Re: Allison 6 Speed GMC 401
 

If I read it correctly, the RV is the high power turbo version. 500HP and 585lbs ft of torque. That is some serious horsepower in any on highway vehicle. They wanted it to behave and feel like a turbo-diesel.

Those two figures tell me they left plenty of torque on the table but the 500HP is the figure that determines how much work the engine will do. That's big bore Class 8 diesel territory.

Re: Allison 6 Speed GMC 401
 

Thought the same thing Bill. Its all upside on the performance end. Early introduction of the 8.0/8.8 were LPG with decent #s. There were federal tax rebates on LPG fuel purchases for fleets. Gasoline versions were better performance. Now you are seeing turbo stuff. CNG is pretty big now as a replacement for diesel fuel. BTW the latest Duramax is pushing 1,000 lb ft of torque.

Re: Allison 6 Speed GMC 401
 

Those new generation Big Block Chevy's are interesting. PSI does the 8.8L, which is related to the 8.1L 'Mark VII' engine (revised cylinder heads), Powertrain Integration does the 8.0L, which is related to the 'Mark VI' 7.4L. To further confuse matters, PSI merged with Powertrain Integration a couple of years ago!

Re: Allison 6 Speed GMC 401
 

The big block Chevy is one tough engine, and I'm happy to see that it continues on. They've been in production and on the road now for 53 years and I can't think of another engine that can claim that.

I have a turbocharged 454 + .060 in my fleet and it's been stone reliable. To bad the truck around it is falling apart. Before it's stint in the truck, it propelled my 4800 lb Chevy wagon on the street and up and down a drag strip for years. (that car now has a 427) Trying to figure out what I will do with it next lol.

My personal opinion is that the big block V6 is much more robust for heavy truck use and would easily handle the boost of a turbocharger, even better than the BBC. One of my 478's in a HM80 will be a test bed eventually.