That was a iron block 5.3L truck engine that they said was just pulled from a wrecked truck from what I remember. It didn't sound like they did any internal work to it anyway. Just a tune. But I too find that hard to believe.

The LM7 in my Tahoe is rated at 295HP/330FTLBS which is at the flywheel.

I would expect 18-20% loss through the drive line which would mean that the engine on the show was producing ~350-360HP at the crank. They did put an LS1 intake on it which would boost high end HP at the expense of low end torque. They also were running a larger throttle body than stock. All of this and a custom tune for the truck and I guess that wouldn't be out of the question. A cam would definitely make this possible.

 

They did swap the intake from the truck to that of a Camaro.

 

Caught me in the edit. I still think there had to have been a different cam in there as well.

 

I blame the boredom of being at work for the quick posting, haha. I don't remember them adding a cam, but it's possible it had one to begin with too?

 

As with anything from a junkyard, the previous owner could have done some work inside. A cam swap on an LS based engine is pretty easy.

 

They also could have skewed the numbers a bit to make it more impressive. It's very possible they gave us WHP for the 4.3 and CHP for the 5.3 to make the swap seem more worthwhile.

 

Or it's possible they gave CHP for both. If that 4.3L was really worn out, 140HP could be at the crank...

 

With almost 200K on it, it's possible I suppose.