Two stroke Engines in Gp?

Question

I know there has been speculation as to the demise of two strokes, but i am trying to remember something that slipped my attention. what was the thing about some team trying to alter the disc valve, turning it 90degrees. to get better cooling. this seems a logical idea, until I think about the exhausts. are we talking two levels of inlet. and how will this effect the power stroke. have i been dreaming or is this actually possible.

maybe the inlet is at the back like a four stroke, but how does that deal with cooling ? Im stumped because I cant remember the details. Help

Answer 1

Hi Proc

Aprillia have been using disc valves on their 125 & 250 racers for some time (even my old Fizzy had a disc valve!). The advantages of a disc compared to a reed (in very simple terms) are a comparative increase in power compared to a reed valve. When the disc is open, it is open if you see what I mean. There are no reed flaps to force open as it were, so in that respect it is far more efficient. But disadvantages are that they have a far narrower power band and are more mechanically complex.

The disc is driven by the crank, and it used to be somewhere at the back of the block (not exactly sure where). But because of airflow (or lack of) and such, the charge was quite hot. Because of expansion,  the hotter the air (or charge) the less you can get into the chambers.

So, if you could move the valves towards the front of the block (or at least in a better airflow), the  air going in would be cooler, and the more you could get into the engine, therefore producing more power.

If you know anything about turbo intercoolers, the principle is more or less the same, ie cooler mixture = more mixture.

So with the use of a bevel gear, that's what Aprillia have done. They've moved it 90' to the front(ish) of the block.

The only problem they've had, is that the bevel gear keeps breaking, or did several times last year as we saw with Passini.

But, (fingers crossed for Bradders) they seem to have got it sorted.

Hope that helps.

Answer 2

Aprillia my good man.

They still use the disc valve in the 250 effort. For the 125 its a standard " reed " system on the 06 bikes , but for the 07 bikes it went disc.

I have been hunting around some of my sado techo web site and for some reason the 08 " RSW" configurations have not been made publc.

Time will tell I'm sure.

Answer 3

There has been no speculation about the demise of two stroke GP racing, it IS going to happen.

The speculation is about it's ultimate replacement.

As far as altering the disc valve and any other supposed attempts to 'save the strokers', just dreaming......