|
|
A classic in design, the
New Class engine was a high-revving 4-cylinder, single overhead cam powerplant with an all-aluminum cylinder head.
|
|
Design
|
The designer of this new breed of engine was a man who was accustomed to success on the track.
Among his many talents,
Baron Alex von Falkenhausen was an engineer, a trials motorcyclist, and a racing driver. In 1947, he won the German national title with an AFM single-seat racecar powered by a 1.5-liter version of the 328's inline 6-cylinder engine.
Today, he is considered to be
one of the fathers of the modern BMW, chiefly because of his M10 engine design and his commitment to
motorsport.
But the design process wasn't easy.
In the late '50s, BMW management thought that a 1300 cc engine should be used in the New Class. Considerations of road tax, total weight, and installed engine volume suggested an engine with a modest displacement.
On the other hand, Alex von Falkenhausen felt the new engine should be capable of 2000 cc. He was able to convince the BMW board to accept a 1500 cc engine, and then he designed a 1.5-liter that could be easily expanded to a 2.0-liter.
"I thought we needed to have a good
2-liter", he said. "So when they agreed to build a 1500, I designed it so it could easily be made an 1800 and then, with a new casting technique, a 2-liter. It was only a year before they wanted a 1600, then in another year an 1800."
The
engine was the basis for every New Class model. In all, over 3.5 million M10/M12 series engines were produced.
The engines powered:
- all the four-door 1500-2000 range,
- the two-door 1600-2002 series,
- the
3 Series models of the '70s and '80s, and
- the 4-cylinder
5 Series.
The 1.5-liter engine featured:
- a single, chain-driven overhead camshaft
- an 8-port aluminum cylinder head
- 5 bearing crankshaft
- over-square cylinder dimensions
- optimum lengths for inlet and exhaust manifold tubes
In high gear, 1000 engine revolutions correspond to only 16 mph, and even at 6400 rpm the piston speed is a low 2980 ft/min.
| "The
1500 engine has been criticized for its lack of flexibility, but we cannot agree with this. On very substantial hills we gave the car full throttle at 2000 rpm in 4th gear, and it did wonders in pulling itself out of such predicaments. Again, this may be due at least in part to the carburetor settings employed, but as we drove the car, flexibility as such (as distinct from torque and low speed acceleration) was very near being outstanding."
Car and Driver review. |
 |
In tests conducted by reviewers, top speed proved higher than BMW's numbers. This is probably a result of the manufacturer averaging 8 runs in opposite directions to obtain a top speed figure. The top speed is thus not merely a "flash reading," but instead it is a truly attainable speed figure.
"Even more important in daily use is the unobtrusive way the car hangs on to its cruising speed, once it has been attained. Repeatedly, over winding roads infested with lots of traffic, we noted average speeds substantially higher than we would have guessed from the way the car handled. This feeling of always remaining at a comfortable, even leisurely, speed level was shared by our passengers in front and back, and is a tribute to the engine as well as to the running gear."
Car and
Driver review.
|
