Re: Monoblock Engine Introductions

Posted by Tim Cole On 2011/8/14 12:05:13

Although it might appear as progress, condemning the two piece motor shouldn't be done in haste.

Motorcycles and radial aviation engines are still using cylinder barrels. I'm not sure, but I think diesel locomotives are using two piece as well. Monoblock motors flex a good deal under load and two piece blocks have different characteristics.

The Model T Ford was the first monoblock I can think of and that was done for cost effectiveness.

The Packard 12 started out as an experimental contract and was, in reality, an Auburn engine (I await the vociferous howls of protest) the purpose of which was to produce a low priced V-12. Bolt for bolt though, nowadays the V-12 is Packard's best all around Senior engine. Its main shortcoming being that it was given the old bore and stroke trick to increase displacement which make it hard on connecting rod bearings. It also has issues with things like the burn rate. If you made the V-12 cylinder heads perpendicular to the stroke the motor would look just like the Auburn 12.

When new though, the Packard Senior Eights were very sweet motors. It's just that the years have taken a heavy toll on their performance. In 1935 Packard put an eight on the Oval and ran it 15,000 miles at full throttle. Not a bad job. If they did that with the V-12 it would have blown up.

The principal shortcoming - in my opinion - of the two piece eight is that the valve train was 1923 technology. The cam bearings were gravity oiled, and the tappets oiled by splash. It was also expensive to build for its output.

Hope this helps