Like all companies, Opel has its share of bean counters. The first thing Mackichen and company learned was that a ground-up GT car was cost-effective. The expense of tooling a body that wasn't shared with high-volume sedans and wagons was not justifiable. There was only one way to build the GT -- adapt it to the existing Kadett platform.
The Kadett Rallye had proved its mettle in rallies, so a Kadett base for their new GT did not strike the Opel designers as a contradiction in terms. Nevertheless, there was a problem.
The GT prototype had mounted the engine as far back as possible for optimum weight distribution. But stock Kadetts had their engines located directly over the front suspension. Debate ensued. One group, Style Auto reported, "Felt that the position of the engine would have little effect on the handling and performance." The enthusiasts within Opel, however, "insisted that the GT would be the best-handling sports car they could produce." The good guys won when two prototypes, using the two different engine mountings, were tested by Porsche team driver Hans Hermann ar the Nurburgring. Herman told them: build it with the relocated engine -- build it right. They did.
Opel GT 1969-1973
Though Style Auto awarded its 1969 prize for the best-designed production car to the Opel GT, some journalists were disappointed. "Something was lost in the translation from show car to production car," commented Road & Track. "In fact, hardly a line remains the same. The (production GT) styling is swoopy and eye-catching, but the proportions which were so elegant in the show car -- are dinky: lines that look exciting on the full-size Corvette look amusing on the GT."
For years we've thought that the loss of the styling edge was due to the usual corporate causes: budget trimmers and production shortcuts. Not so. It was the wind tunnel. Opel put its GT through extensive tunnel tests, attempting to minimize the drag coefficient -- and they did. The tunnel dictated a shortened, kamm back and spoiler. (An item carried over from the prototype was the pop-up headlamp, and some writers felt this was a silly device -- especially since you had to crank a mechanical gear by hand when darkness fell. Had American regulations not banned the use of indented headlamps with flush-fitting clear covers, the frog eyes wouldn't have been necessary).
Ergonomics were an important reason why people liked the production GT. The designers had retained the spacious cockpit of the showcar. A highly styled body is bound to have compromises, however, and the GT was no exception: the pinched body sides cut down a little on shoulder room, and there was not much luggage space behind the seats -- nor a hatch to provide access. Everything else, though, was right: deep, rake-adjusted bucket seats, comprehensive instrumentation, controls within easy reach. Best of all was the list price -- just $3395. For another $99, there was an option that made all the difference in GT performance: the 1.9 liter four (cylinder) from the Kadett Rallye.
The 1.9 stemmed from the family of new six and four cylinder engines introduced in 1965. With a cast iron block and head in Opel tradition, it ran in 5 main bearings. Its design was fascinating -- sort of hybrid between overhead valve and single overhead cam. The double-roller chain-driven cam was located in the head, alongside inclined valves, which it activated through conventional tappets and stamped steel rocker arms. Though it was not a "SOHC" engine in the classic sense (Opel called it "cam in head"), it provided the same advantages -- valve actuation without pushrods. One historically minded reviewer pointed out that Opel was not first with this design: It had been pioneered on a 1937 Leyland truck!
What the 1.9 liter supplied that the 1.1 didn't was, of course, performance. Typical 0-60 times for 1969-1970 models averaged 10.5 seconds, and the top speed was over 110mph. There was also remarkable fuel mileage -- 25 to 30 miles per gallon. The 1.9 proved so popular, in fact, that Opel made it standard on the GT in 1971, though emission laws required a considerable de-tuning.
The GT's unit body was built under contract by Brissonneau & Lotz in France, since Opel was not geared to produce bodies on as small a scale as 20,000 a year. A conventional monocoque, it featured ifs through unequal-length wishbones, transverse leaf spring and tubular shocks; at the rear was a live axle located by trailing arms and a panhard, rod, coil springs, and tube shocks. Despite the rearward location of the engine, weight distribution was 54/46, and the front suspension layout induced strong understeer. Classic tail-out driving was out of the question. One could, however, obtain a variety of handling options in both Europe and North America, including stiff springs, anti-roll bars and a limited slip differential. none of these, regrettably, were in the Buick-Opel parts books.
Happily, casual attitudes about GT stock specs didn't stop everyone. In 1970, Italian GM dealers made representations to race car tuner Virgilio Conrero, whose 1300 and 1600cc Alfa Romeos had virtually retired their class championships, to race-prep the Opel GT. Intrigued by the car's good aerodynamics and sound mechanics, Conrero agreed.
Virgilio Conrero's philosophy is to improve what the factory had accomplished by smoothing out intake and exhaust passages, and carefully polishing combustion chambers. This he proceeded to to do on the 1.9 Opel engine. The bore was increased to 95mm, giving 1979cc, closer to the Group 4 limit of 2 liters. Larger valves and light, domed pistons brought compression up to 11:1. Each engine was finely balanced; stronger valve springs and polished rockers were installed. A pair of Weber type 45 DCOE carbs on a special manifold were fitted, along with a free-flow exhaust, an oversize oil sump and radiator and electronic ignition. The result was more than a 100% improvement in GT horsepower: From 90 DIN, it went to about 190, and torque shot from 115 foot-pounds to 150. The effect on the car's performance was staggering: Depending on final drive ration, Gianni Rogliatti reported, the Conrero GT could do 0-60 in six seconds flat and the quarter mile in 15 seconds -- or 150mph.
Conrero next directed his attention to the rest of the Gt. He installed a special clutch plate and developed ratios for a variety of racing applications. To improve on the fairly wide-ration four-speed gearbox, a ZF five-speed was later used.
Next came the chassis. Rubber suspension bushings were replaced by bronze: Roll centers were altered, spring rates were reduced, beefier shocks and front anti-sway bar were installed, the rear Panhard side thrust bar went out in favor of a transverse Watt linkage. Oversize, ventilated disc brakes, a limited slip differential, large fuel tank, and jumbo tires were installed. Wheel openings were modified to receive the tires, plexiglass replaced glass except on the windshield, and an oil temperature gauge was added to the dash. Conrero's distinctive paint job of red, gold, and silver was the finishing touch.
Conrero Opels were immediately entered in the car-killing Targa Florio, where one took the GT class win and finished ninth overall. Conrero's swarmed over Europe in the early 70's, and were soon in the hands of sporting types who weren't quite satisfied with the basic Russelheim product. A word to the wise: You can still obtain the right Conrero bits for your GT or Manta. They will turn your nice, polite car into a tiger.
Opel GT's were also tuned by French expert Henri Greder, while in America Car and Driver magazine performed a sort of back-yard modification on a GT they named "J. Edgar Opel." The latter has survived, in the collection of automotive. illustrator Russ Von Sauers.
Opel built about 100,000 GT's, and in the beginning it wasn't enough. Until the 240Z took its place as the most desireable import, US customers paid well over sticker for new GT's. The cars were dropped in 1974 because there was no way to modify them to meet the increasing "Safety" requirements. But many have survived in the hands of enthusiasts. Small wonder.
Opel GT's have achieved minor cult status, but are by no means red-hot collector's items -- which makes your task difficult, but not expensive. It's difficult, because unlike the Manta, the GT is subject to rust -- lots of it. Good ones are not in great supply. If your potential GT is a 1969 or 1970 model, it's important to know which engine it has. It makes a big difference. I recently encountered a pair of nicely restored examples: a 1.9 priced at $3500 and a 1.1 priced at $2500. Except for the engines, the two cars were in identical shape. The $3500 figure is probably the extreme of the GT's price range today, but a car with this much character and good looks is bound to increase in value as the years pass. (Note: Prices have appreciated substantially, since this article was written in 1982)