View Single Post
  #22  
Old 11-05-2006, 11:05 PM
Blue_Heron Blue_Heron is offline
Senior Member
 
Join Date: Jan 2006
Location: Gator Country
Posts: 1,416
Default Re: WOT speed on a '83 20' SF w/200

Quote:



Max torque will be at a lower RPM than max HP.
Max torque is the RPM where the motor has the best volumetric efficiency.

Torque and HP are mathmatically related: HP equalls (torque (in #/ft) times rpm) divided by 5600.

If you look at the torque - HP plot from a dyno, you'll see they always cross at 5600 rpm. There's more ft/lbs of torque than HP up to that point, and then there's more HP than torque above that.

If the motor doesn't turn that high, then there'll always be more torque than HP.

If you're getting 95% of the torque spec for a 200, you're probably getting close enough to 95% of the minimum HP spec.

They aren't linearly related, but they're close enough for what you're figuring.

Even if you had the rpm where they measured the peak torque, it would only give you the HP at that rpm, not the max HP.

Darlene
Thanks, Darlene,
As I understand it, the dyno they used is programmed and all they do is enter the model number for the engine they're testing, run it up to max recommended WOT rpm (5500)and see if the torque curve matches up. I don't think they calculate the max HP or do any further analysis on the numbers, but I'm just guessing. I don't know if the torque value they gave me was max torque, or torque at 5500 rpm.

I got most of what I know about the relationship between torque and HP here:

http://www.revsearch.com/dynamometer...orsepower.html
__________________
Blue Heron Boat Works
Reinventing the wheel, one spoke at a time.
Reply With Quote