Reg05

I have a 35' 2001 Fountain Classic (single step). I have upgraded the 502's with a little help from Arizona Speed with the following: CMI e-tops, msd iginition, k&n filters, Dart Pro One aluminum heads, extruded the intake manifold, a more agressive cam.

I only increased my top speed about 3 mph. I am turning about 5,200 wot w/ 26 intimidators. Since I am not happy with this minimal increase, I am looking at either increasing my 502's to 540's or adding a supercharger to my existing set-up. I have spoken to Arizona Speed about this application and Jim says that I could get about 620 na or 700 going the supercharging route.

What are your suggestions? Should I be looking at other engine builders? What expectations should I have about speed increases?

mike11

You could get alot of HP from port work on your heads,ballancing your internals, degreeing your cam and some carb work. What are the specs of the engines. Compression,heads,intake ect ? We have gotten as much as 750hp from aspirated 502 already with those mods which leave you a less tempermental and more reliable engine. If you would like to know more give me a call or email me.
Thx Mike
[email protected]
570-956-2840
www.roccardmarineengines.com

800XCR

We need a little more info on cylinder heads and cam in order to have realistic comments on your existing setup, but something does not seem right.

3 mph = 60 hp over your original 502's.....hmmm...same hp as an HP 500 EFI, but at considerable expense (aluminum heads) over just putting larger intake valves in your stock heads. The msd and k&n provide no measurable performance gains, so the what that leaves you with is the CMI's - definately required - Aluminum heads - should be considerably better than stock 500 heads, but need info on cam to determine their compatibility. I'm guessing there is a little more to be had in your setup. If all components are working together you should be in the 540/550 hp range which should put you realistically 5-7 mph faster than stock 502's

And that's my $.02.

KAAMA

Mike11, The naturally aspirated 502 HP numbers you are quoting sound quite impressive. Let's say Reg05 wants to upgrade to a 540cid engine as he has stated he may do. I am curious of what kind of rough HP numbers your shop can get out of a naturally aspirated, short deck 540cid engine (4.500" bore x 4.25" stroke/6.385" rod), with a single carb, hyd roller cam, 9.5 comp ratio at 5500-5600rpm and still be a "turn-key" piece? Thanks

PatriYacht

I would have to question anyone who says they can get 750 hp out of a n/a 502 and still have decent drivability. 750-800 hp is super cat type power and we know how drivable they are at low speeds.

mike11

We are doing one right now and are expecting around 800 with a tall deck,10.5 to one comp pump gas. 9.5 comp and some head, carb work and a cam change you should see 650-700.

MESABALANCING

I can tell you you can make 750 or 800 hp out of 509 ci but I can't see how it could be done with a conventional type head and low comp I think if you really want to pick up the performance of your Fountain you can go with a larger ci engine that will make more power and torque with unquestionably more reliability . We build marine packages from 500 -1000 hp with a 12 month warranty and also racing engine programs available. Good luck Laz Mesa www.mesabalancing.com