EFI will typically give you additional abilities, including wastegate/boost control, datalogging, etc. With four strokes, I've seen blow through carb users spend more than EFI costs to get their carburetor running right, sometimes breaking very expensive parts in the process. Spark and fuel are considerably easier to manage with electronics. Without knowing the internal plumbing, it is difficult to tell exactly what they are doing but I suspect the turbo has artificially high back pressure that can be changed by bleeding exhaust or reducing the turbo outlet pressure resistance in some way, or it may have unusually low back pressure and the valve can increase it. The diaphragm valve on the turbo outlet looks to be an exhaust bleed. I don't know that this is the result of a calculated design as much as something that was put together trial-and-error. The appearance of what looks like a motorcycle muffler makes me think parts were re-used for economy. As I'd expect, there seems to be a need for some more complicated cross section of piping between the cylinder and the turbo, but in some, it appears to look a lot like a typical motorcycle muffler. You may have to pay some one for consultation time.Ī couple of thoughts just looking at the pictures (if the engines pictured actually run): I still say you will have to do a great deal of testing to get something working well, unless you can contact any of the people that have done it (and documented it) to see if they might give you some hints to get started.
#Two stroke porting kit how to
If I'd spent lots of time and money learning how to make something complicated work, I'd be unwilling to give out all my information for free.
The turbo restriction is after the expansion chamber there exhaust gasses flow is not very speed like in a four stroke.Īnd what about the fuel blow out the exhaust port? Looking the old thread the simple backpressure can contain the boosted mixture?īut it didn't go into specific detail like I said. If you look around you can see 2 stroke turboing sled with big hp gain. But it didn't go into specific detail like I said. Yes, the thread you have linked is that's I mentioned in my post. I think the last post shows a two stroke outboard that has some kind of servo control that can change back pressure on the motor by some type of wastegate.
#Two stroke porting kit trial
I don't know that the power gain will offset the efficiency loss and the weight increase for making the modification.Ī draw through carbureted setup may work, but I suspect with all the exhaust/turbo tuning/sizing that will also influence this, it may take you a long time and lots of trial and error to find a workable combination. This will have to be managed by pipe sizing (volume and diameter) and will have a limit, and may only be operable in a very narrow flow range.
The downside is a ton of fuel will be blowing out as well. The compressor side of the turbo will provide some back pressure that could increase power on the engine. I'd also wonder if spark advance may need to change, and without EFI, I'm not sure how you'd manage this, unless it was mechanical. The crankcase will also have to be able to handle much higher pressures than normal. 4 strokes have captive oil systems at fairly high pressure and good flow is required to keep the bearings cool. As someone with turbocharging experience with V-8 4 strokes, I'd wonder first how you will get oil to the bearings in the turbo.
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