This subject has been touched on in a couple other threads I have going right now. Long story short, I'm looking at a boat that has 2 HP450s in it.

It's my understanding that these are the predecessor to the carbed HP500, just a 454 block. Same internals.

I got another reply saying that they are actually called HP465s. This is when Merc rated them at the prop shaft. Thus they are the same thing as the carbed HP500. The HP500 is rated at the crank instead.

Should I get a serial number and contact Merc?

Anyone care to educate a fool?

Buck

Buck, the HP450 is a 454 with the specs I listed in the thread in the Pantera section. The HP465 is a 502 and has a flat tappet cam.
The merc manual I have for my 525SC has all the specs for all the Merc racing/blue engines and thats where I got the info.


HP 450 specs:

454 CID
4.25bore/4.00 stroke
8.8 comp ratio
Comp test pressure 175 PSI
Idle rpm 700-750
WOT 4800-5200rpms
Base timing 18*
Max timing at 3800 rpms 32*
T-stat 143*
Rect port iron heads 2.25 intakes/1.88 exhaust
Dart aluminum single plane intake
GM forged pistons
GM forged crank
Hydraulic roller cam .576/.598 lift, duration listed as 284*/292*

That about covers it then Griff.

I did some more checking myself. I was looking at an online parts quide for Merc and they did show the 450 being made in 1995 and 1996. This would be consistent with the boat I'm looking at.

Buck

Whatcha getting? Whatcha getting?

Ancient Chinese secret.



I'll tell ya when we get to LOTO. That or ask Foul, he knows.

Buck

buck, just an FYI, in another section of the manual that gives all the timing advance curves, it is listed differently.

Listed with 18* base and a 20* advance module that is all in by 3000rpms for total timing of 38*