Hey folks.

I've got a 740 turbo with a 94 b230ft and an AW70 transmission. The low mpg is killing me - I get 14-15 if I make short in-town trips, about 20 mixed/commuting, and about 23 on long highway trips. That's all pretty bad compared to most people I know getting over 25 (many over 30) mpg.

I also would like a bit more oomph in the car just for the heck of it.

The most obvious thing to me that would help with both of these issues is that the engine was designed with a low compression ratio of 8.7:1. The NA pistons were made with a compression ratio of 10.1:1 if memory serves (maybe that's the 16 valve).

So, has anyone done this? I've heard it talked about, but not many reports of actual people who did it. Did it improve mpg? Did it boost performance? Was it a nightmare involving bent valves or milling a head to get it to fit?

I know a manual conversion would save me more mileage, but that's an awful lot of work for an extra 5mpg - more than even changing out pistons, and then there's a clutch to fail too, and a performance loss (because my AW can downshift faster than I can downshift an M46/47.

I'm curious. Enlighten me, if you will.