Anti-reversion cones

[dpansier]

In Kent Paser?s book ?Speed with Economy? page 37, he details a test of anti-reversion cones in the exhaust system.

I quote from his book ?The theory of exhaust anti-reversion is to prevent hot exhaust gases from flowing backwards into the combustion chamber during the period of intake and exhaust valves being open at the same time. This is commonly called valve overlap?

His results indicated no appreciable speed increase but he did notice a reduction the fuel consumption by one gallon per hour at cruise speed. The anti-reversion cones were tested on a 4-pipe straight stack exhaust and a 4 into 2 with the results being the same one-gallon per hour fuel savings.

With fuel prices being $4 to $5 a gallon, these cones would have the potential to save $8,000 to $10,000 over the life of the engine.
Has anyone duplicated this test and if so what was your result?

Don
RV-7 Finish Kit