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Discussion Starter #1
Good evening,

I am interested in purchasing an E46 3 Series as my next car.

I understand that there are two four pot variations as follows;

The 8 valve model
M43TU B19 1895 cm3 87 kW / 118 HP at 5500 rpm 180 Nm at 3900 rpm
Compression Ratio 9.70:1

The valvetronic 16 valve model
N42 B20 1995 cm3 105 kW / 143 HP at 6000 rpm 200 Nm at 3750 rpm
Compression Ratio 10.20:1

I am trying to do as much research as possible in working out how to go about adding a T3/T4 hybrid turbo to one of these as a means for cheap (Road Tax, as well as sourcing car and parts) vehicle that will also be a pleasure to drive with the responsiveness of petrol combined with reasonable torque and power.

I would hope to achieve something akin to the power of 1.8t offerings of other German manufacturers, but with the driving dynamics of a RWD setup.

With these parameters in mind, I have a few questions;

Why have few tuners turned to turboing the valvetronic engine?

Are there fundamental incompatibility issues with this type of engine?

If so - how have BMW been able to create such an engine with the "twin power" anticipated for the X1?
(see link

Would I be best off sourcing an 8 valve model to avoid valvetronic difficulties?

Any help or advice would be greatly appreciated!

Many thanks


Super Moderator
12,946 Posts
ya can't turbo or supercharge valvetronic engines its extremely difficult and im not sure if anybody has succesfully done it at all yet?

some rumour on us forums but ive not seen one as yet for proof..

valvetronic engines are very poor in efficiency the higher the revs go so are not condusive to high revving or thrashing because of this valvetronic springs and gear would have to become too heavy and robust to handle the higher RPM....

hence why no type of M engine has ever been fitted with valvetronic..
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