What's the difference between the 1990's ProMax's??

[PaulR]

I just picked up a complete 1996 Promax 150 that needs two sleeves so I'm doing a complete rebuild and was wondering what could be done to get a little more out of it? The specs are identical for the 150, 200, and 225 other than the lower unit so where does the 25 or 50 HP come from? Just the intake and ECU??

This motor has what looks like a Titus mod Torque Master 2:1, is the TM as strong as a Sporty?

[JCSmile]

150 and 200 are 5 petal front, 225 promax is 7 petal. 225 has same ports as the 200 but are chamfered, 150's are lower. ECU is different as far as fuel curves go. The 150 comes with a SUPER long tuner, changing that to a 2.4 tuner will give you a lot more Rpm's and has been shown on a few dynos to make at least 15 more hp. Just recently put together a 150 promax for my ventura that had 2 bad holes. We put in vertex pistons, sps rod bolts, other than that everything is internally stock. Used a 2.4 tuner. Someone apparently removed the rev limiter on mine, as it turns 7800-7900 with a 24 Yamaha (also am using 16 amp ignition system as opposed to 40 amp). Currently considering opening up the exhaust chest dump holes to the size of the 225 promax for better flow and maybe a few ponies. Currently am running the stock heads but running thinner head gaskets to bump the compression 10 or so lbs. Your 150 (the promax) is probably the strongest 150 mercury ever built. My motor ran 86 on an xb2002 and has ran 87 so far on my ventura (should see 90 this spring). The Torquemaster should work fine, but the sportmaster is probably stronger.

[JCSmile]

http://www.brucatosvs.com/2l_2article1.html

[PaulR]

Thanks!! Very informative post. I'm guessing the oil injection should go? I'm restoring a Valero YT bowrider , going to run a 260 first but ultimately the boat will have the 150 Promax on it.

[JCSmile]

Yep, chuck the oil injection. Personally, it's just not worth the risk. Especially since your rev limiter is probably in the 6850 range, which is a lot higher than 6000 on all the "production" 2.5's.