Hello!

I have the following engine mods and wonders what boost level I shall run, I want a good safe margin!

- RS*R EXMAG GT-II 80mm SS Cat Back
- RS*R EXMAG 80mm SS Down Pipe
- HKS RS Intake Kit
- HKS SSQV Kit
- Walbro GSS342 255l/h Fuel Pump
- AEM 30-1313 with 3.5 Bar MAP Sensor and Intake Air Sensor


How much boost can a stock engine take? (we are not talking just one 1/2 mile run but a daily hard driven car)

Please I want hard facts no guessing.

 

What octane?

 

20-21psi if you have 93 octane. I don't know what octane you have, though.

 

I'm set at 22.5 psi daily driving with tbe, flash, mbc.

with aem, you could boost up to 23 psi daily without problem, but once you go over 24psi or 25 psi, there is going to be more than normal wear on the turbo.

but then again, there are people boosting 28psi daily with the stock turbo, no play on their stock turbine with alky kit.

it does go out of the stock turbo efficiency level though.

And it really doesn't matter if you have 91 or 93 octane, there are ways to tune it with AEM EMS.

good choice on aem by the way. 30-1313 i hope.

really, long as it's tuned for it, you don't have to worry about safety. But if you're worried about the wear and tear issue, stick with the stock boost level at 19.5 or 20 psi.

since you don't use maf anymore, you could go high as 30 psi on stock turbo, as long as all the supporting mods are there.

 

We have 98 Oct here, I think it's about the same as your 93..

I'm not so worried about veer on the turbo, just the engine! I really don't want to risk blowing my engine.

 

I would agree that close to 21 psi is safe.... much more and you might be a little on the unsafe side. I run 20-21 psi with all the mods in my sig with no probs so far. Here in Colorado the air is thin and we only have 91 Octane though... at least you have good engine management and a Walbro to keep up with fuel demand.

 

21-22 psi if it's the same or better than 93.

 

21-22 sound low...

I had hoped around 24-25psi, can the stock engine handle that?

 

The engine can handle 24-25 psi, but I don't think you can do it on 93 octane. That sounds like too much for that octane. It definitely won't be a safe tune.

Maybe a higher octane would get you to your goal.

 

Well the thing is that all Evo VI with the aprox same mods run around 22 psi and they have crappy internals! With a built motor they boost over 26 psi!
As we know the E8 have much better bottom end so I figured that it wouldn’t be any problems going as high as 25 but you guys think different?

 

You can go to 25, but not on 93 octane. Running 25-26psi on 93 octane will most likely cause you to detonate the engine. KABOOM!!!

The max you want to run SAFELY on 93 is 21-22 psi. Anything over that would need a higher octane like 97-100 octane. Do you understand Reine?

 

The stock bottom end on an Evo VIII is good up to 450whp. Anything over that in my opinoin is too much and not safe. Some people have tuned it for 500whp, but eventually killed the motor. At 500whp new internals are needed to safely run that much power.

 

Got it!

How does people boosting higher do? They can't be running on race fuel all the time.

 

Water injection, alcohol injection, mixed 50/50, or methanol injection allow you to run higher boost on pump gas(93 oct).

 

some run into problems with head studs stretching and blowing a head gasket. i am running 1.6 bar or about 23.2 psi and im running fine. u have to remember that our engine has a knock sensor but im not sure if it can detune the engine if u have a boost controler . i would worry about blowing a head gasket and knock. i run that boost on 93 oct but its not like i beat my car either. i drive it like i was 80 years old. rarely ever boost it at all, and when i do its just to make sure everything is working properly. so remeber if u beat ur car there will be problems, always is.