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November 5, 2005

Weird GM engines

I have known and loved some strange automobile engines in my lifetime. I suppose is part of my obstinate nature to embrace the odd or the unusual, it is far too easy to run with herd, I do not roll that way. Me, I prefer to stand out in the crowd, follow the path least traveled, and explore new territory. In my view a 400 hp small block Chevy is boring; seen one, seen a million of them.

I look for innovation in engine design and I like to recognize engineering daring. Good old General Motors is sometimes viewed as resting on their engine design laurels. What other automobile company would celebrate that their mainstay engine, the small block V8, has been in production for 50 years? But GM used to be in the cutting edge of automobile engine design.

In the 1950's, GM responded to the success of Volkswagen/Porsche and Renault selling millions of cars with air-cooled, aluminum-cased, opposed four cylinder engines by creating their own air-cooled aluminum block opposed six cylinder engine for the ill-fated Corvair. You have to give GM credit for trying by eventually selling a version of that engine with a factory turbo charger. But even though that engine used lightweight alloys to reduce weight, it still came to market heavier than a similar displacement Ford inline six of a more conventional design.

Expanding upon their investment in lightweight engine designs, GM introduced a 3.2-liter aluminum V8 based upon their cast iron block small block design. Regrettably, the US buying public made larger displacement iron engines their primary choices and GM sold off the aluminum V8 to Britain's Leyland Motors where it got stuffed successfully into a succession of saloons (sedans to us Americans), Land Rover products, and even into the MGB.

GM engineers still had faith in aluminum allow engines and were unwilling to let their greater production cost to deter their attempts to put it into regular production. GM's large block engines were powerful but heavy so an aluminum-alloy version was created for specialty (racing) usage. But the limited demand could not justify the costs and the large block GM V8 faded away just as another GM aluminum engine came into production.

The all-new Chevrolet Vega was GM's answer to the rising tide of smaller foreign cars taking market share in America at the end of the 1960's. Looking like a scaled down version of the Camaro, the Vega used an overhead cam in-line four with an aluminum block. The revolutionary breakthrough made by this engine was that it used no iron sleeves to prevent excessive wear between the pistons and the cylinder walls. Previous aluminum block engines need to be fitted with the iron sleeves, but GM and Reynolds Aluminum claimed that they had created a newer, stronger alloy that eliminated the need for the extra expense. It certainly kept cost down... for GM. Vega owners discovered that the engines would hand grenade at about 50,000 miles.

The Vega engine was actually a pretty good design, if you discount that nasty habit of wearing pistons through the cylinder wall. Famous engine building company Cosworth eventually was commissioned by GM to build a double overhead cam version of the Vega engine with mechanical fuel injection. Part of the Cosworth conversion was to add a set of iron sleeves to preserve the engine.

GM currently has an inline 5-cylinder engine that is exclusive to their small and mid-sized trucks. This engine has earned praise for its high torque capability and appears to be selling well. But long before this engine, GM stole market share from industry leader Ford in the late 1920's by offering in line six cylinder engines when you could only get a four in a Model T. Perhaps the most famous inline six cylinder from GM was the "Stove Bolt" six that powered nearly everything in the bottom end of the GM offerings starting from the early 1930's. The Stove Bolt powered the very first Corvettes and remained in production mainly for truck use until very recently in a series of continually updated versions.

But my all time favorite version of the GM inline six-cylinder engine was a Pontiac offering in the 1960's with an overhead cam design. Only sold for a few years because Americans preferred V8 to inline six, no matter how sophisticated the design, the over head cam GM six was America's answer to the Jaguar and Mercedes OHC six cylinder engines that were so successful for those manufacturers. There was an effort to used the OHC six in performance applications, but there was never much interest and Pontiac quietly dropped the engine.

A friend is restoring a 1967 Chevy Nova with a 200 cubic inch inline six. I have urged him to drop a late model 300 cubic inch GM inline six into the car or maybe even a Pontiac OHC six. But he prefers to be a member of the herd and drop in just another small block V8. Ho hum, so boring.

Posted by Scott at November 5, 2005 2:52 PM


No matter what kind of vehicle you have, make sure that the engine that supports your car is truly a tough one. Engine play a very important parts for us to control the vehicle.

Posted by: Terry Brown at November 14, 2005 8:58 PM

Have to say I agree with you 100% on the weird engines. I wrote something similar a short while back that you might want to check out: http://dorri732.blogspot.com/2005/10/every-conceivable-type-of-engine.html


Posted by: Dorri Williams at November 30, 2005 6:04 PM

In the fall of 1968 I ORDERED a 1969 Firebird with a Sprint OHC (250 C.I. 230 HP)in it. My friends thought I was a little off for ordering it with the six in it. The next summer are group went to Cordova Drag Strip to see what our cars would do. I was matched up with 327 Chevelles in my class. I left them at the line but I only had a 3 speed so they would catch me about 3/4 track. My best time was 15.01 seconds, when I unknowingly lost the fan belt at the start. I still have the engine. I'am putting it in a 4 door 62 Nova. So I to am a believer that if you see 1 SBC you have seen all of them. My two cents.


Posted by: Carl Stratton at April 9, 2006 11:47 AM

Carl, I drove a '69 Firebird convertible for years. My father bought it in November '68 and it passed through my brothers and me and is still in the family.

It is the 350. I know they made a 400 which vanished from the roads 10-15 years ago. Too much engine for the car. I have never seena 250. Was that a limited model?

Posted by: Buck at April 12, 2006 2:20 PM

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