View Single Post
Old 07-16-2019, 08:02 PM
WIX51348 WIX51348 is offline
Junior Member
Join Date: Jul 2019
Location: Under CARB scrutiny
Posts: 5
Thanks: 0
Thanked 1 Time in 1 Post

I found a picture on Google Images that has two of the dimensions. It is 17.5cm wide and 10.5cm tall. In imperial that's roughly 7in wide and 4-1/4 in tall. The plastic intake and outlet pieces on the top and bottom probably add around 2 inches to the total height judging by the picture. I will post pictures once I receive it with a comparison to a 212cc clone or something. As to the drive setup, I imagine you could use a chain drive. The blower will turn at least a few thousand RPM, though, so I would use a durable chain and sprockets and have a good tensioner setup. I think using a chain drive would probably the logical step if you are using chains on the rest of the bike, but it will likely be noisy, and will ruin the cool forced induction noises. I am probably going to use a belt due to the lower noise and so that I won't have to change the stock drive setup too much. I will almost certainly need to change pulleys, but I think that'll be much easier than reconfiguring the entire drive. If the belt's the right size, slip shouldn't be a problem. I will probably end up adding some sort of tensioner to make sure I don't have slip and that the belt doesn't come flying off halfway through a run.

On a side note, I also have some experience with that VZ21 turbocharger that gets brought up every so often on the internet. I bought the cheapest one I could find on eBay for ~$150, and I put it on a small diesel engine. It works pretty well, since the diesel is 635cc but runs at low RPM. I haven't had any problems with the turbo and I considered it instead of a supercharger, but there are a few videos and numerous threads on it online and I figured it really wouldn't be worth it working with the added needs of a turbocharger on such a small engine. Given the flow and size of the supercharger, as well as its relative simplicity, I thought it would be a better option for forced induction. There's also the benefit that the boost production on a roots blower is much more linear than that of a centrifugal compressor like those used on centrifugal superchargers and turbochargers. This, I hope, will lead to easier tuning with the carburetor. I also considered fuel injection, perhaps using aftermarket parts for a Honda Grom or a similarly sized fuel injected motorcycle, but after doing research and thinking about the cost and complexity, I have decided to go the old fashioned route and rely on the Venturi effect. The issues with the roots blower are mostly going to be at low RPM, I think. Here, the imperfect seal of the rotors against the case, combined with the fact that each rotor only has two lobes (high-quality automotive superchargers often have more) will create lower efficiency at low RPM. When this factor is coupled with the low power output of the engine at low RPM and the fact that the vehicle has to launch from a dead stop while propelling itself as well as effectively dragging the supercharger, there may be an issue of power output. At low RPM, the blower will probably create more engine vacuum, so a bypass may be necessary as others on this forum have brought up. I would like to avoid this if possible, but I have a rough idea of what I would do if it wouldn't otherwise work.

Reply With Quote