Merc 75 4stroke converted to 90 or 115?

[captdoug]

Has anybody converted a Mercury 75 4-stroke to a 90 or 115?
Was it as easy as changing out the computer?

Thanks, Doug

[Captains Chair]

Do a search on the topic. It has been asked before and the consciences is no. But I guess anything CAN be done, but is it cost affective...

Seems to be an urban legend of sorts.

Chair

[Lunddude]

Originally Posted by captdoug

Has anybody converted a Mercury 75 4-stroke to a 90 or 115?
Was it as easy as changing out the computer?

Thanks, Doug

Yep it sure can be done. Made some phone calls today & did a bunch of research. What I found out is I can change my 75 4S EFI into a 90 or a 115 by removing the restrictor ring and then reflashing my ecm. All three motors with the exception of the gearing in the 115 are basically the same. If you go to the parts section on the Mercury website & click on the electrical section for your model you'll see they offer a ECM in the 75,80,90,100, & 115 all for the same motor. I found a outfit in CA that will reflash my existing ecm for $650 with a 2 day turn around. I have a 07 & I will be pulling the trigger on this one.

[San Chan]

Originally Posted by Lunddude

Yep it sure can be done. Made some phone calls today & did a bunch of research. What I found out is I can change my 75 4S EFI into a 90 or a 115 by removing the restrictor ring and then reflashing my ecm. All three motors with the exception of the gearing in the 115 are basically the same. If you go to the parts section on the Mercury website & click on the electrical section for your model you'll see they offer a ECM in the 75,80,90,100, & 115 all for the same motor. I found a outfit in CA that will reflash my existing ecm for $650 with a 2 day turn around. I have a 07 & I will be pulling the trigger on this one.

So $650 and 2 days, my 90 will be a 115? I don't mind overpower my boat without anyone knowing.

[Hot Runr Guy]

Originally Posted by San Chan

So $650 and 2 days, my 90 will be a 115? I don't mind overpower my boat without anyone knowing.

http://www.simonmotorsports.com/ecu/optiecu.htm

[Yarhcaz]

I would imagine that this voids the warranty right?

[Lunddude]

Originally Posted by Yarhcaz

I would imagine that this voids the warranty right?

No warranty for me anyway it's a 5 year old motor. Sent the ecm off to Eric @ Simon Motorsports today should have it back before next weekends outing. I'll post up results once I've had a chance to test her out.

[Lunddude]

Originally Posted by San Chan

So $650 and 2 days, my 90 will be a 115? I don't mind overpower my boat without anyone knowing.

Living @ 5000' elv. my over weight 4S needs all the help it can get. It's going to be nice to finally run a prop bigger then a 13P. Heck I might even able to put the 17P back on her that she ran @ sea level as a 75HP & stlill was only able to turn 5600 rpm.

[1860Angler]

Originally Posted by Lunddude

Living @ 5000' elv. my over weight 4S needs all the help it can get. It's going to be nice to finally run a prop bigger then a 13P. Heck I might even able to put the 17P back on her that she ran @ sea level as a 75HP & stlill was only able to turn 5600 rpm.

I can't wait to here the results!! $650 for 40 more HP is a screaming deal!!

[Prince of Worms]

Interesting project.
With this modification, will the BIA hp hull limit be exceeded?
If so, will it affect resale?

If an accident, will liability be unlimited?

Unintended consequences?