Are Newer Evinrude 9.9's stronger

[schinkr1]

The engine block on Evinrude 9.9's are 13.2 cubic inches up to 1992, then they went to 15.6 cubic inches from 1993 on. Does this mean the later 2 stroke motors make more power?

Looking to tweak a 9.9 to as close to 15 hp as possible and wondering if starting with a 1993 model year or newer would be better. I know about all the other subtle differences by year (carb, reed shims, tuned exhaust, etc.) but haven't been able to find any info about the block itself.

 

[Pappy]

I have had several of both.
The newer version is easier to work on with the split lower cowlings.
Acceleration may go to the larger block.
Top end? I have not seen a difference in them.
Yes, you know all the changes necessary to make the smaller one into a 15. I have done many of them and when all changes are done those motors really wake up.

 

[Newtosa]

I have a 1974 15hp (15R74G) and love it. Same basic footprint as the 9.9, as you've pointed out. I nursed it back from neglect and love the way it always answers the call. Also like the design, as even kids can get these started.

Understanding the minor differences between the two vintage groups in block displacement, lower cowling (had to look that one up), I would go with price. The older ones are plenty fuel efficient with basic maintenance ; not sure about the newer ones because I've never owned one.

 

[onthewater102]

I've got a '93 and I'm on the prowl for a 15hp carb for it - though I haven't been able to locate one...yet...I can find plenty of 15hp carbs for the preceding model (thru '92).

Here's a write-up I found on the newest generation of 9.9 & 15hp's:

http://www.leeroysramblings.com/OMC_9.9_1993.htm

same author RE: the prior generation:

http://www.leeroysramblings.com/Johnson%209.9_15.htm

 

[Sinkingfast]

If ya get a pre 93 mod the intake manifold to match the post 93. There is an equalizer passage from one runner to the other on the post 93. And the baffle at the carb end is different. Made a large difference with the running quality.

If ya get one with the old style head..one with the thermo at the bottom the newer ones with the thermo at the top is much better. I had to trim some cowl under the lift handle to clear the newer head though.

If ya get an older one with no pisser visible install one. I ran a hose out from the motor to the side of the boat so I can keep track of the water flow.

I did many other mods but I won't get into it here. Oh..I have had better luck with Boyessens over Carson reeds.

7450 rpm with a 10p4b on a 1236 jon according to my tiny tach with my modded 76'.

 

[onthewater102]

Curiosity - how fast do you go in that 1236 with the 15? That's essentially the same hull I'll be using so I'm just trying to gauge whether it's worth it or not to keep up the search for the 15hp carb for my '93.

 

[Crazyboat]

For what it's worth, I used to pull friends as a kid water skiing with my 15, we were about 14-16 then so 120-140 pounds being pulled up.

 

[Sinkingfast]

Onthewater102...displacement rules. Find the carb for the 93. Ebay usually has many. I don't know how fast my boat goes but just do a prop calc...will get ya in the ballpark.

Oh..I don't run it that fast usually ever except when the weather moves in and even then I am careful. I run 20/1 with delayed throttle pickup.

 

[schinkr1]

My build is on the site, but it’s a heavier all weld Tracker 1648. I ended up going with a 1990 Evinride 9.9 and the boat ran 12 mph with two guys and gear. I put a 15 hp carb on it and picked up 5 mph with no other modifications. I’m good with 17 mph on that boat. May add a stainless prop and go up one pitch, but hard to beat for a simple upgrade.

 

[onthewater102]

Onthewater102...displacement rules. Find the carb for the 93. Ebay usually has many...

Pappy deferred to the same logic and gave me the same advice, which was my inclination unless he told me they were the same or I can get my hands on a '93 or later and a '87(late)-'92 carb side by side to see if the ports and vacuum lines are the same sizes given the fact that they're based on the same casting - there is a definite difference in the attachment point for the choke given the different connection designs.

My suspicion is that they were trying to match the prop rated performance towards the end of the production line of the 13.2 cu in models with a larger carburetor but couldn't get there without more displacement, and then carried the larger carburetor forward with the subsequent line of 15.6 cu in motors as they'd already designed and built the tooling to produce it (the models with the black plastic body cover). Jet sizes vary year to year within the range actually getting smaller on the newest 15hp's (1996 fwd), which is where my concern that the port behind the jet might be sized differently within the same carb casting.

BTW Ebay hasn't had a single one in the last 60 days

 

[Pappy]

Propshaft horsepower was standard across the product line in 1984. Well before the change to that engine platform in 1993.

 

[onthewater102]

Yes - but the carb design changed half way through the '87 models to the same design using the same top cover and gasket kit between the pre '93 models as the post '93's - but how deep the similarities run are anyone's guess.