454 Magnum Question

[Greg Guimond]

Looking for some feedback on a 2001 454MAG MPI. Is 430 hours for a well maintained example a lot and cause for concern?

[duckhunter]

Well-maintained BBCs go for 1500-2000 hours in a ton of cruisers, small convertibles, houseboats, etc. If it is FWC and passes a compression & leakdown test I wouldn't hesitate to pick up one with 400 hrs if it is a good deal. If nothing else run it for a year or two and in the meantime plan a pan to intake build. The Mag should have the good rectangle port heads and forged internals too.

From my foxhole it would really depend on what kind of boat it is coming out of, FWC vs. RWC, thorough maintenance records, and good compression on all cylinders.

Shoot, I would rather have a well-broken-in factory MPI BBC with 400 hours on it than a zero hour budget build ebay special.

[CHACHI]

Greg, my '99 454 MPI must have close to 400 hours on it.

I have owned this boat since 2006 and other than a re-circ water pump, I have done nothing to it.

I purchased new plugs 3 years ago, but have yet to change them. Every spring it fires and runs,....... well.

I know to well enough alone.

Ken

[Greg Guimond]

Sounds like the 385hp MAG is the model to look for instead of a stock 7.4MPI. Thanks guys for the feedback :smile:

[gcarter]

Catch22's Mag, though supercharged, was basically stock, mechanically, that is.
I think he estimated 550 HP and was very reliable.

[Offset]

Greg my 454/365 carb magnum from 1994 is still running very healthy. If it has been maintained and passes your inspection I would think you would be fine. They are one tough motor.

Good luck.:thumbsup:

[Greg Guimond]

Does this description look to be accurate? If it is I did not realize that the 454 Magnum EFI and the 502 Magnum EFI had such an advantage.


"Everyone is correct. Mercuiser used to advertise their engines at crank HP. The base 454 was 330 at the crank and 310 at the prop. The 454 Mag was 365 at the crank and 350 at the prop. When they came out with the 454 EFI and 502 in 1994 they started advertising prop HP. So the 454 EFI is 385 at the prop and the 502 is 415 at the prop."

[Morgan's Cloud]

This whole issue of cshp and pshp has been a bit confusing for a while now.
I thought that ALL manufacturers of marine engine packages had to rate them pshp after 1987 or somewhere.

In other words , if you got your hands on a Merc or Volvo product lineup after that date , the power indicated was at the props.

But , if someone is selling an engine only and they know its output , they would be quoting cshp.

I was always under the impression that the 454(MPI)Mag was 385pshp and the 502(MPI)Mag was 415pshp.