Too many questions...or your putting too much thought into this. All cars after 71 were detuned for emissions and various other reasons. The last of the true performance cars in my opinion. No more Hemi after 71 either. It was more government involvement than what Opel decided. Thats why 2.0 from Germany still had a high compression piston.

 

In trying to answer some of your questions, the GT only came with two motors, the 1.1 and the 1.9 Europeans are taxed, like we are for your tag(s), by the size displacement of the engine, i.e. the smaller the displacement, the lesser amount of tax you pay.
The high compression 1.9 ended at the 70 or 71 model year due to what Keith says. Trying to compare the GT and the Corvette are, at least to me, are like comparing apples and oranges, yes, they're both fruit (in this case cars) but, still far different from each other.
Now, you said, you've had 5 GTs, and one of them being a low compression, well, either the other 4 were 69-71(?) with their original hi-comp engines, or the PO's rebuilt them, with more performance in mind.Now, it doesn't take a whole lot to rebuild a lo-comp engine into one with a little to a lot more HP, but, this is limited by the thickness of your wallet. Having had a lot of Opels over the years, both hi and lo comp engines, either stock or owner modified, and in either case, like you have already found out, at the inital take off, you can get most people, but, after that cubic inches does come into play. But, due to the fact that gas is constantly going up and down, staying with a lo-comp, motor for economy is the best way to go....for now, but, it doesn't mean, if you know how to get the most out of your Opel, you can't still have a little "fun"

 

A couple of things to add to the mix.
First, as stated, gasoline in Europe has always been double or triple what we pay here in the US. I think the goal is there handling, reliability, and economy. Most of the GTs sold in Europe had the 1.1 I believe, at least initially. The GT was more of a styling experiment rather than a full blown attempt to create a performance car.
Don't forget also that in it's day the Opel with the 1.1 was about on a par with other imported economy cars for performance and head and shoulders above them in reliability. Where the 1.9 was concerned, it was way ahead of most run of the mill imports for performance and horsepower. I had a buddy who had a Saab Sonnet who always wanted to race my GT (stock) and the GT ran circles around him.

 

:bs2::lmao::bs2:

 

What they said...

GT's had the hi-comp engine thru 70, so the early cars were significantly faster than the later cars. The detuning did not help mpg, it was purely emissions related. As far as I know, the euro-spec Opels maintained the higher compression engines throughout the model ranges, so even the Manta/50 series had more power than we got and they didn't change it when they added FI. That being said, there were more types of Opel motors available in Europe than we got. The vast majority of GT's (early or late) got the 1.9.

As for the speed, a stock 69-70 GT was as fast as my 70 302 Mustang (2bbl carb, 210hp) or my 73 351 Mustang (2bbl emissions 154hp). I could see an early GT giving a later smog equipped 350 Corvette (200-250hp) a run for it's money, but that's about it. If an earlier Corvette was beat by a stock GT, there was something wrong with it. Then again, at that time, when compared to alot of cars with big V8's, easy hp and massive amounts of lazy torque, the Opels were slow. But it's all relative to the time and that is what most people remember. Late 70's and thru the 80's, a good 68-70 Opel could see off much of what was in the showrooms.

The foreign competition for the GT was the Fiat Spider, MGB-GT, the 240Z, the 914, VW Ghia etc. The 240 being the only one with a bigger motor, the rest having the same or less hp, but the Fiat/240/914 generally regarded as having better handling.

 

This is so true. I once raced a stock 76 Vette in my mildly modified* GT and I stomped on him. The dude was crazy pissed and flipped me off at the next light. I just laughed out loud in his face.

*.30 flat top pistons, combo cam, 38 DGAS

 

Low HP Typ 77

Hi
In Germany and Europe, the GT 19S all have the same (68-73) 90 PS-DIN or 102 HP-SAE . . . HC - flat-top pistons
In the US, it was the same in 68-70 - the compression was 9.0:1 and needed gas with 98 ROZ

In 1971 to 1972, the Type 77 have the emission engine with 78 PS-DIN or 90 HP-SAE and a compression of 7.6:1 for use unleaded gas 91 ROZ. This engine has different pistons (dished), camshaft and hydro-lifters.

In the 1972 and 1973 US Type 77, the power was again reduced to 75 PS-DIN. All this was done for the low emission laws in the USA!

By the way, the top speed was not a lot different - 1970 GT, top speed 111 mph; 1971 GT, 110 mph. 1/4 mile, 17.4 sec to 18,4 sec.; 0-60 mph, 10.2 sec to 11.9 sec

Greetings
Norbert

 

We started detuning engines here in the late '60s to meet EPA requirements for emissions. Unleaded fuel was being introduced. In 1971 all cars had to accept unleaded fuel so GM/Opel reduced the compression to meet that requirement. Most US cars went to catalytic converters in 1975 but Opel could meet the requirements without one except in CA. However, had they chosen to import cars in 1976, it would have been required.

Charcoal canisters were added to capture fuel vapors from tanks, I'm just not sure wehne these started. By 1974, EGR valves were added to recirculate cold start exhaust vapors back into the air intake.

As for rust, most Opels except the GT were utilitarian cars, hence used daily. In the snowbelt, they suffered from salt corrosion just like every other car of the time. I remember plenty of rusted Pintos, Vegas, Datsun Honeybees, Beetles.... My Manta was no different but probably lasted a year or two longer than most of its contemporaries. Most cars in the late '60s and early '70s were not yet Zeibarted (rust prooofed). Hence virtually all of them showed signs of cancer after 11-12 years. Opels were no worse than any of the others.

As for reliability, my '74 Manta was the most reliable car I had owned at the time and one of the easiest and cheapest to repair. Parts were getting hard to find as many Buick garages were no longer stocking parts in the mid '80s. I found out early, that my Manta had a tendancy to burn points so I installed a capacitive discharge system and eliminated that problem.

Yes the car was fast at low speed acceleration. I surprised my boss once with its quickness in merging onto Rt 22 from a standing start in NJ. He said his BMW 2002 couldn't do that. At that time the car had well over 100Kmi on it with the original Solex.

GTs and Vettes are completely different classes of cars, hence any comparisons in performance are not valid. It would be better to compare the GT to other small contemporary sportscars and roadsters. Mantas should be compared to Pintos, Vegas, and later arriving Mercury Capris and Datsun 240Z, the latter two being 6 cylinder cars. The Manta's German competition was the BMW 2002 and 320.

I hope this answers some of your 20 questions.

 

Don't know who you've been talking to about GT's but most I've spoken with remember how quick they were and apparently having unlimited top end. :haha: Seriously some of the tales of heard. :no:
Most articles I've run across have the top GT top speed at 115 MPH, red-line in 4th gear. When most people remember the cars of the 60's and 70's, they're either recalling the fastest or the slowest cars not the average cars of the day which weren't too far off from the Opel's capabilities. Read how the magazines of the day brag on the handling of the big block Chrysler products on bias ply tires. IIRC, lateral g's were in the low .7 range for the better cars. I think my 1/2-ton Dodge PU will beat most of the good handling cars of the day. :lmao: Lateral g's isn't the same thing as the ability to change direction such as lane changing, slalom, etc. but still...

Harold

B.S. I have it on good authority they dropped the horsepower to determine survivability of the occupants in rear end collisions. The second theory was, 'being able to sell more replacement cars.' :ugh:

 

European 1.1 GT

Hi
also in Europ,the 1.1 SR was a unsold car. Only 3231 in 68-70 was sold. In USA 342 only in 1969 was sold.
In the USA comes 1.9S with high compression 40620 and 29602 with low compression.

And for myself. For me and my GT is 90 PS-DIN more what I want for a safe drive. My fastest ride in 2010 was 182 Km/h by speedo and 176 by GPS. That's on German Autobahn with a 40 years old car and technik, in brakes it's not funny. So, I used my 71`GT only for stressless ride! And I have an automatic. When other search the gear, I was away a long time.
When I want scary moments to drive fast, I take the 2008 GT 312 hp for a hell-ride after midnight.
Norbert

 

Why? Better gas mileage? Lower cost? Better emissions? Availability?

The reason was to lower the NOx levels. NOx - Wikipedia, the free encyclopedia
The easiest way was to lower the C/R, add an EGR valve, retard ignition timing and even retard the camshaft timing. Then later on, they added a three-way cat.

The three-way burnt the excess fuel (CO) and also misfire (HC) and lowered the NOx by a small amount.

 

Good input, guys.

In defense of my "20 questions", often my goal with a thread is to try to condense all related info on a certain topic into one unified thread. Plus, my ulterior motive is solidify my talking points with people at car shows and to create some display boards listing, authoritatively, why the GT is an important car and to dispell rumors. My GT vs. Vette thread also served this purpose.

I appreciate all of your input about other cars and conditions during the GT era. I started driving in '77 and got my first GT in '79. I've driven 300,000+ miles behind the wheel of a GT in the past 30 years, so that didn't leave a lot of time to drive, work on, or learn about other cars.

There's may not be, in reality, all that much connection between GT's and 'Vettes, other than styling, but in the general public's mind they're like brother and sister. If I had a nickel for every time I've heard "Poor Man's Vette" or "Baby Vette", I'd be a rich man.
On a side note, where'd the transverse leaf spring idea come from that 'vettes and GT's share? Did any other U.S. or Opel cars use that?

Very interesting to learn that Europeans were taxed by engine size and that that would affect a purchasing decision. Was that one time or every year? I wouldn't have suspected that a tax on 4 cylinder engine sizes would be that finely sliced, if at all.

The concensus seems to be that the low horsepower/displacement engines don't vary by any appreciable amount in gas mileage. I was always able to get 25mpg with a 2.0L, Weber 32/36, and a mild cam and I never jetted it or modified it properly. 35mpg seems to be the average that is reasonably attainable on a stock, healthy, 1.9L. Anybody reliably getting more than that in a GT with a 1.1L or a low compression 1.9L?

 

On a side note, where'd the transverse leaf spring idea come from that 'vettes and GT's share? Did any other U.S. or Opel cars use that?

Quite literally, transverse springs were used as far back as horse and buggies.

But they were used on plenty of older cars too. I think Model A's used them.

I worked on this 1950 Willys Jeepster last year and thought the front suspension spring was, uh...familiar looking.

http://en.wikipedia.org/wiki/Willys-Overland_Jeepster

 

too many questions

Okay, I've owned 30 Gt's including a very rare, 1970 1.1.

Supposedly there was less than 40 of them in the US.

The high compression 69, and 70's were quick, but those solid lifters were a pain. The low compression ones, were almost as quick to 40 mph, then they dropped behind. The ones with an automatic were pigs, slow, and the handling suffered.

My fastest GT was an ex SCCA race car, 70 model, that was stripped, lowered, and I hand built a balanced, blueprinted 2.0 with chevy pistons, etc. It would smoke 5.0 mustangs in town from traffic lights, and give IROC camaros fits on the freeway.

It also pissed off 924 porsches, and almost anything I ever raced with it, except for this one pinto wagon, with a V8. He could beat me in a straight line.

But the funniest thing was that 1970 1.1.

It was slow, like I remember a girl in a hyundai excel with an automatic, making me speedshift to keep up with her from the light. True Story.

But it was the best handling with a stock suspension GT I ever drove.

It also was stingy on gas.

And if you had all day, and a long straight, level piece of road, it would eventually go over a hundred miles an hour.

It also sounded like the engine was gonna fly apart any minute, and it probably was.

After reading the OPs post above I should add that the 1.1. got 42 plus.

 

But the funniest thing was that 1970 1.1...But it was the best handling with a stock suspension GT I ever drove. It also was stingy on gas. And if you had all day, and a long straight, level piece of road, it would eventually go over a hundred miles an hour.It also sounded like the engine was gonna fly apart any minute, and it probably was. After reading the OPs post above I should add that the 1.1. got 42 plus.

This is my experience, too. And why I find myself enjoying 1.1 GTs (with their fun gearing) as much as my twin carb'd 2.0L. Plus, the little engines keep me from getting in too much trouble.

 

The used car experience

Most of the folks I meet who've had Opels were the 3rd, 4th, 5th,..... owners, so it comes as no surprise that many of those people hold a dim view. God knows how many rig-jobs were done on those cars before they got them. Plus lack of regular and "special Opel" maintenance, like tightening engine bolts that work loose and adding lead to the gas and zinc to the oil. Living in The Land of Rust here in Jersey didn't help either. I've had at least two people tell me that their GT cracked in two at the firewall. I'm sure they embellished that story a bit, but I've certainly seen some rusted so bad that it was a wonder that they hadn't already cracked in two while parked in the driveway!

 

There was one GT that used to run around here in the mid-late 80's that I was always afraid of. What scared me was the big 'turbo' decals running along the door bottoms, the 'Vette' decal across the top of the window and the Chevy 'Bow-Tie' high mount third brake light that was added to the back parcel shelf...it was so big you couldn't see around it.
But the scariest part was when I found the car in the junkyard and got a closer look at it....some of the wiring under the hood and running up to the headlights was replaced with lamp cord! The fuse box looked like a box of cheap crimp connectors exploded in it.

 

I've had similar experiences as Harold. Everyone says they remember how fast an Opel GT was and how it would peg the speedometer. :banghead: I laugh and they always look at me funny when I tell them it's basically the same motor that was in the Manta and Kadette and they aren't fast and can't peg the speedo. I doubt those guys have ever been in a car that could peg the GT's speedo of 160 mph let alone been that fast in a car. The GT maybe be a bit quicker from lightness and possibly gearing, which would explain the low speed quickness. I find mine is about on par with other cars of the era with similar size engines and weight. Mine is a early 70 hi-comp rebuilt to stock specs (only the top of the block has been decked & trued) with a Weber 32/36 and Pertronix.

 

I've had similar experiences as Harold. Everyone says they remember how fast an Opel GT was and how it would peg the speedometer.

I hear that one all the time.
I just snicker and under my breath say "dang you've never lived"
Look at it this way.
A four cylinder only makes power twice every revolution.
The eight cylinders has double the power strokes!

 

"Why did Opel reduce horsepower in the GT?" To get to the other side! :lmao: :lmao:

Even with the 70's gas crisis, smog regulations, the impact bumpers and safety issues let's face it GM was too lazy to put much effort into their foreign brand red headed step child. GM was too lazy and it could be seen in the quality of their vehicles thru the 70's and 80's. Cadillac, Oldsmobile, Pontiac, Buick, Chevrolet, GMC... why waste their time on improving quality of a little import when they already owned a large portion of the US market?

At least I'm sure that was GM's state of mind at the time.

 

And speaking of . . .

. . . US Opel engines . . .

:biggthump

 

. . . US Opel engines . . .

:biggthump

Useful as usual Otto. You should consider listing the updated SAE net HP figures however, that is the one thing that really throws everybody off.

For example, in Europe the regular 1.9S actually was listed as 90 PS (Pferdestärke = horse strength) or metric horsepower. This is equal to 88.77 SAE net horsepower. However the exact same engine specification in the US was listed as 102 SAE gross horsepower. A significant difference.

The reason this is significant is that the drop in general horsepower numbers in 1971 corresponded to not one, but two significant events. First of all, the emission standards of the day meant that compression ratios dropped, cams got milder, and air/fuel ratios were leaned out. So that drop in horsepower was real and measurable.

Simultaneously, the automakers in the US changed the way engine horsepower was measured. They went from SAE gross ratings to SAE net ratings. Same engine specs, but less power measured. This was more of a paper change, not an actual change to the power the engine made. But it makes the later engines seem much weaker than the early ones, which is not entirely true.

 

While we are at it.
What's a good guess of the power loss(Opel) with the automatic 15-20%?
The manual is around 13% is what I've seen while testing.

 

I think that depends on other factors. Higher stall converters eat some power for sure. But I'd say closer to 20% rather than 15%. I've heard they eat 15+hp on a 90 hp Opel.

And when we're talking chassis dyno's then there's always the wheel/tire combo which figures in. I remember some years ago we played with this on a Honda. Going from heavy 18" rims down to stock 14" rims netted us 9 whp.

I've seen a repeatable 14%-15% loss on a Getrag 240, FWIW.

 

Hey! Lay off my beloved automatics!:grumpy:

You make up for the power loss with optimism!

Plus I can drive with one leg out the window and a beer in my free hand! Try that with a stick!

 

Sooo...you have a GM TH175 Turbo Hydroptimatic transmission?

The old muscle cars were all set up for acceleration not top end. For some reason in a country as big as this, all anybody seemed to care about was how fast you cover the quarter mile. The old Boss 351 Mustang was the fastest production Mustang for decades. It would do 0-60mph in about 5.8 seconds on the old bias-plies. All references to top end for that car are between 110 and 120....same as an Opel GT. Down in Australia back around 69, Ford put out the Falcon GTHO with pretty much the same engine as the Boss 351 (11.0-1, 330hp) as we got here. But the gearing was very different. The car had a top gear rev limiter than kept top speed to right at 140-145mph and relatively docile at low speed.

 

One place to study the high rev engine is the motorcycles!

Small low weight journals on the rotating mass.
Along with very light reciprocating mass.
Consider the bore-stroke ratio
along with the rod-stoke ratio
The cylinder head has to flow good!
The list goes on and on I'm afraid.

 

Fast GT´s

Look at my avatar! These German GT´s were the quickest they ever built!
:yup:
Greetings from Heidelberg/Germany......Janusgelb

 

Is that for real?

Look at my avatar! These German GT´s were the quickest they ever built!
:yup:
Greetings from Heidelberg/Germany......Janusgelb

Those police GT's aren't for real, are they? I thought those model car ones were just a funny design someone came up with. Where would you put the criminals? In the passenger seat? I don't know about German police, but U.S. police have so much gear and guns strapped to their belts that they'd never be able to close the door!

 

i was told but dont know if its true that the guy who owned Schreiber furniture had a 2.8L GT factory made that would have been quick and would not suffer too much from lift at the front , cant say i would like to turn a fast corner in it though

 

The lack of performance is all down to the German insurance companies. This is the reason why every German car is limited to 250 km/h (Except Porsche and R8).
Even a 600 hp Mercedes will stop at 250 km/h!

Every motorcycle sold in Germany has a max performance of 100 hp.

The original 1,9S (high comp) Opel engine produced 90 hp for decades in Germany (and the rest of Europe). The true potential of the engine at that time would probably be around 105 hp, and the myth is that allthough official performance was 90 ps, the engines mostly came out with around 96 hp.

Just look at the 1,9 ltr fuelinjected from the Kadett GT/E which produced 115 hp. But only for a few years before it was replaced with the then standard 2,0E fuelinjected engine which produced 110 HP for decades after. But the Manta i200 produced 125 hp from exactly the same engine (only the cam was different) so this is the true potential of the 2,0 fuelinjected engine.
The later 2,4 ltr from the Omega also was restricted by something like 25 hp all due to German insurance companies politics regarding performance.

Bottomline; a 1,9 ltr with a proper carb, exhaust system, cam, ignition, electrical fan, slightly ported, should easily produce 110-115 hp.

But who cares of the performance of the original engine except if you want to keep your Opel historically correct?
Now a days it's the easiest thing would be to drop in a standard 2,4 ltr from an Omega, and with the right fuelinjection etc, you would have around 170 hp of perfectly daily driving usable performance pulling of from 1.200 rpms

I remember once one of the leading Opel tuners in Germany (think it was Mantzel) said: Nothing is easier than to upgrade an Manta (the B-model), because there was plenty of room for the straight six from the Commodore and cranks where available to increase the volume to 4,2 ltrs, so he would cheaply make such a car which could outperform a Ferrari!

 

The small OHV engine is a little out of place in sportscar. It has only 3 mainbearings making very vulnerable if you press it.
It also only have 2 inletports in the manifold and camshaft near the crank.

Opel never intended this engine in the GT, but they simply offered it due to customers demand, especially because they could just pull it down the shelves.

And of cause the front axle design is almost unchanged taken fromm the Kadett b-model, and was allready outdated at the time of introduction. So the handling with the smaller lightweigt engine improved a lot due to the primitive nature of the axle.
In the Kadett's the small engines where followed with a much smaller and lighter rear-axle. I do not know is this is parallel on the GT, but the small axle also shaves another 30-40 kgs off the weight.

In Europe some of the old rearwheel drive Opel's are updated with the more modern OHC engines from the 80'ties program. The Ascona was sold with the modern 1,3 ltr OHC in the final year of production, but only with a fourspeed gearbox (as far as i know).

 

Its more fun to drive a slow car fast, than a fast car slow.