More Horsepower on a Budget [Archive] - Checkmate Community Forums

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JAnderson

12-24-2002, 01:12 PM

I have a 93 218 Persuader with a 350 Mag and would like a little more. I run 63 MPH on GPS with 23 Mirage Plus at 4200 RPM. This is the best prop I have tried, but I would like to bring my RPM's back up a little. I was told that EMI Thunder Ehaust Manifolds would be a nice addition to this motor. What do you think or what would you suggest for budget?

JAnderson

12-24-2002, 01:12 PM

12-24-2002, 06:12 PM

But!
Every time you change the intake or exhaust flow, you'll want to play with the jets in the carb to make up for the change in air flow. The carb design may not let you change the jets, it depends on the year. You may have to go to an upgraded carburetor that allows jet fine-tuning. Isnt this fun????

1995 2100BR/1995 225 Promax/23" Tempest

Bill

12-25-2002, 12:18 PM

Throew the 21 Mirage back on the boat, you are killing your motor by running 4200 at wot.

vinny p.

12-26-2002, 07:51 PM

Horsepower is directly realted to how empty your wallet is.. Just kidding... But if you are thinking of EMI Thunder exhaust, don't expect much of an improvment over your stock Merc. exhaust. Although it will sound better, I don't think that you will see more than 2 m.p.h. from this modification. I do recommend getting rid of the stock Merc. exhaust. In my opinion, stock exhaust is junk. They leak at the riser gaskets, they have no seperation in the manifolds to seperate the exhaust pulses, the risers are tooooo short for any kind of a larger cam profile. If you want to pick this motor up, push a good cam into it, do a clean up port job on the heads, good valve job and springs. Maybe even kick the compression a bit by milling the heads. Then your exhaust would be more beneficial. /infopop/emoticons/icon_biggrin.gif