BangScreech4-4-2

No, you do the math:

1980 Cutlass curb weight: 3465 lb.
Cd: 0.41
1975 Olds 350-4V hp: 170 @ 3800 rpm
tq: 275 @ 2400 rpm

There's no way that engine is pushing that brick of a car through the air at 142 mph while turning 4250 rpm (which is a good 1850 rpm past the wheezy old smog motor's torque peak, you'll note) through a 2.28 rear gear. It's that pesky physics thing.

Didn't happen. Sorry.

olds 307 and 403

We had our 82 Dodge Diplomat bury the 200 km/hr speedometer but it was a former police car.

svnt442

So in other words you are flat out calling me a liar. Well all I can tell is to believe what you want because it did happen. I was driving the car in interstate 88 eastbound outside of DeKalb Illinois about 3 AM after a foxhunt (CB game) and a guy in a 77 Thunderbird decided he was gonna race me. I just walked away from him and kept going until the car stopped accelerating. You don't have to believe me, but that doesn't change the fact that it happened.
Now don't be so angry and have a good night.

Koda

No, he is not "flat out calling you a liar." This isn't redneck chest beating in the holler here. There's a saying "extraordinary claims require extraordinary proof."

I'll run math.

Speed = 27 inch diameter tires * 3.14 pi = 84.78 inch circumference.
84 .78 inch circumference * 4250 rpm / 2.28 rear ratio/ 12 inches/foot / 5280ft/mile * 60sec/min = 149.6 mph

Drag power = 1/2*Cd*density*area* velocity cubed.
1/2*0.47*0.002377 slugs/ft^3*15ft^2*(218.5ft/sec)^3= 87406 ft*lbs/sec or 159 horsepower

That engine is not capable of provided 159 hp at the wheels at 4250 rpm.

What happened is you buried the needle then started slipping the torque converter and were redlining the engine, but not going any faster. I am going to assume the car had a 120 mph speedo, and you seem adamant you exceeded that, so I am going to estimate you were doing 125 or so.

rustyroger

Quite a few very fast cars had very optimistic speedometers much past 100 mph or so. I remember reading a test report of an Aston Martin DB5 that would be travelling at a true 130 mph with the speedometer telling the driver it was doing 160......

Roger.

BangScreech4-4-2

Thanks for providing that. It seems the most plausible explanation (I was just going to go with it being a long time ago and our memories act up as we age) although I'm still a wee bit skeptical about 125 mph. Perhaps the speedo was a bit optimistic too.

Koda

Agreed, and I took some liberties on the math too, like I have no idea of the cross sectional area of a forward traveling Cutlass, other than about 3'x5'.

svnt442

If the torque converter was slipping enough to show that RPM and you think I wasn't traveling over say...120, that would have caused enough heat to burn up the transmission. Also it wouldn't have been a steady climb and then stop as the fluid would have been breaking down and burning up. None of that happened. The fluid wasn't burned, the trans wasn't fried, and I drove that car with that trans for 5 years and then sold the car. There were never any issues with it.
Also, if I had pushed through the torque converter as you state, the RPM would have dropped like a rock when I let out of the throttle, and it dropped normally as the car slowed down.
It doesn't matter if you believe me or not, and there is no way to have proof of something that I did, on a whim, in 1991. There were no digital cameras or cell phones at the time to document something like that, or you would be able to see the acceleration and deceleration from the lane markings.

rustyroger

No doubt about it, the car definitely managed a genuine 150 mph....on the other hand, no doubt about it, the car definitely didn't manage a genuine 150 mph.......

I'm sure there is a formula for accurately calculating the power required to move something with the drag coefficient and other power losses at 150mph. But gauges on a production car of that era don't amount to much in the way of supporting evidence.

Roger.

BangScreech4-4-2

True. I remember doing a "top-speed run" in the '64 Chevy Impala (409/400 hp, Muncie wide ratio, 3.36 rear) I had in high school. Once you crossed the century mark, the speedo needle would start to swing violently between 100 mph and the place where 140 mph would have been on the dial if it read that far. Thus I was able to claim ownership of a "genuine" 140 mph vehicle.

asx455

In over a week now, no one has yet offered any explanation to the original posted question. Why are there so many different speedometers, from the same assembly plant, in roughly the same time frame, on the same type of car?

Allan R

Bottom line is there weren't a whole bunch of different speedos produced for 70-72 cars from the factory. The factory produced the same units and with the exception of the speedminder speedos, they're all the same. The faceplates are all the same and I'd bet a dollar that any or all of these in the OP have simply had a decal overlay and you'd find the original face underneath. All that's needed to make them work is an adjustment to the speedo gear.

BTW, I did say in my original post that the speedo likely has an overlay and that I remember when the modification came out to convert them to metric. In the case of the 200 km/hr speedo, no gear adjustment is needed as it's a direct comparison of speeds on the actual speedo. Just a different face.

oldspackrat

Hey Allan, not to be argumentative but the speedo that shows 240 is definitely silkscreened or printed just like the regular speedos. I restored that instrument & would have been able to tell if it was an overlay or decal. I can't speak for the other speedos though.

asx455

Well we now know according to Scott, that the 240 Km is not an overlay decal. I firmly believe that the 270 Km is an overlay decal, but it still originated from the factory. So the question still remains. Whether they are an overlay decal, or directly silk screened, why were there so many variable types produced and what distinguished which car got which type?

Allan R

With the exception of Scott's 240 km/hr speedo, there simply aren't a lot of different speedos. just one that every North American production car got at any of the Olds north american factories. IF the car was exported to Europe, the receiving factory would likely have the corresponding speedos to install which makes a lot more sense. Like I said originally, the 200 km/hr speedo was a decal that GM offered through their parts counters for all brands of their product. Nothing rocket science here. I know this for a fact because I worked with Stedelbauer Chev Olds back then and the Service Manager (Ron Pooke) was forced to order these overlays when Canada went metric. There was nothing mandatory for consumers to buy them however as adhering to speed limits is the responsibility of the driver. Even the police were aware of the conversion decals.

asx455

The fact remains, aside from our 120 MPH speedometers that we are all aware of and adore pushing to the limit so much, there are at least three different speed readouts in KPH presented here for cars assembled in North America for the export market. The question remains as to why?

We have documented that the 200 KPH and the 270 KPH were both present on 1971 cars assembled in Lansing, and shipped through the Bienne facilty in Switzerland. Most likely, the 240 KPH speedometer that Scott restored on the 1970 German car, was also shipped through the Bienne facility because that was the only GM facility covering that area at the time. Being that the Bienne facility did not actually assemble Oldsmobiles at that time, and was more of a clearing house for importing them, I believe that rules out the receiving facility adding the speedometers afterwards. Even if they did add them, the question would still remain as to why they would use three different ones?

We also know that Canada went metric several years after this took place so the making of KPH overlays was probably not that common in 70-71.

We'll give it more time, somebody will eventually dig up the answer. Thanks for all the input from everyone so far.