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Just Installed My ATT and WOW

Chevypoor

Chevypoor

Active Member
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Location
Mineral, Va
Been working on resurrecting a 95 GMC K2500 and finally got the exhaust leak fixed. I also hooked the pyro and boost gauges up and took her for a spin. I still have not gotten much past half throttle and she hit almost 15psi! :) EGTs have yet to cross 800 or so. It is a night and day difference between the gm-5 and turbomaster on the 95 Chevy. With the ATT turbo she will spin a tire at will, has excellent response, and in general just flat out hauls the mail.:D

Once I get the rest of the bugs out I am going to load something heavy on the flatbed and see what the ol girl can really do. :sifone:

Just wanted to say thanks to the guys here for the work a few years back in developing and testing this turbo and thanks Dennis for your initial work in developing and selling the turbo. WOW. Should have been this way when it left detroit.
 

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Gotta figure out how everybody else is getting ~15 psi; I never saw over 12 even going up grades with 1000F EGT's . . .

Enjoy the new blower! :thumbsup:
 
I see regularly 14 psi. Have seen 17 psi when towing a boat up to our place in the mountains and regularly see 15 psi towing boats at sea level.
 
I was empty when I saw almost 15psi and was starting to run out of road at about 75. Maybe it is the tune. When I spoke to the guy at Heath about burning the chip he stated that in there opinion the ATT needs a hotter tune and told him fine, turn the wick up. Maybe that is the reason as well and it was in 3rd gear turning above 3200 hundred and still pulling... that may have been a bit more than half throttle :D. On a side note it seems to smoke less than my GM-5 truck.... that was a surprise.

I was unsure what to expect. There are so many opinions and the trend seems to be toward the Holsets. My 95 Chevy is more violent and sudden about its application of power and it has a high pitched turbo whistle that the ATT lacks. That being said there is no comparison. Power is smoother and it feels stronger everywhere in general. The boost comes in quick holds. The more throttle I give it just keeps building power. I was surprised how free the motor felt and how easy it was to turn a tire. I am sure the peg leg does not help! When you hit 70 now its a whole new world.... she just wants to keep pulling. I am thinking the GM-5 on my my 95 Chevy is on borrowed time!:D
 
Do have a fairly recent Heath tune which accounts for the ATT. Perhaps the difference does truly lie in the programming as I focused the goal toward towing and not 1/4 mile performance. Even with a towing focus in the programming, the truck recently did a 12.5 second 0 - 60 with nearly worn out bearings, so there was plenty of get-up and go even with lower psi's.
 
Im still running stock tune and am amazed each time I drive it. Cant wait for the new tune, should be here soon.
 
The ATT needs a tune with dynamic timing, not static like many do. I know when helping slim on his, a tuner who shall not be named(but is liked by many) had a CRAPPY timing table in the tune to say the least. It was no wonder the ATT didn't respond well and was laggy down low with lots of smoke after looking at the tune he was running. Timing shouldn't be X amount for Y amount of fuel, it must vary across the RPM band as well as for each amount of fuel. The tune files I seen from a few different tuners all used timing tables that were basically flat for each amount of fuel injected. Also the ATT being a non wastegated turbo needs retarded timing in the spool areas, but you can go way advanced in the power areas once it is on boost. Tuning is key to making one run right.
 
THEFERMANATOR said:
The ATT needs a tune with dynamic timing,. . . [including] retarded timing in the spool areas, but you can go way advanced in the power areas once it is on boost.
Click to expand...

Timing control is something that the OBD II ECM can handle, correct? Presuming so, for IP installation, should it install in the OE position (IIRC -0.5) and then let the ECM handle advancing / retarding via programming? Or am I oversimplifying as usual?
 
JayTheCPA said:
Timing control is something that the OBD II ECM can handle, correct? Presuming so, for IP installation, should it install in the OE position (IIRC -0.5) and then let the ECM handle advancing / retarding via programming? Or am I oversimplifying as usual?
Click to expand...

Any of the 94+ 6.5 ECM's for the DS4 pump control timing. The TDCO is simply the base setting it can control from.
 
Been driving the truck alot around the backroads.... still need to get an inspection. So far still thumbs up and impressed. She is starting to whistle as the turbo breaks in. Have not hit 14psi again but now if she gets to 10psi hang on.

Would love to do some real time/ dynamic tuning but I do not know anyone in the area. I am also worried about the trans. It runs fine under moderate throttle but at heavier throttle it slips. I think the PO burnt the bans since the fluid was almost black and low :mad2:
 
A shop here rebuilds 4L80E's for $1100 in and out of your 4x4 truck. hard parts like gears and bearing extra, but, frictions and seals included.
 
THEFERMANATOR said:
The ATT needs a tune with dynamic timing, not static like many do. I know when helping slim on his, a tuner who shall not be named(but is liked by many) had a CRAPPY timing table in the tune to say the least. It was no wonder the ATT didn't respond well and was laggy down low with lots of smoke after looking at the tune he was running. Timing shouldn't be X amount for Y amount of fuel, it must vary across the RPM band as well as for each amount of fuel. The tune files I seen from a few different tuners all used timing tables that were basically flat for each amount of fuel injected. Also the ATT being a non wastegated turbo needs retarded timing in the spool areas, but you can go way advanced in the power areas once it is on boost. Tuning is key to making one run right.
Click to expand...

The Mechanical DB2's appear to already do this RPM timing variance and run well with the ATT. It is night and day the 1993 vs. my 1995. Enough that I have considered a DB2 conversion on this alone then there is the PMD costs... Even on the experimental 'Slim' tune the precups mess me up for smoke. Stock tune even smokes. However there is a big difference you can feel between tunes out there and what you and Slim are working on. The throttle is more progressive over the range of the pedal. With the BD valve I think I feel the timing change used to spool the ATT as a flat spot. (Got to pin that down more.) Light throttle around town the BD valve has cleaned it up a lot on all tunes.

Thanks to both you and Dennis for stepping up for the 6.5 community.

Didn't the 1994's GM tune clone a DB2?
 
Thanks for the price info on the 4l80es. Drove her last night and she did not slip once.

Everything with this truck is kinda strange.... it took several days for the turn signals to start working. The power windows would not work at first and then after ten minutes of having the batteries hooked up they work fine. Everything has been sitting so long, electrics and mechanicals, and it seems to take a while for everything to work!

I also have a 4l85e from the 02 Suburban that should work... if it is ok. I think I am going to try some Lucas, control my right foot, and see how far she will go.
 
That is interesting about the DB2 pump being more dynamic. Reminds me of the old carb vs fuel injection....

The current tune from Heath seems well matched to the truck. I only have smoke at a transition from light cruise to heavy throttle and have not noticed smoke yet from off the line.... still babying the tranny. If I give a good blip from a standstill she will puff small black cloud and bark a tire. The smoke I have observed is darker but seems to be briefer than the GM-5 in the 95 Chevy which will lay a grey haze for a long time. I have boost as soon as 1500 rpm. It does spool slower than the GM-5 but in general the acceleration is strong and once the rpm pass 2000 hang on. She will not stop pulling until you let up... even under moderate throttle. I have not observed a flat spot yet. I am very pleased with the ATT and it runs exactly as advertised. A giant leap forward over the GM turbo.... a bonus as the turbo is getting some miles it is getting deeper and starting to whistle. :thumbsup: When she cranks over in a parking lot people will turn to look... even starting she has a very deep and loud sound as the starter spins her over!
 
THEFERMANATOR said:
The ATT needs a tune with dynamic timing, not static like many do. I know when helping slim on his, a tuner who shall not be named(but is liked by many) had a CRAPPY timing table in the tune to say the least. It was no wonder the ATT didn't respond well and was laggy down low with lots of smoke after looking at the tune he was running. Timing shouldn't be X amount for Y amount of fuel, it must vary across the RPM band as well as for each amount of fuel. The tune files I seen from a few different tuners all used timing tables that were basically flat for each amount of fuel injected. Also the ATT being a non wastegated turbo needs retarded timing in the spool areas, but you can go way advanced in the power areas once it is on boost. Tuning is key to making one run right.
Click to expand...

Ferm, when is this tune going to be available?
 
guybb3 said:
Ferm, when is this tune going to be available?
Click to expand...

I have no idea. I was helping Slim early on, and I know he has been working with some other tuners converting it over to an OBD2 tune file. Wo he has been working with I have no idea. I don't have a 6.5 to play with, so theres no sense in me gearing up to do them. I just helped shed some light on tuning using 21st century technology VS the 20th century tuning knowledge GM(and other tuners) used(and are still using). I know if I compared what Slim WAS running compared to the last tune file I helped him with, there was a DRAMATIC change in timing and throttle curves. And after seeing some of the files he WAS running, it was no wonder the ATT wasn't responding well compared to the CKO's that others were comparing it to.
 
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