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i am considering converting to a 4bt in a 72 chevy 3/4ton 4x4 with a sb 400. this motor makes appx 400 lbs torque at 2500 rpm, i read a 4bt makes 300 or so,, my question i tow 5500 lbs a few times a month, wondering what the comparison would be power wise , why do you need a cummins designed clutch if there only 300 or so lbs torque..i know mileage will improve, i am runnning nv4500 and 3:73 gears right know wit ha 31in tall tire,,, all coments appreciated....
 

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biggest difference is where the torque is. 4BT's make maximum torque around 1500-1700rpms which is much lower than most SB V8's.

along the right lines but a bit less displacement, the 360 that came out of my durango peaked torque up around 3000 rpms.
 

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many factors diesels are less suseptible to parasitic drag from the drivetrain..... my 401 barrels up hills with a 5000 lbs load or less, it dynos 370ft/lbs to the rear wheels. 4bt converted rigs that ive been involved with dont have the 4bbl jump when you down shift into third and wind them up but they maintain thier momentum on a hill better.
 
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