allan price all depends on the following: full vw service history any engine work that may have already been done (head re-build for example) colour (some colours such as Helios Blue or Oak Green are more desirable) number of owners whether it's and 8 or 16 valve model. the type of interior - again, as with the colour of the car, some are more desirable than others. If you would like me to send you links to VW forums

The hybrid 2 & 4 (& 6) stroke engine concept has in fact been around for a long time, though no-one has yet overcome the many problems it brings. Ricardo seem to be putting extra effort into the idea and they may pull it off, in fact I very much hope they do.

Just one brief example of two-stroke problems is that an engine in two-stroke mode puts a constant load on the small end and this makes it difficult to get oil into the bearing. A four-stroke small end sees a reversing load stroke-by-stroke and this helps pump oil through to lubricate and cool the bearing. A high output two-stroke would need a high-tech small end, perhaps the Melchior patented design that uses a spherical end to the connecting rod, however this would be quite expensive to make and fit.

Regarding the use of unit valve operation to facilitate the change between 2 & 4 stroke, I have mentioned the problems with this in earlier postings and won't repeat them here. Suffice to say that they have lots of weaknesses to be sorted, whether the valves be electrically or hydraulically operated.

I agree that a two-stroke is not twice as powerful as the same size four-stroke; 1.6 would be nearer the mark I think. I would guess that the cost increase of a two-stroke against the same capacity four-stroke would also be about 1.6 because today's two-stroke needs most of what the same-size four-stroke has, and more in some areas (like the small end).

Taking another example, crankcase compression is now confined to history, as are smokey exhausts. Two-strokes now need valves, not ports, to meet modern emissions regulations. When piston rings traverse a port in the cylinder wall this sets up minute ring flutter(!) that upsets the ring/bore sealing.

The problem of keeping the inlet and exhaust gases separated applies even with a diesel because all the fresh air that you send down the exhaust pipe has to be pumped and this takes energy and creates heat.

Also, if you are producing more power from the same capacity, there will be more heat to be got rid of, therefore the cooling system needs to roughly match the engine's output, not its size.

If I had to put money on it, I would say that we will not see two-stroke engines in passenger cars again. There are better ways of achieving their high-output benefits in cars, like variable-geometry turbocharged four-strokes.

Thanks DD for the rapid response, looks like it is best for me to make do and keep working on the upper body strength!!