SOT: The truth about Corvair engines, Nothing but the facts and experience, please Options

[Dr Evil]

There has been lots of interest in the corvair power plant over the years as a possible source of cheap HP for many vehicles. There are used in experimental aviation, dune buggies, buses (such as mine), and in place of many other air cooled VW power plants. They are fairly cheap to buy and build, very easy to build and maintain, and plentiful with readily available parts from several suppliers.

The main divide in the corvair engine line took place in 1965 when the displacement of the engine was moved to 2.7L and was offered in a NA 110HP, NA140HP, turbo 150HP and turbo 180HP. The only differences in the long block between these engines are the nitrided crank found in all but the 110HP, and the heads: 110 had one single barrel on each head, the 140 had 2 with one acting as primary and one as secondary. The turbos had a single barrel blow through setup.

The heads are the major limiting factor in the design. They are not built in an intuitive way and rob much hp. The 140 head had bigger valves, but like its 2.0L TIV analog, would drop valve seats due to the limited amount of material between the seats in the head, and the inability of larger seats to shed heat as well as smaller seats. This can, and has been overcome by those who have been rebuilding these heads fro decades by making sure the crush tolerance on the seats are correct, and staking the seats in place.

Currently, you can get a set of rebuilt, 140hp larger valved heads, with new hardware and no core for about $1200 from Corvair Ranch in Gettysburg, PA. I bought a set that was rebuilt and had the plenums taken off for tri porting for $1500 shipped off of ebay from Starr Cooke in El Cajon, CA, another well known Corvair entity.

Modified with plenum removed for individual runners:


The above uses an adapter that allows the placement of Weber triples. My set came with this adapter.

Here is a head with a stock plenum, modified with bungs for FI. This is a 140 head as it has two carb bases on it:


Standard engine:


One of the cool things that many ACVW folks like is that the corvair engine has stock hydraulic lifters on it that use standard lifter, push rod, and rocker parts from Chevy. Easy and cheap to obtain.

Another great feature that I like over ACVW is the box design on the case. The top and bottom come off and allow for any maintenance. Swapping rods, bearings, what ever, is easy.

[GS Guy]

Great thread Doc!

The big limitation in the cylinder heads is exhaust flow, not so much with the intake. I've been told by some very knowlegible Corvair hot rodders that the stock 140 2-port intakes can flow more than enogh for what the stock exhaust ports can get out. The problem is the location of the pushrods, causing the T4 style exhaust stub pipes to be smaller and "kinked" a little to clear. The solution is an angle port conversion where the direction of the exhaust is directed away from the pushrods and made larger - that uncorks the head for any serious intake modifications - like the yummy 3bbl Weber converion!

Couple of other links of interest:
American Pi - some very nice high-end (and expensive!) 'Vair hardware
http://www.american-pi.com/corvair/corvhome.html

Rear Engine Specialists - been into hot-rod Corvairs for a loooooong time:
http://rearenginespecialists.objectis.net/...-21.5546474873/

Fellow buggy guy with some trick Corvair EFI hardware:
http://www.blackhawkengr.com/

and here's a good youtube of a tricked out 'Vair engine with lots of goodies running:
http://www.youtube.com/watch?v=uzicgyjY12E...feature=related