cam upgrade
 

Does anyone know what a good cam upgrade, for a 1999-502 MPI 415 HP .

didn't you like the last answer????????

http://www.offshoreonly.com/forums/s...d.php?t=159162

My suggestion would be to get a complete package from a reputable builder instead of trying to piece together your own setup. The package will be proven with dyno numbers and an an ecm recalibration will have already been done.

I have a silent choice style exhaust system. I need a cam that is compatible with it.

Shouldnt make any differance.....the diverters that is. Manifolds and risers are a different story.

You are not going to be able to run any upgraded cam with the stock cast risers. It dumps too close to the exhaust manifold.
The 500efi and 525 cam are both capable of being run with silent choice diverters, just not the factory 502mpi manifold/risers. Also, without some good exhaust, you are not going to see the real gains of any upgrades.

He said it right. One of the most important mods when upgrading for more power is swaping out the stock Merc cast iron exhaust and risers with all it's choked down, crude 90* elbows and replacing it with a better breathing manifold and smoother transitioning tailpipe style riser. For the most part, a better breathing exhaust system must be first on the mods list when looking for more power, otherwise you're just going to be chasing your own tail in circles.

Kaama nailed it. You can try to shove as much air into the engine as you want but if you can't get it out...

Remember, an engine is nothing but an air pump. Start with a good exhaust system. You'll be glad you did.

I did not expect such a response. I left a lot out. I have already installed a set of cyclone S.S. Headers, MSD-6M control box distributor and coil, K&N large size flame arrestor. What I have on hand is a set of 308 Dart Iron Eagle heads (2.250 intake, 1.88 exhaust and 119cc combustion chamber) and a set of Comp Cam roller rocker arms, Cloyes timing chain. I plan on swapping out all the parts at one time. The only thing I need is a cam. I am concerned with water inversion.
Any help on choosing a cam would be appreciated.

Get some flow numbers on the heads and PM "rmbuilder"

You should not have a reversion problem with either the 500efi of 525efi cam, but I think you should get a custom grind to fit your head flow numbers.

The ECM tune will be tough part without the engine on a dyno.

RMBuilder/Bob Madara of Marine Kinetics in New York. (585)654-8583. Bob is high on the list of referals and has helped many here when it comes to marine cam applications.

Bob is great and will talk with you and make you understand why a cam is right or wrong. It is great to have sources like him available to us. Thanks Bob!!!

Bob is great! I have yet to buy anything from him but he has given me real good advise at least 3 times.
Thanks Bob!

Listen to Griff...
500efi cam, with some good aluminum manifolds, and short stainless risers for the captain's call.
Send your ecu to Crockett.
The engine will make 80-100HP more than stock...

OK, I read a little farther.
I'd still say 500efi cam because there are proven programs for the ecu.
The 525efi cam may be on the edge for captain's call. Merc uses large sweeping headers with that cam.

I did a little more research PC perforance and Keith Eickert perforance have a cam kit part #295-011008. he saids it is compatible with a silent choice exhaust syetem. Duration is 284 intake a exhaust , at .050 -224 in. and exh. and 566 int.and exh. at 112deg. Has anyone used this set up

Sure that will work, but do they have a program for your ECU?

Pat
I do not know if they have a promgram for that cam and my set up . I will call and find out . Get back to you later to night


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Pat
Called CP Performance, they told me that they can reprogram my E.C.M. in the same way as Arizona Speed, Flagship, and Keith Eickert would. All I have to do is fill out their spec sheet. Who do you suggest for reprogramming my E.C.M.?

CP prices for the cam is $290.00 and $517.00 for the lifters. Seems to be a bit high. They are Comp Cam parts.
Ken

The price for a new roller cam and lifters is not too far off.
Tyler Crockett or Mark at Precisionmarine EFI for the ECU.
Talk to the programer before you buy a cam. If your not going to dyno the engine, you want a proven combo.
That is why Griff and I have suggested the Crane/Merc 500EFI cam.

my bad

Pat
I called Crocket and Precision Marine they were very reluctant to give me any information about their cam spect .they said that its better then the stock 500 EFI. ,and compatable with a silent choice system. Crockets price is $375.00 and Percisions is $325.00. Both will be able to reprogram my ECM to match what i have already installed, and i will be able to use the stock lifters.

Well, I'm sure that Crockett and Precision have developed their own custom grinds and EFI calibration to match. I think they have 600+HP upgrades too.

From your posts, it did not sound like you had purchased and installed a new cam yet. What cam did you install?

By the way, lots of people have run the Crane 731 (same lift as a Merc 500EFI) with the stock GM lifters. When I install the 500EFI cam I have sitting on the shelf, I'll be checking out if the stock GM lifters will work; they are about half the price.

Bob
I did not purchase a cam yet I am still in the research mod.Crocket and Precision did tell me that their cams are a
custom grind, and i can reuse my stock lifter. I went on line to Crane Cams and look up #731 its not a Crane number.

It sound like you should buy the cam and ecu recal from the same source then...

731 is not the complete part number, it's just what everyone seems to call it.

Good luck with your project.

You have not mentioned re-programing your ECU and in my opinion this will be a must. I went to merlin heads with simular valves, bigger injectors and a mag cam. Lots of changes and the ECU took 6 hours to re program in the boat. Best money I ever spent. Fuel delivery should also be looked at. Tyler @ Crocket Marine does the re-programming and coould advise on the fuel delivery.