I've been told this before, by Procharger and others, but never got around to it. My procharger belt was slipping (new belt this winter) so I tightened it yesterday....WOW what a difference !! I'm getting 7 lbs. of boost (up from 5 lbs) for the first time. For the first time since I've owned the boat, it took off like a rocket...literally ! I don't have any way of knowing how tight it should be or how to measure belt tension but, man, what a difference !! I'm tempted to give it a few more turns with the wrench but don't want to snap the damn thing. Food for thought...

Rocko, what kind of speeds are you seeing now that you tightened it up?

The amount of boost is determined by which pulley you are using, so if 7lb is what your supposed to be getting tightening the belt more than it should be will not be good for it. Hope that makes since.

I only had a minute or two to take it for a test run and ran out of time and water (ran into a no-wake zone) but it rocketed to 70 way faster than it ever had before...When I get a calm day and more time I'm going to run it again and I'll let you know what I get out of it.

It is a 7 psi system but I never knew that. I bought the boat used with the Procharger already (poorly) installed. I know a lot about boats and Mercruiser motors but nothing about Prochargers. It has the Procharger competition fuel system which, I've come to find out, is a necessity for the 7 psi system.

I'll keep you guys posted, thanks for the replies !!

Is it a 8 rib or 12 rib drive? I started out with a 8 rib drive on my m-3 on my baja 272 and the belt had to be ungodly tight or the boost wasn't consistent,especially with any upper pulley under 4.250". I have since upgraded to 12 rib drive,doesn't have to be nearly as tight but still pretty tight,if your finding ANY belt dust it is slipping. I have wiped out a couple idler tensioner pulley bearings over the 300 plus hours I have been running a procharger but I hear they have a upgraded bearing,I just bought one locally last time because I wanted boat back together the next day,Smitty

The belt is a Goodyear GTR-4080652 (8 rib). No dust and I don't have a clue as to the pulley size. My Procharger is an M3SC w/ Intercooler and Aeromotive competition fuel system, by the way. Thanks for the information.