How much hp?

[Bullet848]

I have a 1998 model Mercury 2.5 225 Promax and a 1999 Mercury 300 Promax. Does anyone know what hp they came from the factory with. I was told by several people who own one of these engines that the 2.5 had anywhere from 240 to 250 hp and the 3.0 had around 320 hp. Is this information right. Thanks for any assistance. Karl

[Go Time]

I'd sat they are pretty close ...The Promax 225 is 240 at best but probably a little less and the 300 Promax (not an X motor) is probably more like 307-315....300X is close to 320HP

[TEXAS20225]

i keep thinking the 300 promax did not make 300 hp for some reason but im getting so forgetful i dont member squat these days somebody bail me out

[JWTjr.]

When I was writing for BWB we ran 225PMs on the dyno many times, the earlier ones made in the high 240s (I think the best one I saw was 248 or so) and the worst ones in the mid 230s. As for the 300s, never saw one even close to 300; there were at least 3 we ran that made 275 give or take, but no more.

[TEXAS20225]

And Thank you John i still have most of the first 8 years issue's of that magazine your technical investigations and research were as always mind blowing to me member the champion with two motas on it lol but in the early 90's my 87 model 150 clam shell v6 was a slug i just did not know it

[JWTjr.]

Thanks Texas20225...we had a lot of fun with those tests but upset more than a few when the hard numbers were published. Actually on the Champ/twin 225s, I didn't run that one, then-editor Bruce Smith did. I remember reading it, it was a head turner for sure, but as I recall performance wiith 2 of those engines was about what a good Allison or Bullet would do with just one of them!

[tlwjkw]

I remember reading it, it was a head turner for sure, but as I recall performance wiith 2 of those engines was about what a good Allison or Bullet would do with just one of them!

unless ya talked to tha dealer that had it (or tha other one) on display at tha boat show!.....

[Dave Strong]

When I was writing for BWB we ran 225PMs on the dyno many times, the earlier ones made in the high 240s (I think the best one I saw was 248 or so) and the worst ones in the mid 230s. As for the 300s, never saw one even close to 300; there were at least 3 we ran that made 275 give or take, but no more.

Damb I miss those days you did some awesome tests that were no BS and loved them all.

Dave

[Bullet848]

Thanks for the information. My 225 was modified by JSRE (heads cut, porting, brucato ECU, and a few other mods). I was told it had around 240hp before the mods and was just wondering if anyone else was getting that kind of HP from their stock 225pm. I would like to know what it has now. I guess i need to get it on a dyno. Thanks for the info guys

[Dave Strong]

Mercury always under estimated HP by around 10% so 240 out on 225 PM is about right. If Jay built your motor 250 or so is not unreasonable

DVe

[Dave Strong]

Mercury always under estimated HP by around 10% so 240 out on 225 PM is about right. If Jay built your motor 250 or so is not unreasonable

DVe

[Go Time]

Bullet848....
I ran a pretty much stock 225 promax (STD bore, Uncut heads, single stage TDR reeds, and 23 Degrees timing) I built on a dyno this winter at Sanderson Marine and it made 242 HP. After installation of SVS and programing the ACU, it made 256 (no other changes). I did a write up & blog on it here on S&F.... After owning one of most everything (300X, 280, 250XS, stockers and Promaxes) ...I am a 225 Promax guy...I have 4 of them now . 300X is my next favorite.

[Greg G]

I put my 1999 fully stock Promax 225 on the dyno and it made 245hp on one day and then the next day it made 244hp. It was Spring and air temps were in the 60's.

[baja200merk]

Bush says an X is closer to 330.

I herd the 300pm was weak but didnt know it was only ~275. I found out yesterday the only difference is heads, pistons, exhaust port and chest

[mikiedreb]

..not to hijack the thread, but since many knowledgeable Promax 225 folks are responding, how does the Promax fuel consumption compare to
say 2.5 260 or 280?