Performance upgrades

[Germaine Marine]

I have tested countless props on almost every current Tige engine/trans package. The correct prop for what you are intending is absolutely critical in performance, and can be drastic. Keep in mind, their are countless props with countless combos. Knowing exactly what each element does and controls is essential. You can spend hundreds of hours messing around with props that wont do you a bit of good because you are not even at a decent baseline with diameter/pitch and cup.

[bsreid]

What prop are you running?

[Brianrzr]

Mine is an Indmar also. It seems to be impossible to find information on them. I figured tuning the ECM would be the biggest hurdle. Please keep me informed what you find out. I agree about props, I have been completing a lot of prop tests for my employer and the results are not what people think. But that’s for another thread.

[UNSTUCK]

I'm looking into adding a supercharger to mine this spring....if I keep it. The biggest problem I am running into is finding someone that can tune Indmars proprietary ECM. If yours is PCM it may be easier or harder. I have not found anything to suggest that any GM engine was modified from its original intended use (the auto world) other than maybe the oil pan, exhaust, cooling additions and sometimes intake changes. I know for a fact that my L96 is a stock truck motor with exhaust and a tune. That makes it a perfect candidate for an LSA supercharger. It would of course have to be tuned. If I cannot find someone to tune it then I would have to swap the ECM to something that tunable. This isn't a big deal either, but I haven't been able to figure out if Zero Off will still work with the new ECM. Worst case is I would have to change out the throttle system to a cable and run Hydrophase. I know my way around LS engines very well so this isn't a difficult task. I would save a lot by doing the install myself. I figure it will cost about $6k on the high side and $4200 on the low side. What the option fee for a raptor supercharger or even the older LSA optioned motors? $12k-17k?


A prop change works great up to a point. Unfortunately to do what we do at our elevation, it required a prop that runs the engine at 4500 surfing and over 5000 cruising at a SLOW 22 mph.

[TeamAllen]

Changing he prop to fit your needs is probably easier and cheaper.

[boatwakes]

If it's efi, you're in for some money if you want anything more than stock HP out of it ($10k+) and those gains are minimal, less than 400hp. The cams are ground to a specific horsepower profile which will require a computer (ECM) reflash if you change it. Basically you're asking for trouble on a towboat if you want to add more HP. The marine engines (pre LS) were not designed to maintain the HP of their automotive counterparts due to continuous duty load factors.

[Brianrzr]

I have the 350 hp 5.7. Basically a GM small block that’s been marinized. Has any body tried any performance improvements such as cam swap, head work?