Different Stroke for the Same Old Folks

Drive the same car long enough and ultimately things will change. Yes, you can be the guy with a chrome bumper MGB that is stock as stock can be to appease the blazer-with-elbow-patches crowd, but more often than not, those cars don’t always fare too well against the conditions of daily driving. When cylinder number seven on the Barely Legal e30 trashed a piston ring, another phase of evolution was taking place.

With the “new” motor already in need of a replacement, there was only one logical solution: add more power!

In the decade Bruce and Will Atkinson have owned their 1986 325 Eta, it went from a tired e30 that miraculously survived the roller coasters of high school and college, to an angry little car with some serious muscle under the hood. With the “new” motor already in need of a replacement, there was only one logical solution: add more power!

Back to the Engine Stands

The literal building blocks to this project started by acquiring two working engines from a local BMW dismantler. The first was a 4 liter m60 (the same as what was already in the car), while the other was a 4.4 liter m62 as found in the e39 540 and e38 740 cars. Internet message board sleuths may have an idea of what was about to take place, but for those still puzzled, the Atkinsons were going to combine the high revving top end of the 4 liter with the bottom end of the torque friendly 4.4 unit. This would effectively create the BMW “Frankenstein” stroker.

Keeping everything OBD1 for use in the e30, the 4.4 was stripped down to the short block, then the heads and dual row timing chain from the earlier m60 were installed on the m62. Since the 4.0 heads have a smaller combustion chamber, the compression ratio is bumped up to an estimated 10.8:1 over the stock 10:1.

Aside from the need to cut a custom gasket that sits between the heads and front timing cover (due to the shorter overall length of the earlier 4.0 heads), assembly of the m60b44 is a glorified head gasket replacement. There are a lot of parts and pieces, but this is definitely doable for any home mechanic with some dedicated time and patience. Once the motor is installed in the car and the accessories are bolted up, engine management is taken care of by the stock m60 ECU.

While not a necessary addition, Team Atkinson decided to upgrade to an e39 540i Getrag 6-speed and a UUC clutch/flywheel combo. Using a 3.15 final drive, 80 mph was previously churning 3500 rpm with the 5-speed. Gas mileage was rather poor at 15 mpg, especially for such a small car. With the switch to the 6–speed, fast lane freeway cruising has dropped closer to 3000 rpm in top gear, lowering both fuel consumption and interior cabin noise.

Version 2.0

The m60 4.0 was surely no slouch before, yet it was inherently BMW in its power delivery. Torque was good down low, but up top is where that motor liked to party. The 4.4 on the other hand is a double shot of espresso on wheels. With its longer stroke, torque is available much lower in the rev range. This makes passing maneuvers a breeze without the need for downshifting. Up top power is a little stronger but it would take driving the two engines back to back to really notice the difference. As much as we’d like to guesstimate the horsepower and torque output as being over 300 at the crank, the dyno is the only way to extract some real world numbers.

Is the car that much better to drive? Without a doubt because the motor is resealed and there’s the peace of mind that it’s running reliably. The shift in the power curve is a very welcome change as well, particularly for street use. To be fair though, the original 4.0 configuration was still a blast to drive.

On the flip side is the need vs. want debate. To elaborate, the reason this concoction of a motor was even a consideration boils down to cost. BMW V8 engines are chump change these days and can be had for a few hundred bucks, so experimenting with engines wasn’t going to be too hard on the wallet. Combine that with a car that was already prepped for a V8, and it was a no-brainer. Had the original 4.0 held up though, chances are that motor would have remained in the car.

New Wave Without a Flock of Seagulls

An interesting point that Will brought up is how the V8 powered e30 could be seen as the modern interpretation of a hot rod. In the days of ’32 Fords and ’55 Chevys, building a hot rod meant scouring the junkyards for the cheapest, largest motors you could possibly stuff into the engine bay…all in the name of speed. Fast forward 50+ years and the e30 is still a semi-affordable car, and BMW V8s are littered across the junkyards of America. Aside from having a California legal exhaust fabricated for Golden State residents, I’m truly led to believe that an M60 based swap may in fact be a better bang for buck than the traditional 24 valve six cylinder swap. Also, who doesn’t love the rumble of an eight cylinder powerhouse?

With V8 conversions becoming more and more prevalent, it begs the question as to whether the highly acclaimed handling of the e30 is lost. The 6-speed adds a few pounds, but the V8 is all aluminum unlike the cast iron blocks of the six pots, not to mention shorter in length. When we took the car to the local weigh station, the scales hadn’t tipped 2800 lbs with a quarter tank of gas and a full interior, so any myths of weight gain have been busted. Once you get over the shock of the power increase, the V8 car is surprisingly balanced and easy to drive (provided you have a quality suspension and sticky rubber).

No matter how collectible e30s may get in the years to come, there will always be people trying to make them faster and handle better. Despite having the aerodynamics of a brick and a rear suspension reminiscent of a Volkswagen Beetle, the dedication to these little cars shows no signs of stopping. It’s great to see owners are still trying new tricks to get the most out of their vintage BMWs…even if some of us have a few less marbles than others.

-JC

1986 BMW 325 SPECS (UPDATED)