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Author Topic:   135 Optimax
SteveGMP posted 06-08-2004 09:16 PM ET (US)   Profile for SteveGMP   Send Email to SteveGMP  
I have a 2001 135 Mercury Optimax; 36 hours on the engine. This engine seems to have the same displacement as the 150 as well as the bore and stroke. What is the diference beween the two outboards? Can I modify my 135 to get 15 more horsepower?
Lars Simonsen posted 06-08-2004 09:26 PM ET (US)     Profile for Lars Simonsen  Send Email to Lars Simonsen     
I'm just venturing a guess here, but I suspect it has something to do with the programming of the computer (i.e. a new chip?) Perhaps that and different injectors?

I've got a 135 Optimax as well, and share your curiosity (although I probably wouldn't make any modifications).

I'll be interested to see how others respond.


LHG posted 06-08-2004 11:32 PM ET (US)     Profile for LHG    
The 135 Optimax's run through a 2.0 gearcase rather than the 1.87 used by the 150.

They are also 3 star rated rather than 2-star for the 150.

HP difference must be in the computer and fuel injectors.

jimh posted 06-10-2004 11:25 PM ET (US)     Profile for jimh  Send Email to jimh     
The difference between the 135-HP and 150-HP variants may be one of those apocryphal cases of the notorious "restrictor plate."

A close reading of a part list for each motor, possibly supplied by a friendly Mercury dealer or mechanic, may reveal the precise variation. If it is a restrictor plate, you would probably have to tear down part of the engine to access it and remove it. It may not be worth 15-HP.

My guess is the two engine variants may have similar torque, but the higher horsepower model may turn more revolutions.

frank_king posted 06-11-2004 11:20 PM ET (US)     Profile for frank_king  Send Email to frank_king     
ecm is the diff
jimh posted 06-12-2004 03:46 PM ET (US)     Profile for jimh  Send Email to jimh     

Your terse reply is in direct opposition to something I was told by a Mercury Field Engineer.

bsmotril posted 06-14-2004 05:37 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
The restrictor plate is very obvious when you pull the top cover off the flywheel and look down into the air plenum. There was some kind of warning on it stating removal could result in engine damage. Obviously it would with the stock prop and 2:1 gearcase. Those extra horses have got to be good for another 4-5 hundred rpm on top, above red-line. Not sure if the ECM or software code is different as well.

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