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-   -   Merc 520/ 540 / 565 General Info and Power numbers (https://www.offshoreonly.com/forums/general-q/374688-merc-520-540-565-general-info-power-numbers.html)

DRAG 02-09-2022 04:45 PM


Originally Posted by cheech (Post 4820970)
That's what you got when you ordered the Merc part number?

Yes that is correct. They list it as an I-beam, and their drawings actually show the rod pretty accurately...which I was surprised they were up to date like that. The 525 and 565 clearly show the H beam. I knew when I saw it was less $$ than the H beams that it was going to be something like this.
I have never used a rod like this in anything I've ever built, but I mostly use I-beams over Hs. Just using way more expensive USA (or USA'ish) made I-beams. I'll put big power through them.


Originally Posted by F-2 Speedy (Post 4820980)
Id rather have a GM dimple than that thing............:angry-smiley-038:

Definitely not what I was hoping to see, but there are some guys on speed talk that say they have had a lot of success with these....even over the chinese H beams. I was surprised to see the comments about them. Seems like a popular rod for the local dirt track guys...and that's the guys I'd expect to use a $50 rod in their race engines LOL!

By the way....$445 for 8 rods from Summit, $186 per rod from Merc :)

DRAG 02-22-2022 10:07 AM

Does anyone happen to have a contact email at Mercury Racing that they could DM me? I'm trying to buy another engine but really would prefer to swap the 2 parts that make a 520 a 540....the machined valve cover and the intake plenum. I did not make much headway over the phone. Thanks.

Pismo10 02-28-2022 01:27 PM

So what is that beautiful cylinder head in the photo?

DRAG 12-16-2022 09:31 PM


Originally Posted by Pismo10 (Post 4823323)
So what is that beautiful cylinder head in the photo?

Honda 4 cylinder.

I haven’t updated this in awhile. I did turn my stock 540s 5500 rpm all year. Have turned over 5500 according to my vessel view and never touched a limiter…with the props in the water at least. Hoping to have them running on the Motec stuff soon. No less than a week after I got the 2 QC4V kits Motec announces plug and play for ALL merc power including the 520/540/565 lol. Unfortunately it’s just paper, they don’t exist.

QC4V plug and play plugs right in, controls the DTS, but needs repinned for the NA engines. Working on that and trying to do it without my boat being down.

Merc98 08-19-2025 08:47 PM

I think most have found management of detonation and balance etc is much more important than physical size of connecting rod. Ford 5.0 Coyotes hold more power on those stock sintered I-beams than many built up motors with A/M H-beams because of the precise direct & port injection and ability to alter valve overlap/dynamic compression on the fly. I’m amazed at what these modern engines can do with hyper internals simply because they can manage themselves better, and they hold up better than Joe-shmoes fully forged rat rod motor. I wouldn’t diss that rod for a stocker, looks pretty solid for its intended use.

hogie roll 08-20-2025 08:55 AM

I was surprised to learn that Motecs 450 ECM adds a knock sensor. Im surprised they didn’t come with one. Merc must have just tuned it safely.

Pismo10 08-20-2025 09:44 AM

I believe my 1996 502 Magnum even has a knock sensor.


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