Repowered Scarab, need prop help

[redscarab]

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.

[bajabob]

i go with 23 then wot and check your rpms !that will give you base line

[rumblfish1966]

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

[Hammered]

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

[dcg9381]

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.

[Scarab28]

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.

[DMOORE]

Originally Posted by Scarab28

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.

[1BIGJIM]

Originally Posted by redscarab

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.

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

[Scarab28Germany]

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

[redscarab]

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