There's not much debate on this topic; too much boost will kill your engine. The real question is, how much is too much? More importantly, how much is safe? Two vendors have told me 17 and 18psi. I've seen some signatures with 10 psi and some with 15 psi....and let's not forget the guy up north driving around in the grenade set to 21psi...:lol: :joke: .

Let's hear it. How much boost is everyone running? Please specify if major repairs have been made to the motor....ie head gaskets.

I'm running 17 psi at wot.

You know me, Mr. Conservative, bone stock, let the computer do the figuring out.

As mentioned before, some reduction in EGT's for some un-figure-out-able reason with higher boost levels. Maybe it's because there is more air available than what the fuel can burn, and reduces the temperature?

My thinking is too much boost is too much extra stress on the engine. So, if GM has a limit, I'll just abide by that. They at least want it to go long enough to get it out of warranty, but strong enough to sell the trucks. So, stock sounds good 'nuff for me.

I run at about 14lb WOT range. It seems to make the engine happy. I did crack a piston, but I blame running it hard without gauges and getting the EGT's way too high.

Tim

I survived my cracked piston experience to drive again. 15-20 psi without an IC is asking for the same.

Hey now, i've been to 21 psi on a "see how high we can get test", i think i could go higher but didn't try it.
I'm not running it there all the time. I cruise @ 75 mph, 8-10 PSI, 14-15 psi on the hills. Towing was running around 15 PSI. I will probably make some adjustments when the IC is in though.

I run at 15 psi with an intercooler. The reason I limit it to this is more for the IAT than anything else. I found that anything above this seems to make quite a jump in IAT and it didn't really seem to make that much difference in performance or EGT on my truck. At 13-14 psi I still had to watch the egt when pulling a loaded car trailer on hills and such, but with it at 15 psi I'd have to try real hard to get into the 900 deg range, post turbo. It's happy here, I'm leavin it alone:exactly:

Is your IC a home job or did you get one from one of the vendors and if so, who's is it?

Higher Boost pressures pack cylinders with more air, reduce peak combustion temperatures, reducing oxides of noxious.

Diesels like running 'lean' - more air than fuel - at most all power levels.

6.5 is limiting factor amongst itself, much less IDI for sustainable high power levels..

IMO, based on facts, sustained Boost = 8-12psi , no charge air cooler, depending on ambient; 12-15, peak to 18 with cac; 12-18, peak to 20 with 18:1, cac.

Drag-racing - whatever limit gets you back home.

Surf on over to Banks Talks Tech for the facts, in detail.

Impatient? Can't read? Take my word on it.................

Oh, yeah - mine? 8-15, peaks to 18, sometimes 20 in wintertime.

Conservatively.:cool:

I am guessing that information is dependent on the GM-x turbo. If there happened to be another turbo that didn't superheat the air at 15-20 psi, what would the maximum boost be? See this tool (http://www.turbofast.com.au/TFmatch.html) for more information.

Well unloaded I normally see around 15-16 psi wot. This past weekend I was towing about 13,000lbs behind me up a really steep grade in third gear and heard the turbo scream when I went to wot. Looked down and to my surprise 21psi. I quickly let out some to save my pistons from out running my truck. It might have held it, and it really sounded cool, but I would rather not risk it on a college students budget!! haha

what is the max boost one could see with the stock gm turbos? I have a friend that is running with the waste gate fouled open on his truck. Seems like this could cause alot of uneeded stress on the motor.

If the wastegate were hung open, he would have zero Boost - is that the problem, odee?

Both halves of the third sentence are the key, ST, even for an 18:1 'stock' 6.5.

One day while bored, I cranked up my turbo master just to see what I could get and I could easily get 20+psi but it scared the hell outa me. At least I know what my turbo is capable of.

Normally I run 12psi with my driving style but my turbo master is set at 15 WOT. Been running this way for almost a year with no problems. Knock on wood.