EVOeight

The only real complaint I have about my new EVO VIII is the terrible turbo lag. Below 3000 RPM’s it is a complete turd. This car has the worst throttle response of any car I have ever owned. Once the boost comes on though it is awesome! I am trying to figure out ways to reduce the turbo lag as much as possible. Any input would be appreciated. Here are a few ideas I have so far:

Ball bearing center section for the turbo.

Titanium exhaust impeller for the turbo.

JetHot coating for the exhaust manifold and the exhaust side of the turbo.

ECU reflash. I understand that a reflash can put more ignition-timing advance on the low end before boost comes on. This should help low end torque somewhat and reduce the perceived turbo lag.

Some people think that a boost controller can make a turbo spool faster but this in incorrect. The wastegate spring won’t even open until around 10lbs of boost so a boost controller does not even take over until after that much boost has been achieved.

Free flowing exhaust. I understand that some aftermarket exhausts can make more power on the top end but actually make turbo lag worse because the exhaust gas velocity is reduced. I’m happy with the current top end power.

Stroker kit. I understand that the 2.3-liter stroker kit not only makes more torque because of the increased displacement but also makes the turbo spool much faster because of the increased exhaust volume.

Intake piping. I saw one intake piping replacement kit that claimed to remove almost 18” as compared to the stock intake piping. This should help boost reach the motor faster and reduce the perceived turbo lag.

NOS. I guess a 50HP NOS kit set to come on at 1500 and off at 3000 would help but I don’t want nitrous.

Increase the static compression. I want to stay on pump gas and keep 20lbs. of boost so this is out for me.

Light-weight flywheel/clutch assembly. (thanks GDB).

Anybody have any other ideas about turbo lag reduction?

zyounker

iTrader: (1)

Ok, most of the problem is you...



You are going to have to relearn driving your car.. It is not turbo lag u have a problem with.. it is just driving a turbo car..


The EVO has very little lag.. But you have to keep the engine reved..


You want to see lag, go drive a stock WRX..



-Zach

mrdecibel

iTrader: (1)

I agree. It is a side effect fo driving a turbo car. Spool up is amazing on the evo considering it is using a 16g turbo.

twdorris

At first, that's what I thought the response would be as well. "He just doesn't know about turbo cars." But his post indicates otherwise. He seems to have a good understanding of the concepts and what affects true lag and what just gives the impression of affecting lag. So I'm going to ask a different question.

Which 4-cylinder turbo cars have you driven that are noticeably better than the EVO 8 with respect to turbo lag and/or boost threshold, whichever you actually have an issue with here?

Thomas Dorris

EVOeight

My last car was a 2000 Subaru Impreza 2.5RS. It has 2.5 liters and 10:1 compression. I must admit that is part of the reason I feel so much lag in my new EVO. The only other 4 cylinder turbo car I have ever owned was a 1992 Eclipse GSX. It had bad lag too. I know I will never get the same throttle response as my Subaru in my EVO with such low compression. I was not really trying to. I just was asking for ways to reduce the lag as much as possible. I now have 1500 miles on my EVO and I guess I am starting to get used to it. I would still like faster spool though...

twdorris

OK, with that I'll point out what others have said. The EVO8 is actually rather good with respect to throttle response for a turbocharged 4-banger. Especially with that particular turbo. A 16G is pretty potent and to get the kind of response we *do* have with it is pretty amazing. The suggestions you listed would all help, but some of them are pretty radical. Although a 2.3L or 2.4L block swap would do it, it's not likely to happen any time soon.

Another thing you might consider is removing the MAF entirely (leaving the intake side of the turbo open) and installing something like the GM MAFT unit. I think it's only calibrated currently for 1G and 2G DSMs MAFs, but the EVO MAF isn't too far outta whack. A number of people have reported improved turbo spool up characteristics with that, but it too is a pretty radical step. I certainly wouldn't suggest that setup for standard street use as the ol' airfilter does have its advantages... But if we're throwing out ideas, that's one option.

Thomas Dorris

zyounker

iTrader: (1)

Ok, since you are use to turbo cars.. (sorry for assuming u didnt) The evo is actually VERY good with turbo lag.. but the best way to improve turbo lag is usually exhaust..


There is a stroker kit for the evo.. check with jun.. But it is gonna cost you.. Try exhaust and some tuning 1st.

-Zach

EVOeight

What exhaust would you recomend that will reduce the turbo lag? Should I stay will a smaller (2.5 inch) downpipe and cat back? I have heard that the 3" will increase turbo lag. Any truth to that?

zyounker

iTrader: (1)

Um, Ok with exhaust it is kinda weird on a turbo car..

A larger exhaust will give more top end power.. It will also let the turbo spool quicker..


But a smaller exhaust keeps more lower end torque at the sacrifice to top end power. It also slows the spool of the turbo..



So it is a double edge sword.. Pick a exhaust that gives the top end power from the turbo.


Or pick a small exhaust and have the engine make the lowend power and strangle the top end power from the turbo.


Cant have both.. I just relearn how to drive and keep the revs in the power band if i want the power.


-Zach

silverEVO8

iTrader: (12)

My first turbo car was a Capri with the 1.6L engine. I was not experienced enough with performance cars then to even notice if it had turbo lag I do remember being extremely surprised one time when I really launched hard and the torque steer almost caused me to lose control...

My second turbo car was a 280ZX with A/T. I never actually knew if the turbo was kicking in or not The car was pretty fast to my limited estimation, but again, I could not determine the presence of turbo lag.. I remember my brother's turbo Audi of years ago and that one was a real dog when the turbo quit working... Amazing how much difference the turbo made!

Fast forward a few years to my '91 Miata. I ended up adding a turbo to that puppy. It was a variable vane unit maketed by Corky Bell. I was all pumped up about it and the car made a lot of power. Turbo lag was not very noticeable since the engine was NA to begin with, so the performance was only better after the turbo install. OTOH, that Aerocharger was a POS and self destructed twice in 5K miles..

I've had 2 supercharged cars too. A '95 R type Miata and a '96 Integra GSR. Both got the JR superchargers. Those too suffer from a little lag due to the parasitic drag of the blower drive, much definitely much less than any turbocharged car. I'will say that I think the GSR was as fast as my EVO and prolly quicker in the 1/4 mile if it had LSD and good tires. I actually got a 14.1 @ 99.3 mph with street tires out of that puppy! Unhappily, it self destructed in short order... NA cars (particularly Hondas) are just too highly tuned and run too much compression for safe aftermarket FI...

My last car was a WRX and I really felt the turbo lag. The same thing is apparent with the EVO, but I must admit it's more of a driving adjustment than anything else. Except under the most severe conditions, like accelerating after a 90° corner up-hill, the turbo lag is not bad at all. I think it gets worse as we drive the car more and become used to the gobs of power available under boost , then we get spoiled and expect the same performance under no-boost conditions. Although the turbo lag is real and noticeable, I think driving style can all but practically eliminate it.

Oh yeah, the original question was about upgrading the exhaust to improve the turbo lag problem... IMHO, any opening of the exhaust will result in low end torque losses which will aggravate the experience of turbo lag.... This too is easily remedied by slightly more aggressive driving, but I would not recommend messing with the exhaust as a means to reduce turbo lag. You'll get better performance overall with a freer flowing exhaust, but not where you are looking to improve..

just my $.02

Coolguy949

iTrader: (10)

Welcome to the world of turbos. For a turbo car, the evo is very good about lag.....expecially with a turbo of that size. It has less lag than my old t25 equipped eclipse. If you want to decrease lag get a turbo back exhaust to start with.

zyounker

iTrader: (1)

Getting an exhaust will spool the turbo quicker. but also decrease low end torque.. It really depends on the exhaust and how well it is made for the engine.


EDIT: These are turbo cars.. the turbo is suppose to build the torque IMO

-Zach

Meeyatch1

iTrader: (1)

Hmm..has anyone tried the exhaust from Buschur Racing? I have heard that it is one of the better exhausts in terms of actual results for the Evo.

Incognito

iTrader: (8)

This car doesn't lag much. Try driving a Supra TT w/T72 turbo. Feels like **** before 5000rpm. It's all over after that though

A smaller, ported turbo would reduce lag, but it takes away from top end power.

EVOeight

I was really just trying to get input on ways to reduce the turbo lag. I realize that some turbo cars are worse than our EVO's. I was hoping for more "tips and tricks" to reduce turbo lag than the one's I listed at the top...