help with perf. upgrade 135hp upto 150hp or 175 even!

[MercBassmaster]

Ok, I've got an 89 merc 135 BlackMax V6 that I'm in the process of rebuilding - it's got quite a few hours on it and compression is really low so I'm going to freshen up the top end. What I'd REALLY like to do though is bring the HP on this up to 150 or even closer to 175...now I know that this engine uses the exact same block, crankshaft, pistons, and many other parts as the 150 and SOME 175's. What I don't know is what would be required to get this 135 up into those ranges. I have heard that these all don't use the same heads and I assume that's true due to compression - what I have in mind is to mill my existing heads to bump up compression - does anyone have any advice on how much to mill from stock heads? As for the rest, I assume maybe either jetting the carb's or replacing them will be necc. - but what else? ANY help would be greatly appreciated! You can either post or email me - Thanks all!

 

[Kenny Bush]

Re: help with perf. upgrade 135hp upto 150hp or 175 even!

You are going to have to get different Carbs, Heads, Exhaust.... You might be better off buying a blown 150 and swap the block. I would stay away from the 175.... I think it is dialing up too much HP for that little block. Also you can look at aftermarket kits to hop up your 135. Most HP increases are mainly RPM increases. WiseCo pistons, Boyesen reeds, Carbs or bigger jets..... The sky is the limit...

 

[graddy]

Re: help with perf. upgrade 135hp upto 150hp or 175 even!

Don't forget about the different intake and exhaust ports in the cylinders

 

[clanton]

Re: help with perf. upgrade 135hp upto 150hp or 175 even!

WWW.screamandfly.com, everything you need.

 

[MercBassmaster]

Re: help with perf. upgrade 135hp upto 150hp or 175 even!

Ok, have decided to go with 150 so I can minimize the amount of mods/work. <br />I checked on the cylinder intake / exhaust ports and my dealer says that their actually the same...I had him compare the 89 BlackMax 135 vs 150 part numbers and he told me that their the same for the block and cylinders, pistons, crankshaft and rods...so with that much the same this should be fairly simple (since I'm tearing it down completely, and this is not my first outboard rebuild, "simple" is of course a relative term!). Surprisingly enough, most of those part numbers were even the same for the 175, but I think I'll stick with 150 this time around anyway. <br /><br />BushCat - you mentioned aftermarket kits - do you know what performance kits are available for outboards? or where to get them? Any direction would be great, maybe I can get a kit of sorts to make this simple! I've never seen anything available...BUT, then again, I've always used OEM parts (from Mercury Parts Express Online). <br /><br />Also, it shouldn't be much in the way of RPM increases, right? I mean, it can still only turn 5500 max regardless of 135 or 150HP...right?

 

[MercBassmaster]

Re: help with perf. upgrade 135hp upto 150hp or 175 even!

Clanton - THANK YOU!! I read the site and found a spot to ask questions...so I emailed them and am awaiting a reply! <br />I'll keep ya posted!