What is safe boost?

vegas39 · Jan 18, 2012

All the times I've hot rodded my truck on the flats, I could never hit more than 10 pounds on the boost guage.
Last night I was climbing a grade outside of town and realized I was running 950 on the pyro and 13 lbs boost, I only did this for a moment but was wondering what is the safe boost for a 6.9 motor with studs? So far I have put about 25 thousand miles on my truck with the head studs installed but most of the time never had the boost much past 8 or 9 pounds.

Is it safe to run a constant boost over 10 pounds with these things? Maybe I need to bump the fuel down just a hair.

Ididriver · Jan 18, 2012

It sounds like you could bump the fuel up with egts that low.
And you can run more boost than that with studs.

vegas39 · Jan 18, 2012

Dont know if I would call 950 low, I was only on the hill for a couple minutes but I guess as long as it stays below 1150.
I was more curious if running at 13+ pounds is acceptable for any great length of time, studs or not.

GreenDiesel · Jan 18, 2012

not an expert by any means, but under 15lbs seems reasonable

Diesel JD · Jan 18, 2012

They can hold a lot of boost with studs and you probably won't blow a head gasket, questions are is your turbo still on it's map at those numbers and are those EGTs pre or post turbo. If they're pre turbo hot side) I'd call them very much acceptable, if they're post turbo, you need to back off the fuel a hair or at least watch your go pedal when you're heavy.

icanfixall · Jan 18, 2012

I bet it was really cold so the boost would be up a few lbs from what a normal boost would be.. I feel 14 or 15 is fine with studs. Any higher that the air is really hot going into the engine. But on a realld cold nite when the air is much denser... Go for it and see if 16 or 17 feels any more powerful. The studs and head gaskets will handle it provided they were installed correctly. If this the valve job done in San Diego a few years ago. If so I'm thinking your able to depend on the work. The 15,000 miles kinda tells me its running well.. Besides the trans issues last year.. That was driving me nuts. Actually it wasn't much of a drive.. More like a put sending me over the edge. That issue caused me to buy lots of spare parts.. Wow... I'm back from the edge... :hail

johneich · Jan 18, 2012

icanfixall said:
That issue caused me to buy lots of spare parts.. Wow... I'm back from the edge...

Gary, were did you put the spare parts? certainly not behind your seat!?!

George D. · Jan 18, 2012

Wich hill? state line or apex?

vegas39 · Jan 18, 2012

George D. said:
Wich hill? state line or apex?

It was the hill by the overton turn off. Usually when I climb it there is always someone holding up traffic but last night it was free and clear.
The more I pushed the accelerator, the faster she wanted to go. I finally let out of it when it hit 13 pounds but I'm sure it would have gone a tad higher.

George D. · Jan 18, 2012

IIRC that hill isn't too bad unless you were on it I would consider turning down the fuel espacialy since you have a C6. I run about 900* empty up stateline in OD if I accelerat hard enough to downshift to 3rd I'm at 600-750*ish I max at 9psi if I realy try on a steep grade but I don't have studs.

Of course it sounds like you were pushing it so you're probly fine.

Diesel JD · Jan 19, 2012

Well one thing's for sure on an IDI, you can always just not push it as hard and drive by the pyro. There's no possible way I'd ever turn down the fuel unless it was to pass an emissions test or I was just way too high on EGTs or had lots of smoke. I think you'll probably have to be careful if you get a big load on it especially up in higher elevations however. You don't need less fuel/boost you need more air! Now you have an excuse to get an IC, H2o injection, and/or a better turbo.

FordGuy100 · Jan 19, 2012

Past 15psi these turbos are a screaming. They sound like they are turning some serious rpms.

Reminds of of a 2 stroke engine with no governor, turning so many rpms that it doesn't have that 2 stroke pop and cackle sound, just a loud buzzing LOL

Diesel JD · Jan 19, 2012

Is an ATS 093 comparable to Vegas 39's Banks? I can't remember if he has the non gated or the gated Banks. Totally different turbos...I also don't know if they're both off their maps up there.

6.9poweredscout · Jan 19, 2012

icanfixall said:
I bet it was really cold so the boost would be up a few lbs from what a normal boost would be.. I feel 14 or 15 is fine with studs. Any higher that the air is really hot going into the engine. But on a realld cold nite when the air is much denser... Go for it and see if 16 or 17 feels any more powerful. The studs and head gaskets will handle it provided they were installed correctly. If this the valve job done in San Diego a few years ago. If so I'm thinking your able to depend on the work. The 15,000 miles kinda tells me its running well.. Besides the trans issues last year.. That was driving me nuts. Actually it wasn't much of a drive.. More like a put sending me over the edge. That issue caused me to buy lots of spare parts.. Wow... I'm back from the edge...

yeah i noticed with the cowl intake on the colder days the boost is a lot more instant and the go pedal is a lot more touchy. the other day it was in the 50's and the truck was noticeably slower off the line! ;p

What is safe boost?

vegas39

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