Berg 85.5, 88, and 90.5mm forged pistons and spun cast iron cylinder sets are made of high quality materials. We only handle quality products offering life equal to or better than a new factory VW engine. Many manufacturers produce the same product at various levels of quality. Many suppliers, when ordering (all their parts) from the manufacturer, request to know the lowest price they can purchase the product for , rather than demanding a specific quality standard such as original VW or better and how much that quality costs. Many suppliers, that are simply marketing products, often make claims of original quality, however rarely provide it and price may not always be an indication of product quality. We sell only the quality which will stand up to the test of being at least as good as the original part they replace. Almost every substandard quality piston and cylinder set we have tested (including stock sizes), regardless of a brand name, experienced distortion or poor oil control almost the moment the engine was started. It continued to get worse as we ran the engine.
Some stock sets would show as much as 10% leakage in less than 25 hours of running. Our rigorous testing revealed many failures in less than 5,000 miles of street driving. Dyno tests of 92mm/94mm sets showed as much as 25% leakage (blow-by) after only 5 minutes of running. 20% had leakage around the head from distortion after only 45 to 50 hours of running. Blow-by was so bad that extra vents and breathers had to be added to the valve covers just to complete the tests. Temperatures, both head and oil, were as much as 30% hotter than tests with factory quality 85.5 or our quality 88 and 90.5 piston and cylinders. We will not sell a product that doesn't test at least as good as the stock VW factory quality unless specifically marked. We are clear that many people are running and have run 92mm/94mm sets with reasonable results and do not wish to suggest that they will not run. They only provide some return on your investment and we are sharing our test data with you so you can make the choice that is best for you and is not meant to be derogatory in any way.
** Our "special" Berg/Cima pistons have maximum silicone and magnesium content for use in air-cooled engines (not a cheaper piston for a water-cooled engine). Cylinders have maximum nickel and copper content. They are spun cast in a high-speed centrifugal mold to give an extremely dense cylinder that maximizes heat dissipation and concentricity through years of service. For best rigidity, our 88mm cylinder wall is thicker than a factory stock 85.5mm at the fin area.
POTL. Piston and cylinder sets that are not marked as genuine Berg Specials are the standard Cima/Mahle that we have inspected, keeping only the ones that pass our rigid standards of quality and sizing. The rejects are returned to the suppliers who then sell them to our competitors. We sell you the Pick Of The Litter (POTL). This inspection is time consuming and expensive, however we feel you're worth it.