Tom’s Corner – Smokey Yunick’s Hot Vapor Fiero

Every year, someone asks about the fate of a potential break through engine technology developed by legendary racing engine builder and high performance tuner, Henry ‘Smokey’ Yunick, with his long time partner, Ralph Johnson. In the June 1984 issue of Hot Rod magazine, there was a report on a ‘hot vapor’ motor that Smokey developed using a 2.5 litre ‘Iron Duke’ 4 cylinder Fiero engine that met all the ‘80’s emission standards, made 250 horsepower and 250 Lbs/foot of torque and went from 0 to 60 in 6.5 seconds and got as high as 51 MPG using premium gas!

The ‘hot vapor’ engine did all of this running unheard of high temperatures at an extremely lean air/fuel fixture ratio, which was seemingly in violation of accepted internal combustion engine physics. Traditional theory was to get rid of or manage heat. Smokey was channeling heat for improved performance, the exact opposite of conventional engineering science. Here is how Smokey did this : A standard four cycle internal combustion engine utilizes only about 25% of its potential energy to make power. The remaining 75% is lost out the exhaust or transferred as heat into the cooling system and radiator. Heat vapor technology attempts to recapture this heat energy using it to super heat the incoming air/fuel mixture to more than 400 degrees F going into the cylinder, thereby achieving a perfectly vaporized condition that it said to prevent denotation while ensuring complete combustion. Smokey was channeling heat from the water in the engine’s cooling system plus exhaust heat to progressively warm the system’s induction flow to the required temperature. He and Ralph Johnson were actually fooling around with this concept for more than 3 decades. Smokey did take out patents on the basic ‘hot vapor’ technology but took much of the knowledge with him to the grave.

As for the fate of the original ‘hot vapor’ engines, his daughter Trish still retains 4 different prototypes in long term storage, one is also in the Smithsonian Institute. A friend of Smokey’s, (Tony Allers) has the only good running engine. He built a Fiero that is identical to the original car, using the original drive train salvaged from the original Hot Rod Fiero by Smokey before Smokey returned it ti Pontiac for crushing. Allers drove his car for 2 and ½ years before donating it to the Don Garlits Museum where it is currently on display. This Fiero can smoke the tires at 60 MPH and passes all Tennesee emission tests. ‘Hot Vapor’ technology will not die. The time will come when engines will be fully adapted as a heat pump.

(editors note: This is the first of a 2 part series on Smokey Yunick’s Hot Vapor Fiero. The next Tom’s Corner will look more into the Hot Vapor technology and some of the debate about the effectiveness)

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About the author: Tom Schmidt