Beaten to the punch.

[sussexscooterhead]

I had planned to assemble an electric turbo for my scooter and thought it would be quite unique. Looks like I'm not the only one to have thought of it:

www.ginospr.com/page6.html

It's a little disappointing that the blower is only 2 staged, though. I had figured on making it fully proportional to help eliminate the need for a wastegate.


What actually led me to this site was my search for information on the OKO Powerjet Carb. I don't hear about people using carbs other than the CV variety and I'm curious as to why that is.

I had posted about my plans to track down a small bore pumper carb (which I have) and hoped to generate some kind of discussion as to the pros and cons but heard nothing.

Does the CVT not lend itself to anything but the fuel delivery of a CV?

Any thoughts as to how a more abrupt power delivery would affect the CVT? Especially in what I'll call a 'passing' situation, where you're already cruising at say 30mph but want to acclerate quickly?

[mgreenfield]

....I think a pumper carb should work fine. CV carb just makes actual throttle opening more gradual so a accel pump isnt needed. Cant imagine what ill effect using a pumper carb would have on the CVT. Should work OK, too.

ALSO, cant imagine what a small electric blower could do for you. Carb has to fit on the low-pressure side of the blower to work right. If you can put this blower on carb intake, it probably isnt giving any boost, because increased pressure in the carb throat will keep fuel from flowing into the intake.

...that's the way I sees it.

[sussexscooterhead]

When the intake valve opens and air rushes to fill the cylinder it pulls fuel from the float bowl as it passes over the jet orifices. It creates it's own vacuum similar to how rolling down the window of your car just a crack will allow air to get sucked out by the outside air rushing by.

In order for this to work, I think the carb vent lines need to be run to the intake boot or airbox between the turbo and the carb so that there is no pressure differential in the float bowl. I also think the fuel tank vent line needs to run to the airbox or intake boot so that fuel is able to enter the float bowl.

As things are now, with no modification, the whole system is sitting at roughly 14psi - the pressure of our atmosphere. Things work because every part of the system sees the same pressure- the fuel tank, the float bowl and the venturi.

When the intake valve opens there is 14psi pressure on the other side waiting to rush in and fill the void. With the trubo we would be raising that pressure to who knows, maybe 17-20? It would take some experimentation, I don't know how much they could take.

But in order for it to work I think we'd have to get the whole system working at the elevated pressure.

Does this make any sense? This is just how I see it as I ponder some of the same questions.

[somecallmetim]

Many of the earlier cars with "blow through" type superchargers, like 50s Studebakers, had the whole carb enclosed inside an airbox with the supercharger pressurizing it. All the hoses and linkages passed through (supposedly) airtight rubber seals in the airbox walls. Motorcycles went through a brief supercharger phase and then turbos became the big thing. All 4 of the major Japanese makers had turbo bikes. None of them were really successful, and the turbo 650s and 750s were as heavy and at least as expensive as a 1000 or 1100 "normal" bike, but were no faster and much more troublesome and temperamental. It's hard to make a carburetor work well with forced induction. Fuel injection and electronic engine controls made turbos work OK, but by then we had multi-valve twincam heads and variable valve timing and engines ran great without them. Adding stuff like that to a scooter or just stuffing in a bigger motor isn't so simple, so experimenting with a blower could be fun. You can always take it off again. (I owned one turbo car, and said NEVER AGAIN!!!!!)

[sussexscooterhead]

Just some fun reading:

www.buggynews.com/viewtopic.php?p=61349&highlight=#61349