Thread: Chevy 292 Straight Six

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I'm nuts for six in a row, here in my old age. Been there, done that on most of the V8 stuff, so I welcome something different.
I'd approach this project by bolting a supercharger onto the 292 and backing it up with a 700R4 and a ~3.73 rear gear. With that gearing arrangement, first gear will be 11.41:1 for a good launch and fourth gear will be 2.61:1 for low rpm cruising.

The reason I'd use a blower instead of going the traditional route of cam, compression, valve size change, cutting the head, etc. is because with a naturally-aspirated motor and doing those changes, you will be moving the power range higher up in the rev range and giving up good low-rpm mileage and power. With a blower, you can run pretty much any cam you want to and the blower will make it streetable from low rpm's to max rpm's. The other reason I'd run a blower is that the flow figures on your head will be.....ummm.....less than desirable and no amount of compression, cam, valve size change, etc., etc. will make much difference. The motor is head limited and that's all there is to it. So, it makes sense to me to pressurize the system and make the intake ports a non-player in the equation.

A blower will require a low static compression ratio. I don't know what the SCR of the stock 292 is, but I'd bet that it should be just right at somewhere around 8.0:1 to 8.5:1. Even with the light SCR, the motor will tolerate a big cam at low rpm's because the blower is forcing the mixture into the cylinders instead of the motor relying on atmospheric pressure to push it in. If I were doing it, I'd use pulleys to bring the manifold pressure up to somewhere around 5-6 psi. I'd use long-tube headers with an unrestricted exhaust system and an electronic ignition system that has provision to retard the timing during boost.

There are many different blowers that are available and would work for this application. GMC 4-71 (best eye candy of the group in my opinion), Weiand 142 or 177, Kenne Bell Lysholm twin screw , Whipple Lysholm twin screw, etc., etc.

Here's an example.....
supercharged inline six - YouTube

Contact the guys at Blower Drive Service and talk with them. They've been doin' this stuff for decades.....
http://www.blowerdriveservice.com/contact.php