how mcuh boost?

[mr2turbo]

I did some light searching and didn't find what I wanted, so, How much boost can I run with all the supporting mods, but I've never cracked open the valve cover so I have no upgraded headgasket or arp head studs.


mods are
80k
fmic
evo3 16g
walbro 255
680cc's
3'' turbo back
ported mani and o2
maf-t
mbc
boost gauge
other little stuff



so what's the max boost I can run without blowing a headgasket or lifting the head?

 

[diablos991]

Get a logger and set your boost at 15ish then increase it while monitoring for knock(1g) or timing advance (2g) and tuning what you can out of the maft.

Really, every car is different, so its hard to give you an accurate number.

Also, do you have an AFPR for that 255lph fuel pump?

 

[ericbev]

http://www.dsmtuners.com/forums/showthread.php?t=191468&highlight=stock+headgasket

The stock HG can go along way with a proper tune, and can go even farther with a set of headstuds. They are easy to install and great insurance.

 

[NewTurboTuner]

Its hard to say how much boost you can run. It depends on you setup, and has alot to due with your tune. Every car is different... even if they have the same mods.

You need a Data logger to see what is going on inside the car. Also check your spark plugs to see what they look like. If they are black then you are running too rich. If they are white then you are running lean and probably getting detonation.

I would not go past 15psi without it a DATA Logger, or Wide Ban o2.

 

[mr2turbo]

datalogger shows o counts of knock at 17psi. I want to put race gas in and turn up the boost to 23/24ish psi. so the stock headgasket and hardware should hold up according to the thread ericbev gave

 

[ericbev]

People have regularly seen 20-23psi on pump tunes, but that is obviously circumstantial. You probably have quite bit more to go with your pump tune.

Do us all a favor and update your profile with all your mods etc. It will be helpful for all of us down the road.

 

[daren_p]

Like everyone one said, get a datalogger/use your datalogger and tune for knock. You can blow a head gasket at lower boost levels if the car isn't tuned properly. For reference my boost gauge was reading low & I thought I was running 20 psi on my evoIII and it turns out I was actually running like 23 psi on pump 94, tuned ~11 to 1 without any knock. At that point I had nothing done internally & didn't have any issues.

 

[NewTurboTuner]

With a stock Head gasket, and bolts .....Man you are sooo asking for trouble at 24psi.

You better have it tuned perfect!
I personally don't think it is worth the risk.... but if you really really want too .....Don't go strait from 17psi to 23-24..... dial it in by raising the boost by 2-3lbs at a time.

 

[GVR4592]

With a stock Head gasket, and bolts .....Man you are sooo asking for trouble at 24psi.

You better have it tuned perfect!
I personally don't think it is worth the risk.... but if you really really want too .....Don't go strait from 17psi to 23-24..... dial it in by raising the boost by 2-3lbs at a time.

This is where everybody that is running 24+ psi on pump gas and completely stock engines, chimes in and tells you that you're wrong. I'll be the first one. I ran exactly 24 psi on pump gas, on a completely stock engine for a very long time with no problems.

I always get shit for this because I have a Cometic and ARP's now. The only reason I have them is because I had to pull the head and I didn't have a stock gasket to put back on. So I used the Cometic and ARP's I had bought years earlier when people were telling me that I couldn't run more than 18 psi on the stock head gasket. That gasket and those studs sat on the shelf for a very long time. They'd still be sitting there if I'd had a stock gasket to use when I pulled the head.

The stock gasket works for almost anything, the stock bolts are comparable to the ARP's. If there is no detonation, then I don't see the bolts becoming a weak link until somewhere after 700whp and 40 psi. Most problem's with them is their age and how many times they've been reused.