M5x and S5x over M20.. Why?

[erynapolean777]

Availability? I have a 86 325es with no motor. I plan on swapping in a m50 in it from a parts car. At my local junkyard in north west Arkansas they have about 5 or 6 of those M5x motors. Not a huge classic bmw scene over here so I make do with what is available

[Kershaw]

Kershaw: RHD ITBs on a bone stock M20B25 will destroy any stock M5x swap. And its still lighter, without all the pain of a swap in an ix.

I have a set and I used to have them on my street ix. I took them off because 2 cylinders went down to 90psi and the rest are at 130. So I put them on my Asymmetrik teammate's rallyx car. At least the CF intake cleans up easily, haha.




But you can put ITBs on an m52 as well. I can't even imagine how good that would sound.

http://racehead.com.au/products-page/throttle-body-kits/bmw-m50-52-itb-kit/

[Staszek]

This debate could go on back and forth forever (and has on this and many other boards).

I struggled with this myself. If my M20 was in great shape (or even good) I would have probably kept it and done something with it.

But I always loved the S54 its still one of my favorite BMW engines, and the E30 was always one of my favorite bodies. The idea of marrying the two seemed like heaven.

Beautiful classic body with a reliable fast NA powerplant.

I still cant get into the turbo thing. I did love them in 90's cars back in the day mostly because it was just a kick to have nothing then that huge surge of power. But as I became a better driver and got track time I realized that the lag and the unpredictable nature of turbo boost was a turn off for me. I love the linear power of an NA engine.

I can't imagine a turbo M20 will not be near as fluid as an N54. The N54 which is awesome (we have an N55) still has enough lag that it bothers me when I drive them, so an M20 turbo has no appeal to me personally.

[jeenyus]

How can an inline-6 with a larger displacement not have the same pickup down low as the m20?

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[digger]

How can an inline-6 with a larger displacement not have the same pickup down low as the m20?

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What engine are you referring to?

[jeenyus]

What engine are you referring to?

The post above talking about the n54/n55 still not having that pickup.

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[DBShiznit]

The post above talking about the n54/n55 still not having that pickup.

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On a e90 it may not because it depends on boost plus e90s are heavier

[E's-30]

On a e90 it may not because it depends on boost plus e90s are heavier

I have a pretty modified e90 with an n54, still a little lag I guess but nothing like an EVO or a 90’s car. Very smooth power delivery and I’m hitting full boost before 3,000. Much more low end torque than my m20, lol.

That being said, in my opinion, everyone is using too large of a turbo on the m20. I think a 16g or something similarly sized would be well matched to the car and give you boost below 3,000 and pull to redline and be north of 300hp and be a ton of fun! Area under the curve would be huge.


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[DBShiznit]

I have a pretty modified e90 with an n54, still a little lag I guess but nothing like an EVO or a 90’s car. Very smooth power delivery and I’m hitting full boost before 3,000. Much more low end torque than my m20, lol.

That being said, in my opinion, everyone is using too large of a turbo on the m20. I think a 16g or something similarly sized would be well matched to the car and give you boost below 3,000 and pull to redline and be north of 300hp and be a ton of fun! Area under the curve would be huge.


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Thats the thing, No one throws a turbo on an M20 to have low end torque. It's going to be big turbo big high end power. Also I wonder how many people are running a twin scroll for quicker spool? All of that needs to be taken into account

[E's-30]

Thats the thing, No one throws a turbo on an M20 to have low end torque. It's going to be big turbo big high end power. Also I wonder how many people are running a twin scroll for quicker spool? All of that needs to be taken into account

Honestly I think these cars are perfect between 250-300 hp, anything more than that you lose some of the characteristics about the car that make it awesome.

I liken it to my buddy who has a Scion FR-S that just supercharged it, always felt under powered but now that it is like 300 hp in that light/small of a car it is perfect. Too much more and it would be a handful to drive aggressively.


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[DBShiznit]

Honestly I think these cars are perfect between 250-300 hp, anything more than that you lose some of the characteristics about the car that make it awesome.

I liken it to my buddy who has a Scion FR-S that just supercharged it, always felt under powered but now that it is like 300 hp in that light/small of a car it is perfect. Too much more and it would be a handful to drive aggressively.


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I agree. I was always told by guys who go to the track, 300-350 is what you want and shed all of the weight as much as you can. If you have a good platform with that power you’ll have a pretty good track car


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[nando]

On a e90 it may not because it depends on boost plus e90s are heavier

The E90 335i is like 1,000lbs heavier than an E30. lol. And so many of them are auto/AWD, which is even worse.

agreed that more than 250-300whp in an E30 is pretty silly. I mean, there's Nisse Järnet's ix which embarrasses Veyrons and Gallardos, but usually it just means a car that can't really be driven to it's full potential.

[varg]

But you can put ITBs on an m52 as well. I can't even imagine how good that would sound.

http://racehead.com.au/products-page...50-52-itb-kit/

So up to 20whp gain on an unmodified M52. Considering the cost of an aluminum M52... God that's a lot of money to spend for ~210bhp.

[2mAn]

So up to 20whp gain on an unmodified M52. Considering the cost of an aluminum M52... God that's a lot of money to spend for ~210bhp.

M52 is a seriously underrated motor from the factory. Mine was essentially a stock BMW motor. OEM cams (S52 variety) and an OBD1 intake and it was making nearly 100bhp/liter. (Mine dyno'd 225whp, so ~265bhp)

Add 20 whp to that, and possibly some real cams and you can call it 250+whp out of 2.8L... Id say thats pretty damn amazing, and I loved the power delivery of the square motor (84B x 84S)

[nando]

yeah, I don't think you're going to get 250whp out of 2.8l - but 225whp isn't bad at all. :)