Anyone have experience with drive spacers on a Nordic Rage?
Currently running 496HO, 425hp with lab finished 27P and experiencing from ~15% slip for best conditions light load to ~17 % slip for poor conditions heavy load. I understand that 10-12% slip is ideal.

Also considering future 525hp upgrade.

All insight and suggestions welcome!

Post your performance data so we can take a look.

What drive and gear ratio?
Make and Model of propeller?
WOT RPM?
WOT MPH vis GPS?

Julie

Julie,

BravoX, 1.5:1
@~4550#, 26P stock Bravo1, 5000rpm=68mph, Lt chop
@~4060#, 27P lab finish Bravo1, 4900-5000 rpm=69mph, Mod chop (just about perfect conditions)
@~4230#, 27P lab finish Bravo1, 5150 rpm=71mph, Mod chop (just about perfect conditions)

With the 496 HO you need to run at 5000 RPM at WOT, as this is were the peak HP is produced. This is were the peak top end will be found. I have calculated 14% slip with the numbers that you posted. Unfortunately I don't know what the pitch of your 27P Bravo I propellers are. The Bravo I propellers are only available in the even numbers pitches so a 27P is obviously a modified 26P or 28P. How did they come to be 27P propellers is the question.

Julie

The 27P lab is a converted 28P stock Bravo1's. All the propeller lab re finishers I contacted including Mecury Racing said that based upon my numbers with the 26P stock Bravo1 that the increased rpms to be obtained from the thinner lab finish blades should be offset with about a one inch increase in pitch.

I have now also have a modest increase in top end horsepower that I did not have before along with optimum weather conditions and light load generated the 5150 rpm's noted. This will be the exception rather than the rule which will be in the 5000 rpm WOT with the current labed 27P.

This is why the props are running similar RPMs. I would suspect that the 27P that ran at 71 MPH has a little more cup removed and may be a little thinnner lab. You are basically there and should maybe consider some adjustments that may improve slip.

Julie

Julie:
How does the P5-X work on the Rage? We know it works well on the Heat !
Regards,
Steve

Julie,

Thanks!

Actually both sets of data on the 27P lab that I showed are the same prop just from different days run. I apologize for not pointing out that fact. The 27P lab @69mph did not have the advantage of the modest increase in motor hp I mentioned. The 69mph was run a year ago with 25 hours on the motor and the 71mph was run this Sunday with 80 hours on the motor on the same lake (916 elevation) and ~ same near perfect atmospheric and water conditions. The hp improvement was in the form of reduced exhaust restriction that provides the increased hp at the top rpms. I suspect this is why I could turn 5150 rpms at WOT with the same prop this week and only 5000 rpm a year ago.

My calculations for % slip with the stock 26P is ~17%+ and with the 27P lab is ~15%+ for both runs noted.

Actually it is the 'adjustments' in the form of a drive spacer to improve % slip by 2-3% that I am inquiring about i.e. what is the experience out there with adding a drive spacer to the stock Rage setup with the 496HO?

Are there other adjustments that you are referring to to accomplish the same result of improving % slip? If so please elaborate.

Thanks again for your help!

Julie,

Please let me know what options are available to improve slip and top end.

Thanks!

I typically recommend that you install a drive spacer with 17% slip and above. If you have 17% or greater then I will recommend a 1" spacer to get a little more prop in the water increasing propeller efficiency. I think in your case then I would recommend a 1/2 inch spacer. Again I have not had great luck with the 5B propellers acheiving the goals of top end & cruise speeds. Hole shot seems a little quicker with the extra blade and of course accleration. The 5B works well on the Rage but the 496 HO is the question.

Julie