I only have 3 posts for the day left after this one so Im going to try to make it good.

Question 1:
Instead of using a 2-3mm head gasket, would it be better to just replace the pistons (since the head if off anyways) with reverse domed pistons?

I know on the LS1 engine, it's better to go with a reversed domed piston because there is more squich pad area than a simple dished piston and it will further reduce the chance of knock. Also, the reverse domed piston would make lowering compression possible without having to run a super thick gasket and the risk of other problems associated with thick gaskets. Does this hold true on the S2000s as well? If so, who makes a good reversed domed forged piston and can those be had for around $100 each?

Question 2:
How are the head bolts on the S2000? If the head has to come off for either a gasket swap or piston change when increasing boost to lower the compression, should the head bolts be swapped out for studs? Are the Honda head bolts of ARP quality?

Question 3 (Sort of):
Im considering a high mileage (read 70k+) S2000. The reason follows:

Are there any reasons not to consider this route?

1. I'm considering pulling the heads and replacing pistons and rings (see question 1)

2. With the boost needed to hit 350-400 whp, the clutch has to be replaced anyways.

3. Ive found them in the $13-15k range which makes it possible for me to sell my Vette and mod (turbo kit and engine work) a S2000 without much cash out of pocket.

 

1) Custom dish pistons. Most off-the-shelf for the f20/f22 are high CR pistons. A 2mm head gasket will be ok, but I've been told that the cams have to be re-shimmed for the 3mm gasket.
2) ARP head studs
3) There are more things in question than just the motor and the clutch. If you're boosting, make sure your whole drivetrain can take it. There are people that have passed that mark without a problem, but they are also mostly stock.

 

Headgaskets are the quick way of lowering compression. It works, but pistons are better.

For 350whp you should be at the stock motor internals limits. 400 might be pushing it.

 

the block is already rather strong... it comes with forged pistons and rods.... it's capable of up and aroudn 500rwhp (with lowered compression) ....

if you only plan on doing 350-400.. just get the headgasket, and with the money saved from not buying the pistons you can use that for tuning and other mods that'll compliment your setup..

 

Thanks for the input.

Im not so concerned with the extra $400-500 for the pistons if it will make a difference in reliability. Im not looking to slap something together quick just to go out and goof around. Im trying to see if I can build a S that is as quick or quicker than my vette that can also take some aggressive driving without breaking down.

That's the recommended compression to run 15-16 psi boost? It's currently 11.5:1, right? Would a 8.5-9:1 be about right?

 

put it this way... my buddy had around 430rwhp (before upgrades) 3mm headgasket pushing around 16-18psi.....
he'd smoke vipers on the highway... easily..

now he's pushing 672rwhp at 22psi.... (the motor is fully built now)

compression is 11:1 and to run 15-16psi. go with the 3mm... it'll drop it to 8.7:1? something like that... dont' remember the exact number.... but it'll work.. ... as long as you don't plan on going over the 500rwhp mark you'll be fine with just the 3mm.. and GOOD TUNING... and larger injectors...and it'll be reliable.... however, if you plan on doing a lot of launches and clutch drops... i recomend looking into fortifying your rear diff....

 

Thanks papa5smurf.

You bring up a good point. You said it would pull on a viper on the highway, can you give me an idea how it does off the line since there is an obvious tq difference?

Im sure I can eventually find the answer to this, but I'll lump it here. Is the S a MAF or SD car?

If I went this route, WOT tuning would be done on a dyno, and then part throttle tuning would be done over time while I datalogged normal low-load driving.

 

off the line... it's a toss up... if you're a good driver you can get off the line pretty well.. if you're not a good driver. then forget it...

for instance.. on a stock s at the track... good drivers will run like 13.7-14.... bad drivers will run 14.5-15+.... big difference...

my buddy had issues with traction launching with 430rwhp....however he ran a 12.2 at 117mph or so.... somewhere around there, with a bad 60ft time.... he was launching at around 13-14psi... and once launched boost was bumped up to 16-18psi... (i'm giving you these estimates on the psi cuase i don't remember the exact numbers off hand..but it gives you and idea..)

the AEM EMS does have a two step/two stage boost for launching... where it sets a launching limit at lets say 5k and it'll hold steady boost at that point till you launch...this way you'll be launching consistently..... only issue you'll have to deal with is the traction....