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[PxMetro]

Nice wiki find Kevin, I'd always wondered what the theory was behind the variable inlet.

Here's an interesting article on a Variable Compression 2 Stroke engine. The idea's been around for a while but has recently been picked up again by a collaboration between Lotus Engineering, Quens University Belfast, Jaguar Landrover and fuel injection specialists Orbital Corp. They are boasting fuel efficiency savings of up to 30% when compared with some of todays four stroke engines. It is also able to run on more than just one fuel type and uses "Homogenous charge-compression ignition" meaning no spark plug. I think up to now they have only been experimenting with a single cylinder, but plan to start looking a multi cylinder. One interesting fact I picked up on was that for them to meet the industry standard for cold starting without assistance of -30DegC, the engine compression ratio would need to be 50:1. I think they have managed -25DegC up to now.
 
http://en.wikipedia.org/wiki/Variable_compression_ratio

[Marks DTM Calib]

Loads of engines have variable inlet manifolds.....inlcuidng diesels!

That's interesting, I certainly didn't know that diesels did!

I take it having a variable inlet on a charged engine wouldn't be useful then?

Yep, its basicaly what the swirl flaps do on the multivalve diesel engines.

When they actually stay attached to the rod

Nah, fixed once and for all in 2006 with a modified inlet

[feeutfo]

Loads of engines have variable inlet manifolds.....inlcuidng diesels!

That's interesting, I certainly didn't know that diesels did!

I take it having a variable inlet on a charged engine wouldn't be useful then?

Yep, its basicaly what the swirl flaps do on the multivalve diesel engines.

When they actually stay attached to the rod

Nah, fixed once and for all in 2006 with a modified inlet

Interesting, neighbours e39 D has had swirl flaps removed and blanking plates fitted, reckons it makes no odds to remove them, they are about the area of a 1pence piece on his....absolutely appalling construction btw.