I currently have a working 1981 e21 Euro 320/6 with 4-speed getrag. Just bought from the junkyard a 1983 e30 323i Coupe MT with a 5-speed getrag and has plans of restoring it.
Now I have been driving the e21 since forever and think that the m20b20 engine needs more power for my taste... I have anti-roll bars on the front (thickest) and back which translates to a better driving experience. I have heard that the e30 has better handling so I am looking forward to it.
Transplanting the e30's 323i plus tranny into the e21 has crossed my mind -- the e30 restoration is expected to be done 2-3 years and during that time, I might get the chance to come across better engines (M42? M50?) Another approach is to transform the 320/6 into a 320i with the parts from the 323i.
If you're me what would you do? My goal for each is for spirited weekend driving -- and eventually decide which one I would sell based on which I think connects with me more...
for more power in the e21 320/6:
What gearing is in the rear end?
Putting a 5 speed in the e21 will require a different drive shaft - could be an issue?
Build a 2.5 M20B25 with a 885 head, use your intake and carb and maybe add some shorter headers. This will be a simple drop in with no fuel system changes and everything on your engine will just bolt to the 2.5. I also used the 2.0 distributor in my 2.5 engine. I am running a holley because my stock carb was toast, and I know holleys.
https://www.youtube.com/watch?v=rMrdh8F73SU
- - - Updated - - -
Added bonus is if you have smog or over inspections for the car it will look exactly the same to the eye!
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
I have an e30 m20b23 swapped to m20b25 EFI in my e21 and it's probably slower than an e30 325i but more fun to drive.
Restore e30 323i and you will love it if you keep it the way it was designed. M20B23 with L-jetronic is an excellent engine and it goes well with e30 chassis. In my opinion (and I have owned three 323i's and a couple of 325's over the years) e30 323i is better balanced and more fun than e30 325i. 323i is also significantly lighter and 2.3 is higher revving than 2.5.
I know others will disagree, but 139 or 150 hp that 323i has (depending on the particular engine) is little too much for the e21 chassis.
Just my 2 cents...
Max
By 'gearing' you mean my differential? I think its a 3.64 Non-LSD (How I wish it were an LSD). I remember being disappointed by the 4-speed on highway driving as the high-rev on 4th tells me the engine is giving more but the transmission cant convert that much more power.
There are a lot of machine shops here with cheap labor so fabbing a drive shaft would be one option.
I have an Edelbrock installed.
Last edited by dlguadiz; 05-19-2019 at 08:45 AM.
Updating post -- found out belatedly that the engine on the e30 I bought is not a 2.3 but a 2.7 eta with 200 head. I decided that I will strip the e30 of all its parts and keep it in storage (have plans of heavily modifying it for track use once I get a decent enough budget).
So now I have these e30 parts to use on my e21 (also have suspension, brakes, etc.):
1. m20b20 + 4 speed (Getrag 242) + mechanical pump attached to engine
2. m20b27 + 5 speed (Getrag 260)
3. 731 head
4. Carb intake manifold with Edelbrock quadrajet and corresponding harness
5. 323i intake manifold with L-Jetronic and corresponding harness
Which combination of the above would be the most fun to drive? I also have Dual exhaust with 2.5" inlet (from an F90) and have a 3.64 Open differential on the e21. I'm gonna stop buying now.
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