96 Rude 115 - convert to 140?

[fishfury]

My '96 Evinrude 115 crossflow (E115TLEDA) is being rebuilt right now as the #1 cylinder overheated. I want to get 140 HP if possible (boat's max HP) and I'm told I only need larger carbs to get it. Can anyone help me confirm this and let me know exactly what carbs to find and anything else I might need to make it work? Also, any special treatment I might need to know after such a conversion...and is there anything I can do to keep my water deflectors from swelling up and blocking water flow? Many thanks in advance!!

[flabum1017]

What boat is that on? The compression can be raised by locating a set of old 135 heads for more umph. You already have the bubbleback exhaust. Some port work can be done but you have to be careful if it's on a heavy boat. The higher you raise the ports, the less bottom end you will have. That engine also has the 1 5/16" carbs....the 1 3/8" will flow more air, but again if you have a heavy boat this is not recommended.
with higher compression and raised ports, you will need to burn high octane fuel to keep it together.

I doubt you will see 140 out of it. The same motors that were rated at 140 years ago were rated at the crankshaft. Motors are rated at the propshaft now so the old 140 was really in the 115 neighborhood.

As for the diverters..... they usually swell and block water flow after an over heat or due to excessive corrosion in the cooling passages. Generaly you should be pulling the heads once a year or once every two years as a regular maintenace and replacing the diverters as needed.

If you want 140 HP, I'd look into a 140 looper conversion.

[fishfury]

It's on a 17' Champion bass boat, no jack plate, 22 Raker. It's a little slow out of the hole, not too bad, but top end speed is like 37 mph with all my gear in it (about 100 lbs not including passengers or water in livewell) and I've heard of this boat/engine combo getting up to 52 mph. I'm not sure if this qualifies as a heavy boat or not...

The guys rebuilding it are not doing any work other than a rebuild @ .044 over or something like that because it was already rebuilt @ .03.

Would it help to put on some 135 heads and that's it? If so, any particular year? Does they have to come from a crossflow 135?

What's involved with a 140 looper conversion? I'm trying to get some more umph like you said without going overboard on the $$.

Thanks for the tip on the diverters, that's what I thought, but never really knew they had to be checked before.

[Riverman]

Your engine is already making 140 crank horsepower, it is not worth it to do mods in your application. If you bolt on 135 heads you will have to run premium fuel too.

Consider a 140 looper, it is a different engine that makes 140 propshaft horsepower.

[hsbob]

riverman is right. then mods most people are talking about are the older crank hp motors. if you look between the heads of your 1115 you'll see the bubble pack. that was the tunner used on the older 140s. a 140 looper is the way to go.

[fishfury]

After the responses, I'm thinking I should just get the 115 rebuilt and live with it until I sell the boat to go bigger all around unless converting to a 140 looper is not a big deal money wise. I'm not working right now so I do have the time to find parts but I don't really know what's involved. I would not want to spend more than say $600 to convert to the looper. So, where does that leave me?

Wow, I started this thread late last night and have already received several responses so I really, really appreciate the help here. This forum is a gem - I wish I had posted questions weeks ago :]

[flabum1017]

If your'e able to get it on plane with a 22 Raker and only getting 37 MPh, something is wrong. My 16 Baja with the same motor and same prop turns 5600 RPM at 56 MPH. Maybe the motor is too low

[fishfury]

Thanks for the feedback on your boat. Maybe it would be worth it to put on a small jackplate so I can experiment with the motor height and maybe even better performance overall.