Here is one of the more creative conversions I have read about. This relates to the other thread about the BMW with corvette conversion.
Here is the write up from the owner:
THE M3 EVERY M3 ENTHUSIAST WISHED BMW WOULD BUILD
I never wanted a BMW until they put the 3.2 M engine in the Z3. I loved my 2000 M roadster. I loved my 2001 M3 convertible. I’ve owned many Porsche Speedsters including lightweight Carreras, one of which, I built a 904 engine for. I had a 1978 Turbo, a 512 Boxer, and most recently an ERA Cobra for which I built a stump pulling, all aluminum Shelby 464 cid motor that produce over 400 hp and 400 ft lbs of torque from 1500 to 6000 rpm. However, I have gotten hooked on Bimmers. If you read any Bimmer info you frequently run into the people who whine about the E30 M3 and that it was the only real M car and why doesn’t BMW make another M car with the feel and spirit of the old M3. Now at a portly 3400 and 3700 lbs. the E46 M3 coupe and convertible will never feel like the E30 at 2800 lbs. I do plan on getting my no option, except SMG, '03 M3 coupe down to 3200# (no fuel included) by installing lightweight seats. We'll see how close I can get to that weight. We’ll see if I even take delivery. I’ve followed articles about E30s with 3.2 M engines, E36s with the big and small BMW V8s and they look interesting but why get hung-up on only Bavarian power plants when Detroit, i.e. Corvette, has invested bucket loads full of money into developing a new, all aluminum and plastic small-block V-8 that is simple, light and can be mildly tweaked to produce gobs of emission legal power at a very reasonable cost.
I originally was going to do the fairly popular engine swap of putting the wonderful 3.2 M engine in an E30. After researching the cost and the amount of work involved I concluded that the aluminum V8 was less expensive, about the same weight, had much more power and would take about the same amount of work.
The first step was to obtain, in this case rent, one of those foam replicas of a small-block Chevy engine and a tranny and make a trip to the local junkyard. Imagine the looks you’d get walking through a junkyard on a Saturday afternoon with an engine under one arm and a transmission under the other. Anyway, it became obvious that there was plenty of room in an E30 engine bay for a small-block Chevy so I knew the LS1/ LS6 would also fit. I studied all of the transmission and bell housing possibilities and the new aluminum 6-speed T-56 from ’98 and newer Cameros and Firebirds got the nod partly because it was made for the LS1/LS6 but also because measurements indicated it would fit well.
My appetite was sufficiently whetted that I decided to look for the chassis. The obvious choice is a pristine E30 with a blown engine for about $500; very, very difficult to find, especially when you are in a hurry. Next is a piece of crap with a blown engine but if you ever do get the drive train in you have to spend a fortune turning it into a decent car. I bought a very nice black 1987 325is for $6000 and started planning all of the modifications I would make, 5-bolt wheels, bigger brakes, etc., etc. I hated to take that super little car apart. It had only 95000 mi on it. I knew I couldn’t sell all of the parts I was going to take off of it for enough to reduce the investment significantly. Then along came a very nice 1988 M3, at what I later came to realize was a steal at $7000. I remembered that this car had 5-bolt wheels, bigger brakes, wider fenders, a 4.10 diff., quicker steering, tighter suspension and better suspension geometry. I couldn’t turn it down and I was sure I could sell the 325 for what I had paid for it so I brought the M3 home. The thing that I wasn’t prepared for was the added bonus that all of the parts that would be discarded were saleable for enough to almost cover the original cost of the M3.
When I say LS6 or ZO6 I must confess that is only for bragging rights and hp identification. The engine is actually a new LS1 I purchased from Shaun Carter (email@example.com). 95% of the parts on the LS1 and LS6 are identical and by changing the cam, doing some head work and adding an LS6 intake manifold the LS1 can easily produce more power than the LS6.
I was committed once the engine and transmission were purchased . When I raised that tranny up into the tunnel and bolted it to the engine I had to pinch myself it fit so well. The shifter actually fit exactly in the center of the hole in the tunnel where the original shifter was. I did end up moving the entire unit ¾” back to improve the overall configuration. In order to move it back I had to modify the GM Holden Austrailian oil pan. It looks like this engine and tranny were made for this car. The weight of the engine and tranny should be very little more than an iron-block BMW 6 cylinder engine and tranny so brake and suspension modifications are not necessary although I will undoubtedly do some. The entire balance and feel of the original E30 M3 should be retained but with about twice the horsepower and torque and without having to rev the engine to 7500 rpm to get the ponies. The gear ratios are perfect for the 4.10 diff. and the 24.6”, 215/45/17 tires on 8” rims. At 60 mph in 6th the engine is at 1625 rpm. What a cruiser!
Mild modification, aluminum flywheel, cam, re-flash ecu and mild headwork (about 200 hours of my own time) will put over 400 hp to the rear wheels (450 at the flywheel) and that should satisfy any M3 nerd; even me.
Will I toast the diff., the axels and the rear trailing arms? Probably, but I can make the modifications to install an M5 or 7 series diff. and axels if needed. The trailing arms can be beefed-up for more strength.
I completely disassembled the new engine to check everything out and blueprint it. I up-graded the rod bolts, ported the oil-pump, installed ARP head-studs, up-graded the timing gears (Cloyes) and chain (HME-G68VC-60), Comp Cams chrome molly pushrods, modified a GM Holden oil pan, installed a carefully selected cam (.569” intake and exhaust lift, 522/526 duration @ .050). I checked the specs. out of many, many valve springs and settled on Lunati PN# 73100 with Ferrea titanium valve spring retainers.
The cooling system is complete. I’m using a Meziere remote electric water pump (pn# WP 316 S) mounted in front of the windshield washer fluid container behind the right headlights, which I will control from a rheostat to control water temp., a Summit Racing aluminum radiator (pn#380325 or 380425, which ever one has the lower hose on the driver’s side) and a Spaal 16”, 2.48” thick electric fan that Summit ordered from Griffin for me. I fabricated .5” aluminum adapters to fit the water inlet and outlet holes in the block and welded Earls 90 degree aluminum, ¾” hose barb fittings to them for my water lines. I am just finishing the exhaust system which consists of stock stainless GM headers (I can’t remember which GM car they’re of off but Shaun would know), cut and modified with 2.5” down pipes connecting to 2.5” tubing back to the Edelbrock 5512 muffler. I will begin installing the engine wiring harness, finalize my brake master cyl. choice, connect the brake lines and select my wheels and tires.
There is a multitude of little problems to sort out but that’s what I love doing. At age 58, and while in my 31st year of dental practice, this project is providing me with, other than my family, my greatest moments of personal satisfaction and mental stimulation.
I do reconsider this project frequently and sometimes, after talking with an E30 M3 fanatic, wonder whether I’m defiling the Marque. But it doesn’t take long for me to become re-enthused about an E30 M3 with serious non-high-revving HP at almost no weight or balance penalty. Why not! These cars are not THAT rare. They are very cool and they’re the cheapest, coolest way to make a serious BMW hotrod. I sold my ’01 E46 M3 convertible, and plan to replace it with a 9/6/2002 build-date, ’03 M3, SMG, zero other option, coupe, with seats to be replaced with 15# race seats, to produce a 3200# car (still 250# more than a Porsche). If I do take delivery, it will provide my daily transportation while the ’88 takes shape. The closer the GMW gets to completion, and it is very close, the less inclined I am to take delivery of another new car with all of those worries about the first door-ding, the engine failures and the feeling that you have to park it five miles away from the nearest car in the mall parking lot and still run out every five minutes to see if a beater, Detroit ‘70s sled, with 200# doors, has parked right next to you.
Come on BMW, give us some cool stuff. At least a lightweight (under 3000#) E46 M3 with aV8 or even a well engineered torquey little 6, at a reasonable price, not cheap, not near $100,000, not without air, but reasonable. We beg you!
To take delivery of the ’03 coupe or not? I feel I’d have to press the dealer to give me a 100,000 mile engine warranty to feel comfortable. But, do I really want it at all as I get closer to completion on the GMW?