MDchanic

An article about old turbo cars in the Times Automotive section:

http://www.nytimes.com/2014/12/21/au...ttom-well&_r=0

- Eric

oldcutlass

Interesting read.

rocketraider

Good read.

I still say the Jetfire's biggest problem was Oldsmobile's absolute refusal to consider dropping the CR on those engines. Had they done that all that alcohol injection setup could have been eliminated and they could have possibly upped the boost a little bit for even stronger performance.

I also thought it quite strange that they elected to keep, for all practical purposes, a single exhaust system on the turbo cars. Guess it was to keep the backpressure up to spool up the turbo quicker.

Still a great effort by both Olds and Chevrolet. Turbocharging was exotic technology for cars in the early 60s and I don't think GM has been as adventurous since as they were with the BOP-ettes/Corvair. Face it- after their little run with innovation, they became downright conventional.

joe_padavano

As opposed to what? There's only one turbine outlet. So long as the total flow of the single pipe is adequate, there's nothing to be gained by splitting it aft of the turbo (except the additional weight of the second pipe and muffler). Frankly, a single pipe has greater flow capability than two pipes of equivalent cross section due to the greater surface area of the twin pipes and thus the greater boundary layer drag. The other problem is that the Y-body cars were only configured for a single exhaust, with the pipe running in the tunnel next to the driveshaft, with a single muffler crossways behind the rear axle. Running two pipes and mufflers under the floorpans, as some people do, significantly reduces ground clearance. On my 62 I used a single 2.5" pipe to a Camaro transverse muffler with two exhaust outlets. I figure if two 2.5" pipes are enough for 455 cu in, then a single 2.5" pipe will flow enough for 215 cu in.

rocketraider

Joe, that reasoning can also explain why, for many years, dual exhaust Oldsmobiles had two different size headpipes. The single exhaust pipe carried over to the DE cars at the same size and configuration. The dual (usually LH) pipe was generally 1/4" smaller diameter. Runs muffler shops crazy...