DeVIIIn

Hey guys! Ive got some questions about power limitations on my 03 evo VIII. It’s US spec. My engine is coming back from the shop this week and just has me thinking on what I need to worry about breaking later. It has an eagle chromoly crank Manley rods and wiseco pistons. All safe to 900 according to MAPerformance of course that’s maximum and not recommended. 2.3L stroker. Stock cams and valves but the head has been completely surfaced with new valves and lifters. Does anyone know how much power a stock 4g63 head can handle? Stock turbo as well. And what about the transmission, driveshaft, and transfer case? Just looking for a safe number to run for a while before I have money to upgrade the weak links. Thanks!

2006EvoIXer

iTrader: (1)

Personally, I don't like 2.3 because I would limit the rev to under 7500rpms. And maybe 8000 in kill mode, but I'm sure it will increase the cylinder and piston skirt wear since 2.3 pistons have short skirts.
This reduced rev limit makes the tranny gears shorter. So you will have more engine torque *with your 2.3 over 2.0* and have to shift sooner. Most peple go with 4.3:1 or 4.1:1 final drive to increase the gear range, but that comes with a side effect. PM me if you want to know the side effect.
Don't worry about what limit a stock head can make because stock head won't be your limiting factor. Your tranny and especially your transfer case will need to be watched. Select your clutch carefully that you don't shock your tranny and TC to the point it eventually fails. And if launching hard, get softer tires that will flex to minimize the drivetrain shock during launches.
Your stock turbo will make instant torque but probably maxes out around 400whp. With a 2.3, the turbo I'd run is a Black, but if you want instant power, a Red is the smallest I'd run.
Why didn't you upgrade cams and valve springs while engine is out?

*edited for you Sean

2006EvoIXer

iTrader: (1)

I think S1 (and maybe S2) cams compliments 2.3 best. I wouldn't go any more aggressive since you shouldn't be revving too high.

LetsGetThisDone

iTrader: (1)

You need to put cams in it. Otherwise let it eat..

Stock turbo will prob make close to 500wtq on a 2.3, and 410-420whp. I did 412hp/455tq onna built 2.0 with stock turbo.

All your other parts will be fine othe than typical issue that the stock 03 trans have with the input shaft, and then the tcase seem to randomly go bad. But it won't be because of your HP level.

LetsGetThisDone

iTrader: (1)

Double post

DeVIIIn

For everyone saying, I know what the pros/cons of the stroker are, but I’m not concerned, and that ship is already sailed so it’s too late to change now. The reason I’m not upgrading cams is basically just money. That stuff is hard to come by lol. Just making sure I’m not going to break anything by running a stock head for a few months and making sure the tranny can handle it

2006EvoIXer

iTrader: (1)

Make sure you find a competent tuner to keep your wtq in check to protect your drivetrain (especially on small turbos). Clutch should be sprung. Stock tranny should be fine until you change final drive. Transfer case is your weak link if you are still stock. Change your fluids often and pay attention to the metals in fluid.

LetsGetThisDone

iTrader: (1)

There is literally zero concern for any drivetrain part with the stock turbo, unless he's going out drag racing, which at that point it would matter if the motor was stock or not, **** breaks anyways.

Changing the final drive in the trans has literally nothing to do with limiting torque.

cficare68

iTrader: (6)

With a built motor I wouldn't even look at an s1 cam. S2 cam is okay but with a stroker motor I would look at a cam built or a for stroker motor. GSC R2 or the Kelford 276 High Lift cams are much better options for his application.

2006EvoIXer

iTrader: (1)

Well, I know I damaged my evo 9 1st gear with 425 ft-lbs of torque at local drag strip. It was just built (evo 8 3rd and 4th gears) by local evo shop with carbon synchros. And with my hard launches with new exedy twin clutch, engine bounced on launches and 1st gear now whines like a semi even with clutch pedal down of rolling over 5 mph. So with 500wtq, I would think he can do the same with an aggressive clutch, even with an evo 8 1st gear, which can handle more power since its shorter geared. It is rare, but it happened to me. I agree that the TC will not be a concern until the turbo is upgraded, which is an easy mod.

My main point is don't drive your evo like drivetrain is indestructible because when it breaks, I bet sean will not contribute to fix it. It will be your cost to fix. Transfer cases can break in stock form and with a built motor, it becomes easier to damage.

LetsGetThisDone

iTrader: (1)

Sounds like you broke it. Not the torque.

2006EvoIXer

iTrader: (1)

How frequent will you refresh your motor? If every 40k, then you don't need to worry about limiting redline and take it to where it stops making power. Then big cams is your best choice with a big turbo. You probably should have ported your head to open up enough for the larger displacement and upgrade exhaust manifold with turbo since stock exhaust manifold will be very restrictive.

2006EvoIXer

iTrader: (1)

ok Sean. I guess it will be him breaking his if it happens to him.

DeVIIIn

Maybe I worded it wrong. My concern isn’t BREAKING something in the head it’s more so about air flow. Someone mentioned porting it which we all know is expensive as hell. I don’t plan on launching it repeatedly but we all do it from time to time. I haven’t decided on a clutch yet but I know it’s going to have to be strong. I’m definitely on a budget though. I just don’t want the head to be suffocating the engine and cause problems. Safety for the entire car is primary concern, but of course we all know that something will break eventually for sure. Weak link tips are much appreciated.

DeVIIIn

Is there any way to prevent those things? I may as well upgrade while I’m here so I don’t have to worry about it.