How many RPM's?

[194265]

No. 5250 is a constant, it does not change, when the rpm is 5250 and divided by 5250 the torque is the same as the hp. This applies to all engine, there are no exceptions! The torque peak is another thing, it can peak anywhere in the power cure. It can peak at 10000 rpm or 514 rpm, its just at 5250 rpm the torque and the hp will be the same Thats my .02

[Mark75H]

Did I say 5250 changed?


Again, this is irrelevant to the question at hand, merely confusing.

[194265]

No Sam you did not say it changed, you and I were both answering the earlier posting and you beat me to it.

[SS 201]

Was speaking of auto engines not of whackers. Forgot this was a outboard forum, however 5250 is where torque and HP cross, the power range above that can change but 5250 doesn't. Go to engine dyno program and you will be able to observe.

[Mark75H]

Was speaking of auto engines not of whackers. Forgot this was a outboard forum, however 5250 is where torque and HP cross, the power range above that can change but 5250 doesn't. Go to engine dyno program and you will be able to observe.

Its the same for 4 strokes and 2 strokes ... no difference ...


but again, not relevant to this discussion, its just a math and graph thing, not a motor thing.

[194265]

In regards to all production outboards that produce their peak HP between 5000 & 6000 rpm, I will stay with my original propping statement of 10% above the HP peak. Thats my .03 worth.

[SS 201]

All engines still HP and Torque meet at 5250 however when building a big engine the chart will sow higher numbers but 5250 still remains.

[Mark75H]

5250 remains a numeric constant in math, but means nothing to the original question of this thread.

5250 is a tool to express horsepower as derived from torque and speed; nothing else. 5250 tells us nothing about any particular motor or the motor's useful abilities.

[JohnsonM50]

As for the O-Q endurance of the parts is it, which will differ per motor. To put enough load on to slow the recommended Rs & how much stress it can take this way at X#'s under has nothing to do with 5250. Since the running R's for some motors is in the 5 digit range A motor built & tuned for such performance would probably not do well at 5G's or so.

[PIP]

I don't understand many things, but help me understand how cars like the 1970 buick gs 455 stage 1, with 455 cubic inches, and only like 375 horsepower (also only had a hydraulic cam) could pull that big heavy car down the quarter at 12.5 with a 3.42 rear and air conditioning? I always heard it was because it was such a torquey motor, but surely a solid lifter 454/450 ls6 chevelle, or even a 396/375 (both 454 and 396 with solid lifters) would smoke the buick, but they didn't seem to. In fact, it seemed to get the 454 and the 396 into the 12 range you needed 4:56 gears or so.

Any thoughts on why this was? The point is, if you do the math of h.p. X rpm = torque, it seems the ls6 would be much better at pulling weight down the 1320, but i don't think it was. I know, i know, set-up is everything, but it sure seems those buicks would require less set up and run faster, and i am not really a buick fan.

Curious, please school me up. Thanks ronny