The Corvair Myth: 1965-66 Corsa

1966 Corvair Convertible Corsa
1966 Corvair Convertible Corsa
Inside Dash
Inside Dash
140 hp motor
140 hp motor

If you are new to the Chevrolet Corvair as a collectible classic car there is little doubt you wonder what are the differences between the Monza and Corsa models. They look the same, minus cosmetic emblems or trim on the outside. The interior between the two models is only somewhat different, the Corsa has a tachometer, manifold, engine head temp gauges, clock, speedometer. It clearly looks like a sports car. The Monza has three large gauges: a speedometer, clock and fuel. Everything else about the interior is about the same, minus some emblems.

There remains a myth of sorts even today that the Corsa was somehow the "racing" model. The reality is that it simply was the top of the line Corvair model and most of the differences were basically trim and minor differences between the Monza and Corsa. The myth is perpetuated by the fact that Chevrolet only made it in 1965-66, so to a collector, they are more desirable and valuable. Since that time, many misunderstandings about the Corsa have been passed on. The greatest misconception is that the 140 hp motor was just that. Fact is, a 140 hp inside a Monza or Corsa with a 4 speed are exactly the same. If the car has an automatic, then the main difference is the cam. The 140 hp motor was slightly different with larger valves and a dual exhaust which makes the motor sound much louder like a Harley. Monza's did not have this. One could buy a Monza with a 140 hp motor until until 1969. One did not have to buy a Corsa to get the 140 hp motor.

In 1965, the Corsa came out and was priced from $2500-3000. You got a fancier package and higher quality, a 140 or 180 Hp motor, a different dash. In 1966, the last year for the Corsa, the main difference and improvement to the engine was in the Saginaw transmission common with many other Chevy's. The other important change was the linkage to the secondaries. Other than this, everything else was nearly the same but for cosmetics.

The myth of the 140 hp engine is that until the engine hits 3500 rpms in any gear, you have only 110 hp, just like the Monza. At 3500, the secondaries begin to provide more gas, thus more power. Good for fast take offs from a stop, in and out of traffic on a highway or needing a sudden boost. Many buyers back in 1965-66 probably were under the illusion that the 140 hp motor was 140 hp at any rpm. Perhaps the salesman did not even know this.

Driving in 2nd or 3rd gear at 3500 or greater rpms creates a lot of engine noise and compression, one wonders if the engine is going to blow up before you shift. Most people shift at 3000 or less rpms until reaching 4th, so in effect, most drivers of a Corsa do not have many opportunities to gain the benefit of 140 hp, except on a highway. Who, but for a drag racer, would push their engines to 3500 rpms and beyond in 1st, 2nd, 3rd gears? Few. Traffic, police and speed limits pretty much prevent this for any length of time.

The 140 Hp engine is robust. The Corsa was an attempt to create a racy, sporty Corvair by adding two additional carbs (for a total of four). Because of physical and design limitations, Chevy could not create a true 140 hp motor for the car, but they could push the motor to 140 hp at 3500 rpms or more. At 3500 rpms in 4th, you are around 60+ mph, reaching higher rpms increase the horsepower. From a standstill, one can race and whine out the engine for fast shifting through the gears, hitting 3500 rpms or more briefly and then shifting. This makes for rapid acceleration. At best, it is 0-60 mph in 10 seconds. But again, most normal drivers and collectors do not drive in this manner, so the myth of the 140 hp remains.

The Corsa does accelerate faster than a Monza due to other reasons. It is more valuable from a collector POV and resale averages a few thousand more than a Monza in the same condition. Many Monza's are converted into a Corsa by changing the dash. So, beware. Only the VIN will tell you if it is a true Corsa.

The myth still lingers. Just remember that you only have 140 hp at 3500 rpms or greater, until then, you are driving a 110 hp. You will greatly see the difference on the highway or from 0-60 race, as you blitz through the gears BUT the Corvair was never meant to be a muscle, race car. The way it looked perpetuates the myth even today. People see it and say, "that is way cool".

Comments 8 comments

BigRed 6 years ago

"The myth of the 140 hp engine is that until the engine hits 3500 rpms in any gear, you have only 110 hp, just like the Monza. At 3500, the secondaries begin to provide more gas, thus more power. Just remember that you only have 140 hp at 3500 rpms or greater, until then, you are driving a 110 hp"

The secondary carbs open due to throttle pedal input (approximately 3/4 pedal travel, depending upon adjustment), not engine speed. If you lay the throttle wide open at idle, it'll have all 4 open at idle.

"Driving in 2nd or 3rd gear at 3500 or greater rpms creates a lot of engine noise and compression"

Compression? What? The compression is caused by the piston rotating up in the cylinder bore "compressing" the air/fuel mixture. Works the same at idle or at redline.

"The 140 hp motor was slightly different with larger valves and a dual exhaust"

The 140 also had higher compression, and a 12 pass oil cooler

"Just remember that you only have 140 hp at 3500 rpms or greater, until then, you are driving a 110 hp."

NO internal combustion motor EVER MADE makes peak horsepower at idle. They all make peak hp at a certain engine speed. The 140 does however make more horsepower at ANY GIVEN RPM RANGE than the 110, since the 110 makes less than 110 at low revs.

"Because of physical and design limitations, Chevy could not create a true 140 hp motor for the car, but they could push the motor to 140 hp at 3500 rpms or more"

Physics is funny like that. The internal combustion engine is basically a big air pump, and as such, air generally flows better at higher velocities (higher rpm speeds), thus making more horsepower at higher rpms. I don't know where the "true" comes into play, but since how ALL motors are measured, the 140 horse makes a "true" 140 horsepower at approximately 3150 rpm, and peak torque around 2800.


roy 5 years ago

i,m tradeing for a 1966 corsa what do i look for in the vin to make sure it is a corsa thanks


Rick 5 years ago

The difference between the Corsa and Monza? The Corsa BASE engine was 140 hp and the OPTIONAL engine was 180 hp. The Monza had the 140 hp 4 carb as its MOST POWERFUL

option.

Hp and Torque are equal at around 5250 rpm for ANY engine that can run to that rpm. Hp is a calculated number based on just two factors - torque and RPM. So the 140 engine breathes better such that its torque does not fall off as sharply as the two carb single exhaust engine. Think about it. If the 140 engine is producing 145 ft lbs of torque around 4500 to 5000 rpm, I can see it making 140 hp as the torque drops slightly over 5000 rpm. I recall the 140 being rated at that peak, about 5200 rpm. THE 140 ENGINE IS ONLY MAKING ABOUT 100 HP AT 3500 RPM!


Bob 4 years ago

In any engin you do not hit the peak hp infill a certain rpm in the 110 you didn't have 110 hp until 4400 rpm and this goes for the 140 or any other internal combustion engine


Javi Iturbide 2 years ago

I'm about to go and check out a 65 corvair hardtop 2dr. Coupe, it has the 140 engine w/ the 2 carb set up( not the 4 carb set up, and w/ the 2 speed powerglide trans, ad said 2500 but willing to negotiate. Any advise for me when checking the car??


Lgbpop 21 months ago

Javi, how did you make out with the 2-carb "140?" Did you find out the truth about it when you saw the car?


javi Iturbide 19 months ago

that 65 i checked out was only a monza w/ a 110


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perrya 19 months ago Author

I sold my 67 Monza 75% restored, ran great, for $4200. Bought for $900.

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