After Market Cylinder Heads

Anyone into air-cooled VWs should understand the principal of air-cooled.  That’s what cools the engine.  Air !

Over the last few years, I’ve begun to notice ‘Lack of Attention to Detail’ more and more on most after-market heads.  The biggest area concerning me is the lack of cooling passages in the head casting itself, or too much flashing from the casting of the head during manufacture. The factory heads don’t have this issue…thus the reason for this article with pictures.

I have three sets of heads, and two are from factory sources….the after-market head comes from a well known supplier.

Picture #1 (below) is of a factory German head. You can see through the head fins, and this is indicative of good casting and good air flow and cooling when installed.


Picture  #2 (below) shows the same head.  Notice the passage cast through the head just above the flat for the intake manifold.  This is non-existent on the after-market head.  There is no possible way for air to flow and cool the intake area of the head since the passage(s) aren’t there.


Picture #3 (below) shows the Mexican factory head….it has very good flow and the air passage for the intake area is evident.


Picture #4 (below) is of the after-market head…..there is not any hint of an air passage.  It’s not even designed to have one!  Air-Cooled???


Picture #5  (below) shows the excess ‘flashing’ on the after-market head from the casting process. This restricts air flow and will make your engine run hotter. The heads are the source of 95% of the heat generated when the engine is in operation.



This is not what I will install on any engines I build.  Of course the after-market suppliers will be happy to sell you remote coolers and fans to help cool an engine that is starved for cooling air. It’s only money…..your money!!