Originally Posted by GoreWound
for this amount of effort to get that little power wouldnt it be more worthwhile to try and do a turbo upgrade?
considering that either way it is a more of a "because we can" thing than a "because it's a good idea" thing I would wager it being more worth it to have the power increase be available all the time and not need an extra fuel type.
that said between the extra metal, the fuel pump, solenoinds, battery (and if you need it once you have the thing running an oil cooler) by the time all is said and done the extra power would just be enough to make up for the extra weight
having just typed this out I feel the need to add: that pointless bike would be really awesome regardless.
It's been tried before with small engines and so far I hadn't seen a single successful small engine turbo application.... part of the problem I will admit is just about every one of them I've seen had way too big of a turbo to be practical... there's no way a Briggs 5hp can push enough exhaust volume to spool up a t3 turbo... it maybe able to spool a gt15 or an ihi rb31 up to about 3 psi, but by the time ya spent the money on the turbo, the necessary plumbing and all, not to mention the space required to fit on a bike or go kart etc, it quickly becomes cheaper and easier to move up to a bigger engine or to soup up the existing engine beyond what that amount of boost would have improved... it takes about 15psi boost to double the output of an engine minus the efficiency percentage, and minus whatever else needs to be done to prevent the engine from self destruction like timing retarding, lowering the compression ratio, running higher octane fuels, and so on... so a turbo that can produce 15psi boost that has a 70 percent efficiency can basically increase power by 70 percent at 14.7 psi... this is good for automotive engines and motorcycles 500cc and up, but pretty much useless for smaller engines due mostly to the lack of availability of small enough turbos, but with all this being said, adding an ihi rb31 size turbo to a pred 212 would be a worthy experiment since it is enough engine to spool the turbo to around 8 psi if you can beef up the head studs, add in a billet rod, and drop the compression ratio down to around 7.5:1, of course, that'll get you from 6.5hp to about 9hp and most of us in here know there are other ways to get that kind of power a lot cheaper...
I think I even saw a company that makes a supercharger for the Honda z50 but the price tag is more than the bike..
Can it be done? Yes, definitely, but is it practical? Not really, but if budget allows and you got a few engines to experiment with, it sure would look and sound cool... I have seen people successfully turbo charge a small 12hp diesel tho... that was cool on all counts.