Building 540 stroker for my Prowler
 

Spun the engine coupler about a month ago. I did not hit anything. Pulled the O/D and motor. Had to replace the lower unit on O/D. The propshaft had a slight twist in it probably from previous original owner and, when disassembled, found more damage. So while I had the motor out I was going to update the lower end with ARP main and rod bolts, new oil pump, one piece rear main seal, harmonic balancer and cam chain. Got taking it apart and started ringing off oil pan bolts. It was not pretty. So it was decision time. 502 had 400 hours on the clock and is a pile of rust inside and out. It was a FL boat. I saw the corrosion and errosion of the block last year when I installed the Dart heads. I was surprised the Cometic gaskets sealed. So started looking for a short block. Got one coming from CNC-Motorsports. GenVI 540 with 9.4:1 compression ratio, 4.250 stroke, 4.50 bore and ARP main and rod studs. Got a new Comp cam and roller lifters, recommended by Comp technical support, that is a little more radical then the OEM cam. According to Comp I should see a 30 to 40HP increase. So with the new balanced and blueprinted block, Dart heads, IMCO exhaust, 10 quart racing oil pan, 3" aftermarket oil cooler, complete MSD, improved cam, high volume oil pump, FWC, etc., I should have a pretty strong ride for next Spring.

Also, removed the Y pipe. Man there is a lot more room behind the engine. Did a big cleanup in the engine bay, meaning dirt, grease, wiring and steering/hydraulic fluid and lines. Rewired and replaced both bilge pumps and hose. After almost 15 years, original wire and hose was brittle.

Anyone have this motor or one similar in their prowler? If so, what prop are you running? I have a B1 24P and am not sure if that is going to be enough. Thinking of getting a B1 26P. Any thoughts or experience with this setup would be appreciated. Any speed numbers?

I welcome your comments.

Ed
'99 Sonic Prowler 260
502 MAG/380 Hours/B1 Drive/B1-24P Prop
Dart PRO-1 Aluminum Heads/SS Intakes/Inconel Exhausts
Comp Cam Roller Rockers/Push Rods (.375")
Cometic SS Head Gaskets
ARP Head Studs
IMCO Aluminum Exhaust
Hardine Polished SS Risers
Complete MSD Ignition/Cooling Fan
Denso Iridium Plugs/MSD Plug Wires
K&N/Hardine Marine/PWR Air Intake
ECM Upgrade
San Juan FWC
RACOR Water Separator
Corsa Silent Choice Removed
Custom PWC Cold Air Intake

I'm running a 540 putting out 650 hp, 630 lb torque. 2" sport master lower and bravo 1 28 pitch. With this set up boat runs 75. Still needs some dialing in though.
Profiler heads.
9.8 compression
DUI distributor
Professional products intake
Carb 900 - 1000 cfm. Custom work done to it

Thanks for the info. I have EFI and to get that amount of power, I ordered an upgraded throttle body. I'll tinker with it more once I get it running and see what happens.

Ed

The 540 with the stock efi setup made about 600hp. I did do some machine work to the intake. Machined the runners down to match the floor of the plemtium..Also machine the the inside of the runners down 1 inch to help with air flow. I ran that set up one season.

I ordered an upgraded TB from TPiS. Increases TB bore from 60mm to 68mm. That should help.

Ed

What RPM are you running at WOT? Is that speed GPS?

Ed

Motor made peak power @5300. I'm turning it 5100..Needs some prop tweaking for another 2 - 300 rpm.. Yes that GPS speed..


Mike

So are you going to come down to a B1 26P to get the 200 to 300 RPM?

Ed

I'm Actually building a new motor around 700 hp. Hopefully I'll be able to spin the 28 where I need to be.