Procharger

I recently mounted a stageII procharger on my Baja 272, 502EFI with Stainless Marine exhaust system and a Land & Sea stern jack. Before the installation I was running 67mph(gps) with a 25" Mirage 3 blade. After the procharger I had to go to a 30" 4 blade bravo to keep it out of the rev limiter. I am running 5lbs of boost and was planning on picking up a little more than I did. Everything that I had read told me that I would pick up between 14 and 20 mph but I can only manage to pick up about an honest 10 mph. The boat is running a little rich but I figured this was a good thing. My question is has anybody with this similiar set up had the same type of results or do you have any suggestions to get me to that 15 mph pick up? Thank you for any response.

Your 502 MPI should make at least 650-725 horsepower with that State II. If you're hitting the rev limiter which is 5050 RPM with a 30" prop, you have to be going much faster than 77 MPH. If you do the math you should be at around 82-86 MPH with approx. 10-14% prop slip. If you're hitting the rev limiter, the problem would be in the prop, not the Procharger. If you can spin a 30" prop at 5000 RPM, you must be going faster than 77. The way you figure it is like this:
Prop Pitch X RPM divided by the Gear Ratio X 1056. That shows you your theoretical speed with no prop slip. Then you take that Theo speed - your actual speed and divide that number by your actual speed. That gives you your prop slip which for your boat should be 10-15%.
I have a 25' tunnel with a 502 & a Stage I Procharger. Before the Procharger, my top speed was 70 with a 26" Bravo I prop. After the Procharger and a little experimenting with props, my top speed is 94.5 on GPS with a 28" Bravo I that has been lab finished and bent to a 29.5"
Be sure you're not running too rich. Check the fuel pressure with a manuel gauge hooked to the Procharger fuel pressure regulator. Be sure you have at least 50-55 lbs, but be sure it's not way high. That Stage II pumps fuel into both ends of the fuel rail and if the regulator is set too high, it will foul plugs, etc. - Hope you get it straightened out. I think it's a prop problem.

Thank you for your reply Steve. As far as props go I tried a 26" and a 28" 4 blade bravo, a 27" 3 blade mirage. All 3 were in the rev limiter with the 28" giving me the best performance. Also it is impressive to see your gains with the procharger. That gives me hope to get where I want to be or maybe i'm there and don't know it but I doubt it.

I've got a 272 with a 502 EFI and the best speed that I can get is 63 mph on GPS at 4900 rpm. I'm using a mirage plus 23" prop. I'm thinking about installing the stainless marine exhaust manifolds, the stern jack, and the procharger stage 1. How much speed did you pick up with just the manifolds, or the stern jack? How is your boat handling in the upper 70's? Did you have any clearance problems between the intercooler and the rear seats? How is the idle quality and drivability with the procharger setup? Any info that you can give will be a great help.

272, before I installed the exhaust and the stern jack I was running 62-63 mph. I installed the exhaust and the stern jack at the same time, so I really don't know which did more but it took me to 67 mph. The boat handles very well in the upper 70's and the intercooler will not fit behind the seat. I had to do the remote mount deal on the side of the motor. The boat idles the same as it did before the Procharger. I have been very happy with the Procharger, I was just expecting a little more pick up than I got but Steve makes me feel a little better with his calculations. I only used the gps with the 26" and the 28". So I actually might be better off than I thought with the 30" although it only shows 77-78 on the speedo. If I can be of any assistance feel free to ask.

Originally posted by Steve:
Your 502 MPI should make at least 650-725 horsepower with that State II. If you're hitting the rev limiter which is 5050 RPM with a 30" prop, you have to be going much faster than 77 MPH. If you do the math you should be at around 82-86 MPH with approx. 10-14% prop slip. If you're hitting the rev limiter, the problem would be in the prop, not the Procharger. If you can spin a 30" prop at 5000 RPM, you must be going faster than 77. The way you figure it is like this:
Prop Pitch X RPM divided by the Gear Ratio X 1056. That shows you your theoretical speed with no prop slip. Then you take that Theo speed - your actual speed and divide that number by your actual speed. That gives you your prop slip which for your boat should be 10-15%.
I have a 25' tunnel with a 502 & a Stage I Procharger. Before the Procharger, my top speed was 70 with a 26" Bravo I prop. After the Procharger and a little experimenting with props, my top speed is 94.5 on GPS with a 28" Bravo I that has been lab finished and bent to a 29.5"
Be sure you're not running too rich. Check the fuel pressure with a manuel gauge hooked to the Procharger fuel pressure regulator. Be sure you have at least 50-55 lbs, but be sure it's not way high. That Stage II pumps fuel into both ends of the fuel rail and if the regulator is set too high, it will foul plugs, etc. - Hope you get it straightened out. I think it's a prop problem.

Originally posted by carreraeagle:
I am a little confused
Steve, your numbers for figuring speed arnt working

Originally posted by carreraeagle:
Originally posted by carreraeagle:
I am a little confused
Steve, your numbers for figuring speed arnt working
Here's the formula: Go wide open throttle. Multiply your prop pitch times the RPM you are turning at wide open throttle. Then multiply your drive gear ratio times 1056. Divide the 1st number by the second number and it will give you your theoretical speed with no prop slip. Example: If you have a 28" pitch prop and can turn 5000 RPM you multiply 28 x 5000 = 140000. Then say you have a 1.36 gear ratio. Multiply 1.36 x 1056 = 1436.16. Then divide 140000 by 1436.16 which gives you a theo. speed of 97.48 with no prop slip. If you were actually going only 90 on your GPS or radar or speedo then you would take 97.48 minus 90 which is 7.48 and divide that # by your actual speed - in this case 7.48 divided by 90 = .08 or 8% prop slip.
If you have a Cat that's pretty good but V bottoms etc. have a lot higher prop slip. At least it gives you a starting point to see what your boat might do with a certain pitch prop etc.

Thanks Steve, those numbers work great.I have 10% slip on a 20ft carrera eagle with a 350 mag mpi stern drive.

I have a 272 Baja with a HP500 with a ProCharger at 5LBS boost. The carb was rebuild by Nickerson, MSD Ignition, Electric Fuel Pump, I turn a 28 4 blade at 5200 the boat runs between 80-82 depends on the load when the water cools I turn 5400 @84-85. Now Why I am writing is I just left the shop and saw my heads. I blowed a head gasket which in turn cut the head between cylinders. In checking out the problem I was told that the factory head gaskets will not hold up with a procharger. It would have been nice for ProCharger to recommend the FelPro gasket up grade. Sure wish I knew that sooner And I hope you all with a ProCharger checks out what I am telling you. My engine lasted 2 years with the ProCharger. Now looks like I can turn more R's & make more HP's.