Upgrade Mercury/Mariner 9.9hp to 15hp?

[JerseyDog]

Has anyone ever done this, know of someone who has done this and/or if its even possible? Apparently there might be a package that can be bought from Merc.

 

Or maybe its an urban myth.

 

Anyone?

[Guest Trophymuskie]

Sure it can be done but the costs are higher then trading in the 9.9HP for a 15HP.

[solopaddler]

Actually, it's not that big a deal in my experience. Simple matter of upgrading the carb, exhaust, and some gaskets, and presto 9.9 becomes a 15hp.

If you're not sure call the closest Merc dealer to you ask about the conversion kit, cost, etc.

[boatman]

The Holy Grail of engine mods.

 

I don't know anything about Merc/Mariner so I don't know if it can be done. However, in order to know if its possible you need to post the year of your motor. Then someone will have to cross-reference all the part numbers to see what parts are different. You'll probably have better luck asking this question at the iboats forums. Or better yet ,search their archives (as crappy as they are) since this question gets asked a lot.

 

http://www.iboats.com/bbboard/bbBoard.cgi?

[Daplumma]

Might be better to buy the 15 and the 9.9 stickers.In the states many lakes are restricted to 9.9 hp or less so the guys buy 15 and change the stickers.I have heard the carb makes the differance.

Joe

[boatman]

Yeah, people do that here too, Daplumma. I actually saw an Evinrude 20-35 hp rebadged to 10hp at the dealer the other day. Me and the service guys had a good laugh about that one.

 

Anyway, its impossible to know what you'll need to do for your motor without referencing the parts catalog to your exact year since outboard companies make subtle changes to their motors all the time. Also, dealers don't normally sell a "conversion kit". They will probably just try to sell you a new motor - the buggers. Either way, if you find out what parts you'll need you'll then have to buy those parts used making sure to get the exact parts you need (referenced by part number not year) otherwise it would be too cost prohibitive.

 

Seriously, you'd be better off selling your motor and buying a used 15 hp, but I understand the appeal of modification. If you go this route, the best thing to do is find a 15hp parts motor of the correct year and pillage parts from it. Make sure you know exactly what year(s) you need and don't settle for something close.

[Guest Trophymuskie]

Sure it can be done but the costs are higher then trading in the 9.9HP for a 15HP.

 

Been sponsored by Mercury and working with my dealer this question has come up a few times and this is your answer. I believe you have to change from the heads on up, I don't think you can gain 50% horsepower with a bigger carb you actually need more bore, bigger valves as well as a bigger carb.

 

If anyone knows anything about the price of parts it would cost $5K for the parts of a $2K motor.

[hawg_hauler]

Pretty hard to change the heads on a 9.9/15 Merc. Is it really worth all the effort just to gain 5hp. I don't believe that you will find a conversion kit to do what you want from a dealer.

[Cast-Away]

I did this very thing to an old 1975 7.5 HP merc by moving it up to a 9.8 HP. The carburator gets adjusted and a larger exhaust port is added. I'm not sure about moving from 9.8 to 15, I believe that it is a different block.

Contact Paul at Top Gun Marine, he did mine way back when. 905-775-0862

[Entropy]

I understand that it is an exhaust and carb swap.

[Terry]

it use to be just the carb and exhaust

everything else is the same...don't know about the newer ones

[Cast-Away]

Sorry to let the air out of your tires but the 15 HP still has a larger block then the 9.9 like it was back when I upgraded mine as mentioned eariler. The 9.8 is 209 cc's and the 15 is 323cc's which means that they are two different blocks. Your engine is maxed out. If you had an 8 HP you could move it up to the 9.9. I got this information from Mercury's website.

[sirfish]

I don't know about Merc ,but, the 70"s to 88 OMC can be converted with the simple carb swap/exhaust mod. I have seen this done on my buddies motor and what a difference. Good luck let us know how you make out.

[Entropy]

Go here

 

http://www.smalloutboards.com/m99.htm

 

example of a conversion down the page on the right side.

 

Entropy

[Guest lundboy]

A lot of motors share the same block, just different tuning such as carb, and exhaust (older models).

 

For example the 2007 Evinrude eTEC 75HP, has the exact same displacement, weight, bore & stroke, gearcase, mounting brackets etc., as the 90HP. Except for the computer software (tuning), air intake, exhaust, maybe injectors everything is probably the same. If the weight is the exactly the same (most vendors don't publich accurate weights) there wouldn't be too much hardware difference.

 

My model year Ficht RAM 135HP shared the exact same displacement block, weight, B&S, gearcase etc. with the 150HP and 175HP! Spec wise there was no difference, outside of output.

Edited May 24, 2007 by lundboy