Tighter heads on a Promax 300
 

Hi!



I trust you are well.

I have a Promax 300 1999 model with a new 2002 powerhead. I have mounted a Brucato SVS Intake and A High Flow Reed Plate. Rest of the engine is stock.

I am looking for more power, and I would be pleased to know where to get hold of tighter heads for this motor.

What kind of gain could be expected, and what kind of octane is reccommended? Highest octane number in Norway is 98 RON.

Do you reccommend to modify the ECU / ECM to get most out of the engine?

I look forward to hearing back from you.

Happy Holidays!



Cheeers, Toffen - Norway

Rapair in Texas does ECM work on Mercs.

You can cut your stock heads, as long as you leave around .020" of squish (not sure what your piston deck height is). 145 psi should work with your fuel, but you should go to standard electrode plugs (not the gapless ones) and keep a sharp eye out for signs of detonation (speckly insulator). Also get a diemaker's flashlight (has a 6" long small diameter flexible neck with a small bulb on it) and check your piston dome color after a hard run - top of piston should be milk chocolate color (not dark brown, not light tan).

Rapair will sell you an adjustable ECU where you can adjust your mix and set your rev limit.