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Evo X with Map EF4 turbo power band

Old Jun 1, 2016, 06:23 AM
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Evo X with Map EF4 turbo power band

Hi I have a Map EF4 , map short runner manifold , map rev 2 intake manifold, with built 2.0L block, GSC S2 , +1mm GSC valves, super tech valve springs and retainers.

The issue is I am making all my power up top. I am getting 500whp on pump 93 at 28-29psi at 8k rpm and my redline is at 8200k. Does anyone have a similar issue. I didn't want to rev the car high but the tunner says the turbo will make power past 8600k.
Is there any one with a similar setup that was able to make power earlier or will I have to raise the red line ? Also car has boost lag from 40 rolls 2nd gear at 5k rpm. Boost breaking is the only way to solve that ?
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Old Jun 3, 2016, 06:17 PM
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Without seeing a dyno graph I can't tell what you really mean by getting all your power up top--HP or TQ. I think you mean HP and that's a good thing.

Hitting peak HP at high RPM is normal and good. But 500 WHP and 28 PSI on 93 seems dangerous, I wouldn't track on that or drive it hard in high summer heat. I only run 26-27 PSI on E85, and make about 471 WHP on the 5150 MD which I'm told is about 550 WHP on a DJ.

On a turbo upgrade, peak torque should come somewhere between 4000 and 5000 RPM, depending on the turbo and tune. With the EF4 I would guess closer to 5000 RPM. Stock turbo peak TQ is like 3500 RPM.

If you have a built 2.0 motor, built right, with springs, you should be good to 9000 RPMs. With my built motor I set the rev limit to 8700 to be safer (I have an MR and the trans doesn't like spinning as high as a manual.) I try to shift by 8500, but on the track sometimes I forget.

I recommend setting your rev limiter at 8500-8700, not sure why, it just feels like a good limit vs pushing it to 9000. Ok to touch 9000 occasionally on a drag strip, but if you set it there your likely to keep hitting it.

My car, like yours, keeps making tons of power all the way to redline--I have an ATP GTX 3576

Last edited by lbcevo; Jun 3, 2016 at 06:28 PM.
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Old Jun 7, 2016, 01:52 PM
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have you considered switching to a less laggy turbo? On a 2 ltr I'm at 400 wtq on a 7670 at just after 4k rpms and it holds that until 7600.
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Old Jun 8, 2016, 08:11 AM
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Torque * RPM/5252 = HP

If you want to make more power down low you need to do it with torque (if you want to make more power anywhere really). The way I see it you have 3 options...

1. Smaller turbo - would spin up faster allowing you to make more torque earlier in the rev range, you will probably suffer a bit at the top end with this method.
2. E85 - you stand to gain about 20% more torque by running E85 but you will need to deliver about 30% more fuel so you will need to make sure your fuel system is up to the task.
3. Displacement - Stroked, sleeved and bored, or both. This is by far the most expensive option but would yield great results in terms of better low end torque and earlier turbo spool.

My recommendation - E85
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