EFI and Two-Strokes

[Stuart Baly]

> I thought you might be interested in my project.  I am attempting to
>turbocharge small single-cylinder two-strokes (125 and 250cc dirt bike
>engines) for land-speed record attempts and the heck of it.  I am a
>veteran of Formula SAE, and can't bring myself to carburate anything.
>My only experience is with Haltech and Electromotive controllers,

I remember reading a tech article in a bike magazine a few years ago 
where someone asked about turbocharging a two stroke. I can't 
remember the details, but the guy reckoned it would be a really hard 
task. The problem is that the exhaust port opens (is uncovered) before 
the transfer ports open, and then closes after the transfer ports 
close. So, any boost pressure above the naturally occurring crankcase 
compression will only serve to shoot air-fuel straight out the exhaust 
port, wasting fuel and losing boost pressure.
	The key to avoiding this (and this is where my memory gets hazy) is 
to modify the porting so that the exhaust opens after the transfer. 
There had to be something else involved - otherwise you'd have a 
cylinder full of burning gas exhausting down the transfer ports into 
a crankcase full of air-fuel mixture - ouch. Maybe it was direct 
injection.. how do two-stroke turbo diesels work? 
	Good luck with it. If you can solve these problems and double a 
two-stroke's power, you could just about go into orbit.

Stuart.
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Stuart Baly (s.baly at bom.gov.au)
Technical Officer
Cape Grim Baseline Air Pollution Station
Cape Grim, Tasmania, Australia
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