New impellers baby !!!!

[swatski]

...different size driveshaft

Good point! I should have known that... I did know that. I forgot what my solution was. Probably nothing good though... LOL.

 

[swatski]

Top speed ever was before tower and no other passengers with less than half a tank i did 52 mph gps (55ish dream o meter).
Did a short run the other day with full tank, cooler of drinks, cooler of food, wife, three kids, a friend, his coolers, tower up, bimini up etc etc. Niel and i ran side by side a bit and we both said 47 mph.

That is pretty awesome with that load, actually.

 

[swatski]

I know you have posted before but I believe you run 14/20 on both sides without any tweaking to get them to match and saw both gains at the low end and in top speed. Is this correct? How much gain did you see in top speed?

Are you seeing 9,800 RPM on one engine and 10,000 on the other?

Have you tried removing the air filters and or ribbons to see if the increased airflow would bring you back up to 10,200?

What do you think about running 13/19 on one side and 14/20 on the other?

@islandracing, thank your for your insight into these issues.

I think the MR-1 HOs are so well air vented, the ribbon delete might still help but probably not by much if any. 1.8 are completely different story. Unless you are running at the rev limit already, ribbon delete gains are typically 150-200 RPM on top.
The MR-1 HO are like 1.8 SVHOs - tuned to the max out of the factory.

 

[Speedling]

I think the MR-1 HOs are so well air vented, the ribbon delete might still help but probably not by much if any. 1.8 are completely different story. Unless you are running at the rev limit already, ribbon delete gains are typically 150-200 RPM on top.
The MR-1 HO are like 1.8 SVHOs - tuned to the max out of the factory.

If you go get a caliper and start doing the calculations, the MR-1 throttle bodies really seem to have way to big of an intake and way to big of an exhaust.
Even thought it's bored and stroked from the 998cc bikes up to 1050 it isn't going to fill those intakes until about that 14,000 rpm mark.
Now, one things the bikes have that we don't is ram air. Ram air never really gets past like 1 psi, BUT, since most engines are creating vacuum, it's actually more significant of a boost than you think. If there was a way to get ram air into these boats, it would certainly help the MR-1 out as far as power. I've gone through a LOT of scenarios, but on the water it's just hard to find a good spot. It would also mean having a whole different style intake. The waverunner guys have done it and have systems in place with favorable results. And then you need to get into tuning with the A/F ratios as well.
In any case... I want to see how his impellers do when tuned up for him!

 

[dan144k]

I am getting the feeling it may be time to learn how to adjust my own impellers pitches.

 

[swatski]

Go for it! You will love it.
And then you will show the rest of us how to do it!

--

 

[Speedling]

I am getting the feeling it may be time to learn how to adjust my own impellers pitches.

The aftermarket ones are much harder like @swatski noted.
Look on greenhulk for prop bending 101.

 

[swatski]

The aftermarket ones are much harder like @swatski noted.
Look on greenhulk for prop bending 101.

Excellent point, Mr Speedling. @dan144k Probably forget about the leading edge all-together. But trailing edge 1-2deg should be no problem (for someone with your power tool skill set)!

 

[buckbuck]

Just leave your cut off wheel in the tool box, Big Boy.