Is Wikipedia Wrong On The “GM 122” Engine? Are These Two Engines Related? Obviously Not

I know wikipedia isn’t always right, but it certainly is a superb resource that I use quite often, although I have to keep up my guard. The other day, MM had a junkyard find of a Cimarron, and he referred to its OHV four as being an “Opel-designed 122 pushrod engine“. And he included that link, which led to a wike page on the GM 122 engine. Now that didn’t seem right at all. I’m not trying to play “gotcha” with MM, but I’m quite certain that the OHV four, which originated with the 1982 J-Cars as a 1.8L, and was eventually made in 2.0 and 2.2 L versions, had absolutely nothing to do with the Opel-designed fours that led to the Brazilian-built SOHC fours also installed in some J-Cars, including the turbo versions.

For one, the bore and stroke of these engine are totally different, usually a good tip-off. And needless to say, the blocks seem to share not the slightest resemblance. As I remember it, the OHV four was developed alongside the Chevy 2.8 V6, and shares some aspects of its design. Not coincidentally, all the OHV fours and the 2.8 V6 have the same 3.50″ bore, usually a pretty good tip-off of communality. The SOHC fours had bores of 3.34″ (1.8) and 3.39″ (2.0).

Here’s wiki’s questionable text:

This engine family, produced by General Motors globally, was originally designed by Opel in Germany. In OHV form, it was available in the US beginning in 1982 for the GM J platform compact cars and S-series trucks, although originally in use from the 1970s globally. It is different than the engine used in the Chevrolet Chevette which was also an Opel design. For the J cars it evolved through 2002 when it was replaced by GMs Ecotec line of DOHC 4-cylinder engines. In the S-10 related models it evolved through 2003 when it was known as the Vortec 2200. Production ceased consistent with the replacement of the S-series trucks with the GMT 355 sub-platform.

On a separate development track, this engine family was also available in a SOHC form. The SOHC version featured a belt-timed valvetrain. The water pump was also driven by the timing belt. For the US market, this version was used primarily from 1983 for the J-body compact cars through 1994 although the turbocharged version did make a brief appearance in the N-body Pontiac Grand Am. The SOHC version also appeared in the Opel Kadett E-based, Daewoo produced, Pontiac LeMans for the US market. Globally the engine then evolved along three paths. One path leading to the C20NE and then the C20XE when it obtained a Lotus-developed DOHC cylinder head and in 2000 was renamed Ecotec. Another smaller variant retained its SOHC design and was known as D-TEC having been licensed and produced by Daewoo. For the Brazilian market the SOHC-equipped engine is currently a member of both GM Family I and II – the larger model being known as Flexpower and the smaller Econoflex which is available in the 2010 Chevrolet Agile.

There’s a whole other wiki page on the GM Family II engine, which seems essentially correct:

The Family II is a straight-4 piston engine that was originally developed by Opel in the early 1970s. It was used in the Opel Ascona and Opel Kadett and their corresponding sister models the Vauxhall Cavalier and Vauxhall Astra. In the US the SOHC engine was available from 1982 to 1990 including a turbocharged version known as LT3.

Over time, the engine evolved to include many modern features such as DOHC and Gasoline direct injection. Family II has also expanded to include a range of Opel-derived 6-cylinder engines. Many General Motors subsidiaries, including Holden, GM do Brasil and recently GM Powertrain have adopted this design. It is also starting to be used in hot rods as an engine swap.

No mention of the Chevy OHV four here. What’s the verdict? Obviously, wiki is all wrong on this one, as the Chevy “GM 122” engine obviously has nothing in common whatsoever with the Opel “Family II” engine. The GM 122 engine was strictly a GM North American engine cobbled up with a few shared parts from the 2.8 V6 engine, in order to meet the bean counters’ cost objectives for the NA J-Car program. Somebody please correct wikipedia!