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Old 03-18-2010, 11:47 PM
 
Location: Lafayette, Louisiana
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Back in the 1980s, Pontiac Sunbird and Buick Skyhawk had available a single overhead cam four cylinder engine. Why did GM shut down this engine, replacing it with an OHV engine? Why didn't GM continue to develop upon this existing technology they had inhouse?
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Old 03-19-2010, 12:03 AM
 
Location: Lafayette, Louisiana
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I looked it up and found that in 1988, GM offered two different 2.0L engines, OHV and SOHC. The OHV was 90hp and the SOHC was 96hp. The SOHC offered slightly better mpg numbers as well. But at some point the SOHC was dropped from the lineup and replaced with the OHV engine. Also dropped was the turbo verson of the SOHC engine. It originally made 150hp but was later bumped up to 165hp, more than the V6 offered in the Z24 Cavalier. The V6 offered smoother acceleration but lower 0-60 numbers than the 2.0 Turbo. This 2.0 Turbo was only offered in the Sunbird GT and the Buick Skyhawk T-Type back in 1987. With improved interior, improved suspension, and an intercooler these models would have been the car to beat back then. Guess it's just another example of where GM could have taken over the market but choose to languish in the also ran catagory.
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Old 03-19-2010, 08:36 AM
 
Location: U.S.A.
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Old 03-19-2010, 08:44 AM
 
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That pic is actually pretty accurate - the OHV was the cheaper engine, and "almost as good", so why not go with almost as good and save some money? No one is seriously going to buy those Japanese cars, right?
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Old 03-19-2010, 09:18 AM
 
6,368 posts, read 13,382,403 times
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Quote:
Originally Posted by sailordave View Post
Back in the 1980s, Pontiac Sunbird and Buick Skyhawk had available a single overhead cam four cylinder engine. Why did GM shut down this engine, replacing it with an OHV engine? Why didn't GM continue to develop upon this existing technology they had inhouse?
Quote:
Originally Posted by sailordave View Post
I looked it up and found that in 1988, GM offered two different 2.0L engines, OHV and SOHC. The OHV was 90hp and the SOHC was 96hp. The SOHC offered slightly better mpg numbers as well. But at some point the SOHC was dropped from the lineup and replaced with the OHV engine. Also dropped was the turbo verson of the SOHC engine. It originally made 150hp but was later bumped up to 165hp, more than the V6 offered in the Z24 Cavalier. The V6 offered smoother acceleration but lower 0-60 numbers than the 2.0 Turbo. This 2.0 Turbo was only offered in the Sunbird GT and the Buick Skyhawk T-Type back in 1987. With improved interior, improved suspension, and an intercooler these models would have been the car to beat back then. Guess it's just another example of where GM could have taken over the market but choose to languish in the also ran catagory.

You ask a question then 16 minutes go by and no one replies so you answer it yourself.

What was your point? Just taking another opportunity to bash GM?

By the way, nice picture.
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Old 03-19-2010, 10:01 AM
 
Location: I think my user name clarifies that.
8,293 posts, read 22,505,414 times
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Quote:
Originally Posted by sailordave View Post
Back in the 1980s, Pontiac Sunbird and Buick Skyhawk had available a single overhead cam four cylinder engine. Why did GM shut down this engine, replacing it with an OHV engine? Why didn't GM continue to develop upon this existing technology they had inhouse?
Because it was a piece of crap. At least the old 1.8 engine, with aluminum head & OHC was crap.

Also, there's hardly any point in asking questions like, "Why did GM do this?" and "Why didn't GM do that?" - especially when it comes to things they did in the 70s and 80s.
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Old 03-19-2010, 10:27 AM
 
Location: Pomona
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I'm not so sure about why such a big deal for OHV vs. OHC ... they both work. Pushrods allow for a more compact engine, and with the cams down low, a lower center of gravity. Fewer moving parts means less mass to move, for greater efficiency.
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Old 03-19-2010, 02:55 PM
 
Location: I think my user name clarifies that.
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Originally Posted by Narfcake View Post
I'm not so sure about why such a big deal for OHV vs. OHC ... they both work. Pushrods allow for a more compact engine, and with the cams down low, a lower center of gravity. Fewer moving parts means less mass to move, for greater efficiency.
Correct me if I'm wrong, but wouldn't an overhead-cam engine typically have fewer moving parts than its counterpart?

My thoughts on this are very simple. There are some OHC engines that are absolutely fantastic. Then there are those that are crap. Either result is not due to them being OHC. It's a whole slew of other factors.
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Old 03-19-2010, 03:20 PM
 
14,777 posts, read 34,606,813 times
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Originally Posted by Omaha Rocks View Post
Correct me if I'm wrong, but wouldn't an overhead-cam engine typically have fewer moving parts than its counterpart?

My thoughts on this are very simple. There are some OHC engines that are absolutely fantastic. Then there are those that are crap. Either result is not due to them being OHC. It's a whole slew of other factors.
In an OHC setup the cams move the valves directly (with some older designs still pushing on lifters).

In an OHV engine, the cam pushes on push rods that move lifters that move the valves.

The trade off for OHC's is the running gear that is necessary to drive the cams. This is the "timing belts" you often hear people talk about needing to be replaced. This is really the only achilles heal of an OHC design.

OHC allows for more optimized flow into the cylinder heads and higher RPM operation do to the lower mass of the valve train. This means that OHC is generally more efficient than OHV setups. However, OHV is a more compact, simpler and generally lower weight design.

They both have their place and either setup can result in a "good" or "bad" engine. OHC is more popular now as it allows for greater efficiency which allows you to get more power out of a smaller displacement engine.
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Old 03-19-2010, 04:06 PM
 
Location: Southern Arizona
9,310 posts, read 25,723,770 times
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Quote:
Originally Posted by sailordave View Post
Back in the 1980s, Pontiac Sunbird and Buick Skyhawk had available a single overhead cam four cylinder engine. Why did GM shut down this engine, replacing it with an OHV engine? Why didn't GM continue to develop upon this existing technology they had inhouse?
My feeble guess would be sales and/or demand, Dave.

Offering two engines with about the same features and output was probably not cost effective so the experts chose the one with the most demand.

Unfortunately, 4 cylinder engines have never been "hot sellers" in this country. Not for GM, Ford or Chrysler and not even for Toyota, Nissan and Honda.
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