boost?
 

how much boost is to much on a 94 stock head gasket and bolts?

from what i have read on here around 50-55 with a retorqe

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dont know how long that last though

I dont like seeing over 40 psi without head studs. Anything above that and you run a good risk of blowing the headgasket anything below is relativley safe

on my 95 i ran 40 psi maybe a little under for about a year and had no problems. the third day that i tightened up my boost elbow i saw 51psi and pop my head gasket blew. scott is right keep it under 40 psi for good reliability.

ok thanks for the help :tu:

If your gonna keep the stock turbo. i wouldnt go over 35psi.

What is stock boost I don't have a boost gauge yet what do they push stock

mines stock and im pushing 24psi. but im also running on 5 cylinders most of the time :argh:

what if you have head arp head bolts instead of studs can you push it over 40?

Usually in the 18-22psi range, depending on a few things... Auto/Man, Year, etc.

I only saw 16-17 or so before I added a boost elbow (not an adjustable one, just one with a small-calibrated orifice that came with the #0 plate.), then I saw 23ish.

I'm gonna block off the WG and see what it blows to on the stock turbo, with minor AFC mods (housing slid forward and 0 plate in the 'normal/mid' range. Was previously in FF but I wanted lower EGT's at WOT.)

The only point of getting studs is keeping from blowing your headgasket. and i wouldnt push it that far because you can gernade the turbo

Yeah with studs I build 55 on the street with my turbo. When i had my stock i could build 42 and but i didnt like doing it. And like dirt diver said we do studs to prevent headgasket issues. But i wouldnt build over 30-35 psi boost for your turbos sake

I agree with the limits imposed by a stock turbo-low 30's is about it. My experience on the headgasket itself is different. I've been running 45 psi since Jesus was a baby, with the occasional 50 hp shot of nitrous thrown in for good measure, and my timing is at 15.5 degrees. Original gasket and bolts, not retorqued, with 272,000 miles on it. Running like a champ. I may be the luckiest SOB on Earth, so don't assume you can do as I'm doing and not pop the gasket. I'm just throwing this out there.

ive heard if your timeing is under 16.5degrees you wouldnt have to worry about it. When your timeing is above that, thats when you gotta start wondering

im running about 36psi on the stock turbo with no issues, i had no idea stock boost was around 18, my truck has been tampered with before i got it. am i pushing the turbo to its limits? its a 5 speed truck so its got the bigger turbo.

Yes, you are pushing it to the limits. It's not that it'll necessarily fly apart (though there is a chance of that), but rather that you're running it beyond the airflow and boost range where it's efficient. That means it starts adding much more heat to the air than a properly sized turbo producing the same boost would add on the same engine. In technical terms, the adiabatic efficiency drops way down. Hot air is less dense than cool air. This means that a given volume of hot air contains less oxygen (and less of every other gas that's a part of air) than cooler air of the same volume and pressure. This is why we have intercoolers-to get the benefit of pressurized air without paying the full penalty of the heat that turbochargers add. When you push the turbo too hard, it adds so much heat that the intercooler can't get rid of enough of it for the extra boost to really help. You end up working the shit out of your turbo for basically nothing, when backing the boost down a few pounds would be much easier on the turbo and not really lose anything in terms of mass of air delivered to the engine.

my truck always makes a loud growling noise when i really lay into it, is this caused by excessive drive pressure on the exhaust side or do all cummins make this noise? the tone of the noise is very similar to the growling noise you would hear from a manual tans lugging below 400rpm but alot louder, louder then the turbo and exhaust combined... thats about best way i can think to describe it. i cant decide if its just loud injectors, just a weird exhaust note that im ot used to hearing, turbo noise, i just want to know if this is normal or related to my turbo being pushed to hard.

that being said, the turbo shows no excessive wear, in fact its in really good shape. the reason im afraid to dial it back is because im ok with the waste gate bleeding off some drive pressure at wide open, but i really don't want it doing it all the time because it will make the turbo spool slower, and ill have to dial back the star-wheel to prevent excessive smoke. is there any way around this? id like to limit the boost but i dont want to be bleeding off drive pressure all the time, i want it to spool quick and then the waste gate start to open up... is this how it will function if i make the waste gate functional again? im really very new to this, im normally pretty good with engine stuff, i built and tuned the motor in my last truck and im familiar with forced induction but this is my first turbo(had a blower on my last truck) and this is also my first diesel.