hypothetical question

[mrdrh99]

Ok.... Imagine this... Same boat, load, weather/water conditions. What would be the difference in performance between a 7.5 HP and 9.5 HP? How often do you guys actually go wot? And would the 9.5 be more fuel efficient at same speed? Thanks guys!

 

[ronaldj]

2 stroke or 4 stroke

 

[mrdrh99]

Oooo.... Good question.... Both are 2 stroke

 

[ronaldj]

The 7.5 and the 9.9 are probally the same engine

 

[mrdrh99]

Here is the linkhttp://fayetteville.craigslist.org/boa/4479431158.html I'm looking at the second one. 9.5 vs the red 7.5…

 

[fbpooler]

Depends on the boat, but the larger motor would be faster of course. Water conditions determine the speed you will run normally, but the fuel consumption will be very little with either motor provided they both plane the hull.

 

[mrdrh99]

Good to know... BTW, the 2hp is at the mechanic's getting looked over. I'll use it in smaller water and as a backup. Anyhow... I'll get reviews and put up a report soon

 

[Sinistre1]

You'd actually need to run them both in your set up. Would be close (as in not much practical difference but I wouldn't be surprised to see that if the 7.5 needs to be run WOT to match THAT particular speed, the 9.5 might be more fuel efficient if it was around 3/4 throttle or so. Really trial an error with such close HP. You could approximate it if you know the rpms and the volume of the combustions chambers and such... but in reality... the difference in actual fuel savings should be nominal for those 2 engines assuming they are both in good shape/ tune.

 

[mrdrh99]

I got the 7.5... It was in pristine condition and had the fuel tank. The 9,5 wasn't bad but adding the fuel tank in line would be another $75-100 and I kinda had my mind set on the 7.5... Plus the guy offers free repairs for 12 months!

 

[Sea Rider]

Will need to know which CC is the smaller, which CC is the larger one to compare. If the smaller planes at 3/4 throttle the larger will do so at less throttle. Will achieve a faster hole shot, wot plane with a larger HP engine, providing that boat is perfectly deck weight ballanced, engine and prop are 100% operational. Once on plane can throttle back to cruising speed to achieve less fuel cosumption and extend your boating range than going full wot all the timne.

Sometimes when getting out of the hole with bit underpowered engine is much better to throtle to medium throttle, let engine rev up nicely to that point and then go full grip, Call it a 2 stage wot plane procedure. Underpowered engine generally loses some seconds to catch fast rpm from idle to wot,

Happy Boatting