Prop Advice. ,,,,,,,please
 

I have a 1996 29 Scarab.


Had a Whipple put on it. Whipple recommended a 28 Bravo 1.

I put it on and was only turning around 4500 rpm. I was way low so I went to a 26 and had it labbed. I jumped up to around 5050rpm. The rev limiter was moved to 5400. I want to be spinning around 5200 to 5300 wide open.

What change do I need to make to get to 52 to 5300 rpm?


Any help would be appreciated.


Thanks,
Shawn

Re: Prop Advice. ,,,,,,,please
 

Shawn,

We can look at taking an inch of pitch out of it which will increase the RPM 200. I am refferring to a true re-pitching of the baldes, not just simply a cup adjustment.

Julie

Re: Prop Advice. ,,,,,,,please
 

I will contact you when i get home. Working in Iraq right now.

Thanks bro!

Re: Prop Advice. ,,,,,,,please
 

Sounds great.....stay safe over there!!!!!

Julie

Re: Prop Advice. ,,,,,,,please
 

First I would do some checking on your motor, two diffrent 29 Scarabs I know well, turn 28p Bravo 1 props well, one with Procharger and 5 lbs on 502 efi turns 4800, the other is 8-71 on a 502 and turns 5200. The Procharger motor was dynoed at 602 hp at 5000 and I would think a Whipple would make that much. How much boost are you running? I would think with 6lbs or more your boat should easily turn that 28p, and not have to decrease your pitch. 28p at 5000 should be right at 78 mph with 12% slip assumption.

Re: Prop Advice. ,,,,,,,please
 

When I first tested the engine I was at about 3 to 5 pounds of boost. Not that much. I think thats why it wouldn't turn the 28. I know the boat is heavy. I think I could go to a smaller pulley, but not wanting to push the motor to hard even though I think it can take it.

I don't mind pushing it some to get what I want but not to compromise the motor integrity. Let me know what you guys think.

Thanks

Re: Prop Advice. ,,,,,,,please
 

As a reference point, I'm runing a 28 Scarab excel with a procharger.

Re: Prop Advice. ,,,,,,,please
 

28 Scarab excel - procharged 7 lbs boost, 28 bravo one, 74 mph, 5600 rpm

Re: Prop Advice. ,,,,,,,please
 

I would give it 1-2 lbs more boost or raise base timing 2 degrees(kip at cam motion says most intercooled supercharged big blocks will gain 20-40 hp from 2 degrees timing). I raised my base timing on similar setup after getting dissapointing results on the dyno and gained several hundred rpm's and a few mph,Smitty

Re: Prop Advice. ,,,,,,,please
 

Thanks Smitty,,,,I'll look into it when i get home.