What do I do?

[Hatemy7]

So apparently my motor was built for boost, so what do I need to change so it can be strictly for NA. High comp per say.

Thanks for the help

[JDM AE86]

thinner head gasket will help but not alot. change out the pistons with some high comp ones. You could seel the low comp ones to make up for buying some high comps.

[Hatemy7]

^ that's it?

Here is what my motor has


It's sporting Carillo pistons, Godspeed H-beam rods, ARP head studs, ACL bearings, HKS valve springs, Colt Cam camshafts, oil galleys in the crank (42mm) had the ball bearing seals removed and then tapped and hex plug screws set. The crank was modified to induce better laminar oil flow where there was a 90° turn in the galley.

The pistons and rods all came within .4-.5 grams of each other. Here's the original thread of the build.

The rings were gapped for boost (top ring .019"/.49mm & second ring .020"/.52mm)



So all I would need to change is the head gasket and pistons?

[JDM AE86]

I would keep all the parts you have and just swap the HG and pistons. But booost is alot of fun also

[Hatemy7]

I know boost is fun but it's me that is the problem. I know if I had boost I would be punching it all day and everyday lol even on the way to get the mail.

So if I get high comp pistons would it be smarter to get bigger cams as well and port the head out?

[dr.occa]

This is the motor I built for a customer. The rings are gapped for boost too. It's no big deal though.

Like others have suggested; go with a thinner head gasket to bump up compression. You can try having the head shaved PLUS a thinner head gasket to regain compression ratio. It would be less work than pulling the pistons.

Go with a Toda or HKS lightened flywheel. I've been running a Fidanza lightened flywheel myself for a number of years and it hasn't given me problems.

The cams are still within the factory ECUs management range. I really wouldn't go anymore aggressive unless you can bump that compression up and run either carbs or stand alone.

If you do change the pistons to 10:1 or 11:1 pistons, re-gap the rings for NA and keep the cometic head gasket which I believe it came with. Don't quote me on the head gasket though . It's been a while and I'm not sure if I mentioned the head gasket in the build thread. I'm being lazy at the moment and don't want to go through it.

[Hatemy7]

It's ok Jonas I appreciate it. I really want to keep it piston. Since I've been all about rotaries lol. My cousin has told me that I should go rotary but I just want a kool 4cylinder and see what kind of fun I cn do you know.

I might look for a stand alone ecu like haltech 10 or mega squirt to run ITB's on it. We shall see. Does anyone here know a good tuner?

[Hatemy7]

Also will high compression hurt my durability? As far as a daily!?

[JDM AE86]

Also will high compression hurt my durability? As far as a daily!?

They made these in high comp for years that are still on the road.

[Hatemy7]

Oh ok thanks bro. Once again guys I apologize for the dumb questions

[dr.occa]

No dumb questions here when you're wanting to know.

Try a Cometic .8mm head gasket. p/n C4170-030. You'll bump up your compression. You can find 'em on ebay right now for $93 shipped.

Remember to torque the ARP nuts w/ oil and at their recommended specs & passes and in proper order.

I'm currently looking for work so if you happen to be in the "mood" to pay someone to do this for you...cough...cough...ahem.

[Hatemy7]

Lol I sure will man. Message me your number plz

[JDM AE86]

Im some what looking for some low comp pistons and will be pulling the high comp ones out of one.

[Hatemy7]

Bro let me know we can trade ASAP!

[dr.occa]

Um, you might not be able to trade internals unless it's a full rotating assembly trade. The piston, wrist pin setups may be different.

Oh, and the pistons are .50 (.020) over. Here's the old thread where I posted the info.