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Boost?

bison

bison

Well-Known Member
Messages
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176
Location
Near Peace River-Alberta
I was just curious,and put a boost gauge on the 95. GL4 turbo
cruise gives only 1 pound,climbing a 7% hill at 2000 rpm/100 km/cruise on, boost gets only 3 psi.Truck pulls good,no shift down,RPM steady.
WOT nets 4 psi max.
kinda meagre me thinks,is this normal?
 
Sounds like mine before I did the 4" exhaust. With my GL4 before I got a turbo-master I'd see 3-4 lbs at cruise with boost up to 10-12lbs
 
Heath really insists that his chips need a turbomaster (or home made version of one) to get the benefit from them. Then again if you are happy with the performance you have now, I'm sure you are burning less fuel with the low boost than you would pushing 10 lbs.
 
bison said:
I was just curious,and put a boost gauge on the 95. GL4 turbo
cruise gives only 1 pound,climbing a 7% hill at 2000 rpm/100 km/cruise on, boost gets only 3 psi.Truck pulls good,no shift down,RPM steady.
WOT nets 4 psi max.
kinda meagre me thinks,is this normal?
Click to expand...

Very close to what mine was before TM. First mod i did was guages.

TM added boost now, 2-3 cruisuing, 9psi boost average on my highway hill climbs.

EGT's on same climb went from 900 to 650-700, just by TM alone.

Still have factory exhaust kitty ran away though...

FWIW TM set to 2 1/4", most i've seen burst is 12. No codes on stock 'puter.
 
My dually will push 12 PSI easy with the TM and the Heath Chip, Banks exhaust system.

Very good power and will run 18-20 MPG on the hiway running light.

MGW
 
My factory GM8 with factory ECM and factory vacuum waste gate is just happy as a clam with 13-15 psi over barometric. I don't know what that'll do for EGT's, but that's what the ECM calls for under a heavy foot with empty truck.

I live at 4500 ft elevation (typically 650 torr), so I think more boost is necessary here. ...which is why I'm driving a turbodiesel and not a naturally-aspirated gasser. Well, that and the diesel just sounds so much better.
 
Matt Bachand said:
Very close to what mine was before TM. First mod i did was guages.

TM added boost now, 2-3 cruisuing, 9psi boost average on my highway hill climbs.

EGT's on same climb went from 900 to 650-700, just by TM alone.

Still have factory exhaust kitty ran away though...

FWIW TM set to 2 1/4", most i've seen burst is 12. No codes on stock 'puter.
Click to expand...
Well,maybe i sneak that TM in there if the wife aint watching,see what happens, I dont want to spend money for the pyro on this one though.
My Wife gets a little hairy if i fool around with her veh.:nono:
 
Im still using factory vacuum setup, with Engh chip, and my GM4 is happier than ever pushing all sorts of boost. and I just got a turbine pressure (backpressure) guage in too.

At cruising 70-75MPH its like 4-5psi, less if cruising slower. But if I punch it I get 13psi easy accelerating at any speed. Uphill in OD doing 70-75MPH it will TCC lock and push sustained 13psi on relatively long steep hills.

And I was most impressed testing out my backpressure guage when at top of speedo at 85mph I romped on it and got a good amout of more power and 16psi boost and was off to at least 100MPH with ease. Having 3.42 gears my top end might be better than others, but I'll need to have the laptop hooked up next time to see what PCM says how fast Im going.

Not sure if Engh does something to vacuum solenoid duty cycles, but its a lot better than when I had the Hypertech, which was just dumping more fuel.
 
buddy said:
Im still using factory vacuum setup, with Engh chip, and my GM4 is happier than ever pushing all sorts of boost. and I just got a turbine pressure (backpressure) guage in too.

At cruising 70-75MPH its like 4-5psi, less if cruising slower. But if I punch it I get 13psi easy accelerating at any speed. Uphill in OD doing 70-75MPH it will TCC lock and push sustained 13psi on relatively long steep hills.

And I was most impressed testing out my backpressure guage when at top of speedo at 85mph I romped on it and got a good amout of more power and 16psi boost and was off to at least 100MPH with ease. Having 3.42 gears my top end might be better than others, but I'll need to have the laptop hooked up next time to see what PCM says how fast Im going.

Not sure if Engh does something to vacuum solenoid duty cycles, but its a lot better than when I had the Hypertech, which was just dumping more fuel.
Click to expand...
That would be another thing to look into(engh chip) Dont know if no gauges would be wise though?
 
buddy said:
And I was most impressed testing out my backpressure guage when at top of speedo at 85mph I romped on it and got a good amout of more power and 16psi boost and was off to at least 100MPH with ease. Having 3.42 gears my top end might be better than others, but I'll need to have the laptop hooked up next time to see what PCM says how fast Im going.
Click to expand...
100mph is that all :D my 3:73 with 12 psi boost on the ATT is good for 106 mph with 300# of Buckstop bumper on the front end, my previous best IC'd with GM-8 was 119 mph and Heath h/o lift no big bumper, I'm leery to explore what speed she would do with 16 psi boost ATT & Walbro, I'll probably need to be running the WMI to run up there long. Maybe someday I'll need to do a Bonneville run with tires rated for go fast speeds
 
I dont know how fast i was going, since my speedo only goes to 85, and I didnt have laptop plugged in. And I had power left to go faster.

It was a cool night , maybe 50ish, but my EGTs only went to maybe 6-700.
 
buddy said:
I dont know how fast i was going, since my speedo only goes to 85, and I didnt have laptop plugged in. And I had power left to go faster.

It was a cool night , maybe 50ish, but my EGTs only went to maybe 6-700.
Click to expand...

Wow, that's nice and low. Wondering what WMI would do for the engine at those speeds during the day?

In the middle of a road trip right now.
Cruising at 60 MPH my boost is around 2-3. When I hit 70 it's up to 5 PSI. By the time I hit 80 it's at 10 PSI. From what I remember hearing, the amount of wind resistance increases drastically from 70 to 80. At 80, my EGT's are closing it just over 900. Once I go with a bigger turbo, intake, IC, and more fuel, I wonder if that will change much at higher speeds.
 
buddy said:
I dont know how fast i was going, since my speedo only goes to 85, and I didnt have laptop plugged in. And I had power left to go faster.

It was a cool night , maybe 50ish, but my EGTs only went to maybe 6-700.
Click to expand...


Got a GPS unit ??? NVMTNLION bested my 119 with a 121mph per his GPS shortly after I pegged 119 on my GPS, he had to "one up me" :D
 
Yeah, and everyone thinks 153MPH is impressive :) They'll get that truck going 180 the next trial.

I dont have a GPS unit, but the PCM should be able to output what its seeing through GMTDScan, and I'll let you know if that works.
 
Yes scan tool will grab the mph, it's what I use when grabbing data, I like the max speed feature of the GPS though at that speed :eek: it's better to have both hands on wheel rather than one on wheel and other on the scanner save data button/screen to know when I've actually hit my max speed.

Last time I talked to Bill he said because of rev limiter set for 4000rpm, he was limited to "just" 153, hoping to hit 160+ next time out :thumbsup: with rev limiter for 5K
 
Buddy what was your backpressure at your 'impressive' 100mpg 16psi run?

"I'm dropping the Hammer Harry!"

- "NO you're not!"

Anyone?
 
The backpressure guage was reading around 28psi backpressure, but I haven't verified it reads correctly. Ill tap it to intake and compare it to PCM boost sensor and other boost guage. And I might tap it in by the turbo instead, even though the pressures should equalize fast enough. I was impressed by the power available, 100MPH is not that impressive, especially when I was running 160MPH when the Z28 was stock.
 
with the reputation of the 6.5 and the fact that the truck isnt very aerodynamic and weighs a lot more than your camaro i will say it is very impressive
 
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