I just picked up an EFR 7670 for my Evo 1 and I'm quite excited about it, though I'm still planning out the engine to back it up. I've seen the insane 600+ wtq dynos of 7670s on 2.3L strokers here, but I'm walking a line between response and keeping a transmission together (DSM/Evo123 transmissions are quite fragile compared to Evo 8/9). I'm hoping for some input from similar experience because I just can't pin down a decent enough estimate.

I know the 7670 has a ton of airflow capacity and can lag, so what's the best way to minimize that lag while staying under 450 ft-lbs at the wheels and doing 500whp+ peak? Everything on my list means it's going to come on decently in the mid-range and fall off top-end. Setup just in case:

EFR 7670, .92 IWG
T4 twin scroll, cast short-runner manifold
Stock Evo IM & TB
Tomei 260* cams (similar to Kelford 264s), Manley valve springs & titanium retainers
94 octane
8.5:1 compression

So, would it be the stock 88mm crankshaft with 156mm rods, a 94mm crank with 156mm rods or 100mm crank with 150mm rods that does the trick? No intention to rev it above 9000 on any setup.

 

2.2l sounds like a good option in the 2.0 block.

 

Do not run the 94mm crank with 156mm rods, it will cause issues. Get 153mm rods from English racing.


If you want to rev it to 9k, do a 94mm. If you want a little faster spool, and have a redline in the lows 8's, do a 2.3. Running pump gas, it should be easy to keep torque in check. Especially if you're running electronic boost control.

 

I would rather keep it under 8000 to use ECMLink Lite otherwise I need to rewire my car for a standalone. That said, my boost control is probably inadequate (Blitz SBC i-D which has proven good but probably couldn't pull boost to reduce torque). ECU-controlled boost only on a better ecu platform.

I think 94/150 or 88/156 are the only options.

 

You can get 153mm rods from English Racing to go with the 94mm stroke..

That being said, you should be able to run wastegate pressure on any boost control setup. And on 94 octane, you're not going to make crazy torque. The 600+ tq cars you see are all running E85, which is a whole different ball game. I still say go 2.3 and figure out how to limit torque.

If you get the trans built, it'll handle a good amount more power.

 

Noted on the 153mm rods, but Eagle/Manley 150s are everywhere

Depending on setup, 94 here is usually good for 25 psi on larger turbos. I came across this dyno, it's painful to see. On a 2.3 with a 7670, 23 psi still does 525 ft-lbs. Even the 19 psi low-boost setting doesn't go under 450.




Contrarily, this stock-block EFR 7670 EvoX on 93 octane+meth doesn't even do 400 ft-lbs at 29 psi, so I'm just lost.




With Evo/DSM transmissions, it's not a matter of 'if', but 'when' the transmission breaks doing 500 ft-lb 3rd/4th pulls. The gears just aren't strong enough, neither are the hub/slider assemblies, and straight-cut is the only upgrade that will take it.

ECU is the limiting factor here, I just realized that I can't go on without one. Apparently Haltech makes P&P stuff for my car, so pulling lots of boost at 4000 on a 2.3 or giving me 9000 RPM capability on a 2.0L would be easier than what I'm doing now.

Apparently E85 and 31 psi on a 2.3L are worth 200 ft-lbs over a 2.0L on 93+meth, so I just don't know anymore. /s

 

E85 is a HUGE advantage for making more power everywhere. It can handle a lot more timing and boost. And alcohol brings its own oxygen to the party, so E85 usually makes about 40-50hp more than gas even with the same timing and boost.

 

Care to elaborate on that one? Thinking of doing a 2.2 for my build and took it 156mm rods were the go. This affects what pistons you have to use, correct?

 

The wrist pin has to be moved up too far in the pistons, it negatively affects the rings, and a few other things. There is a reason English uses a custom 153mm rod in all of their 2.2 94mm 4g63 engines.

 

What twinscroll cast manifold are you going with? I'm looking for a manifold solution to EFR my GVR4.

 

Yup, corn sauce sure makes the power, especially on the torque spike where RPM is low enough to make killer torque but boost is allowed to past 30+ psi. I think your earlier statement was correct that I'm too caught up on numbers. I'll just run a 2.0 to save my transmission, if it lags then I'll mess with cam timing or something, but I hardly think it will be disappointing (it probably makes more power than a 16G everywhere anyway).

I have an OnGreenPerformance manifold, it's probably 15 years old. It's actually a replica of an HKS manifold made for Galant VR4s, but with minor changes, notably the fact that the whole turbo flange is divided and the wastegate flange clocked. The HKS kit had an O-trim T67 on-center turbo (or something), wastegate, downpipe with integrated wastegate dump, etc. I just need to have the wastegate port divided to the flange and then blocked off. It sure puts the turbo far from the block, which is worrying, but nothing that chopping up a rad support won't fix. At least there's lots of room for oil and coolant lines in there The odds of finding another are pretty slim due to the age, and there weren't many made to start with.

 

I don't think you will get accurate estimates of numbers looking at evo x dynos. Their stock head flows as much as a ported 4g63 head. So it will spool faster and hold power better than what you might actually see on your setup. Since you said you wanted to keep under 8000rpm, I'd say go with 100mm and call it a day. You won't rev high enough to see the real benefits of going with the 94 or 88 instead.

I think you will have to go with more aggressive cams and ported heads, or add meth to hit 500whp on a 7670. You can use matchbot to confirm, although the hp estimates on there is very simplistic.