Best swap when ultimate power is not the goal, but lightness and efficiency are

[somecarguy]

Yeah I know I am swimming against the grain. I like the whole drive a slow car fast thing. I like the vibe of the M20 in my 89 Sedan. What I find cool about BMW is that they basically stuck with the same format and displacement but added technology, occasionally added lightness. I'm curious as to which motor you all would pick if a light, efficient, revvy car is the goal. I feel as though the m54 is the ticket - am I right that it is all aluminium even in its USA format?

[e30oe21]

The M54 weighs about the same as the M20 from what I've read. If you want light and can live with 140 hp, go M42. If you like fabrication, go rotary powered.

[msservices]

M42/44 with an overdrive manual trans and a 4.11 diff

[somecarguy]

The M42 is a cool motor but I don't think I'm going from six to four. Having read more today it does seem the M54 is the way to modernize the M20 without a weight penalty but with more significant effort than swapping earlier motors.

The 'problem' if you call it that, is that the M20 is that it is a great little thing.

[superj]

I agree. My m42 318i was fun to drive and balance was better (not that i could tell, i read that it is)

[digger]

Yeah I know I am swimming against the grain. I like the whole drive a slow car fast thing. I like the vibe of the M20 in my 89 Sedan. What I find cool about BMW is that they basically stuck with the same format and displacement but added technology, occasionally added lightness. I'm curious as to which motor you all would pick if a light, efficient, revvy car is the goal. I feel as though the m54 is the ticket - am I right that it is all aluminium even in its USA format?

N52 is better than M54 in that respect in NA is a requirement

[somecarguy]

Without a doubt N52 hits the nail on the head for lightness, efficiency (and power) but pushes the envelope in terms of effort. Curious to hear about your monsterous sounding M20 build btw.

[msservices]

In that case I’m changing my answer to LS1

[somecarguy]

Funny. My neighbor has an LS swapped FD RX7. I was super excited to drive it, the swap was nicely done. After the novelty and burnouts wore off we both came to the conclusion its too much of the wrong type of power. I realize The Internet disagrees.

[msservices]

I would think the sound would make up for that

[superj]

ha ha ha, as much as I am not for chevy swaps, I would imagine the sound also would be enough. I agree with msservices for that