I was just wondering if boosting the evo to 19psi to redline is safe. I know at lower rpm's its at like 18.7 or something and then drop to 16.6 or something. dont know the exct numbers. But jw if this is safe. I have heard of a ton of poeple boosting over 20psi to redline. Thanks.

 

Should be just fine... That's what I do daily in my GSX, with a 20g turbo and stock internals... Works just fine...

 

Perfect...stock is 18.5 so you can EASILY do that and more!

 

Is this still advisable in the lower 91/92 octane areas?

 

I'm going to be blunt. If you have to ask questions like "is it safe to run 19psi to redline" or "is it safe to do it on 91 octane", then the answer is no. Don't do it. I'm not trying to be a you know what. I'm trying to steer you guys in the right direction. Learn what's involved in running a car at 19psi daily, get the proper monitoring in place, THEN you'll be able to answer your own questions. When you no longer have to wonder if it's safe, it'll be safe.

Thomas Dorris

 

Its safe. You'll probably endup with that after adding exhaust (full exhaust) and intake.

 

I love the EVO to death... but the one thing that irrates me is the STi lovers are saying that the STi will be boosting 14.5psi i belive...that is really low compared to the EVO and they're number better.. interms of hp and torque.. is 19psi safe? YES, wasn't the 4g63 capable of handeling up to 22 or something... but obviosly 14.5psi is alot safer...

We'll just have to wait and see...

 

hey

make sure you heed twdorris's advice. the EVO ECU in NOT like the old gsx's. and if you are in cali or wherever that runs 91 octane, be especially careful. the gas here is **** water, and if the car runs lean for any reason (a cold night 4th gear run on the hiway) you could do some serious damage. this motor is VERY solid, but make sure you have something to monitor boost, egt's, A/F ratio, etc before turning up the boost.

just be careful, and you will be rewarded.

josh

 

lets see.......

Evo VIII stock + 91octane = knocking like hell

Evo VIII 19psi to redline + 91octane = ring ring, hello Mitsubishi my motor blew up yesterday... sorry sir your warrenty is voided....

 

19 psi stock 14.5psi stock

 

good thing I run with 94 octane gas... 19psi to redline =

-Shahul

 

or a blown engine...wtf do I know

-Shahul

 

No.
The most boost you can run on 91 octane is probably about ~15psi.

You cant compare boost pressure between different cars, using differnet turbos. 18psi to a t3/t4 turbo is not the same as 18psi on a t88-34d thats the difference between 300hp and 700hp.

Sounds like someone knows what they're talking about

 

Do we know what the compression difference between the two cars is going to be? That will make a huge difference on hp as well. The big difference is that in one car you have 2.5 l of 14.5 psi air, and in the other you have 2l of 19 psi air. Total amount of air wins.

The turbo comment is correct too. The same psi is not the same air flow in different turbo's. One thing though, is that I am not sure that the STI turbo is any larger than the Evo. In fact I think it is smaller. I don't believe though that it can efficiently reach 19 psi, so those who think you can just boost the STI are mistaken. It won't get there.

Once again though, both are awesome cars. You need to look at the whole package of each, because picking apart pieces will get you nowhere. If you can actually get one of these cars, you are going to be more than happy, and to those not getting them, it shouldn't be an issue.

 

I thought about ignoring this, but decided what the heck. 18psi on a 2 liter motor is 18psi on a 2 liter motor. As long as the two turbos aren't completely out of their efficiency ranges, they'll both fill 2 liters with the same amount of air at 18psi. Going from a decent sized t3/t4 running 18psi on my 4g63 to a t88 running 18psi on my 4g63 isn't going to add 400 hp. Displacement is the limiting factor there.

[edit]Upon reflection, I've decided I may have misread dmora's post slightly. If he's talking about the original comparison between 14.5 psi on a 2.5L motor to 19psi on a 2.0L motor, then his statement is at least partially valid. You have to consider displacement in that comparison and you have to consider turbo efficiency. But I still object to the t3/t4 at 18psi compared to a t88 at 18psi generating +400 hp on the same motor.[/edit]

Thomas Dorris