Mike's fuel-injected, turbocharged, intercooled motivation!
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Unlike the late model Corvair factory turbocharged engine, which uses pistons and heads that yield 8.25:1 C/R, the stock 140 engine has a C/R of 9.25:1. Bolting a turbocharger to it requires internal modifications. One of the mods Mike used in his over-the-top turbo was tested and proven by Bob Helt, who sent us the following text and illustration to explain the procedure. |
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Lowering C/R - by Bob Helt The best way to lower the compression ratio is to have a machine shop mill up to 0.070" off the top of each piston in the area not opposite the quench area in the head, as shown in the illustration. This will produce fairly consistent results that won't require "CCing" or piston rebalance. By milling out the step in the head and setting the gap to 0.035" we have improved the quench action but this may not be sufficient to allow operation on regular gas. A further milling of up to 0.070" off the top of the pistons under the valves and spark plug (and not opposite the quench area) will lower the compression ratio. We now have the optimum condition of efficient quench action and highest possible compression ratio for a turbocharged application. |
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| Below, a close-up view of the Corvair engine destined for the Avenger chassis. The A/C compressor, just above the wastegate in the photo, is mounted on custom brackets and only draws about 6 horsepower, much less than a stock set-up. According to Mike, his set-up also results in better cooling. |
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This engine, which came out of the Corsa, should motivate the 2,000 pound finished Avenger to awesome acceleration and top speed, well into the new Millennium! Mike will fill the hole left in the Corsa's engine compartment with the 140 engine out of the Avenger and he'll press the car into service as a daily driver. Good luck with the retirement projects, Mike, and keep us posted on your progress! |
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