M20 or M30 for turboing?

[deian]

Hi,

Which engine is the hardiest or best engine to put a turbo on?

What preparation work would benefit an engine for a turbo? And which engine is the easiest to tune for this kind of work.

Thanks

[Ritchie]

Im hardly an expert but i would reckon its six and half a dozen when it come to the work involved of turboing either but obviously you will get more power out of the M30 and i know its really strong, probably stronger than the M20.
Im sure Ant will come along and offer a wealth of information and Toby about the M30..

[FormerMember]

From those two i'd pick M30 out of E34 (CR 9:1) which can take 1 bar boost (=> ~400hp) with stronger head gasket and -bolts so it's easier and better option. More low-end torque too.

M30 has also timing chain, not belt as M20 has so it's more reliable. And of course more cubic inches..

[chu346]

M30 has also timing chain, not belt as M20 has so it's more reliable. And of course more cubic inches..

I've not heard of the M20's belt being unreliable yet.

I think if your starting with a 325 that has a decent engine then just turbo that, if your starting with anything else you may aswell go for for the M30. You can always change the M20 to M30 later.

[ric325i]

oh there are really good debate about this topic.

do a search have a read there is plenty to read

[FormerMember]

M30 has also timing chain, not belt as M20 has so it's more reliable. And of course more cubic inches..

I've not heard of the M20's belt being unreliable yet.

No, it's not as unreliable as in M40 but chain is always better than belt

[Morat]

There's going to be a lot of weight over the front with an M30 turbo, isn't there?

[FormerMember]

There's going to be a lot of weight over the front with an M30 turbo, isn't there?

Not much, relocate battery to the trunk and good set of springs & shocks and i'd bet that you won't feel the difference unless you slam it around at trackdays.

edit: M30 is 40kg heavier than M20 (everything bolted on).

[ric325i]

yeah not too much weight at the front and the balance will be almost exactly the same as a m20 if you push the big 6 far enough back. then put the battery in the boot.

also any understreer will be easily compensated for by the extra power at the rear

[deian]

But don't 325i's come with a battery in the boot anyway? Both of my last ones did. I only weigh 60kg's anyway so i can go for a heavier engine. He he.

[FormerMember]

But don't 325i's come with a battery in the boot anyway? Both of my last ones did. I only weigh 60kg's anyway so i can go for a heavier engine. He he.

Yeah, all sedans do come with battery in the boot. Cabrios and tourings have battery in the front.