ATT info

[Rockabillyrat]

Regardless of what turbo you choose. Obtaining quick spool time with a boost to drive pressure ratio close to 1:1 is the sweet spot. The two non vgt turbo platforms I've seen accomplish that on a 6.5 are the S300 and HX40. Of course neither one right out of the box is perfect for a 6.5. Quadstar has had great results with the Hx40 based S60. But he had to rework the trim and a/r ratios to get it to perform the way it does. Another guy took a S360 and changed to a smaller open scroll turbine housing with good results. As far as the ATT goes. Ive never driven a truck with one. I've also never seen specs or data logs so it's hard to say how it compares to the others I've mentioned.

 

[WarWagon]

@Rockabillyrat Would love to see some videos or Dyno of the other turbo's. IMO the next step is a Ball Bearing turbo because they light off so much quicker than a JB turbo.

Some Dyno data:

ATT run vs. HX40II

Statistically the power output on the 1986 6.2 Military engine is the same for both turbo's. There is bragging rights if I was selling an air filter. Except one turbo wins torque while the other wins HP. Yet, the numbers are so close - less than 5% there isn't a clear power winner IMO. Driving...

www.thetruckstop.us

Put the screws to the HX40II on the rollers.

So I finally made the time to get the 1995 down to the rollers. I joined another forum's diesel dyno day. :sifone: 208 HP and 394 TQ. Was 66 Degrees F today. At the end of my last run the boot blew off the intake at 22 PSI. I thought the radiator cap was venting while everyone else was...

www.thetruckstop.us

Videos:

ATT videos

Someone was saying there wasn't enough ATT video's so I decided to upload some. Because I had that kind of free time yesterday, and because any excuse to drive my truck and make videos is worth it. So here ya go. The first one is a 0-80mph run with max fueling. Don't mind the shaky camera, it...

www.thetruckstop.us

DB2, ATT, and Yank stall converter...

 

[Rockabillyrat]

@WarWagon I think John has some videos of the S60 on the website. And I'm friends with the guy that did the S360 on facebook. I will see if he has a good video of it. But dyno numbers are non existent for both. The only number I've seen are from some of the data logs they both did.

In my opinion if you really want to get the most out a turbo upgrade on a 6.5. You need to take the factory exhaust manifolds, cross over pipe, and upper intake manifold and throw them all in the trash. The whole setup is a joke. I dont know what GM was thinking. The upper intake is a massive restriction. The cross over feeds into the rear of the turbo manifold right at the rear two cylinder ports. And to top it off the 6.5 is the only diesel out of the big three to run an open system. A fully divided system with a twin scroll t4 turbine housing in my opinion is how the 6.5 should have came from the factory.

 

[WarWagon]

@WarWagon I think John has some videos of the S60 on the website. And I'm friends with the guy that did the S360 on facebook. I will see if he has a good video of it. But dyno numbers are non existent for both. The only number I've seen are from some of the data logs they both did.

In my opinion if you really want to get the most out a turbo upgrade on a 6.5. You need to take the factory exhaust manifolds, cross over pipe, and upper intake manifold and throw them all in the trash. The whole setup is a joke. I dont know what GM was thinking. The upper intake is a massive restriction. The cross over feeds into the rear of the turbo manifold right at the rear two cylinder ports. And to top it off the 6.5 is the only diesel out of the big three to run an open system. A fully divided system with a twin scroll t4 turbine housing in my opinion is how the 6.5 should have came from the factory.

Took me a min to wipe the Adult beverage off the monitor from laughing so hard over that. Can you imagine the GM 6.5TD team watching @n8in8or Tahoe, that fixed all that, run door handles with a decade newer Trailblazer SS that has a 395 HP 400 lb-ft Corvette LS2 in it? (Speaking of shoehorned half-baked GM ideas: If the weak transmission behind the LS2 didn't literally gernade or the rods ventalate the LS2 block from the front sump oil pickup running dry on launch... the TBSS cooling fan is on GM Par for an airflow mess. And the 25 cent sized cold air intake, really??? That is the best shop queen Old Bankrupt GM could come up with? ) I 1000% agree on the 6.5TD manifold mess.

However the GMx turbo is so bad the manifold mess doesn't matter as much esp. for those being Frugal. Remove the "Asthma Attack turbo" and the rest of the joke of manifold system is diminishing returns. But when one does chase it all down...

Seriously in context of the OP's question on specs... Dyno slips and Track times are where the BS stops. I believe this site still has a dyno fund. I, and I suspect others, would love to see what these different turbos are putting down. How the turbo handles the entire engine RPM range is also of interest as it's difficult for some to simply throw away RPM under 2000.