Want some opinions, and hopefully some experts with experience. I have twin 575sci's with now about 45 hrs of run time on both, should have about 60 hrs by the end of the season.

They are 02's so head gaskets are a give in. They sat for a while so head work and valve springs are also a give in.

I have read to send the blowers to DPME for stripping and rebuilds, good idea or something better?

Should I chill them, or does it cause more problems? This thing will already load up fairly bad on long idles runs, hear chillers make it worse

I keep reading to change them cam to full roller, 525 grind...why?

The fuel burn off boost on these engines are terrible. Read a boat test on a 42 fountain with 525's got 1.3 mpg cruising, same boat with 575sci got .7 mpg cruising at similar RPM. I am seeign the same thing, they are terrible to cruise with....so I just run WOT Anything that will address this?

What is the best single pump fuel system conversion out there? The stock system is complicated and I believe part of the fuel burn problem.


Who has the best ECU burn for this engine, or should I go custom after the mods?

I am not trying to shoot the moon, its just these engines are antiquainted and fuel burn is not on par with others. I want to make it reliable, and still appear to be a stock improved merc racing engine for resale. I will not remove EFI system

I am not against sending this engines out of my area if the builder can provide crates.

If you are a builder and have a complete package that works, but shipping is an issue I would be willing to buy the parts from you and have them installed local to help pay for the advise. But I want proof your formula works

Not looking to make 850hp drive breaking HP. Looking for a little edge, and improved reliable power that runs like it should.

If you think it is fine just the way they are I would like to hear why as well

My 575's were upgraded a few seasons back and could not be happier in how they perform.

Work was done by Dorr's Marine Engines up here in Maine. Tim Dorr has been in business for 30 yrs. He attends Merc Schools every year and is at the top of his game.

Here's what was done:

Swapped out the dished pistons for flat tops, (8.3:1) 4.500" bore

Swapped out the lame flat tappet, .559 lift cam for a full roller grind, very similar to the 525EFI.

Cometic MLS head gaskets

Ported and polished stock heads (in hindsight, should have gone with aluminum)

All new valves, Ferrea, Inconel EX. Severe duty stainless intakes.
Titanium keepers

Whipple low profile intercoolers. (plumbed w/seperate transom mount pick-ups, outlets dumping on drive tops)

Smaller pullies, 6.5 lbs boost

Blowers completely re-freshed by The Blower Shop.

ECU's re-programmed with 5600rpm limiters, calibrated to run cold. -I believe they are 120 deg thermostats.

All these mods make for a much better/cleaner running engine. Fuel burn below boost is very reasonable. Zero soot on the transom, no wake zones are a breeze, just idles like a stock 525.

Dyno runs were made without intercoolers at 3.5 lbs boost. 698hp. We feel adding the intercoolers and smaller pullies should ad about 60 hp or so.

If you don't mind travelling to Maine, I guarantee you will be impressed with Dorrs Marine. His facility is just as impressive as his work.

Kurt

Gellner supplied me with the pieces ( heads, cam, ecm reflash) in his recipie
3 years ago, they run great.

The 2 things that probably make the most noticable difference
are the ECM reflash ( takes care of the quirky running characteristics) and the hyd roller camshafts ( added power)

I have the stock fuel system and everything else looks stock

Picked up 5mph

"Should I chill them, or does it cause more problems? This thing will already load up fairly bad on long idles runs, hear chillers make it worse"

Yes, go with Intercoolers and reprogram the ECU's. The engine will burn cleaner. No soot on the transom.

Kurt, can you elaborate on the heads. I know the aluminum heads would be better. I'm just curious on your reasoning and what your experiencing.

Thanks

There was a lot of money put into reconditioning and porting. Should have just bought new AFR heads as they would have probably cost the same or just a bit more.

Did you change the heads or port the stockers? I assume you are still running stock boost, and no chillers? What was the total HP gain? Did you notice a difference in overall drivability?

Upgrade? Looks like you have new engines

What drives are you running?

Was the ECU burn done on a dyno or was it an off the shelf MAP you picked up?

The stock heads were ported. Boost upped to 6.5 lbs. ECU was not done on dyno, it was sent out. As mentioned, it runs much better/cleaner than a stock 575, presently got 110 hrs since the rebuilds.

I feel the key to long term reliable boost is intercoolers. Reduce the intake charge temps, reduce the threat of detonation.
In order to keep fuel from 'puddling' at idle/no wake, you must eliminate water passing through the coolers (otherwise, it turns the atomized mixture back into liquid form) As mentioned above, we plumbed the intercoolers with separate transom mount pick ups, to strainers, to intercoolers. No pumps involved. When on plane plenty of flow. (also installed pressure relief dumps)

Drives are XR Sportmasters. It's a light boat but at this power level, lower gear sets get punished,

Good luck!

Kurt

I recently did some of the same things.

Sent blowers off for rebuilds to DMPE - they are the best IMO.
Replaced flat tappet cam with all full hydraulic roller parts
Replaced heads with brand new, bigger, aluminum Brodix heads. Like someone said, by the time you port and buy all the parts for the stockers, you might as well have bought new ones.
Smaller pulleys to make up for lost boost (new heads flow better that you actually lose boost)
I didn't put intercoolers on mine, as I was already tapped out on $$$.

One thing that mine does have is, a lot of soot on the transom!! Very annoying sometimes.