Can I get 150hp out of my 135hp Honda outboard?

fiddlebick

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I read an extensive thread on another forum concerning concerning 135 vs 150 hondas.  If what I read is accurate, the 135 is the exact same engine as the 150, but has been tuned down, and does not utilize the variable valve timing, resulting in the absence of the power band at 4200 rpms, Same engine, same weight, but a price difference at the dealer and less hp.  I know little about outboards or the ECU that controls their performance, but the answer I read involves having the ECU firmware remapped, and involves no other changes at all to the motor.  I am asking if anybody has any experience with this type of upgrade. I did find a couple of companies that do marine ECU tuneups for Hondas, but they both were located in the United Kingdom.  I find this odd, seems there would be some American companies involved with this.  The ECU remap is a common upgrade in the Honda autos, so I see this as a viable option for more hp.  Can this work for 90 vs 115hp hondas as well?  I am surprised there is not more discussion of this on the forum.
 

Jack M

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If you have a honda dealer in your area . Go in the back and talk to the mechanic .If it sound like he knows what he is doing ,perhaps he would do it on his time for a few bucks .

Cash is King .
 
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halveb

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Not saying that this is the case because I don't know but I fear this is an EPA question.  I have a high performance Mercury Racing motor with an aftermarket ECU that is tunable by the individual.  This is only possible because it is a two stroke motor that isn't EPA Star rated.  My understanding is that it is illegal to mess with the new green motors.

You may be able to find someone who has the device to read the map and alter it but it likely will be a backroom deal.  As a result I would be very cautious since you could grenade your motor if not done properly.  There are some companies offering tweeks to modern ECUs one I have dealt with on unrelated products is Simon Motorsports.  I don't think they handle Honda but they may know if someone does.

Just to be clear I don't think what Simon Motorsports does is illegal but I beleive these types of changes are regulated by the EPA in some fashion.

Good luck.
 
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fiddlebick

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I posted a similar thread this morning on "the hull truth" forum and got a reply from a certified Honda Tech.  He said no, there are intregal differences in the camshafts of the two outboards, the solenoid required on the head to initiate the VTEC is not there on a 135, and the ecu cannot be "reflashed"  as he put it.  I will also add that the forum thread that had me interested was from several years ago.They were discussing it, but not one testimony from anyone saying they had made the conversion/upgrade.,   It makes sense that if it were possible, I would have been able to find lots of feedback from owners who had it done.
 
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