Mercury Racing HP 500 EFI vs std Mercruiser Marine engine
 

Short story, I've bought a boat advertised with Mercury Racing HP 500 EFI engine. All the visible parts on top show that as well, but the longblock, upon inspection, is not a Mercury Racing product. I've gone to court, 2 years now. Problem is that for a young female judge, an engine is an engine is an engine. We know better.
Does anybody have a kind of comparison between a Mercury Racing longblock and a normal marine engine longblock? What's done extra to the Mercury Racing (stress testing?). What parts are only in the Mercury Racing longblock? Why is it better, longevity wise?
If you have links to documentation, even better...
https://cimg8.ibsrv.net/gimg/www.off...72eae16259.jpg
​​​​​​​

Over a 502 mag, the 500 EFI I believe has the following improved parts. Manley H beam rods, vs stock GM I beam (these may not have been added until 525), JE pistons vs stock forged pistons, bigger intake valves, The 525 EFI used a Kellogg crank, I'm not sure if the 500 EFI did. Blocks are the same, neither my 525 or 600 SCI engines used bow tie blocks, I would assume the 500 EFI is the same. Different Cam, the 500 EFI used Crane 169621, Crane roller lifters.

I'm pretty sure the 500 EFI is hand assembled at Mercury Racing, 502 mag is assembled on a GM assembly line.

I may be off on a few things, but these are the biggest differences.

Do you know the block and head casting numbers?
The head numbers are under the valve covers but the block is on the port side rear deck below the distributor

Merc racing assembles the engine. It would have forged internals but still a GM block. What has been misrepresented that you are going to court? Have you looked inside the motor to see part numbers to prove its non-authenticity?

I rebuilt 2 500 EFI's a year ago, sealed engines never been opened and they had dimple rods in them............so I think Mercury or who ever was assembling them used what ever they had laying around at the time of the build. Also years ago I rebuild the 502 mags in my 33 Outlaw and one engine had dimple rods and the other one had Manley H beam, so who knows

Well...you've got an uphill battle for sure...and you've probably spent more in legal fees already than any 'difference' (provided there IS one) is worth.

I am certainly no lawyer but you'd have to prove intent to defraud, is what I am guessing you're after? And...if the seller is not the original owner, he and any previous owners could have simply made the assumption it was all Mercury Racing. Which based on the comments from very knowledgeable people, it still COULD be.
It could be that, once these (if any) differences are noted...broken down with comparison data and photos, side by side examples...you might have some "proof: that there was some skullduggery in the past.
Maybe.
And...then what? WHO, exactly, do you go after? As mentioned earlier, if the person who sold it to you is not the original owner, he can simply say, "Dammit...I got duped too!" and that'll be the end of it.
Unless there was some provenance (serial numbers of original engine/drive/etc) that came with the boat that now would be in dispute from any evidence you might show...you STILL just have a nearly impossible claim, the way I see it.

Thanks. Will all due respect, I don't need legal advice on the case, and just as a FYI, the seller has sold this boat once before with a car engine longblock, so there's no doubt it's misrepresented and and there's no doubt it's deliberate. My only problem is to convince the judge that the loss from this deliberate misrepresentation is significant. So if anyone has anything to add to Endeavour32's excellent post, on the technical part, please post it.

Thanks

Ive opened up several 502 Mag MPI's that have the Kellogg crank, Mike Tkach and Ive had this discussion and he has found these cranks in a 502 mpi also

To be a 500 it has to be a 502 block. If its a 454 things will still bolt up and look the same. The block casting number will tell what it is and if its a Gen VI or earlier

How did you determine it was not a genuine 500EFI ???

IMO, the actual $$$ value between a real 500EFI and cloned 500EFI is probably only $3000-5000.
The 525EFI style sweeper headers on your engine are actually more expensive than the standard 500EFI E tops.