If you could use any engine in the E30...

[BeirBrennerE30]

turbo s54 or s62...

[FredK]

I think I'd do an LS7. Hand built, dry sumped, outlandish power, all aluminum, heads are 8V each so they're very compact and lower the car's CG, and a longblock can be ordered from jegs.com.

[Bimmerman325i]

Aside from the unobtanium F1 engines, I'd take a built N/A S38 or S54. Only non BMW engine I'd put in would probably be the hayabusa-derived V8...for some reason LSx swaps just don't seem right to me.

[Charlie]

20b or 27b rotary.

-Charlie

[e30lov]

realistically speaking.. LS1 for sure.

somewhat realistic ls7

[gearheadE30]

S42 would be awesome, but for the price I would probably do something with an S38. That's probably my all-time favorite BMW motor. After that, an N54 (I think that's the TT one, right? The new numbering system is killing me).

[Griffin]

I'd put a 13B-REW twin turbo rotary from a 93-95 RX7.. super lightweight and would make for even better handling - and a ton of character.

[NC325iC]

lets break this down into a few categories: were going to assume i have 4 e30's
a= touring
b=cabrio
c=coupe
m=m3

Naturally aspirated (realistic)
a= s62 (need power to haul stuff right?)
b=s52 (its more of a cruiser)
c=s54 (plenty quick and realistic)
m= s54

NA (yeah right...)
a=b=c=m=s70/3 (mclaren gtr v12)

FI (realistic)
a=N63
b=NA- this is a cruiser dont want to hamper it with the problems of FI
c=N54
m=turboed s54

FI (crazy world)
a=b=c=m= turboed s70/3

Diesel
b=c=m= nope
a=m57tu2d30

i like to keep it bmw

[NC325iC]

I'd put a 13B-REW twin turbo rotary from a 93-95 RX7.. super lightweight and would make for even better handling - and a ton of character.

and a pretty sweet explosion

[Miasma]

+1 on the Dry sump LS1/2/6/7 whatever. With a T-56. I love the sound of a V8. And the dry sump will allow for a much lower and further back placement=Badass handling.

I wouldn't even really do anything to the motor. Just pop it in with some bolt-on's and go.

[-Jelko-]

Being realistic...s38...being unrealistic...s38 mit kompressor ;)

[Farbin Kaiber]

[bimmerboy12]

Im sure everyone has seen this...

[-Jelko-]

Im sure everyone has seen this...

Now that car has twin turbo v12 ;)

[gearheadE30]

I actually would not mind some form of a V8. Actually, it would be amazing to have an e30 truck with an LT4 (the 4-cam motor? I can't remember) and a T-56. I probably wouldn't do a whole lot to the motor, either.