Originally Posted by mcprodesign

Stock 575 sci motors with yR5's for Years and no burn on the pistons plugs or anything,. How is this possible. That is the question. Maybe the blower shop makes just that much better 250 blowers. I am at about 6-7 psi boost. I would really love to know .

Originally Posted by 4bus

The 575sci is 550 at the prop, 575 at the crank....stock.

I don't have a prop shaft dyno, most don't......so most aftermarket mods are referred to as crank shaft power so the world can relate, without doing the merc math.

The way you learn is to put out bad advice? You started up my shorts, questioning my set up, recommending plugs 4 full heat ranges hotter to the OP, and making out-landish claims and comparing my boat to yours (there is no comparison, we have different bottoms)

Why should I be at 104 mph? I could be at 110 mph if I wanted. I want a boat that works every day, and is rare to break. Sure there is speed to be found with short lowers, 5-6 blade props, bottom work, things to lower my slip and put even more stress to my XR drives that are already being fed too much HP.

I'll take my 98 mph every day, and 101 mph on the 5850 limiters when the conditions are right. 15 percent slip is not the best, but drives are in the water, and 15 takes a little bit of the stress away.

There is one thing I agree, you are making HP if you are running he speed you claim, and turning the RPMs you claim with a side by side small step lightning. Where your HP came from will remain a mystery I guess? Because an MSD box, with 3.5 pulley and chiller won't get you turning 5800 rpm at 100 mph in a 38.

What props are you spinning to 5800 ?

Originally Posted by cheech

I'm actually confused as in this thread you say they have been running great, but in This One Here you state one had a hole in the piston.

Originally Posted by mcprodesign

Gear ratio 1.5 prop 32 p rpm 5600 speed 98.0. I know I say 100 and it will go 100. Just not where I tested. I tested at 1300 feet of elevation on a flat calm lake . SO I "assume" it will go 100 in the right conditions , plus I have a new motor (it always ran kinda weird before). My star motor was carrying the old motor a bit. You can tell when you accelerate. So maybe even 102 when it's all said and done. But I am confident of 100 @ 5700 rpms give or take. I never told anyone what to run in their motor.

Originally Posted by high&Dry

Well your 32 bravos are actually 31.5 (or less) and that makes for 11-12% slip...........must be doing something right.

Originally Posted by mcprodesign

Stock 575 sci motors with yR5's for Years and no burn on the pistons plugs or anything,. How is this possible. That is the question. Maybe the blower shop makes just that much better 250 blowers. I am at about 6-7 psi boost. I would really love to know .

Originally Posted by mcprodesign

Well this is off topic, but If you run your boat hard testing props all day, be careful backing the boat back in the water.Cold water can go in the exhaust pipe and get into the cyl. The heads are hot and some cold water splashed in the exhaust and shrunk the valve seat enough to dislodge it. It has to be a perfect storm. The motor has to be hot. The water has to be cold and the valve has to be open so the seat can fall out. Happens with alimun heads and cast iron heads. And It happend to me. Just sucks, but i will deal with it. Also bad exhaust manifold gaskets can cause water to get in there too. It happens to bone stock marine engine now and then . ask anyone. The solution.. Change the friggin props out while the boat is in the water.