Don't turn the page yet! You might be thinking to yourself what an asshole this guy is for putting a Chevy motor in a BMW, but let's look at the details.
First, this '75 530i originally came with a 3.0 straight six, capable of 176hp. Second, the E12 (1972-81) chassis was the first 5-Series, so its technology is undeniably primitive today. Third, a rebuilt 7.0 aluminum-block V8 is smaller and lighter, and makes triple the power of the 33 year-old factory motor. Considering these factors, perhaps Joe Cain's Frankenstein creation makes more sense.
"For as long as I can remember, I've been interested in cars," Joe began. "My brother was into it and got me hooked. I inherited some hand-me-down cars and started messing with them. As far as motor swaps are concerned, I've always done them. I even did a Jaguar XKE with a small-block before this project."
So when Joe went to work on this tired 5er, he naturally decided on a V8 rather than the expensive option of rebuilding the original motor. The organ donor was a sprint car - those funny-looking open-wheel cars with enormous spoilers that race on short ovals.
Joe continued his story. "Steve Kinser is the most successful sprint racer out there. He gets his motors from Donovan Engineering in Torrance, CA and at the end of each season, they give him a new motor and he sells the old one. I got one of his old motors and converted it from alcohol to gas."
New JE pistons, a forged stroker crank and Cosworth rods ensured a stronger motor, which he sealed with 220cc AFR ported heads and an Ultradyne hydraulic roller cam. Feeding the 11.3:1 high compression motor is a Victor Jr intake manifold and Demon 850cfm carb. It's all cooled by a CSR electric water pump.
With the motor complete, Joe hoisted his creation into the engine bay and discovered the car was 0.5" higher at the front. "A cast iron small-block is close to the weight of the original motor," he explained. "But this is a much lighter aluminum block. It's also shorter, so I moved it back for better weight distribution."
Under a carbon engine cover is this 7.0 stroker small-block Chevy V8 with Victor Jr intake manifold and Demon carb
Surprisingly the original front motor mounts remain intact, and he built a bracket so the Chevy mounts could be adapted to fit. "Anybody can get in there with a hacksaw, but its more challenging to make it removable. I could refit the original motor if I had to..."
When the motor was finally installed, it dynoed at 543hp. And to put it to the ground, Joe opted for a Tremec five-speed manual with aluminum flywheel and Centerforce clutch. "Tremecs are intended for GM cars and look identical to the factory tranny," Joe elaborated. "However, they're upgraded for people who want a factory five-speed but don't like the ratios. It's nice for people who are pushing more power."
You might imagine the hardest part of the project was now over. "I spent more time on the rear suspension than on the motor," he revealed. "At the time, I couldn't find an inexpensive M5 diff that had the ratio I wanted. However, the Jaguar diff was strong enough but I had to make an adapter cage for it - the center section bolts right in. Then I welded the cage to the subframe so the diff can be unbolted."
The rear diff featured a 3.54:1 gear ratio with 80% limited-slip. Joe also fabricated shorter, stronger axles, heat-treated the stub axles and swing arms, before upgrading both sway bars. Custom-valved Bilstein coilovers give Joe the adjustability he wanted for track events.
Other highlights on Joe's chassis include custom aluminum hubs and a power steering rack from a European E21 3-Series. He admits he didn't need to do the swap, but making space for a suitable exhaust meant he had to relocate the brake booster and rack. "With the modifications done, there's actually room for a big-block Chevy!"