Hitchcocks Forum

saw this for sale on that well known auction website.

I always thought the distributor drive shaft on the classic engines was begging to be replaced with a little draw-through mechanical supercharger.

Well it is certainly unique, but having looked on the link to the website it looks to put out roughly the same amount of power as a 612.

Not knocking it, just saying.

So a 250% increase in power output and probably cheaper...

It looks like the steering will be restricted, at least as soon as the forks are compressed.

stinkwheel wrote:I always thought the distributor drive shaft on the classic engines was begging to be replaced with a little draw-through mechanical supercharger.

Is half crankshaft speed fast enough?

A.

I suppose that depends on how you attach it to the shaft. All mechanical superchargers are initially turned by 1x crankshaft speed.

Problem is that you need either a relatively big blower turning relatively slowly, or a small one going round fast. I DIY supercharged my trials car which has a 1 litre, 3 cylinder engine, using the blower from a VW Polo 1.4 litre TSI. I did all the normal calculations on pulley sizes (geared it to run at 2.25 engine speed) only to find it produced little or no boost on the rolling road. I subsequently discovered that it had 1.93 to 1 step down gears inside......doh!

I bought a pair of gears which I had machined to fit, which brought it back to 1:1 gearing. It now gives 12 psi boost and that increased the output by 60%.

A Bullet could be run through an Aisin 300 or 500 blower but it wouldn’t be straightforward to fit one on the dizzy drive because it would need to be geared up.

Sticking a turbo on is surely only part of the job. Won't it make the engine even more likely to go bang?

Pugeot made a 125cc scooter with a dinky supercharger on. Rocking horse poo though.