Repowered Scarab, need prop help
 

I recently repowered my 1989 Scarab Excel 28', weight 4600 lbs. ,new bravo 1 2nd design 1.5:1, bottom rough (someone bottom algae painted it) .
removed tired 454, removed vengeance 14" x 19p prop.
Installed 415hp 502 w/hp manifolds, edelbrock perfomer intake and 750 cfm carb.

Thinking of using a Revolution 4 4 blade prop.
Most local guys here reccomend a 14 5/8 21p
Wellcraft reccomends a 14 5/8 23p
Mercruiser site calculates a 14 5/8 19p

Any expert advice for a good starting point pitch?
I'm sure not gonna start with that old 14" x 19.

i go with 23 then wot and check your rpms !that will give you base line :cool-smiley-027:

I would agree with Bob , go with the stiffest one ya got and see where your at

I have 21's on mine with stock 454's right now and a much heavier boat. I would say that motor combination would spin a 23p easy

I can't comment on the 4 bladed prop.
I've got a 385 hp 23.5' boat, ~4000 lbs.
It's proped with a 3 blade 23P Mirage plus.
The OEM prop was 23P also.

I'd probably start with the equiv of a 23P prop and go from there based on RPM. Make sure your tach is properly calibrated.

Stock 89 excel came with 365 hp and 23" mirage. That combination runs about 60 MPH at 4900 rpm.
With the add HP, I would look at a 24 bravo 1. Remember, it's a heavy boat and requires bow lift, not stern lift.

I'm going to agree with Scarab 28. Bravo should give some good bow lift.



Darrell.

You increase in HP was under 100HP. I will have a hard time believing with that heavy of a boat you can increase the prop from a 19P to a 24P or 25P. I would get a test prop from BBLADES as he suggested. He got me dialed in:D

Hi redscarab

i have a 28 Scarab Excel from 89 too.( 502 EFI 415 Hp EMI Exhaust))
A three Blade was very bad in overall performance
I had a Labsinished Bravo 24Pitch with 63 Mls/4800Rpm
After a EFI upgrade from Tyler Crocket Marine, (Aircleaner,EFI Progamm, a little more
Fuelpressure, recomended in a older Hot Boat for the 502EFI)
Now I have a 26 Bravo from B Blades with changed Rakeangle to bring the Boat out of the water, the made a labfinish too.
The Boat is driving totaly diferent than before, it´s goes now over the waves not thru, that´s much smoother and faster.
Now 67-69 Mls at 4700-4800 on the River (Rhein) no Saltwater where i think the Boats ar always faster.
I can Recomend a 4 Blade Bravo and BBlades withe the Rakeangle and Labfinish

Good Luck

Hans
Germany

Thank all of you for your advice, I will put it to good use.