Do i need to rebuild my engine before i put on a procharger? 400hours 1999.
502mag mpi

run 5psi and put the engine in a dyno.

Only take a compression test?

I would probably go ahead and freshen it up. You at least should do the top end and install good valves and head gaskets. However, the bottom end doesn't have much time left, so you would be ahead to just do it now.
You may also want to consider a cam change while you are there. It will really help that engine breath.
Lastly, put it on the dyno and tune it. It has a Mefi 3 so you are fine there. Don't forget to upgrade the fuel system both on the engine and in the boat. Let me know if I can help. Good luck.
Eddie

OK
I have silent shoice and steinless marine manifolds, is it posible to change to a another cam without removing the silent shoice system and install long risers?

You say: bottom end doesn't have much time left?
do you mean the piston rings or all bearings++
Thanx
Marius

You could do the top but then you are running on borrowed time. You may get a season or two if you are lucky. Two would be very lucky.

You can't really put any more cam in with a silent choice. If you freshen it, I would go for more cam ditch the silent choice (use mufflers if sound police are a problem). I have owned a procharged 502 both stock and modified. Eddie is right, you can really wake it up with some cam. If you freshen back to stock, you will hit the wall in the low 600 hp range. For a nominal amount more, you can have it really sing season after season.

I did my stock 502 when it had 288 hours. After Eddie tore it down, I learned I probably would not have gone more than a season more.

Come join the madness. It is a lot of fun.

You can get away with just a tiny bit more cam.....almost not worth it. As Bill said, ditch the silent choice and install mufflers if noise is a problem.
As for the bottom end, I say do it because it only gets worse with more time. The cylinders take on an egg shape over time. You can do it now and possibly not have to bore it, or you can wait and have to bore it to 4.500. As the cylinders take on an egg shape, they start leaking more and more. You will start to have excessive blow by and oil comsumption. Do it now while you have the chance and the engine is out. You need to do the top end and it should be pulled out to do it anyway.
Eddie

Why the cylinders take on an egg shape? i work with bmw cars and that is never a problem. Do i need new pistons or new rings?

Im looking for 70knots on my baja 232, today i have 62knots on the gps. Do i realy need over 600+ to get that speed?

What hp numbers are we talking if i ditch the silent shoice and go for more cam?

Thanx

Marius

You can spend the money now or when it blow's apart you can spend a lot more later your choice . Seen it done lot's of times . I would think it is cheaper to do it right the first time but that's just me. good luck

This isn't a car. It is under MUCH more load than a car loafing down the interstate in overdrive. The egg shape happens over time from the piston loading against the cylinder walls when it hits BDC and when it rocks at the top of the bore as it changes direction at TDC.

To pick up 8-9 mph will require about 125 hp over what you have now. A stock 502 Mag makes about 425 at the flywheel. You will need a solid 550 hp to hit 70 knots. 600 hp will get you about 73 knots and 650 hp about 75-76 knots.
I just did a bone stock 502 Mag with a Procharger. We just redid the fuel system (bigger lines, 1:1 boost referenced regulator instead of the crappy one that comes with the Procharger), modified the fuel rail so it can supply enough fuel, and installed the M3 Procharger. It made exactly 625 hp with 3.2 psi boost. It was about out of injector, so any more power will require larger injectors also.
Eddie

These 502mags love some positive pressure makes the crapy stock intake not care. The machinist I use for my racecar had a bone stock bottom end 502mag with stock injector making 728hp on the dyno at 6psi with a M1 and clean up ported head. Dam impressive for nearly bolt ons. 355hrs and leak done numbers under 14 percent.

I have love for any forced induction but it’s the age of the turbo.. We can make over 1000hp with a 2.0 liter 4cylinder , 74mm turbo, on a mild tune up and dam near a stock head. If they don’t like to flow force it.

At what point HP wise should you start worring about the stock rods?