Mr. Wizard Looks into Outboard Torque Curve Claims

Mr. Wizard Looks into
Outboard Torque Curve Claims

100 HP and Above
by Mr. Wizard

Even with all his sorcerer powers, Mr. Wizard can't understand the torque curve claims made by outboard manufacturers in recent years. Every time they bring out a new one, they brag about it having better low end torque, improved midrange torque, higher torque, broader flatter torque curves, etc, but they rarely show us the curves. Can all this be true or is it just smoke and mirrors? It is even more confusing when you throw in all the two-stroke vs. four-stroke claims and all the different technologies involved. He is about to blow a gasket.

At his insistence, we are going to start collecting the PUBLISHED torque curves here for current and recent outboards (100 horsepower and up, two or four stroke) so he can compare current and future engines.

If you see any more, please drop us a note and point them out to us, scan and email them, or email us for a number to fax them to. Thanks for your help, together we can make life easier for Mr. Wizard and all learn a little more about outboard torque curves.

Published Power / Torque Curves

Note: Different dynos may produce slightly different curves for the same unit, even if the data is corrected for operating conditions (temperature and barometric pressure).

Power Curve for 1997 Mercury Marine Optimax is an Orbital technical paper. Click on Figure 9 on the right side of the page. Power equations can be used to convert the power curve to torque. We will try to get Mr. Wizard to do that the next time he drops by.
Torque Curve for Suzuki 115 two and four strokes is in their product literature, Product Information DF 90/115 on the right hand side of page 5. Document is in Adobe Acrobat (.pdf) format. Adobe has a free dowloadable viewer.
Torque Curve for Honda 225 four stroke with VTEC (variable valve timing and lift electronic control is on Honda Marine's 225 web site, but the axis are not numerically labeled. It indicates the step in the torque curve made possible by VTEC.

FEEDBACK / HELP

If you have any comments or find some other torque or power curves PUBLISHED in marketing literature, press releases, magazines, technical papers, web sites, etc, for outboards 100 HP or above, please drop us a line at polsong@virtualpet.com.