83mm Cylinders - Head End Groove

[bugguy1967]

On a 83mm 1500 cylinder, what is the purpose of that undercut below the mating surface at the head end? The mating surface to the spigot is 94mm, but the undercut's dimension tapers down to about 88.3mm (.104" wall thickness). Why so thin? Was it meant to conform better to the cylinder head when torqued?
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[Rome]

Probably for material and weight savings. The full-diameter top end locates the cylinder within the head with just a hair side clearance to the combustion chamber bore. The heads are probably just deep enough that no additional cooling fin would fit that is higher than the current top one. Reducing the neck of the cylinder top from the full diameter down to the 88.3mm would save a few ounces of weight and iron per cylinder. Multiplied by 4 cylinders, then by the many production years of the 1500 engine in the type 3 and then the Beetle, the savings would be considerable. Gallery shot:

[bugguy1967]

Thanks. Someone else hypothesized that as well. Seems like a poor way to save money though, especially in such a crucial area that actually sees a great deal of heat and friction.
_________________
"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[RWK]

No money saved there, that was machined in, so actually more cost per cylinder, I would guess more surface area to dissipate more heat.
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73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[FeelthySanchez]

[bugguy1967]