raker 26p

[ditchdigger21003]

I have a Raker 26p prop, and only turning 4800rpm at W.O.T. can anyone tell me around about what pitch prop i might need to get my rpms up around 5800? I'm thinking a 25p, or maybe a 24p.

 

[Silvertip]

Re: raker 26p

Optimize engine height first. Then think about props. (150 - 200 RPM/inch of pitch up or down).

 

[steelespike]

Re: raker 26p

Not an expert but What speed are you getting at 4,800? I'll assume the Nitro is a light fast boat.That said 26 is probably asking too much.An Etec 150 on a Checkmate Pulsare 2000 20 ft 1400 lbs running a 14.5 X 22 prop gets 61 mph at 5,500 rpm planes in 3.1.Of course I don't know how its 1.86 gear ratio compares to your motor.
A 1" pitch change is good for about 200 rpm.So a 22 would give you about
an 800 increase and 5,400 rpm.A 20 about 5,800.I think your motor developes at 5,000 It would seem to me 5,800 is a little beyond its best output.The Etec maxes at 5,850 500 above its rated rpm.

 

[ditchdigger21003]

Re: raker 26p

I'm running about 53mph @ 4800rpm. I want to be turnning about 5500/5800rpm. A friend is letting me try his 25p 4 blade prop. Any input on 3 blade vs 4 blade would be greatly appreciated.

 

[steelespike]

Re: raker 26p

Generally a 4 blade will lower your top speed and rpm.Usually a 4 blade is used to improve low end performance.Also sometimes for extreme loads
houseboats etc.

 

[walleyehed]

Re: raker 26p

You're not really "IN" the power band yet.... the 200 per inch is out the window here. The 4-blde you mention may give the same RPM with less speed if just bolted on, and as with any prop, you must maximize the set-up so the engine is as high as the prop and/or water pressure will allow.
The 24P raker may get you what you need by adding additional lift and speed to reduce drag....this is where the 200/inch goes out the door...
Decrease drag by raising engine, which will increase speed lifting boat more creating lower drag.
Where is the mention of this being an ETEC? is that what we're looking at here?

 

[steelespike]

Re: raker 26p

You're not really "IN" the power band yet.... the 200 per inch is out the window here. The 4-blde you mention may give the same RPM with less speed if just bolted on, and as with any prop, you must maximize the set-up so the engine is as high as the prop and/or water pressure will allow.
The 24P raker may get you what you need by adding additional lift and speed to reduce drag....this is where the 200/inch goes out the door...
Decrease drag by raising engine, which will increase speed lifting boat more creating lower drag.
Where is the mention of this being an ETEC? is that what we're looking at here?

I just used the Etec info to compare in the ball park performance.
Obviously the raker pretty much throws that out the window.

 

[walleyehed]

Re: raker 26p

In this case, I think 1 may see a 700-800RPM gain going down 1 step in the raker.