Hi guys,

First time posting here, as I am on the MLR in the UK but it's a bit quiet..
My car spec is as follows:
Evo IX GT Wagon (Manual), ETS 4" Intercooler, Radium fuel system and pumps, 3" IC pipe kit, 4 bar map sensor, Precision 6062 kit (ETS), Billet crank, Oliver rods, Wiseco pistons, stock head with uprated springs and retainers. Haltech Elite ECU.

The engine is freshly built and run in, my tuner has mapped the car on the Haltech (he really doesn't like it, lol) and said we're pretty much out of flow at the top end to make any more than 624hp (499whp). The transmission I have is being rebuilt but I want to have the drenth I've bought installed. Tuner says he needs syvecs to deal with sequential and get to the power levels safely.

My question regarding cylinder heads is do I need to spend all the money on a stage 3 head to make 750hp, or will oversized valves, a good polish and cams get me there?

Car will be running on 99 octane pump fuel or ratman (renegade) race fuel. I have no desire to run ethanol.

 

run a cnc head and be done or rebuild it with kiggly springs and kiggly hla and some good gsc cams, are you running 2.0 or stroked? for what porting heads cost you can have someone like arligton machine or speed lab or headgames do a cnc head

 

Hey, I'm running a 2.3 stroker, it's capable of pretty much anything up to 800hp I'd think, just want a MIVEC head that can flow..

 

If your tuner says your out of flow up top I'd look at your turbo. Evo head flows pretty well. What are the specs on the turbo? What compressor housing and what turbine housing. Depending on what they are that maybe your problem not a ported head. That turbo should make 700-750 hp but to the crank. Being your on a hub dyno I think your turbo is the problem being it may be out of housing. To answer your question about the head my answer is going to be no. If you put good springs and a decent cam in it you will see gains. With a port and polish you will see some gains but not as much as the cam. Over sized valves being 1mm really don't do much in my opinion when you look at what those really are. 1mm isn't much and I will argue that with anyone. The gain would be minimal if that.

 

Stock cams? If so, there is your answer. Then turbo. Then headwork.

 

Being a 2.3 you may be limited to 750whp or so. Sometimes the 100mm crank can flex and cause some issues. Stock Mivec cams aren't as bad as non Mivec cams but an upgraded set of cams is a good idea for big power or stroker engine.
I wouldn't worry about head porting . A turbo change would net higher gains.

Not sure how your dyno compares to a dynojet but if you are maxing that turbo out at 35-40psi then It may be out of steam. A 6466 would make a bit more but you may find the limits of the crank.

 

yep

 

He is in UK, they run 99 octane, and quote BHP, not WHP.

So considering pump fuel, even 99/100 there is no way to pull more than 28-30psi.

Head is the last thing to worry about on Evo, the stock valves are already a bit oversized, I am pretty sure Evo X valves are smaller- but it's whole different head.
I heard over and over by very knowledgeable people, to not install oversized valves.

2.3 should not rev past 8500, so you have a choice of GSC S2 or R2.
R2 are really high lift and supposedly do better on strocker than S2, I have stroker, and I never found data to show R2 outpacing S2 on stroker.
English Racing may have some data, but I never found it, and I tried hard to find it.

I think it's best to keep the 2.3 to 7500, with worst case occasional 8000rpm jaunt.

You will benefit from intake manifold like Magnus V5.
You are peeking about 6500, carrying it to 7000, so an intake manifold will allow maybe another 500-800rpm of rev range that is useful, and maybe 30-40bhp.

I don't know that you run stock cams, I doubt that, but if that is the case, there is another 40bhp easily in the S2 or R2.

I would leave the car alone - 6062 is probably as big as you can go to not push torque peek far out beyond 4500rpm.

 

I wouldn't pull the head at this point since the motor is built, but drop in a set of cams like R2's or something equivalent. A 62mm turbine is small for a 2.3L so I would opt for a 66-68mm and run a slightly smaller compressor inducer so 6466 or 6468. The turbine upgrade will provide more benefit vs a compressor upgrade and the motor will become less knock prone at higher boost vs a smaller turbine. So R2's and a turbo upgrade and your good for 600+whp.