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2 BBF = 3 SBC when it comes to torque

February 8 2008 at 6:03 PM
Tom Slayton  (no login)


Response to Small block ~v~ big block (and....did you know a marine 427 has more than 300-hp? )

The best source of CC motor information is right here on the Forum at http://www.network54.com/Forum/424840/message/1172181250/

I have this bookmarked and refer to it frequently.

All this discussion about torque brings up some good points. For instance, a pair of 427 big blocks are putting out essentially the same general global torque number as three (3) small block Chevy motors. I am using the average between the 307Q and 327F for my SBC torque data.

If you are running a pair of 327F motors for instance, and you wanted to know the difference between those and a pair of big blocks (in this instance, big block refers to the 427) then you would be running with the equivalent of three small block motors to match the prop spinning torque of the larger motor. If you had three motors, you would be penalized with the inefficiencies of three sets of underwater gear (drag) coefficients.

As you get to the 350Q, the 330 footpound torque number is big enough to equate to something like two 427 motors are equivalent to two and a half 350 motors. In any case, it's a substntial boost to the ability to move heavy weight.

Also, back in my memory bank I remember discussions about crate motors, and the need to understand what you are actually buying. The point was made, to never buy displacement, but to always buy power specifications. In this case, the power spec would tell what horsepower was delivered along a specified rpm curve, and also that important and often left off torque number. Someone said to be careful or you may end up with a taxi cab block, and that thought rang home with me.

Tom

 
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