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Rapid Transit BMW: Meet an Early 5-Series With a V8 Swap

story and photos by don weberg

Every car company has specific models that put them on the map. While BMW can boast a flock of such important cars, the original 5 Series sedan helped endear the manufacturer to legions of fans.

The car first appeared for 1972 and made its U.S. debut as a 1975 model. The 5 Series still represents a major chunk of overall BMW sales. And why not? It’s seemingly the perfect family machine: not too big, not too small, well balanced, easy on fuel, comfortable in all conditions, and built to a nice standard.

Like so many mass-produced vehicles, the majority of those original 5 Series cars have since found their way to that parking lot in the great beyond. Of the few remaining today, only a miniscule portion have been modified.

Enter Joe Cain, owner of a 1975 BMW 530i . His car is perhaps the perfect sleeper, as its mild, clean exterior hides a potent upgrade: The original inline-six has been replaced with a 543-horsepower, 427-cubic-inch V8 backed by a Tremec five-speed transmission.

Basic Beater

“Really, it’s been a sort of rolling laboratory,” Joe explains. He had the project in mind and spent a few years looking for the right donor chassis; he bought this particular example three years ago. Between the low miles, solid body and good interior, it seemed like a promising car.

After taking a detailed look, however, Joe discovered that the maintenance had been neglected. “I don’t think the last owner ever even changed the oil,” he explains. “We trailered it back and began going through it.”

Joe quickly yanked the original engine and transmission to get the planned swap underway. “The only real obstacles were the factory brake booster location and the worm-and-sector steering box,” he explains. “Once the box was replaced with a rack-and-pinion and a smaller brake booster was relocated upward and outward, there was now enough room to fit a big-block Chevy with room to spare.”

While he refers to the big block as a future project, his initial V8 isn’t exactly timid: He went with an all-aluminum, 427-cubic-inch small-block V8 that had originally been built for sprint car racing. Its previous owner was Steve Kinser, 20-time World of Outlaws champion and one of that sport’s biggest stars. Even though the Donovan engine was originally built to run on alcohol, it was redone so the BMW could survive on pump gas. The compression ratio is still a rather high 11.3:1, so the car isn’t exactly a slug.

“I’ve never raced it, but if you step on it, it had better be pointed in the direction you want to go because you’re going to get there really quickly,” Joe adds.

The rear of the car required more work than the front, he explains, as he needed a setup that would handle the huge increase in power. The result is a mix of European parts: a Series I Jaguar XKE differential that’s linked to Porsche 930 CV joints via custom shortened Summers Brothers 300M steel axles.

Joe also reinforced the sheet metal located above the differential, while he notched the trailing arms for increased tire clearance. He can now run wheels as large as 18x10 inches.

Sleeper Hold

Even though Joe has more than doubled the displacement and tripled the available horsepower, the swap actually shaved some 50 pounds off of the nose of the car. “You really can feel the improvements on the steering, braking and balance of the car,” he explains. “Now most of the weight is behind the front wheels, not upon and beyond it.”

And unlike so many hotrods, this BMW is civil. It sports a parking brake that works, while a custom Ron Davis radiator keeps everything cool. A CSR Performance Products electric water pump supplies the reverse-flow cooling system. Unlike traditional small-block V8s, this system feeds the heads first.

Joe’s car does have something in common with most hotrods: It’s still a work in progress. “We would work with a design or concept, put it together, and see how it worked,” he explains. “And if we didn’t like it, we’d do it over. If it worked, we’d take it apart and make it look right.”

The result is a sleeper that even tricks the hardcore BMW fanatics. Thanks to its later-model taillights, fenders and hood plus the Euro-spec bumpers and mirrors, the car looks newer than it is.

The real surprise comes when the hood is raised. “People are often shocked by what’s under the hood,” Joe says, “but no one has said anything negative about it. I think it’s because I used a car no one really cared about for the build. If I’d used a 2800 or 3.0 coupe, it probably wouldn’t be so well received.”

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Comments

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Aspen
Aspen Reader
7/25/17 9:36 a.m.

Good article, really nice car.

AngryCorvair
AngryCorvair UltimaDork
7/25/17 11:57 a.m.

I love me some E12!!!

BlueInGreen44
BlueInGreen44 SuperDork
7/25/17 12:03 p.m.

Very nice.

759NRNG
759NRNG HalfDork
7/25/17 12:10 p.m.

A WOO(steveK) heart plus a fine set of German threads equals a true winner IMHO.

grover
grover Reader
7/25/17 12:25 p.m.

I wonder if they have all the gauges working, seems like they would, engine bay looks solid.

T.J.
T.J. MegaDork
7/25/17 1:26 p.m.

I love that car.

mad_machine
mad_machine MegaDork
7/25/17 3:08 p.m.

one of my favourite models of BMW

M2Pilot
M2Pilot HalfDork
7/25/17 3:24 p.m.

Very very nice. I hope the a/c works better than that in the '75 530i that I owned

conesare2seconds
conesare2seconds Dork
7/25/17 7:21 p.m.

That thing is awesome.

Jerry From LA
Jerry From LA SuperDork
7/27/17 12:56 p.m.

No one will miss a 530i drivetrain. BMW was determined to meet emerging US smog laws in the mid-'70s without the use of a catalyst. Unfortunately, the result was a large thermactor-equipped motor with horrible drivability under any conditions. The later 528i debuted in '79 with a 2.8 liter 6, better EFI, and a catalyst. It was essentially the same car with a MUCH better powerplant worth saving.

I love the lines on this thing. It's got a great stance after the mods. BMW had it so right during that period.

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