Friday, October 07, 2011

How Do Ya Want Your Peterbilt?


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When most people think of a needle nosed custom Pete, this ain't gonna come to mind. This goes beyond any kind of pulling a load.
This is Jay Leno's 1960 chopped Peterbilt with a 852ci two-stroke Detroit Diesel twin-supercharged V12 mated to an Allison 4-speed automatic transmission from a Greyhound bus. The engine produces 500 horsepower and nearly 1000 lb-ft torque with a red line of just 2,800 rpm. Built by the Blastolene Brothers.

"Just 2800 rpm." One of the hotrod tricks for the old mechanical four stroke motors like the Cummins 855 block or the Cats was to mess with (replace or just stretch the crap out of it) the throttle return spring and shim it up so that the cutoff of 2100 rpms could be exceeded. You really didn't want to make it a habit, or a ventilated block was a distinct possibility. Part of the idea was that the fuel "curve" would be fattened so that lower rpms could get more juice. Of course, other mods were necessary to get the fuel to flow. More diesel, more power. At any rate, 2,800 isn't really radical at all.

 Plus, this is a Detroit two stroker. It will not run without a blower. Yeah, it sounds cool to clearly have a  couple of superchargers mounted, but they are pretty much standard Roots style blowers that have been on Detroits since day one. The drag racers, in their search for more power, had in these blowers the ready ability to force more air into a four stroke gasoline motor with instant throttle response, as opposed to a turbo.  In fact, this engine is from the V71 family - twelve cylinders of 71cu in makes 852 cubes total. Probably the most iconic Detroit is the 8v71 - called the 318 because that was the horsepower rating. There was also a 6v71 and this twelve cylinder isn't much more than a couple of them mated. The 6 and 8vs were put into all kinds of equipment, but what the public encountered was mostly buses and trucks. The sound of an old bus roaring away - Detroit power.

Even though these Detroits were blown, they really only compared to their naturally aspirated competitors. And, the way to increase the power was to throw a turbo on, just like the straight breathing four strokes. The 350 Detroit was an 8v71 with a turbo. I drove a "Silver 92" - which was one of the last two strokers. Detroits were always painted an odd green color, but the "new" ones were all silver. The example in the Ford cabover I drove for several years was an 8v92 rated at 475hp, and like all Detroits, the torque curve was all above 1500 rpms. Part of the old trucker lore was to properly drive a Detroit powered truck, before climbing behind the wheel, one must place one's hand in the door jamb and slam the whee out of the door. That would put you in the proper frame of mind to wind the crap out of it and try to abuse the motor. If you took it easy on them, they had no power. They always had to be" on the boil." Contrast the Cats, which were all about low end torque and lugging.

And five hundred horses from that old V12 ain't bad, but contrast to my current Acert Cat at 550hp, and I hardly ever go over 1700rpms. So, five hundred horses in something that light is nothing to sneeze at, but this is obviously set up as a cruiser. It's been tweaked, and I'd bet all the internals have been lovingly picked for their performance characteristics and then polished and balanced, plus the fuel pump tweaked.

If ol' Jay got tired of this puppy and decided to give it to me, I'd not turn it down. However, I'd bet most SBC powered Deuce coupes or similar would suck it's doors just because they're so much lighter and wind up so far more quickly. As a "Just Because We Can" exercise, it's full of win.

H/T Nunkle Kim

5 comments:

lisa said...

I have seen some other stuff that he has and boy do I wish I had the money he has invested in all those lovely beauties!

Jeffro said...

I'd be happy with the bucks he has in his Duesenbergs.

drjim said...

I've seen some equally impressive things at the tractor pulls I used to go to back in Illinois.
Still, a "truck" like this sure would turn heads on Cruise Night!

Dad Bones said...

Right about now I wish my computer had some big speakers to help me get the feel of that powerhouse.

Cedar View Paint Horses said...

"Six in a row makes it go". Wifey won't let me put that sticker in the back winder of the truck - says it's "hickish". I told her I'd take the gun rack down....

Nonetheless, me likes my Cummins.