I would also call Paul Pfaff engines because to me it kind of looks like one of his. Westcoast boat manufacturer and he did have alot of his motors in westcoast boats. Seems likes alot of his motors / blocks are painted Red. Also might agree that it could be based off a GM performance crate motor.

It could be a 454 or 502. Its not a stock engine. You can't tell which by just looking at a pic. It has a 500efi fuel injection system, but they can be used on a 454 too if tuned.

Step one, get block number. If it's a 502 you'll know a lot. If it's a 454, you'll have a lot of questions.

the injection unit looks to be the one arazona speed makes&sells,i have one in the shop i got several years ago.

The crate motors came in that style (RamJet stuff). I'd lay money it's a GM crate motor and fuel injection.

+1 you beat me to it..merc dont have the access plate on top of the throttle body with the 6 screws,azsm does..but az usually has fins on top of their intake but that is the satin ones..

the west coast guys dont know what a mercruiser is so they go by name of imco ..

looks like something someone morfidited together,,with out a build sheet or block casting numbers its going to be hard to tell what it is..for all we know it could be a motor out of a 92 suburbam with all the fancy stuff on it to make it look sellable..

The throttle body is a GM unit from an LT1 or RamJet 502. We sell 58MM and Mono-Blade Replacements.

Doesn't matter if the owner is boat savvy. Just tell him from the front of the motor look at the rear left where the bell housing bolts on and just give you the #'s. he could also look down near the front motor mounts and see if it says 7.4 or 8.2 on the block.

99 volvo GSXI 454 ??

Volvo started their red paint motors in 2000. just saying The Intake is not what Volvo used.

I thought if its the GM 502 ramjet intake that it was taller on their crate motor than the one shown. if U can find a pic of it U will see its alot taller - the runners are longer. Maybe someone cut down the runners on this one.

Its the same intake that Paul Pfaff used on some of his motors plus seems a lot of his motors R red. Also agree that could be something from Arizona Speed & marine.

the sides of the block will be stamped 7.4 or 8.2 so look for it. Still the long block could be a GM crate motor with this fuel injection set up.