JNVA17

This is my first "build" doing with my cousin who is a 4g63 guy so we're both confused. I put 75mm high comp pistons in my d16y8. New bearings seal rings etc. my compression is reading 240 across the board. Do to some bent valves I haven't been able to start it yet but we are worried there is too much compression. There wont be enough high octane booster im the world for this thing to run properly. How can I lower compression I was told a thicker head gasket and another head. Which d series has the thickest head gasket and which d series VTEC head yields the lowest compression. I'm aware that pistons lower compression but something about the size of combustion chambers. I saw a post on google about low compression head y8 vs z6 but I can't find it. Thanks.

ezone

Speaks volumes. Poor research? Parts supplier and manufacturer offer no help? Their websites?

Essentially meaningless without other data. There is no easy way to tell the compression ratio from a compression test number.

Not a whole lot higher than a normal compression test reading IMHO. I wouldn't have been surprised to see 220 on a compression test from an unmodified engine.

How in the hell would you get these compression numbers "240 across the board" if you have "some bent valves"? (You shouldn't.)
You better back that truck up. There is probably a different reason it won't run.

What is the static (calculated) compression ratio?
(Or the advertised compression ratio for those pistons.)
Google for a how-to if necessary.


Will this setup use a knock sensor? (EX? Yes.)


Stock compression was 9.6:1.

We have K engines with 11:1 compression, and a few JDM K engines with 11.7:1 all running pump gas (91 Octane or higher recommended).

If you aren't over that number, and you get everything else correct, I'd think you will be OK on a steady diet of high octane pump gas.


HTH

JNVA17

The compression ratio is 12.5:1 tik pistons?? and I didn't get it started because the valves were broken haven't had time to put the rebuilt head back on. 4,3,2, were at 240. 1 was at 0 bc it had 2 broken valves. Idk how to test compression so I didn't do it I just looked at the gauge.

ezone

Ooooh ouch. That's probably too high for the street. Bad research.

I'd try to swap for different pistons first. Somewhere around 10.5:1 to 11:1.....depending on your needs and expectations.
You will have the head off to do valves, now is the time to correct the piston problem the right way.

Or look into maybe have the pistons cut down a little by a machinist to lower compression.
IDK if you can open up the combustion chambers in the head, and I have no idea what else can fit to get a bigger combustion chamber. Maybe someone else can answer that.

I think that double head gaskets are just asking for trouble down the road. IDK if anyone makes head gasket shims for this application, but you can look.

HTH

JNVA17

So after research and talking to the local Honda guru I need to upgrade my cam injectors fuel pressure regulator Ecu tune and fuel pump for this car to run properly at high rmp. My question is what stage cam would I need to run? also what's the difference between stages?

KyleSJ6033

The double head gaskets is a no no. They sell a 2mm headgasket for the turbo applications that lower compression. I personally have a turbo civic.

The civic is going to need a better valve train also. You could put brian crower valves and shims in and raise the redline about 800 rpm and still be safe. The weakest part in the civic is either the rods or the valves. If you decide to run this car at high rev and not upgrade the valve train also you will surely float a valve.

Like dude said in an earlier post back that truck up

Slow down and think about what you are doing. You will need better injectors, upgraded valve train (including valves), higher octane gas, upgraded computer, possibly rods, and a decent tune just to run with the pistons you have. The best money ever spent on a car is a tune. Without it your car wont acheive the total power of the bolt ons you put on the car or worse you destroy the motor from being to lean or wash the cylinder walls out by to much fuel which both end in catastrophic engine failure.

First you have to get the car running again.

As far as the cam stage its user preference. I have seen the stock cam make over 400 hp on turbo applications and be very reliable. But its up to you the stage one cam I believe does not require any valve train upgrades and is a bolt on application. The stage 2 however has such big lobes on the cam that upgraded valve train is a must. So you decide where you want your project to land.