I apologize if this has been covered, please point me in the right direction.

Just curious if it is possible to convert a 500HP carb to 500EFI? If so, what's involved and is it worth it $$ wise?

Hi,

Kind of a subjective answer, but probably not worth it. It's fairly expensive, as you need to buy ALOT of new stuff, from the plenum, to the harness, pumps, injectors,etc. etc. All in all you won't pick up any noticeable HP or torque, something less than 3%.

The carbed HP 500 is a great engine, uncomplicated and reliable as you can get. Most of the 500 EFI long blocks I've sold in the past few years were converted to HP 500's with a simple intake manifold and carburetor purchase.

The EFI is generally superior in terms of spark plug life, idle friendly and ease of starting. The trade off is the carbed engine is just plain simple. Not alot of electronics to worry about, no clogged injectors, no vapor lock issues, no failed IACs, etc.

Having had both types over the years, if I didn't look under the hatch, I probably wouldn't have known if they were HP 500's or the 500 EFIs??

Hope that helps.

Steve

I have a pair of 1995 HP500 carb motors. They have been very well maintained and run perfectly. Start everytime, idle well, and haul butt! The only difference I can see vs. EFI is that I let mine warm up before taking off. If I don't they'll want to stall when going into gear.

This may be a better (Cheaper) Option than the merc stuff. It is basically the same but you would have to paint it blue. I think the camshaft is a little different but I am not sure. Price per kit is like $3500.00 per kit

http://www.azspeed-marine.com/marine-0.html