After searching high and low for a local dyno I can’t find one to test my build so everyone is welcome to take a stab at it.

525EFI cam LIFT: .610"/.627" DURATION: 289°/297°
Edelbrock Performer RPM Oval heads with the chambers cleaned up.
Performer Rpm Airgap intake gasket matched
QF850m carb
Comp Cams magnum rockers
~10:1cr

0 is certainly possible. :p

575-595

I like your style!!! :)

This guy doing pretty much the same build but with a smaller cam and lower compression got 588, but I’ll guess 575 which would be plenty. I’m still looking for a real dyno to find out.

Cam in the similar build. 242/248 duration, 0.566/0.566 lift, 112 LSA COMP stick.

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The biggest thing I’m guessing power is are we talking stripped with dyno headers or full marine trim with boat exhaust. Usually a very large difference. Mark at MER performance has proven in back to back dyno sessions runner length on NA builds can be as much as 30-40hp.

Stripped with dyno headers. I have CMI headers running full wet but that’s just too many variables to consider.

Older Sport headers.
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YEs. Still short runner. NA wants longer runners variable to build but generally in the 30-32 inch range with id varying. This is also one of the reasons 525s came with sweeper headers to help get the power. Of course sweeper headers are too rich for my blood. Lol. Just know you’ll be leaving power on the table over a longer runner exhaust

That’s of no worry as it’s not a max power engine build and I’ll be perhaps +75hp over the stock ZZ502 that I built this off of. In fact, I’ll probably switch to manifolds when a nice set pops up and loose even a little more.

Another Coors light of your desired coldness! ;)

Given that I cant find a dyno willing to dyno anything not built in their shop we may never know so I must accept the highest number as that is what pleases me. So far we are at one million HP!

The only dyno shop I could find was three hours away and almost $2k. Screw it - toss it in and send it!

First start up. The distribution hose fell off of one nipple of the headers hence zero water out of the SB exhaust, but otherwise ran like a champ.

Sounds good

Thanks! It’s a simple build but I’m happy with it. It was more than I wanted to bite off as the boat is in a remote storage and very little garage space to work with. It’s not something I’d want to do again without a proper shop.

The new game. Will it hold together for ten minutes, ten hours, or ten years??? Lol.

It does sound nice. Play with props a bit if your able i only mention cause your peak hp might be a little higher than you plan on running. Not sure.... I ran a 244-248 installed (4 deg adv) in 496 and peak hp was 5,800 with hyd rollers and 6,000 with tight lash solids rollers. Just throwing it out there.

Along with a catastrophic year to boot. At least proposal A passed here in Michigan. Can't wait to see if the drive through fast food orders get better or WORSE. Low payed construction workers building house smoking weed all day etc. The finished product what ever it may be gonna be interesting. Great it passed regardless. Maybe we'll get more tourism here in the NW. Ya mon! :bong:

Ive got a few laying around to play with. So far the favorite prop with the old zz502 was a 25p Rev4 at 5200 with a 1.65 Bravo on the Islander so we’ll see what direction this goes. There’s a pretty good chance that I’ll still get to splash this year.

Ha! If we weren’t getting drained at every corner. A small rental space that was $800mo 5 years ago is $2500+ these days.

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Well at least now we have extra smoke from the fires to justify the high costs. :p

Is the plan to still get the motor dynoed? Take it from someone who really wishes they dynoed their motor when they had the chance, have it dynoed!

Where does the inner SS pipe end in reference to the weld on those CMI's? Be nice if it was back far enough to have wideband o2 sensors. No need for dyno.

I do agree that a dyno would be optimal but at this point it’s shoved in the boat and hopefully not coming out. I do have a wideband so tuning on the water will be done. If it was a higher end build then I’d definitely make sure to dyno it, but it’s pretty much just a warmed over formula of a stock Merc. As long as the machine shop did their job it should be ok.

The water doesn’t exit until the last 1/2” of the tip which is nearly to the transom. I’ve ran a wideband with an O2 for two seasons now with no issues even with that 110lsa ZZ502 cam, which was definitely sucking water.

Finally made it out with the new engine and all went well! Still shy of two hours run time (probably an hour of that on the hose) so no wot runs but from cruising at 3500rpms it launches hard and keeps pulling where the previous engine fizzled out a bit. Pretty stoked with it.

The Holley Sniper works like a charm and I don’t miss fiddling with jets the slightest. Having a small issue setting the IAC to the correct parameters but it runs great.

Idle 13.5
cruise 12.8
WOT 12.5

Verifying AFRs with a wideband on the odd bank and the two sides are within .2 of each other, as near as I can tell.

Cold oil oil pressure at cold was a bit high for my taste at 75psi but eventually got back to 60 and 20 at idle after a moderately brisk run. 30w Brad Penn break in oil.