Procharged 29 not getting the speed it should???
 

Hey Guys,
I recently installed two procharger kits on my 2000 29 Scarab with twin 350 Mags. The engines have 300 hrs on them and seem to be running very well. Before the install I was getting 63.5 mph on the GPS (Raymarine A50D chartplotter) spinning 4600-4700rpm with Mirage 23's. After the install the boat is showing 70 mph on the same GPS spinning 27 Mirage pluses at 4600rpm with 4 lbs of boost. Fuel pressures seem fine and this past weekend I tried 25 Mirage Pluses and although I'm pushing a couple hundred more rpm the boat still doesn't go any faster. I'm wondering if you guys have any experience or ideas as to something I may be missing. Everything seems to run very well and the ECU's were re-mapped by Mark at Precision Marine so I believe the ECU's should be about right. Your thoughts would be appreciated.

Boost is on the conservative side at 4 lbs. Crank it up to 6 or 7 lbs and hold on.

I was thinking the same thing (about the 4 lbs). :drink:

Ok I will ask what kind of numbers were you looking for ? As mentioned the boost is soft but at 300 hours on them before you started I would stay soft .

sent you a PM

I know the 4 lbs is a little light but I thought that maybe the engines aren't spinning hard enough that the pro chargers can make the extra lb of boost. I'm wondering if I should just buy a new pair of GM marine long blocks from Michigan motorz and start from scratch. Thoughts?


As for speed, I was hoping for at least 75mph on the GPS. Hope that's not being too greedy for this setup.

I thought most peoples 29's ran 67-68 stock. 23's turning 5000rpm is what most post up. Maybe you were starting with something a bit off that is slowing you up.

With Twin 350's Stock You Should Be Running 68-70 Mph. You May Have Something Else Going On. Are Your Tachs Reading Correctly?

Just a thought, check the tension on the blower belts..............:coolcowboy:

I have always noticed with this boat that it doesn't seem to pick up much speed in the last 1/4 to 1/3 travel on the throttles. It seems like I only get a few more mph after 2/3 to 3/4 throttle. I even checked the throttle plate and it is not fully open until the throttles are.

one thing is did you get the spacers out of your K plane so your tabs will come all the way up. mine had the spacers in them and gained some mph after I had them taken out When my boat was stock it ran 67 to 69 mph after I put the pro chargers on it it ran 80 to 82 mph with 28 four blade bravo one props Now I do not have the pro chargers on any more do to the people that were working on my boat but that is a very long story and i'm now going in to all that right now
I ended up rebuilding both motors with all forged steel internals full roller and arp studs and bolts on everything and felpro head gaskets now I am ready for the pro chargers now So if you do the bottom ends make sure you have a very trust worthy shop to do the work for you and close by to check up on progress