Prop for TQ or HP for top speed???
01-25-2005, 03:08 PM
#31
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Re: Prop for TQ or HP for top speed???
Originally Posted by Michael1
As far as peak horsepower, and best top speed, many of you got it correct. It is at the horsepower peak. Engine torque is one of those figures which is interesting on the dyno, but not important overall, because we have transmissions to change horsepower into drive torque. If it was important, we wouldn't have Formula 1 cars with their little 183 cu. in. engines doing 0-100 mph in 3.6 seconds.
Michael
Michael
Anyone want to bet who will be sipping rum and coke at Sloppy Joe's?
Chris
01-25-2005, 05:23 PM
#33
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Re: Prop for TQ or HP for top speed???
Torque is king!
I raced my 28 Pantera in 2003 with a 540 CI motor turning 5800 RPM - Motor made 625 hp @ 5800 RPM . Turned a 26" prop - Boat 77-78 mph but took forever to get there.
Changed the cam so HP peak was now at 5000 RPM . Boat turned a 28 " prop @ 5000 RPM, midrange and acceleration were awesome . The tradeoff for the 2-3 mph in top speed was well worth it .
It comes down to hull design - Efficient hulls can use the hp to accelerate hard and run fast (cats , stepped hulls ) . Traditional deep vs' need the torque to accelerate hard and run good top speeds .
Bottom line - The boats' hull design dictates what works best . One engine recipe does not work for all !
Torque =acceleration , HP = speed
I raced my 28 Pantera in 2003 with a 540 CI motor turning 5800 RPM - Motor made 625 hp @ 5800 RPM . Turned a 26" prop - Boat 77-78 mph but took forever to get there.
Changed the cam so HP peak was now at 5000 RPM . Boat turned a 28 " prop @ 5000 RPM, midrange and acceleration were awesome . The tradeoff for the 2-3 mph in top speed was well worth it .
It comes down to hull design - Efficient hulls can use the hp to accelerate hard and run fast (cats , stepped hulls ) . Traditional deep vs' need the torque to accelerate hard and run good top speeds .
Bottom line - The boats' hull design dictates what works best . One engine recipe does not work for all !
Torque =acceleration , HP = speed
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