500EFI to 575SC Conversion
 

I have two stock 500EFI's I am going to install some 575SC intakes. Anybody done this? Looking for suggestions of which way to go. My initial thought was to leave the compression stock, 8.75, keep the 500 roller cam, and just put 4lbs boost & let it go. Changing the pistons is not an option. The 500 cam looks like it would work OK but is there a better one to get? The 741 cam is real close to the old flat tappet B&M blower cam other than its on a 112. Wanting to be able to run on 87 if possible or 89. Any suggestions would be appreciated!

Linnie,
Did you pick up the blowers yesterday? Hope it worked out.
I noticed they had the smaller AZSM blower pulleys. You'll get more boost with those. May want to freshen the valvess and new head (Cometic) gaskets. Stock 575s have lower compression and need 91+ octane.
Good luck with the change over.

I had a set of 500 efi's in a 35' fountain and added the Vortech SC Kit and was VERY happy. You have to run 92 octane, which I think you would on any bolt on blower application. Without changing the pistons to lower compression you will have detonation issues with raising the compression after forced induction unless you use high octane.

You may also want to check if you add the 575 intake and blower to see if your injectors will work. You are going to definitely need an ECU reprogram no matter what you do but I just don't know if the stock injectors would work. I changed injectors cam and had ECU reprogrammed but had great results with no blower roll and had manners around the dock. Not to mention the 700+ hp with fuel injected reliability.

Will need a larger pulley, i think the ones I got are 3.5", i hear stock was 4", I may need larger ones. The ECU's were redone in 05 by Arizonia Speed. They may be MEFI4's, going to look at things better later today. I did a freshen up about 60 hours ago, bearings, rings ,lifters, springs, oil pumps, timing sets, and cometic gaskets.

I am going to mail off a engine to Mark @ Precison to dyno & tune, we are going to start with 87 to see how it likes it. Hoping to at least get it to work with 89 as that is what is avalible at marina's. These are throttle bodies with huge injectors.

Send the injectors off to be tested.....you know what that mistake cost me (us).

May do it, I thought you had bad fuel.

what props are you running

No. I pulled all 16 injectors and sent them off. I marked which motor and which cylinder they came from but did NOT tell the guy which pistons were tore up.......he called me and told me which 2 injectors failed and they matched the problem pistons/cylinders. Mark was positive the bad injectors were in the motor we never sent him...I just can't remember now which one we sent and which one stayed here.

The bad fuel issue your remembering is from after that rebuild, the boat had sat for nearly 2 months. The 2 month old fuel used while re-tuning the ECU actually showed some deterioration compared to the fresh we used as a test in a 6 gallon tank we rigged in the engine compartment.

Russ you were also positive that the eng you did not send was the one that had the problem,
Mark