Re: Operational Engine Stand
Garret makes a turbo even smaller than the vz22/ rb31 that they claim an engine as small as 100cc can spool, it's the gt06 and it has a 21mm inlet with a 32mm compressor wheel so it's tiny, I've seen the specs for it on garrett's Web site and it claims to push enough air to make about 80hp.
The vz22/rb31 is slightly larger and can be spooled by as small as a 100cc engine so it would work on a pred212 but we're still talking about maybe doubling the stock horsepower at 15psi boost, but with a turbo cam, lower compression ratio, billet rod, and run on race fuel it could make up to about 30hp from the 212, but most people would get between 10 and 15hp or blow the engine by getting too greedy with the boost but not want to spend the money to do all the other upgrades.
I've been thinking about using a gt15 or rb31 turbo to boost my Buell blast up to around 55 to 60hp, which would be enough to make that bike really fast without blowing a rather close to stock engine. It may need lower compression and an ignition curve that could retard the timing as boost goes up as well as a way to feed the right amount of fuel to keep from going lean under boost. The Harley 40mm carbs do work well for blow thru systems by using an electric fuel pump and a boost sensing pressure regulator, then using a pitot tube in the boost line to pressurize the bowl vent it will force the right amount of fuel thru the main jet once tuned right. These carbs also work well for draw thru setups but with draw thru there are other problems to overcome and you can't run an intercooler.
For trying to turbo or supercharge a 2 smoker it can be done but there is another set of rules to flow since the expansion chamber acts as a supercharger one needs to make more boost before any increase is noticed, I've seen a turbo banshee set up for drag racing and it too, 8 psi to make the same power it did stock or un boosted, but above 8 psi it became wicked fast. It's been done way back when Detroit began making 2 stroke diesel engines for trucks and heavy equipment, but they used a blower mainly to blow the air into the cylinders and not for boost since the cases couldn't be used to draw in the fresh charge, these weren't originally designed to make boost but they did find their way on top of flathead ford's and the rest was history. Detroit did make "high power" versions of their 2 stroke diesel engines tho by adding turbos that blew into the blowers, they also incorporated an exhaust valve to keep the fresh charge from simply blowing right out the exhaust. I've also seen some 2 smokers that had a wall on top of the piston to help keep the charge in which worked at higher rpm but not so well at low rpm since there was enough time for the charge to go over this little wall and out the exhaust similar to why an expansion chamber works best at a certain rpm range but not as well above or below the range it's tuned for.