Turbo charging a 2 stroke outboard

[champ20B]

All considered but I'm not looking to make big power just lookin for 15 to 20 hp as for more fuel I was thinkin my stock 50hp carb has 55d main jet change to a 60d jet with a adjustable wastegate turbo start at 2 psi make a pass on fresh plugs check the plugs color and go from just looking for a simple bolt on system nothing crazy

That would likely be a good approach to start with, as far as checking the plugs for fuel rich/lean mixture if a fixed jet is the goal. Starting out low in pressure would be safe, though you may get over (1.5 HP) per cubic inch with ease if the turbo is working good, with slightly bigger carburators..... A (15HP) increase can be easily obtained with this motor with much milder mods. Even if using a mild turbo, it is feasible that it can do a good bit more. The 40 OMC is a good reputable engine to build up from. It can probably take on or beat a Merc 500 in stock form. The internals are quite stout in appearance as well. I cant think of nothing else to say... If you plan to do this project though, I'm sure it can work pretty well. It would be the talk of the lake for sure!! Have a good one!!

[Kevodaniel]

That would likely be a good approach to start with, as far as checking the plugs for fuel rich/lean mixture if a fixed jet is the goal. Starting out low in pressure would be safe, though you may get over (1.5 HP) per cubic inch with ease if the turbo is working good, with slightly bigger carburators..... A (15HP) increase can be easily obtained with this motor with much milder mods. Even if using a mild turbo, it is feasible that it can do a good bit more. The 40 OMC is a good reputable engine to build up from. It can probably take on or beat a Merc 500 in stock form. The internals are quite stout in appearance as well. I cant think of nothing else to say... If you plan to do this project though, I'm sure it can work pretty well. It would be the talk of the lake for sure!! Have a good one!!

What mild mods are you talkin bout only other thing I know would work is put a 50 hp head on and shave it thanks for your help

[Bill Van Steenwyk]

Right up front, I have no personal experience with turbos on a 2 stroke. I would strongly recommend Tim Kurz as someone who has experience in this type build.That being said, the most successful turbo applications come with electronic ignition, electronic fuel injection, and other controls to manage engine function and paramaters during the RPM range that the engine is operating in. I have had a number of cars since the early 80's that were turbocharged and have some knowledge as how they were successful.

For example at the turbo builds boost, if the compression ratio stays the same, detonation can occur as compression pressures rise as the turbo builds boost. Unless some way is provided to take care of this such as reducing timing BTDC and/or enriching the fuel mixture, much damage can be done. These are changes that need to be done as the engine is running up thru the RPM and load range and that is why most successful turbo/supercharging applications on cars available to the general public have been done since the widespread use of electronic engine controls became available.

In the mid 80's a company called Land & Sea came to a Kilo trial in Moorehaven Florida with 2 V-6 Mercs, one turbocharged and one with expansion chambers. Many problems were encountered during the attempted runs, burned and stuck pistons and other associated problems. I asked one of the engineers on the project what had been done to provide adjustment for the problems mentioned, and had the stock electronic ignition and fuel injection been reprogrammed to take into consideration these changing parameters. He looked at me as if I were nuts. "What do we need to do that for" was the answer I got. My comment was look at the problems you are having and think about it for awhile, take into consideration what causes these type problems and then take steps to remedy them such as enriching the mixture, lowering the compression ration, backing the timing down, etc. That is where an electronic method of doing these things can solve many problems as these adjustments can be made while the motor is running thru the RPM range, instantaneously.
As far as oiling the turbo, this can be done by tapping some crankcase compression to force oil from a small container and oil the bearing with a total loss system and then refill between runs as needed. Some type check valve might be needed in the line.

The above problems and ways to solve them (electronics) are the main reason turbos have become one of the ways, that auto manufacturers especially, are solving problems such as more power when needed from a small displacement engine, fuel economy measures, along with emission requirements. One of the stock Merc engines sold presently is supercharged and most certainly has electronic controls to adjust the various things mentioned.

In short you have a very good method to accomplish all the above, but it must be able to be controlled to overcome problems as the RPM and power increases.

Again, Tim Kurz who is on this site probably has more published experience with this than you will easily find anywhere else, and could probably be a big help if contacted.

[Kevodaniel]

Ecotrons make a 2 stroke fuel injection kit and can be used for boosted applications it's 500 dollars pretty sweet lookin setup look it up

[champ20B]

What mild mods are you talkin bout only other thing I know would work is put a 50 hp head on and shave it thanks for your help

Actually, your engine is a 44.9 cubic inch two cylinder. The 55HP version was of the exact same specs with only a few minor changes. I don't know what they were, but an OMC parts manual might be something that could clarify what parts were different.

[Kevodaniel]

Actually, your engine is a 44.9 cubic inch two cylinder. The 55HP version was of the exact same specs with only a few minor changes. I don't know what they were, but an OMC parts manual might be something that could clarify what parts were different.

I have the 50 hp carbs and boysen reeds on my motor the other things that were different was the head carbs and exhaust tuner