I have a b18b1 that I am boosting. My goals are 400whp+. I have 10:1 srp pistons and eagle rods. My quesiton is, how thick should I order the headgasket to get it down to about 9 or 9.5:1?

thanks

 

Stock thickness is fine. Tune the hell out of the car and enjoy the responsiveness. No need to lower compression unless you don't trust your tuner and his abilities.

 

Additionally, thick headgaskets will only increase quench distance, which increase the motors potential to pre-ignite. Unburned hydrocarbons can create hotspots that melt pistons and pre-ignite cylinders causing damage.

Like stated, stick with that compression ratio and tune it wisely. If E85 is accessible to you, then that's something you want to look into. 105 octane, nice gain in torque over gasoline...it's worth it.

 

You wouldn't be able to find a HG that will lower your CR by that much anyway.

 

huh? LOL

OP... that compression ration is fine. I am running 9.8:1 in my setup and I love it.

 

For every .010" added in head gasket thickness you will drop about 0.3:1 Compression for a stock bore. The same holds true for the reverse effect. The biggest head gasket I have seen is .051" Cometic but there is probably bigger LOL. Your stock one is .030" in case you didn't already know.

So to answer your question get a 0.051" thick to lower your compression to about 9.4:1 and this is ASSuME-ing that you have an actual compression ratio of 10:1 ... Just because that is what the pistons are don't mean that is what you have. Did you get the head milled or the block decked, ect., ect...

 

ok, I have since picked up a gsr head to put on my b18b block. I was told the head was never planed before. So Does anyone know what this will do to my compression? I seen those online calculators, but I don't know enough about engines to fill in all the info needed lol.
I am after doing some more research, I do plan on trying to keep my compression around 9:8:1 or 10:1 but my tuner said not to make it any higher if possible.

again its a b18b (10:1) block with a stock gsr head

thanks

 

I had a Cometic .065" on my 585whp Motor, 8.2:1 with Ethanol FTW lol

It was stated above roughly every .010" will give you +.3 in comp ratio, not sure how accurate that is but it sounds about right.

 

yeah, I understand that, but I wanted to know if putting a gsr head on the b18 block is going to make my compression higher than it already is and around how much higher.

 

stock is 9.2:1, according to the very simple online calculator located here http://c-speedracing.com/howto/compcalc/compcalc.php , if the block has not been cut you will be at 9.73:1 with an uncut GSR head.

 

how high a psi can u run at 10:1 comp

 

PSI has nothing to do with power so your question can not be answered, different turbo's make different power at the same PSI

 

ok then a garrett t3/t4 57 trim b18c1 stock compression does that help

 

my block is 10:1 with a b18 head on it. Im wondering what a gsr head would do to the compression

 

shut your mouth if you don't know what your saying.

 

Sorry to bring this back from the dead but it was exactly the info I have been looking for now second question I'm sleeving h22 to 88mm but wanted to steer clear of any work on my combustion chamber stock being 87mm I am pressuming there will be a compression bump? currently getting GE sleeve short block assembly 11:5:1 compression pistons and throwing jrsc on it I have already talked with GE rep. For FI clearances so now I'm trying to figure out tuning I would like to stick with pump gas tho. And currently at schofield barracks in hawaii and highest pump is 92 oct. ??? So I need suggestions. Also pro 1 are going In and they are NA cams so with the "overlap" I kno it's not good for FI but will this help keep chamber Temps down?? I was planning a 250 NA build but with all the money invested I did not want to stop at 250 so. I need solutions. Thank you

 

You'll be fine, no need to lower compression.

 

that's it.... you'll be fine, ok.

 

Assuming you run 93 and have a good tuner you'll be fine.

as long as you run the jrsc at stock boost levels I don't see an issue, as IATs will stay within reason. if you up the boost with a smaller pulley or stacked pulley system then you'll need an intercooler and/or methanol injection to keep the IATs within safe limits.

the higher static compression does lower the detonation threshold, especially with higher IATs but even at high pressure levels the jrsc won't break any power records... you might be able to squeeze 275 out of it with minimal work but anything above that is going to require serious work.

I think the pro1s might be too much cam due to the overlap but you can always try to dial some out.

the other issue is the header, the jrsc doesn't like long runners. it likes short runners like a miniram turbo manifold. the kamikaze header has worked wonders on supercharged b series cars but I don't know of any similar header for h series motors.

 

So talking with GE mfg. According to my build specs I would get roughly 250 NA and adding jrsc I'll only get another 25? (Not being sarcastic either) ^ what am I doing wrong?, will the SC be pushing outside of its efficiency range? My cam overlap? Or is it that I will have to tune it down to make it run well and lose a bunch of power? Thnx for the header tip btw. Either way 275 will be tit's Im just wondering.