Turbo charging a 2 stroke outboard

[Kevodaniel]

I have come across some small engine turbos that will support 100 hp has anyone tried this if so what was the outcome I'm thinkin about tryin it on a 99 40 hp johnson it seems easy enough to hook it up just trying to figure out boost preasure and jet size to get the perfect air/fuel ratio with out destroying it any thoughts or suggestions

[champ20B]

I have come across some small engine turbos that will support 100 hp has anyone tried this if so what was the outcome I'm thinkin about tryin it on a 99 40 hp johnson it seems easy enough to hook it up just trying to figure out boost preasure and jet size to get the perfect air/fuel ratio with out destroying it any thoughts or suggestions

You would need to rig up an oiling system, separate. It would require regular auto engine oil. You could probably do this with a diaphragm pump as long as the oil is cooled by a separate water jacket as it is recirculated or use an electric fuel pump. Also, it would not be a bad idea to cool the induction between the turbo outlet and intake with a water jacket as well ( intercooling system ) to densify the charge.

The early Detroit diesels that trucks and other industrial applications used were two cycle. They had a roots type blower that pressurized the engine intake. When the piston reached bottom, the pressure would scavenge the cylinder while the exhaust valves opened briefly. Then the valves shut and compression took place. When the compression was maxed, a mechanical injector sprayed fuel in and combustion occurred ( no glo- plugs. it cranked under compression alone!). Later on, a exhaust driven turbo was added to the blower for better power, which proves that a turbo can be driven by the brief action of two cycle exhaust.......

[LittleCharger]

Tim Kurtz is the guy to talk to, he's on here.

http://www.boatracingfacts.com/forum...ighlight=Turbo

[Kevodaniel]

You would need to rig up an oiling system, separate. It would require regular auto engine oil. You could probably do this with a diaphragm pump as long as the oil is cooled by a separate water jacket as it is recirculated or use an electric fuel pump. Also, it would not be a bad idea to cool the induction between the turbo outlet and intake with a water jacket as well ( intercooling system ) to densify the charge.

The early Detroit diesels that trucks and other industrial applications used were two cycle. They had a roots type blower that pressurized the engine intake. When the piston reached bottom, the pressure would scavenge the cylinder while the exhaust valves opened briefly. Then the valves shut and compression took place. When the compression was maxed, a mechanical injector sprayed fuel in and combustion occurred ( no glo- plugs. it cranked under compression alone!). Later on, a exhaust driven turbo was added to the blower for better power, which proves that a turbo can be driven by the brief action of two cycle exhaust.......

I have thought of an oiling system I think a windshield washer pump would work if I used thin oil like 0w 20 or or like you said the exhaust I would take the exhaust plate on the side of the motor build a identical one with a hole cut out In the middle with a pipe and flange to bolt turbo to and run a intake into two carbs without inter cooling it shouldn't be much heat produced only running 5 or 6 psi of boost

[champ20B]

I have thought of an oiling system I think a windshield washer pump would work if I used thin oil like 0w 20 or or like you said the exhaust I would take the exhaust plate on the side of the motor build a identical one with a hole cut out In the middle with a pipe and flange to bolt turbo to and run a intake into two carbs without inter cooling it shouldn't be much heat produced only running 5 or 6 psi of boost

You may need a "filler block" to go between the exhaust ports and the plate. This would likely need to be a "wet block" that is water cooled unless dry blocks are used. They bridge exhaust from your ports to the exhaust cover to go into the pipe(s) for efficient flow.

The guys that run modified OMC engines can help you with that if such is used and/or available. I believe they do race this engine or one similar with good success. Filler blocks are typically used where megaphone pipes or expansion chambers are permitted in modified class racing.

You will need to have a oil canister to run 30wt or close. This is just to lubricate the bearings in your turbo alone. You need a petrol rated pump to recirculate it. This oil will get hot as hell, so the canister needs to be cooled to preserve the bearings in the turbo. The charge will get hot too, though cooling that may be optional, this will give the engine more power.

Most importantly!!!!! If your engine is a VRO (variable ratio oil injection), get rid of it. You will need to premix your fuel at about 25:1 just to be safe for such a power increase. That's what OMC "A" motors use. Penzoil is the best in my opinion.

[Kevodaniel]

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

[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!!

[champ20B]

PLEASE REMEMBER THAT MODIFYING ENGINES CAN BE DANGEROUS AS PARTS CAN FAIL AND ENGINES CAN PROBABLY BLOW APART DOING THIS!..... One more thing though to correct myself earlier after meditating on the mechanics of this, a diaphragm pump will no longer work if your motor is a two stroke and equipped with such. Your crankcase will be under constant pressure once the turbo is wound up. You would need an electric pump for fuel and one to circulate oil to lubricate your turbo.

Furthermore, you need an extra surplus powerhead(s) for experimentation. You need to set up an adjustable pressure relief from your turbo feeding the motor. You need a pressure guage there to note how much pressure is in the intake that you can go to before the test engine fails. You would also need a fully adjustable carburetor because fixed jet carbs aren't worth a crap when you start modifying. A slightly rich mixture to start, is a must, and can only be promised with a fully adjustable unit of some sort. Again, this can be risky to do.....that's all I can say for any input. Good luck!