500efi to 575sci conversion, what's needed?
 

Hey guys I'm debating trading/buying a pair of 575s for my 31 american offshore, I really wanna get into the triple digits, and the 500efi motors that I have aren't going to do it. What's all needed to put 575s in? And if anyone is interesting in trading let me know, engines have 170hrs on them and are spotless!

A Larger fuel tank!!

Less expensive to bump the 500 EFIs to 600+ HP.

The 500efi is a great starting point for a whipple. 700+ is very realistic. The 575's are flat tappet engines, and the blowers can be problematic at times.

+1 3.3 whipples and the ecm's can be remapped

Agree with the above. I have 575's and at the first rebuild of me owning them we made them roller motors and did a lot of work to make them "right"! Now they are 700hp :)

That said, you have a great platform to Whipple yours to 700. You get a whole new set of problems with the 575's.

It's not cheap, but I'd also look hard at the Whipple's.

I'd also consider going with larger cubes and staying NA if you don't want to deal with blowers. It's pretty easy to hit 700+ hp with a nice reliable set of 540's or 572's. If they were built with forged bottom ends and had flat top pistons, the CR can be dropped with thicker HG allowing you to add blowers to these engines and make a lot more power in the future if so desired.

+100 on whipping the 500s, and I am a 575sci owner. There is some real old, and sometimes oddball tech with the 575sci. You will not find direct replacement injectors, intakes, blowers, and thermo housings anywhere on the market. A 575sci can make some serious HP (mine are bumped quite a bit) but they are engines for a diy guy that doesn't mind tinkering and inventing solutions to engineered problems! The 575sci may also be the least fuel efficient injected engine merc made

Whipple the 500s, keep your stock parts, safely make 650hp and return the engines to stock before you sell the boat. The whipples on the used market pull big money. You will recoupe most of your money in the end, which never happens in the boating world :)

Eh....but blower whine drops panties!!

Just seems pricey to whipple the 500s at 10g per engine, I could sell the 500efi and buy some nice mild 600hp 540s that will run forever