Quote:
Originally Posted by 1972RedNeck
I will agree that if you are doing an engine swap for mileage only, it will take a LONG time to pay for itself.
That's why I have a Honda that gets 60 to 80 MPG.
I'm still not convinced that you can get 700 ft lbs of torque out of an LSx and still have it be driver friendly and be able to tow heavy.
The reason i went with a 4BT is that the 7.3 that I had was shot and I wanted more power and I like Cumminses and lots of headaches associated with swaps. I probably should have went with a 6BT but I was told by many people that "you couldn't get any power out of a four cylinder" - so I did.
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Well, to start off with, the 700ftlb number is kind of meaningless; it's the same deal as peak HP numbers. I can put more than 700ftlbs on that input shaft if you hand me a long wrench, but that doesn't mean I'm suitable as a truck engine.
HP is what actually does the work, and that is why when talking about the power output of the "real" diesel engines (as in big OTR/equipment stuff) HP is what is always used. Torque is only a measurement of force, which does nothing without speed; speed x force = HP.
Say you have 300HP with your diesel, and I have 400HP with a BBC; if I run @ the same RPM you are running at (and am making less torque there),
I am as a result making less HP. However, if I kick down a gear and wind up it, I'll pass you like you're chained to a pole. Why? You have more peak torque, but don't have the extra speed to make more actual power. This is where everyone seems to get confused; HP
at the speed you intend to operate the engine at is what actually pulls the truck down the road.
From everything I've read, a 4BT pumped up like that will kill itself in short order if you actually load it up and start up the side of a mountain WOT.
For example, take the
893CID 3406E Caterpillar; the versions that made 435HP or more had 2-piece pistons with steel domes to resist melting them (or whatever) under sustained heavy load. A 4BT is only 239CID, or roughly 1/4 of the size; hard for me to believe that adding 654CID only adds 135HP...
As far as hot-rod power like that, a
V6 Camaro my father stuck a turbo setup on at the place he works at made 421HP @ the wheels (or about 500HP @ the crank); this engine had nothing done to it besides the turbo, and as a result ran like stock until you opened it up.