After breaking the car in, I finally got to take the car up and past 5k rpm...is it just me or does the evo 8 pulls harder b/t 3 and 5 (around 3500 to 4500 to be exact) than anything above 5k (although the engine is a lot louder then)?

 

I would assume this to be true as max boost is at 3500RPM and tails off after that. We need to have max boost all the way through the powerband...Boost controller maybe??

 

That's most definitely true. The butt-o-meter is going to feel torque more than horsepower and the EVO below 4-5K is all about torque. Shortly after 4K, things get pretty boring. The boost has dropped by then and holds steady at a pretty meager 15-16 psi (?). Can anyone confirm that number. The shop manual actually says to check that it's holding ~12psi!! Anything above that is supposedly out of spec. Dunno. Maybe that's just temp manual error stuff.

Thomas Dorris

 

Once parts become available an intake will really help. You may be able to use a K&N FIPK kit from a 2G eclipse with some fabrication on the hold down brackets.

 

I don't know if a boost controller would help hold the boost. Maybe I'm wrong, but I'm guessing the turbo can't sustain that much boost at higher RPM. That's the price you pay for having your max boost at 3500 RPM though.

 

A 16G turbo should be able to sustain 20-21 pounds of boost to redline efficiently. It can actually hold more than that, but eficiency goes out the window above 21 pounds.

 

It's a Mitsubishi 16G turbo that we DSM guys have been running forever. It'll easily hold 19-20psi to redline on a 2.0L motor. It's not the biggest turbo, of course. In fact, it's the smallest turbo a self respecting DSM would be caught running at the track, but it'll do. ;p

The shop manual shows a "standard" boost control solenoid wired to the ECU, but I don't know if there are other little things that end up controlling what happens. If it's "just" the ECU, then we can probably get that "fixed" with just an ECU upgrade. Or, of course, you can go with a manual setup. Either way, get the boost back up, lean it out a bit up top, and hold on. All that missing power is there, it's just untapped right now.

Thomas Dorris

 

From looking at the power curve of the EVO, there is definitely something wrong after 4k. Compared to most of the other power curves, this one falls down quite a lot. After looking a bit more into this, Vishnu Performance had a graph with the A/F numbers and it looks like that the stock ECU adds enormous amount of fuel the higher you go in the RPM band. This would certainly be one of the ways to preserve the engine and stop it from blowouts. We loose a lot of power, but at least car is still running

Also, as Tom mentioned about the boost control solenoid. It would be very easy to check whether ECU is sending any signals at the higher RPMs to keep things in one place. Graph of the solenoid activity thought the band would help here.

Oh well...


Fedja