Prop suggestions???
 

Guys,

Have the lucky "opportunity" to select new props due to losing a prop shaft and prop running over the weekend in our river. Anyone have some first hand knowledge, not just a give this a try opinion?

Here's the scoop on the set-up:

1999 35' Fountain
HP500s warmed slightly ~590-600hp
Bravo drives with -2" Bravo SHop shorties
Was spinning 30P Bravos labbed by BBlades

Perf was:
Fall, cool weather [email protected] gps
Hot, humid summer ~5-5100rpm@76-78ish

Looking to get slip numbers down as they seem pretty high. Also open to buying/labbing a set of props rather than replacing the 30P Bravo LH I lost in the river. If Bravos seem to be the ticket from everyones consensus, guess I will need to get on the horn to BBlades and get a matched set...

Also, Hydros usually came on these boats... any sense in going back that direction? I believe I have seen a lot of discussion on P5's and P5X's... any comments there?

Thanks for all the great suggestions and great knowledge on this site!:cool::drink:

razor1115

Something is off here, my 99 35 with stock 500 carbs ran a solid 80 any day and a best of 82-83 in perfect conditions on a cool day, with stock 26 Hydro Quad 4s or the Merc lab 28 Bravos, standard lowers at the original X dimension. If you are in fact making close to 600 hp you should easily be high 80s or maybe even close to 90 mph.

The Hydros were my favorites for handling in rough water and at speed, the Bravos were good cruisers and worked better at low speeds and on plane. Both sets ran essentially the same speed on any given day.

My P5Xs seem to be a good prop on the 35 with raised x-dim. When I purchased my props from Tom at Hydromotive, he said unless the x-dim was extremely high that I should stay with the P5Xs. So, I really don't have an info on the P5s.

Ragged,

Are those gps speeds? I didn't think I was off at all. The all- stock boat specs at 77-80 mph, I believe. Throw in another ~60hp = +3 mph (a stock hp500 is rated at the prop, so they realisitically put out 530-540 hp at the crank) and raise the x-dim = +1-2 mph. That puts me at +4-5 mph over stock.

That said, puts the boat at 81-82 on it's worst day (from the 77 mph spec) and 84-85 mph on its best.

I know the prop efficiency could be better. Am I missing something?

razor1115

More or less, no GPS speedo on the boat but based on numbers from a friends boat when side by side, so the numbers are pretty accurate.

The HP 500s were 500 hp at the crank and 470 hp at the prop per Merc. So I would assume your hp would be 90-100 more than that on either end. Using the 20 hp per mph general rule would put you into the numbers I mention. And the short lowers on a 99 model should add a couple more. To make the 600 hp from the base 500 you most often do heads, cam, and better exhaust. You didn't mention what was done to perk yours up.

The engines were gone through at the time of the Crane valve spring update (a problem everyone has heard about) The only thing that wasn't swapped was the exhaust.

Dyno sheets show 620hp at 5400 rpm before they start dropping off. That said, timing was dialed back from 36deg to 34 by installer before me (I verified) That probably cost 25-30hp. So now were at 590hp. Throw on stock exhaust and forgot we probably lost another 20hp.

That leaves a net of ~570ish - another 10hp for accessories = 560hp. That's how I arrived at the +60hp over stock hp500 (@ the crank). Does that seem realistic? It would be awesome to get to 90mph, however.

Suppose a new exhaust might pick up a couple mph... and a more efficient prop.

razor