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Tech Forum : I know this is probably sacrilege but...

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      - I know this is probably sacrilege but...
jdench   Posted Thursday, Apr 27th 9:52pm [Edit] [Quote] [IMS] [View car]
Post nr. 30

Sussex, UK
1979 E21 323i, 1998 E36 323i touring
With Petrol getting to be 1/litre (that is $9 a gallon to you good folk in the US) has anyone considered putting a M51 engine in a e21?
Any thoughts would be appriciated

imaradiostar   Posted Thursday, Apr 27th 10:12pm [Edit] [Quote] [IMS] [View car]
Post nr. 708
Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i
yes, I have.

I think the BMW td 4 cylinder and a six speed would make a wonderful combo.

There's a company somewhere in the US that imports them but they haven't answered my emails.


jdench   Posted Friday, Apr 28th 12:14am [Edit] [Quote] [IMS] [View car]
Post nr. 31

Sussex, UK
1979 E21 323i, 1998 E36 323i touring
I wasn't thinking of the 4 cylinder, it is a bit asthmatic in the e36, I was thinking more of the straight six 2.5 tds, which has lots of torque, and actually sounds reasonable for a diesel I know they offered a 324tds in europe, but the 2.5 has a lot more shove. But saying that, the 318tds engine might be OK in an e21.
Will give it some thought, I just like the idea of a relatively uncomlicated diesel engine and a big lump of torque from 2000rpm

kpeters   Posted Friday, Apr 28th 12:38am [Edit] [Quote] [IMS] [View car]
Post nr. 749
San Jose, Costa Rica
1981 320/6 Kastanienrot-Metallic 5spd
M21's are no good right?

bmw_m_320i   Posted Friday, Apr 28th 1:26am [Edit] [Quote] [IMS] [View car]
Post nr. 594
Helena, Montana
none right now :(
m21's are great, I've driven all over the east coast in 524td's and never had any problems, and I got 45mpg with the a/c on

jdench   Posted Friday, Apr 28th 1:28am [Edit] [Quote] [IMS] [View car]
Post nr. 33

Sussex, UK
1979 E21 323i, 1998 E36 323i touring
that might be an idea, I think the problem will be getting hold of a 324/524 donor, the 325/525's were sold here in England, so it's easier for me to get a m51 (striaght six) diesel engine, unless anyone has one lying around that needs a new home?

kpeters   Posted Friday, Apr 28th 2:11am [Edit] [Quote] [IMS] [View car]
Post nr. 750
San Jose, Costa Rica
1981 320/6 Kastanienrot-Metallic 5spd
Hmmm good because I heard a mechanic complain about M21's realability issues.

An M21 would be easier to get, at least here. And cheaper also.

bmw_m_320i   Posted Friday, Apr 28th 3:45am [Edit] [Quote] [IMS] [View car]
Post nr. 595
Helena, Montana
none right now :(
the only problems I've seen with m21's is just to make sure your cooling system, and timing belt are in good condition, which that goes for any engine. I've seen an injection pump go on one before, but that was because the owner was using bio desiel that had a high ethenal content which broke down some of the seals internally, which it wasnt designed for that anyways, so thats not the cars fault, that's pilot error.

Tricord   Posted Friday, Apr 28th 2:27pm [Edit] [Quote] [IMS] [View car]
Post nr. 939
Belgium, Europe
323i Baur
An M21 is basically an M20 that runs on Diesel. So you can use E21 motor mounts, gearbox, even flywheel and clutch if you like.

You'd need the M21 diesel injection system and electrics. Not sure about the exhaust, but I think you'd need some custom work between the manifold and the center muffler.

The biggest question remains the fuel tanks. Can they be used to store diesel right away? What about the fuel gauge?

Anyway, I've seen E21's online with M21 conversion.

The M21 have a good reputation. The naturally aspirated (90hp) ones are bullet proof, the turbocharged ones (110hp if I remember correctly) are sensitive to turbo heat, especially on the head. So make sure you have proper heat shields between the head and the turbo, and an additional electric fan is never a bad idea.

aussie323i   Posted Friday, Apr 28th 4:58pm [Edit] [Quote] [IMS] [View car]
Post nr. 492

1979 323i
well my brother inlaw has an e39 525tds and all I can say is that an e21 with the m51 intercooled motor would realy fly... his e39 has plenty of torque and can sit on 110mph all day :-)

We drove from bournemouth to edinburgh a few weeks ago sitting on 90mph most of the way and averaged 37mpg...
when he sticks to 70-80mph, he gets about 42 mpg.

With the much lighter e21 chassis, the ecconomy and performance should be quite stunning- think a much torquier 323i (the intercooled m51 has around 150hp).

bmw_m_320i   Posted Friday, Apr 28th 6:23pm [Edit] [Quote] [IMS] [View car]
Post nr. 596
Helena, Montana
none right now :(
it appears that the intank prepump and sending unit are the same, except US verions use a differnt intank pump. So you should be able to use all of your stock items for diesel, you will have to change what type of fuel filter you have though, the 524td's have a larger filter/water seperator in the engine compartment, its a spin on filter, and has a manually operated priming pump built into the filter housing

The ultimate though would be to swap in a M67.....BMW V8 diesel torque!

g323   Posted Sunday, Oct 19th 8:51am [Edit] [Quote] [IMS] [View car]
Post nr. 310
323i 1982
tricord, where are these m21s youve seen online? id love to see examples.

Where could i get an m21 in the US? anyone know?

KenDanielson   Posted Tuesday, Oct 21st 4:17am [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 192

Petaluma CA
'82 320is, '78 320i
Hunt the pick-a-parts for an e28 with the diesel (524td?). They show up occasionally.


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