Turbo usage

[mlewisariz]

Looking for info or opinions about installing a stock turbo system on a non turbo engine. Any problems w/non turbo heads and valve differences? All parts are 1963. Have most turbo parts including distributor and the engine is a 98 or 102 horse. How about camshaft differences? The install would be in a non stock build so engine tin is not an issue. Any thoughts?

Mike

[bbodie52]

1963 80 hp and 150 hp Turbo heads produced a compression ratio of 8.0:1. The 84 hp (Powerglide), and 102 hp heads had a smaller combustion chamber volume that produced a 9.0:1 compression ratio. The lower compression ratio is essential for the turbocharged engine to help control and prevent detonation.

The turbo heads have an oil return tube hole in the right head to accommodate oil return to the engine from the turbocharger.

There were many other engineering changes in the turbocharged engines, including different piston rings, different exhaust valve material, different valve guides, a stronger crankshaft and stronger connecting rods, etc. A unique camshaft grind was used in the turbocharged engine. The article below does a good job of covering the engine differences...

Under Pressure
The 1963 Corvair Turbocharged Engine



Under Pressure from Hemmings Classic Car
November, 2006 - Ray T. Bohacz

On October 2, 1959, the Chevrolet division of General Motors introduced what was unofficially known as the American VW Beetle fighter, an air-cooled, rear-engine economy sedan called the Corvair that was to do direct battle with the German import. In many ways, the Corvair was better suited to the North American market than the VW, offering a larger and much more powerful six-cylinder engine, available automatic transmission, a variety of body style choices, a real heater and a much smoother ride from a longer wheelbase and overall larger package. Though very successful, the Corvair and its variants (including a van and a pickup-type truck) seemed to cut out a niche in the market that had only some overlap with the demographic of a potential VW owner. Thus, the little Chevy didn't steal many sales from the Beetle, but was effective in expanding the market for rear engine, air-cooled cars.

The Corvair found acceptance in varied segments of the market, something the VW could not boast. Residents of urban and the newly forming suburban communities saw value in the design of the Corvair, while those in rural areas enjoyed the superior traction of the car's rear-mounted engine when splashing down dirt roads. The fuel-efficient engine allowed for economical trips to town, and the lack of a radiator meant there was no concern that stones from the road might punch a hole in the cooling system.

Enter the Monza Spyder
Wanting to capitalize on the American motorist's growing lust for power and sportiness, a high-performance Corvair model was introduced, the Monza. The major performance option was identified as Regular Production Option (RPO) 649. Checking this order box delivered a Monza with a naturally aspirated engine that employed a high-lift camshaft and heavy-duty valve springs that increased the power rating 22hp for a total of 102hp. The Monza quickly took the sales lead in the Corvair line as its high-performance engine became the most popular Corvair powerplant.

Not one to ignore a sales success, GM marketing executives felt that the Monza concept could be stepped up a notch if a truly high-performance engine were to be offered in the convertible and club coupe. Thus, the Monza Spyder was born.

Since the air-cooled engine was a horizontally opposed design, it did not lend itself readily to a substantial increase in displacement as a traditional inline or V-type engine would. The engineering team quickly recognized that the Spyder's performance goals would only be met through the addition of a forced-induction system.

Both belt-driven superchargers and exhaust-driven turbochargers were examined, and each technology offered advantages and drawbacks. Though providing instant throttle response, a belt-driven compressor would be awkward to package in the limited space the Corvair engine compartment offered. The supercharger would have to occupy the area that was used for the spare tire. The tire then would have to be relocated and would consume a large portion of the trunk capacity. In addition, noise and vibration from a supercharger would diminish the Corvair's refined attitude among economy cars.

When the engineering review was completed, the advantages of a turbocharger far outweighed the higher engine speed that would be required before artificial aspiration would be introduced, along with the inherent lag. Thus the 150hp turbocharged Corvair Spyder engine was born.

The Spyder Engine
Numerous problems needed to be conquered before the new engine could be brought to market. The structural design and strength of the engine needed to be able to withstand the 48-percent higher horsepower over the normally aspirated engine. Changes were necessary to the crankshaft material, connecting rod cross section, piston ring material, exhaust valve and guide composition, compression ratio, distributor advance curve along with ancillary components such as the carburetor, air cleaner, exhaust system, fuel lines and clutch. In contrast, the special camshaft and heavy-duty valve springs from the normally aspirated high-performance engine would be retained.

Early in the development program it became evident that the carbon steel used in the crankshaft of the basic Corvair engine was not adequate for the cylinder pressure of the forced-induction Spyder engine. Cracks appeared in the fillets and radii during rotary fatigue and stroking durability tests, which had been increased in severity to simulate the loading from boost pressure.

Chromium steel was then substituted as the material of choice. After the crankshaft was quenched and tempered, it was subjected to a special surface hardening process, consisting of a low-temperature liquid nitriding. Use of the chromium steel and the special treatment provided increased hardness and fatigue strength to the fillets, largely through more uniform and deeper penetration of the heat treat than would be possible with carbon steel. Chevrolet laboratory tests for rotary fatigue proved that over 500,000 cycles could be experienced without failure. The standard carbon-steel crankshaft failed under the same conditions at about 100,000 cycles.

The connecting rod presented a different issue. The production rod did not have the column strength to withstand the greater piston loads, but a change to a higher quality alloy was not as practical as an increase in rod section. With the increased column section, the rod would operate at the same 44,000 p.s.i. stress level as the lighter rod in the normally aspirated engine.

Image 2 of 6: Many aspects of the Corvair engine needed to be modified to accept the higher horsepower output and additional heat that the turbocharger produced

The greater output of the Spyder engine also increased the propensity for blow by, necessitating a new crankcase oil separator. The conventional engine separator allowed excessive oil pullover, and a development program conducted jointly by the Proving Ground engineers and the laboratory produced a good design.

It was necessary to chrome plate the top compression ring because of the higher ring loads, which caused scuffing with the standard ring when used in test engines. Approximately 0.004-inch minimum chrome was used to reduce upper ring wear and to minimize any possibility of cylinder bore scuffing caused by increased gas loads. The ring material was of a premium grade and was considered a high strength centrifugal iron.

Likewise, the dynamometer durability testing proved that the standard piston was not strong enough either, as cracks appeared around the pin bosses. A new piston designed with reinforcements in the needed area eliminated the concern.

The valvetrain of the normally aspirated engine was used with the exception of the exhaust valve material and guide. The heads of the exhaust valves in the turbo engine were made of Nimonic 80A, which was considered a "super alloy" whose principal components were approximately 68-percent nickel and 20-percent chromium. The alloy, whose excellent high-temperature strength had it employed in turbojet aircraft engines, was applied to the Corvair due to the high combustion temperature under boosted operation. Exhaust valve temperatures were about 200-degrees higher than in the standard engine. A chromium silicon steel called Silchrome No. 1 was used in the valve stems for its excellent scuff resistance.

The exhaust valve guides were also changed from cast iron to an aluminum bronze alloy to improve heat conductivity while retaining good high-temperature anti-friction qualities.

The distributor advance curve of the turbo engine was designed for 24-degrees of initial advance and a spark retard mechanism was devised that was actuated by intake manifold boost pressure. The mechanism used the vacuum advance unit as a positive pressure device to retard the ignition timing when the turbocharger was evoked.

Ignition voltage requirements were substantially higher at maximum cylinder pressure, and thus a high-output coil was designed to meet the task. The coil had 20-percent greater voltage output than the coil used on the normally aspirated engine.

The compression ratio of the 145-cu.in. turbocharged engine was 8.0:1. In contrast, the normally aspirated Monza engine had a 9.0:1 ratio.

The clutch in early test cars failed prematurely under aggressive driving and it was calculated to need a higher pressure plate loading. This value was increased from 980 lbs. to 1,350 lbs., but the disk size was retained at 8 inches.

Another Spyder specific difference was a cylinder head temperature gauge. The instrument panel gauge received a signal from a thermistor sending unit mounted in the left cylinder head at the number six spark plug location. If the temperature reached 575-degrees, a snap switch at the number-one cylinder closed, illuminating a red bulb on the instrument panel and sounding a buzzer alarm. In the absence of any component failure, all that was required to cool the engine back down was a temporary reduction in engine speed or load until the warning was canceled.

The test turbo engine employed the same fan shrouding and cooling components as the standard engine. Therefore, it was believed that some cooling problems were to be expected. But GM found it extremely difficult to overheat the engine. Cooling was adequate for sustained cruising in 100-degree F. ambient temperatures and for short test runs at over 100 mph.

Since it was not likely that Spyders would ever be subjected to sustained cruising speeds of over 100 mph, it was necessary for the team to try to deliberately overheat the engine. Even when this was done, the engine cooled quickly when the car was slowed to 60 mph and was then capable of increasing the velocity back to over 100 mph.

The final package was evaluated on extensive road trips. On one excursion, two turbocharged cars were driven to the GM Proving Grounds in Mesa, Arizona, then back to Michigan via Pikes Peak in Colorado. Temperature conditions on this test trip varied from zero to 85-degrees F. The cars were driven at altitudes ranging from 1,000 to 12,500 feet above sea level. The road conditions varied from dry to ice and packed snow, and the weather from bright and sunny to snow, sleet and fog. Both Corvairs performed without a hitch.

The Turbocharger
The induction system included an air cleaner, a single side-draft carburetor, turbocharger and inlet pipe. Air, after passing through the air cleaner, entered the carburetor and was then drawn into the compressor section of the turbo. From there it was discharged to the induction pipe, which transferred the compressed fuel and air mixture to the cylinder bores.

The turbo weighed 13.5 pounds. A large-diameter pipe was used to assure effective oil drain-back from the bearing housing despite the foaming that would result from rapid oil flow and high rotational shaft speeds. Seals at the ends of the shaft prevented lubricating oil from entering the incoming charge or the exhaust turbine section. A carbon faced seal was used at the compressor-end of the shaft, and a piston-ring-type seal was used at the turbine end. A cast-iron heat shield kept exhaust heat away from the bearing housing and compressor-end of the turbo.

The turbocharger was joined by a hose connection to the induction pipe, which tied into the two intake manifolds. The unit was mounted approximately 4-inches off center, to allow space between the exhaust pipes and the interior heater duct work. The exhaust system was designed for optimum utilization of the exhaust gasses for the purpose of driving the turbo. The exhaust manifolds were connected together by a crossover pipe that lead to the turbine housing. No method to cool the compressed charge air with a heat exchanger was explored.

As installed in the car, the turbocharged engine provided approximately 90-percent more usable horsepower than the normally aspirated base engine. Peak cylinder pressure was produced at 3,200 rpm, and 210-ft.lbs. of torque was realized at that engine speed. Maximum boost pressure was 10 psi and resulted in a compressor rpm of 80,000.

A Sprightly Performer
Durability testing was done concurrently with the development of the engine so that new designs could promptly be tested. The relatively short time available for the development made it vital to determine the durability characteristics of the engine.

The varying power curve also modified the fuel and ignition requirements, which were determined by the test cars. Changes in restriction in the intake and exhaust systems, for example, raised or lowered the output of the engine, which further impacted the back pressure. Such relationships made designing the calibration on paper without real world testing impractical. While dyno testing helped determine the wide-open-throttle fuel and spark requirements, most of that work was accomplished at the Proving Grounds or during road tests. The vehicle durability testing was conducted on what GM called a modified Schedule U. This schedule is normally rated at a severity level of 4:1, with every mile equivalent to four miles of normal customer usage. In the case of the Spyder, however, it was felt that customer usage could be more severe than that of a standard Corvair. Accordingly, the durability test was designed for a 6:1 severity.

Each lap of the regular Schedule U covered 28.5 miles at an average speed of 40 mph, including a variety of surfaces from smooth highway to 9.5 miles of hill routes and Belgian block covered roads. The average speed of the turbo cars was increased to 55 mph and the run's high-speed portion was increased from 50 to 70 mph. A considerable number of stops were included, and every restart was at full throttle.

The Spyder engines were then disassembled for inspection after the completion of 5,000 miles of the test schedule. They were then reassembled and put back on the schedule for another 5,000 miles.

A turbocharged Spyder was rated at 9.8 seconds for 0-60 mph with two occupants on board. A standard Corvair would take 16.5 seconds to reach the same speed.

The passing performance of the turbo engine was considered to be excellent. When driven at normal turnpike speeds, the car had passing potential acceptable for the most demanding driver. There was very little lag during acceleration from a road load condition with the production engine. This was due to the small diameter, high-speed turbine that was constantly spinning.

The limiting speed of the engine was from the pump-up of the hydraulic valve lifters. This occurred at 5,700 to 5,800 rpm. Allowing for a safety margin, the tachometer redline was identified as 5,300 rpm.

The Corvair turbocharged engine was well received by the public. Prior to the last Corvair coming down an assembly line, the Spyder engine production was canceled due to the focus of the product line toward economy minded consumers. The appeal of a larger engine, rear-wheel-drive performance car was just too strong for the little turbo to overcome in the showroom. But Chevrolet must have learned there was a market for small, economy car-based hot rods. In 1974 the division introduced a twin-camshaft Cosworth version of the Vega, and just last year, a supercharged SS model of the front-wheel-drive Cobalt. The Spyder engine's DNA lives today -- a true Mechanical Marvel.

https://www.hemmings.com/magazine/hcc/2 ... 66023.html

The engine section of the attached 1963 Chevrolet Corvair GM Heritage Center Specs provides technical details of the turbocharged engine.

[mlewisariz]

Oh...Well I guess I should see if some of the extra sets of rods I've got might be turbo parts. I know there is a timing cover and 1 head with 6 valves(no springs,keepers,or retainers) Also need to check the crankshafts. The 63 motor referenced isn't mine,but the owner asked me about my turbo stuff working for his build.Thanks for the help.

Mike

[notched]

If you started with a 164 engine you would already have the better rods as well as other improvements

[miniman82]

You can turbo literally any engine, but if you want it to last you have to consider the punishment some of the parts would take. I personally would trust the pistons, rods, crank and heads on a 110 to take turbo abuse. What I would upgrade are the exhaust valves, bronze guides, slightly stiffer springs, and the ignition. No reason it wouldn’t work, just has to be put together correctly. And you can get away with slightly higher compression, I don’t think the engine would even notice 8.5:1 but 9 is probably pressing your luck depending on where you live. If it’s hot, forget about it. If you aren’t afraid of a little water/methanol injection, you won’t have any problems no matter where you are.

[toytron]

Hey Nick, do you have any recommendations for water/methanol injection?

Sent from my [device_name] using Corvair Forum mobile app

[notched]

I put my own methanol injection together using a Snow controller and nozzles, braided lines and reservoir from Devil's Own. I spray straight methanol as it is way better at controlling detonation than water. I never had much luck with water.

[toytron]

Could/would you post it here? I am interested. Where do you get the methanol from also.

Ed Stevenson

[thewolfe]

I use 50/50 water/methanol. Some use blue windshield wiper fluid which is something like 60/40 water/methanol. I use distilled water and heet. Those little yellow bottles of gas tank moisture remover that is available at just about every department store. It is pure methanol. You can get methanol cheaper in larger quantities but is very easy to find in those little bottles nearly anywhere. I have mine set to come on around 8 psi and I use about 1 bottle per tank of gas(and I boost often). They're like $2 a bottle

[notched]

I run straight methanol and have run over 30 lbs of boost with it. You will not be able to run anywhere near that much on water. I buy the methanol (5 gallons at a time) at my local track which is close to my house. In a pinch I have used straight denatured alcohol but it has become very expensive.

[thewolfe]

30 lbs of boost in a corvair motor?? Or are we talking some other vehicle?

[notched]

Buick Grand National. David Clemens ran upwards of 30 lbs of boost on his old turbo Corvair engine albeit on race gas. It's definitely doable if your tune is up to snuff.