The other day when playing around I had the E/J set on 3X5 (no trans upgrade yet) and I got a warning alarm on the E/J. The boost hit 30.4 :eek: I thought I remember reading somewhere on the DP that anything above 28/29 was too high. Is that right? Am I risking something by going WOT and getting the boost that high? What happens when I get my trans upgraded and start running the E/J on 5X5? Any help would be appreciated.

Is there such a thing as too much:rolleyes: ??

If you didn't touch the turbo I think your OK no matter what. No matter what setting. There are LB7's running over 50psi with Aurora5000's. However, someone with more LLY experience should chime in.

And a final note: "Anything worth doing, is worth OVERDOING!!!"

Hm........ I was just investigating boost the other day.
The conclusion was that the stock Turbos on the earlier LB7 were good for about 35lbs. After that things may deteriate fast. 01-04 models have the stock wastegate set at 31 lbs. Not sure about the newer Duramax turbos, other than I understand there is no wastegate.

Another thought is: do you have a guage reading the 30 lbs of pressure ?. I am told that Edge/Attitude monitor only reads off the stock Map sensor and will not give readings over 27 lbs. (My knowledge is more geared toward the 01-04 Duramax)

The other day when playing around I had the E/J set on 3X5 (no trans upgrade yet) and I got a warning alarm on the E/J. The boost hit 30.4 :eek: I thought I remember reading somewhere on the DP that anything above 28/29 was too high. Is that right? Am I risking something by going WOT and getting the boost that high? What happens when I get my trans upgraded and start running the E/J on 5X5? Any help would be appreciated.

I've seen over 30 ( the limit of the attitude reading from stock sensor), the LLY will go a LOT more than that.

McRat had a gauge on his and IIRC was over 40psi w/ some programming.

Different turbo and psi levels between LB7 and LLY.

Stock OEM boost settings for all LB7 engine is 18 -20 psi, that's it. When aftermarket tunes are added the boost will go as high as 27 at sea level. This is because the wastegate cannot flow enough to lower it futher. Any time you take an LB7 turbo above 32 psi you are playing with fire. One should talk with Got Juice about his testing and his infamous Juice Grips. On a stock OEM LLY you will see 20 - 22 psi stock. With aftermarket boxes stacked I've seen as high as 44 psi but only for few very short dyno pulls. Will they live at that level is yet to be seen.

I don't know where the limit is, but I did find out the hard way that 46 psi is too much :eek: Some may hold up for a while at these numbers, but mine blew the first time.

Stock OEM boost settings for all LB7 engine is 18 -20 psi, that's it. When aftermarket tunes are added the boost will go as high as 27 at sea level. This is because the wastegate cannot flow enough to lower it futher. Any time you take an LB7 turbo above 32 psi you are playing with fire. One should talk with Got Juice about his testing and his infamous Juice Grips. On a stock OEM LLY you will see 20 - 22 psi stock. With aftermarket boxes stacked I've seen as high as 44 psi but only for few very short dyno pulls. Will they live at that level is yet to be seen.):h

LB7 Turbos... the Short Version Taken with the assumption of Sea Level Elevation. Boost Read at Inlet to engine.

42PSIG=Boom. No Forgiveness whatsoever.
40PSIG=Boom. Same as 42PSIG
38-39PSIG= Borrowed time.... bad hooey, slowly slowly SLOWLY back out od the throttle.... one good bark is all it takes to trash the turbo at this level.

35-37 PSIG.... you are 'relatively' safe. Walk out of your burnouts.... not all turbos are created equally..... I had one let go after 8 months of running the snibbins out of it at 37.... the new replacement that went in died in 2 weeks at 36 PSI. WTF is up with that?

35 and under PSIG, you are close to the edge and probably will not F anything up at this level*

*Disclaimer* To be 100% 'safe' please drop .5PSIG of boost per 1000' ASL you live at..... it's the only way i believe safe as a general rule of thumb. Air density also decreases with high temps and low humidity. For arizona climes I would suggest losing .7 PSIG of boost per 1000' ASL.


Oh.

One

More

Thing




Back Away From The Juicegrips(TM)):h

HDmax, did your turbo let go or a head gasket. Anyone know what pressures the head gaskets will take? Juice, what pressures are you running now with the twins?

Rob

HDmax, did your turbo let go or a head gasket. Anyone know what pressures the head gaskets will take? Juice, what pressures are you running now with the twins?

Rob

I don't know where the limit is on a non studded head with the stock ml gaskets.
Currently running 50 lbs with no issues. The system is capable of 80 PSI, buuuut I am not going to push beyond 50 right now for a couple of reasons.

Reason#1 Head Studs are not installed.
Reason#2 At 50 PSIG I am currently burning all the fuel that a stock CP3 Pump can push through. I get the initial black cloud on a dead stop takeoff, then everything is clean so there is no reason to go any higher.

Certain LLY stacks will make 40+ PSI. Van Aaken + Predator is one, hit 45PSI.

Jury is out whether the additional boost actually helps. I ran a 40+ PSI for many 1/4mi and dyno runs, as well as extensive street use.

HDmax, did your turbo let go or a head gasket. Anyone know what pressures the head gaskets will take? Juice, what pressures are you running now with the twins?

Rob

This happened two year ago next month, it was the turbo. It grenaded while I was manually shifting the ole girl. At about 3900-4000 rpm she squealed like a pig in heat, then started pouring white smoke, it was so bad, I could not see past the back bumper, the entire highway was 100% fogged. People had to pull over because they could not see anything.

The shaft was completely clean of any fins in the turbo. The hoses, turbo, and intercooler was replaced, and this turbo whistles 5 times better then the original one ever did. I think it had a bearing problem or something, because the new one made a huge difference.