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Replacement turbo

I was lucky enough to go for a little hell ride in TD's truck on Saturday. He did a bunch of 0- too fast :) runs.. (80 or so).. I was very impressed with the pulling power of the ATT difference.

There wasn't much difference if any 'turbo lag' between GM-8 and ATT that I noticed. She took off fast and strong. I look forward to the happy day I install one of these on my beast.
 
When comparing a GM8 with stock PCM program and an ATT on a good performance program, it may indeed seem similar, like no delay or lag in boost. And its most prominent off the line, and we know all too well how you accelerate like you have a hot cup of coffee on the dash.
 
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buddy said:
When comparing a GM8 with stock PCM program and an ATT on a good performance program, it may indeed seem similar. And its most prominent off the line, and we know all too well how you accelerate like you have a hot cup of coffee on the dash.
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:thumbsup::thumbsup::thumbsup:

You are very, very wrong Buddy...........






I only drink Iced Coffee :)

And I agree, i'm getting tired of typing the same old things...

I never had another 6.5 to compare mine to for overall health/feel/sound/vibrations. When guy was here his crossover was rotted open and it sounded like shit.... :) lol

I'm now more confident than ever about my engine. I treated her on the way home, I gave her some 2700, and a teaser of 3000 RPM. Just for a second. It was extremely smooth past 2600. The Air drone dissapeared.

I also dropped down TM another 1/4 inch or so, spring now really loose, close to 2 1/2". I was able to give it more throttle without boost climbing over 10 so I don't code... Anyhow she rode strong but IAT's crossed 200, cruised at 150, but worked every hill at 180-190 as GM-8 Boosted higher, so did the IAT's, and EGT's. (EGT's topped 850-900 pre turbo).

Morale of the story here, maybe I should just stick with what I have... Because, as well all so painfully know I drive like a grandpa who thinks nothing is worse than spilled coffee.:tiphat:kiss:
 
Matt Bachand;270099When guy was here his crossover was rotted open and it sounded like shit.... :) lol
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Absolutely true. After I had it replaced, I actually had some turbo whistle from the ATT and some boost as well ( I would think).
 
I have the ATT on my '99 with the Heath GL4 flash. No question about the power difference. Peak boost seen has been 12 psi. From a dead stop climbing up a fairly steep local hill with a 6000 lb boat in tow the stock '95 would peak out at 35 mph while '99 copntinues to accelerate all the way up reaching 45 mph approach the top of the hill. This is probably over 1/3 mile max.

The claims of mileage gains with the ATT have proven very illusory for me. Almost 2 mpg less than the stock '95 on the highway. While towing the boat, I'd routinely get 400 to 430 miles out of a tank, while the '99 sees about 350 miles. That's about 1.5 mpg less. It pulls great, but it does suck more fuel. It also runs consistently cooler.
 
BIG - T, have you driven it alot unloaded without hammering on it to get a fair MPG report? Your GL4 is also commanding alot more fuel, so I'm not sure how this could be the ATT as it is proven to provide less backpressure?
 
Matt, I bought the '99 in Illinois near Moline and drove it back to SoCal in January. It was driven on cruise control at a pretty constant rate of 70 to 73 mph. We averaged about 15.6 mpg, whereas the '95 averages about 17.5 doing the same.

As I'm sure you've seen from my posts, my winter weekends were spent doing mods and repairs on the trucks. Spring was spent on maintenance and repairs on the boat. So only recently have I towed the boat around with two trips from Fullerton to San Diego to fish. I know what my '95 consumes for those trips. Probably need more time on the '99 for such trips to determine the real mileage, but I do know it's less.

Am I mashing the pedal? When I need it, yes I do because now I have more power to play with. The rest of the time it's highway cruising speed.
 
The '99 has 3.73 rear end; the '95 has the 4.10. Go figure.

The '99 burns no oil; the '95 burns almost a quart every 3,000 miles and has since I owned it at 40K miles.
 
Burning oil = MPG's it is an oil burning engine after all.

The only fair comparison BIG-T is the 99 before ATT and the 99 with the ATT. Any numbers comparison there?
 
No before and after with the '99 as I bought it with the ATT installed. Eventually, the '95 will get the ATT and either the Heath or Kojo. It's my son's now so he needs to come up with the cash for that.
 
Theres a few things there, the aftermarket program allows you to use more fuel and you have HO injectors that will flow more fuel than standard injectors at the expense of some atomization. And your 99 has a high flow oil pump and piston squirters taking power off the crank. Tire sizes can play a big part in fuel economy, if the 95 has taller tires it may negate the 4.10 gears.
 
Here is a very brief description of what is wrong with the GM turbo, a photo of how the A Team fixes it and a link to purchase one for yourself.

"Restriction."
 

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The GMx utilizes the cobra head elbow which does reasonable. You need to take the picture from the other aspect. The cobra head widens where it flattens so that the cross sectional area is the same, so the same volume space. The smooth bend is better, but its not as bad as it looks from that view.
 
It appears that is the major difference in GM1-4 and GM6-8. They shortened the turbine housing and had to move the wastegate lever into the elbow. Vice the GM4 that has the whole wastegate inside the longer turbine housing.
 
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