TOPIC: differnce between Mk58 ,merc 400 and 61 500

The specs look identical. Where did the extra 5 hp come from?

These motors were built and I do not think there were any hard / fast rules as to what HP they could put on the sticker.

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They had to put on what Carl and the marketing people deemed would sell in the " show room / boat yard " at the time.

on the 500 there was a short exhaust tunner .

That tuner makes sense a little exhaust work could easily come up with 5 HP. It also would not show up in the specs I was looking at. Compression etc.

The '500' with exhaust tuner bolted to the bottom of the powerhead also had flo-thru exhaust, which would easily account for the extra 5hp, I reckon.

Cheers............ed

Did the non Threw prop Exause 500 have the exaust tuner? Just wondering?

The 1961 500 was the first 44 to use tuned exhaust. It had a short 6 inch or so tuner to direct the exhaust out and down the tower. The 1961 500 did not have thru prop exhaust.

The 1962 500 was the first thru prop 44.

The 1958 MK 58 was the first 44 and is basically the same as all other pre 1965 44's except the use of tuners.
Conrad