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Dyno Results

Yeah, I am gonna upload a few pics of the ATT setup I was running until something came up. It was a real clean look. It should be back to this in a couple of weeks.





ATT I.jpgATT II.jpg
 
Looks good! Did you just reuse the pieces of intake that you cut?

I think it is interesting that your peak torque is at 2700rpm with the GM3, mine falls off at 2500 but pulls like a sob getting there.
 
Yeah, we just re-used the original piece that was cut then got some pipe that was roughly the same size and thickness and cut and such until after enough trial and error we found a good cut to them and then welded them together, smoothed out the welds after mock up, polished a little and bolted her in. The piece I am using right now with the GM-3 is an original off a 94. I left the electronic square box thing bolted in and found an adapter to plug the single hole and that's where I am measuring boost off of. It works out having two different intake designs so if I ever need to go with a GM-x series I can use the one piece and then use the other for my ATT setup. Yeah peak torque seemed a little high to me but honestly it ain't bad. She pulls really hard from about 2300rpm to 4000rpm without breaking a sweat. When I am cruising around town I don't need that much power on tap down low in the rpm anyways. And she doesn't even struggle then either. I have never been happier with a vehicle I have owned honestly. I make decent power off what relatively little fuel I am putting in, can tow what I need to great, and still get 20-21mpg highway unloaded.
 
Nice pics of the ATT, does look good, and those are really great dyno numbers considering the few mods you have done to it and with the original GM-3 turbo. Did you have any mods done to the injection pump to put out more fuel when it was rebuilt or just a "stock" rebuild that you then decided to do the 1/4 turn to get the extra fuel to the engine? You got a really nice optioned truck too with 1-ton capacity, non-dually, mechanical fuel injection, and good ol' 5-speed stick trans. Now that's a combo!
 
I know. My dream truck has always been a Singe Rear Wheel One-Ton Regular cab with a 5 speed and a diesel. I never thought it would be a 6.5L diesel, but after having it for this long, I am happy it is a 6.5L. I enjoy it. and it was a stock pump that when it was being rebuilt, I had them turn it up 1/4 turn. and I know they are good power numbers. I thought with the very few mods I did and as little fuel as I am putting in that I would be around 175-180 at the rear wheels especially with the GM-3. I surprised myself. But I am happy with it. I am looking forward to the ATT getting back and depending on performance, adding a bit more fuel and putting her back on the rollers. It isnt so much a matter of time but a matter of money at this point.
 
Nice numbers! I can't wait to get mine on the dyno. I thought your torque peak was high too, but what really stuck out to me was the HP peak, 3807 rpm, and you said it pulls hard to 4000 rpm, I thought these DB2 pumps were governed to 3600 rpm?

Again, nice job, looking forward to seeing the results with the ATT.
 
I like having my peak torque up that high to be honest. If I am towing I am gonna be in my 1:1 gear (4th) and that means since I won't be in overdrive, I will be up high in my rpm. Roughly 3000rpm. Right around my peak torque. I have close enough gearing and my low gear is 6.34:1 so I don't need torque super low to get going good. And my motor on the dyno hit governor at 4000rpm. Like I said, she pulls damn hard getting to 4000rpm too once I climb above 2200RPM. My friends 2003 Duramax that pulled when I did made peak torque (770ft lbs) at 2700RPM. Only 100rpm less than me. and 406rwhp. I can't remember at what RPM he made that though. It was fairly high in the RPM range. I know that. I thought it would have made peak torque lower as well but for some reason both of our motors made peak torque at roughly 2700-2800RPM. He just made slightly more lol
 
Oh i know what you mean, nothing wrong with having torque a little higher, safer for the engine anyway.

Ha agreed with the gearing. I too have 4.10s and the 6.34 1st NV4500. I think mods that allow the engine to perform better at higher rpm work well with this tranny since the gaps can be a little far apart and you need to wind it out, especially when towing.

Maybe the place that rebuilt your pump also adjusted the max governed rpm? Everywhere I have seen the governed speed for these 6.5s was 3600 rpm. Again nothing wrong with increasing it though, these motors love high speeds, that's what I plan on doing :)
 
I don't know the max RPM limit on these motors. I know the old motor that was in the truck would govern at 4000RPM as well. And I can definately relate to the gears being just a tad far from each other. If you count Low gear as first gear, then when I am in 2nd I really have to rap the motor above 2500RPM just to come into 3rd comfortably and not smoke. Running through the gears, I have to rap them out to 3500rpm just to be able to come into the next gear right where the turbo spools. But I love the truck.
 
I enjoy my set up too but mine does govern at 3600 and starts cutting fuel at 3400. I pull 60mph in 4th ~2700-2800 rpm IIRC. The truck does great. I too think higher RPM's=less stress on the internals. This is why I think the ATT is a great option since it shifts the torque band even higher.
 
You can go 1/3 turn on the IP. 1/2 turn if you watch smoke and EGT. What altitude are you at? The higher elevation the less fuel you get to use even at 15 PSI as the turbo enters choke at higher elevation and doesn't give you as much air at 8000 feet as it does at 1000 feet. So 1/2 turn was too much fuel for my truck with the elevations I went to.

There are a couple of other adjustments on the DB2 you can play with...
 
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