HP vs RPM's Question

[Frank Acampora]

Re: HP vs RPM's Question

The fundamental mistake you are making is in the curves. HP is one curve and torque is another curve. When plotted together, at some rpm they cross on the graph, but this is NOT necessarily the max HP. It also may not be the max torque. As rpm increases, HP increases even though torque is decreasing, until the declining torque offsets the rpm gain. (And this may not be at the rpm at which the engine is rated.) THEN, HP starts to decline. Example same engine block --one engine geared at 1.87 to one and rated 85 HP at 5250rpm. Same block geared 2 to 1 and rated 90 HP at 5500 RPM. Lower gearing lets engine rev up a little more and develop more HP--same block, same torque curve. Rated different HP at different RPM Remember RATED Hp is not necessarily max HP that engine could develop. A little simplistic I know, so don't nitpick.

 

[smiley2007]

Re: HP vs RPM's Question

http://www.evinrude.com/NR/rdonlyres/45154B7B-C4C3-4820-9C20-417494DDA86F/0/PE342.pdf

if you look at the engine section on the stats....

the pdf shows the max power at 5150 and max revs at 5800

so when proping which should one aim for ???

 

[Texasmark]

Re: HP vs RPM's Question

Didn't say max power was 5150 it said it was rated there. Just like the thread above about the older mercs that were rated at 11 hp where OMC rated their engines (4500) but it was capable of 6000 and at 6000 they were pumping out 18.

I got waxed back in those days as I was an OMC nut at the time. Didn't realize the Mercs were turning that kind of rpm's till we started racing.....I didn't race, my buddy and his dad did and I went along (to the river where they raced) for the fun of it.

I did expect to see an actual torque curve on the Adobe Acrobat data sheet on e-tec.

At least we are getting some exposure to some technical stuff. But, like I said before. The only way you really know what your rig can really do is to get out and run it. Usually you'll have your answer in a matter of minutes......but seldom do you get to tweak the setup before you plunk down your cash!

Mark

 

[smiley2007]

Re: HP vs RPM's Question

Didn't say max power was 5150 it said it was rated there. Just like the thread above about the older mercs that were rated at 11 hp where OMC rated their engines (4500) but it was capable of 6000 and at 6000 they were pumping out 18
Mark

thanks

after much looking found the grafhs for a 225 etec on the bomb site

http://www.evinrude.com/en-US/

under "e-tec challenge" then "hole shot" - gives the torque graph

and under "drag race" gives the horse power graph which goes up to 240 hp

interesting very interesting my dear watson :/:/