| Agreed!February 7 2008 at 5:06 PM | Bill (Login billinstuart) |
Response to Small block ~v~ big block (and....did you know a marine 427 has more than 300-hp? ) |
| I agree "horsepower" is meaningless in marine engine comparison. Horsepower is simply :
Torque x RPM/5252.
No big mystery. The dyno measures torque..horsepower is computed. Horsepower at 5000 rpms is meaningless when you cruise at part throttle at 3000 rpms. 438 @ 2900 rpms is respectable, but well within the range of a properly built 383 Chebby or 454. The 383 has a long stroke, comparable to the 427..long stroke, long rod (in the engine dammit) produces midrange torque.
The small block is a few hundred pounds lighter than a big block Chevy (BBC), and ANYTHING is lighter than a 427 Ford with cast iron accessories.
The BBC is a little torquier because it has a longer stroke and rod, and even a puny BBC should be capable of over 400 ft.lbs. @ 3000 rpms. This is at full throttle, btw.
Diesels have high AVAILABLE torque because they run at higher loads than gas engines. They also cruise at rpms close to "wide open". I wouldn't be surprised if diesels ran at 80% of capacity, and gas engines at 50% of capacity. Diesels are more "fuel efficient" for 2 reasons..1) There is more energy available in diesel fuel than gasoline, gallon for gallon 2) they are more efficient because of the higher compression. That's it. No magic to it.
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