175hp merc? or magIII

[STVBOY]

I am looking for a merc that will make 175hp but turn close to 7000rpm. What do you have to do to a magIII 150hp to make 25hp more? Change the front half, raise the compression? Any thoughts would be great!

[David]

I don't think you are going to get a Mag III to 7000 rpm, unless you underprop it big time, or do some porting.

Mods? Remove the timing module, set timing to 25 degrees, bump the compression to 135 psi, and change the tuner. The latter is a bit controversial around here. Maybe two stage reeds.

It would be simpler just to buy a 200.

If you really want 200 at 7000 rpm, buy the export market XR2 from down under if its still for sale. Search in the engines for sale.

[pyro]

Buy the powerhead for sale here:
http://forums.screamandfly.com/forums/showthread.php?t=116234
It's a steal, and it's exactly what you want. 180 HP @ 7000 rpm.

The XR2 is also another possible choice. Don't confuse this europe/au racing motor with the "150 XR2", which was an entirely different 2.0 fishing motor, which was also the original "Magnum 150".
The euro/au XR2 is actually rated 6000-6500 according to my service manual, showing a HP decrease on the chart above 6500.

Why do you need it to turn 7000 rpm?

a stock Bridgeport EFI like mine makes 240 HP at 7000 rpm, and weighs less than a Mag III. Why do you only want 175 HP ?? :D

[STVBOY]

I was thinking of running the Parker Enduro in AZ next year. In the division I class the most power you are aloud is 175hp! The reason I said 7000rpm is that I dont want to run a really big prop to make the boat go 85mph. I know 200hp on my boat will run in the low 90's so I figure a 175hp should make it atleast run 85mph.I am just worried a 2.0 will not have the tq that a 2.4 would have.

[David]

How do they check for HP?
175 propshaft or crankshaft?

I'd go for 175 @ 6000 rpm and have the motor last. Isn't that the ticket for an enduro?