After installing my Kennedy Boost Stick, I have noticed that if I go WOT the boost pressure will peak at 35 psi and it scares me and I back off the throttle. The most I could get stock was 24 psi. I have the 06 LLY and know that GM dropped the compression on the LLY/LBZ for emission reasons....but the question is...How much boost pressure will it take?
It works great... I get better mileage, lower EGT's and way more power, just don't want to blow a gasket or turbo.

50+ psi on stock headgaskets and stock headbolts.

50+ psi on stock headgaskets and stock headbolts.

WOW...never thought it would take that much....Thanks Ben:rolleyes:

Just so you know, the engine can take that much, but that is pushing it with the stock turbo. It may or may not cause failure. 35 is right at the limit of the stock charger. I try not to go over 32 and prefer to keep it at or below 30.

Just so you know, the engine can take that much, but that is pushing it with the stock turbo. It may or may not cause failure. 35 is right at the limit of the stock charger. I try not to go over 32 and prefer to keep it at or below 30.

When I researched Kennedy's site, he mentioned that 32 psi would probably be the max pressure but mine is peaking at 35+ psi. Would my Predator set at 120 have anything to do with that? I don't want to blow up the turbo, but I don't believe it is spinning any faster, just that the vanes are changing pitch more than the stock limits and providing more boost pressure.

Is it spiking to 35 or sustaining 35?

When I researched Kennedy's site, he mentioned that 32 psi would probably be the max pressure but mine is peaking at 35+ psi. Would my Predator set at 120 have anything to do with that? I don't want to blow up the turbo, but I don't believe it is spinning any faster, just that the vanes are changing pitch more than the stock limits and providing more boost pressure.
32 sustain for LB7 turbos. dont know about the lly/lbz/lmm turbo

WOW...never thought it would take that much....Thanks Ben:rolleyes:


The question was how much would the engine take. Ben answered the question correctly so why the:rolleyes: smiley?

The engine will need studs to maintain combustion sealing over 55PSIG.:)

50+ psi on stock headgaskets and stock headbolts.



care to show me how to do that:eek: im on set # 4 and havent seen 50 psi

YET:D


any idea as to why im going through them?heads where checked each time

Is it spiking to 35 or sustaining 35?

I'm not sure and a little scared to find out. Definately spiking to 35, I'll have to try it again and hold it WOT for more than a few seconds. I'll let you know.

The question was how much would the engine take. Ben answered the question correctly so why the:rolleyes: smiley?

The smiley is so now I can stop worrying about the motor blowing up.

The engine will need studs to maintain combustion sealing over 55PSIG.:)

I don't plan on ever getting to 55psi. I'm happy with it the way it is.
I'll just worry about destructing the turbo now.

i keep hearing that it can hold a constent 35 and have a max spike of 40

care to show me how to do that:eek: im on set # 4 and havent seen 50 psi

YET:D


any idea as to why im going through them?heads where checked each time


Your drive pressure is probably crazy...

How much timing are you running?

with my HTT on drive pressure never exceeded boost so 42psi max

with VVT ive seen as high as 85psi on a few tunes ,but got that lower to maybe peak of 55-60psi for quite a while before blowing gaskets

timing when i blew my last set was 27.2 peak and my timing is lower than most in the lower RPMs

I'm not sure and a little scared to find out. Definately spiking to 35, I'll have to try it again and hold it WOT for more than a few seconds. I'll let you know.

its useally on shifts you will see the spikes,

Remember that the compression is lower on the LBZs. Lets the turbo build the cylinder pressure not the static compression.

How do you figure drive pressure. Is this something EFI can read? Or do I have to figure it out some other way.

-Kyle

How do you figure drive pressure. Is this something EFI can read? Or do I have to figure it out some other way.

-Kyle

you can do both,but i just rig in a gauge 0-100psi fuel pressure gauge and tied on to my DS exhaust mainfold ( BD ) and then ran a chunk of tubing to the gauge sensor

i do plan on logging it though and for that you use the external inputs and use a calc.PID

Sounds simple enough... No problems with melting the tubing though?

-Kyle

Tried WOT today and it holds 32 psi until it shits then pegs the gauge (autometer 0-35) for 2 seconds then returns to 32psi.

Sounds simple enough... No problems with melting the tubing though?

-Kyle

no not at all, you must realize that the tubing line doesnt flow,if it did then it would get real hot,im geussing it never sees over 400f max

i use t304 SS but other has used just a high heat hose and there still OK


and yes its very simple,proably the single most benificial mod ive done
stock tune has a ton of drive pressure,compared to a lb7,ive yet to check the lbz

Tried WOT today and it holds 32 psi until it shits then pegs the gauge (autometer 0-35) for 2 seconds then returns to 32psi.I think you're alright.

The question was how much would the engine take. Ben answered the question correctly so why the:rolleyes: smiley?
The engine will need studs to maintain combustion sealing over 55PSIG.:)

Agree, the question was how much will the engine withstand, but it seems ffden didn't realize the turbo would blow first.
Seems the extra info tought ffden, (and maybe others), something he didn't know, and may have saved him some problems and $.

Tried WOT today and it holds 32 psi until it shits then pegs the gauge (autometer 0-35) for 2 seconds then returns to 32psi.

SHIFTS not Sh*ts

SHIFTS not Sh*ts


i got a laugh

care to show me how to do that:eek: im on set # 4 and havent seen 50 psi

YET:D


any idea as to why im going through them?heads where checked each time
:damnit1:

Agree, the question was how much will the engine withstand, but it seems ffden didn't realize the turbo would blow first.
Seems the extra info tought ffden, (and maybe others), something he didn't know, and may have saved him some problems and $.


what do you mean by this? the turbo will blow before what?

I believe he means that the stock turbo will fail before the max boost pressure it can obtain damages any other part of the motor.

-Kyle

I believe he means that the stock turbo will fail before the max boost pressure it can obtain damages any other part of the motor.

-Kyle


IC, i geuss head gaskets dont count:D

IC, i geuss head gaskets dont count:D
Only for Canadians:D

Only for Canadians:D

I bought my truck in Texas and it was made in Flint, Mi...so if it blows a gasket...Do I replace it with one made in Mexico or China? Or do I order one from Izuzu in Japan?

Tried WOT today and it holds 32 psi until it shits then pegs the gauge (autometer 0-35) for 2 seconds then returns to 32psi.
same here on my lly with same tune and same gauge.

My turbo lasted with spikes of 35+ and sustained 32 for about 10,000 miles. I removed the ppe crack pipe and now spike 32 and sustain 30, on a new stock turbo.

I would be careful with the the boost foolers. My boost gauge only showed 35 and it would spike all the time on shifts, especially when towing. It also caused lots of turbo barking on wot runs when letting off the pedal.

Pull the intake tubo off the turbo and shine a light in. You can see the fins and check for excessive wear and play. You could tell mine was starting to go, fins on the edges wear a darker cooler and they had small chips and bends on them. Lasted for 2,000 miles after I saw this. Truck ran fine then started have bearing noises from the turbo about 1,000 miles after checking the fins.

Getting a stock turbo is easy and if you get a good deal they can be found for $300 or so. Replacing is the pain and cost more then the turbo.

I am not sure it is worth the extra couple pounds of boost. I never noticed a drop in 1/4 times with the fooler and sotp meter couldn't tell a difference. On a stock engine and stock turbo I don't think it is worth it. If you can spike 30 and sustain 28 or so with just programming I think you are safer in the long run.

Just my experience and suggestions, others have had better luck.

Our 2005 would go to 59PSI sustained with a certain tune and a GT4202R charger on the stock head gaskets.

Your biggest fear with a stock charger is not the headgaskets, but instead, melting the turbine or vanes. You are looking at EGT's not boost for danger signs. Anything over 1600 deg even for short bursts puts your charger at risk.

Casper ate two OEM VVT chargers before we gave up on them. But headgaskets were never a boost issue.

Our 2005 would go to 59PSI sustained with a certain tune and a GT4202R charger on the stock head gaskets.

Your biggest fear with a stock charger is not the headgaskets, but instead, melting the turbine or vanes. You are looking at EGT's not boost for danger signs. Anything over 1600 deg even for short bursts puts your charger at risk.

Casper ate two OEM VVT chargers before we gave up on them. But headgaskets were never a boost issue.

You have answered my question. Thank you McRat.:)