.
9:1
10:1
even, 10.5:1

which one would you pick and why.
running approximately 16psi of boost, daily driven.

10 or 10.5 will be ok

im currently running 10 or maybe just abit higher, when i built mine everyone said to go high comp

[Express_Parts]

If you're only going to run 16psi you're better off going with a higher compression piston otherwise it will seem to be laggy in low revs because it will only b the turbo making the compression.

[ProECU]

wouldn't go past 10 on a B16 because without headwork to reduce the volume of the chambers, you will need a large domed piston to get compression - and thats not ideal for a turbo motor.

[dzyn3]

past 10 meaning over 10? eg 10.5
or under 10? eg. 9
this is referring to a b18.
=)

[Limbo]

mate if you wanna run 16PSI your gonna need closer to 9:1.
Otherwise if you not gonna rebuild stick to 10PSI

[dzyn3]

9:1 you say? just been hearing mixed opinions, peopel saying raise it, keep it std or lower it.
kinda want to know pros and cons, and i'm hoping the tuners or people with the exp can come in and shed some light.

[ProECU]

9:1 you say? just been hearing mixed opinions, peopel saying raise it, keep it std or lower it.
kinda want to know pros and cons, and i'm hoping the tuners or people with the exp can come in and shed some light.

do you have problems comprehending what I told you?

[dzyn3]

just a tad ProECU.
my bad, if you could kindly rephrase it in more simpler terms would be great.

[ProECU]

dont touch it, you'll fuk it up guaranteed!

[dzyn3]

hahaha, words of a wise man.
i'm not touching it, tuner/builder has said go for 9.0:1, by all means, i trust him.
BUT i do want to know what would be the pros and cons of using a different compression ratio.
lol
that's practically all.
lol.

[sparkles]

the tune is just as important as the engine build, the safer the better :)

[TODA AU]

i just want to know the peoples opinions, and experiences with people running after market pistons in their b-series Hondas, which are boosted.
mainly a b18c2.
9:1
10:1
even, 10.5:1

which one would you pick and why.
running approximately 16psi of boost, daily driven.

All three will work,
Depening on the size of the turbocharger used, will depend on how well each comp level will work.
It is true you will make more power & have better response with higher compression. (To a point)
That is you will get more power for the same boost with more static compression.
However as compression increases, the tuning window gets smaller.
This means quite simply, it's easier to blow the thing up.
You may get all sorts on nonsence thrown at you about this, but you should know that the compression ratios you've quoted are neither all that low or all that high.
In that, I mean that 9.0:1 C/R will by no means turn your car into a low compression slug.
If you have a smaller turbo that is likley to put more thermal load on the engine. (GT25~28 or similar)
IMO, for a daily driver, I think you should eir on the safe side & go for 9.0:1 C/R
The downside will be reduced power output in favour of improved reliability.
Also slightly inferior fuel consumption & a little more percieved lag.
FWIW, we use 9.4~9.5:1 on road turbo engines with GT30 or larger turbines.
C/R's of 10.0:1 or higher are generally for drag use or what you'd find in a bolt-on set-up with lower boost.
Hope that helps

[IEVAQ8]

if ur gonna spend the money, do it properly and raise it, if u want to run 16psi for the sake of running that high boost setting, then lower the comp so its safe........
or if u wanna save money leave it stock and run 10psi............
personally, i would leave it stock and run 10psi.....once and if it blows, rebuild with higher comp..............
think about it, stock comp with 10psi may make (figure of speach) 200kw
higher comp with less boost say 7psi will make 200kw.................
like 'Express_Parts ' if you run that much boost on lower comp, the turbo will be making the compression and be lagy off boost...........
ur choice, speak with ur tuner, see what he/she is happy/comfortable to tune and their recommendation
i would check a few builds on this site & compare.............................
or speak to some reputable tuners on this site,
'TODA AU' as he metioned above

[Sexc86]

exactly... i just see it as lowering compression is just robbing you of power...

just leave compression the same and lower the boost... rather then lowering the compression to run crazy boost that really will probably only see the same power but putting more stress on your engine hardwear. IMO

[Weq]

Im going to slightly agree with toda on this one.

In my experience, low compression daily driven is the only way. Australian pump fuel is just too veried. A small bit of blowby will reduce octane level more and can induce pinging without u even noticing. With low compression you get a more forgivening buffer. I ran 8.5:1 on my civic. It felt no different too 9.6:1 on my first build.

Octane levels can be fixed with water/meth injection... or race gas. But race gas isnt daily friendly. Remmber our fuel is alot different to US fuel, our 98ron is eqiv to there 93.

Just my opinion!!

[destrukshn]

i'm building my current b18c2, with 9:1 compression.
i just can't justify, building a motor, 10:1 running the same psi, and gaining what probably a extra 10-15kw?
i like knowing the fact that dropping it will make it more reliable, and safer, it's not that much power your losing, and it won't become a slug.

you guys are probably more talking abotu cars that will drop they're compression to 8:1 or 7.5:1
9:1 i reckon, is a safe bet, and that's what i will be going with, and also recommend.

[Weq]

There was a good thread on honda-tech recently about the evo guys making 620whp on pump gas. On 30psi. The honda-tech crew love racegas and didnt beleive you could run 30psi on street fuel. They called BS. Even the big tuners didnt believe the numbers. But they were proven wrong.

And low compression is the key. The there is a definate movement in thinking away from hi-compression these days.. Sure u make less power per PSI, but at high boost levels (1bar plus) i think its safer to turn the boost up.