Gearing in 1980s 4-cylinder cars

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I have a 1984 Chevy Cavalier. It has a 4-speed manual transmission, code M19.

According to the data I can find (car has no tach to confirm), this has a 4.10 final drive ratio with a .81 4th gear ratio. With 24" tall tires, the calculators say that at 85MPH, the engine will be turning almost 4000RPM in 4th gear (top gear). (I thought it was interesting that I could shift into 4th at 25MPH without any complaint from the engine, but this short gearing explains why!)

Is this common for 1980s 4-cylinder vehicles? Given that, when they were designed, 55MPH was the fastest legal speed?

Does anyone know what the redline for the engine in this car is? It's a 2.0L "122" engine, code LQ5. I've been unable to find this info.
 
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I have an 85 Skylark 2.5 with the 3 speed lockup and also without a tach, but the RPM is up there on the highway doing about 75-80. Still does get 35 MPG though and doesn't seem to mind cruising like that all day long. Not sure of the gearing on mine but the three speed was known to keep highway RPM high.
 
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My '08 Mitsubishi Lancer GTS 5-speed ran fairly high RPM on the highway. Online vehicle specs show a 5th gear ratio of 0.82 and 25.6" tire diameter, so not far off the details of your Cavalier.
 
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My 88 Jetta GLI16V was 4000RPM was 80MPH and 5000 RPM about 100 MPH.

I was amazed I drove from CO to NH going about 75MPH and did not bother motor. My cousin kept at 100MPH /5000RPM in 115F southern CO desert weather for about 1.5hrs no ill effects. It spec 15W40 winter or 20w50 summer.
 
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I always assumed the only reason gearing has been getting longer is due to fuel economy and emissions requirements.

Thinking back to petrol engine'd vehicles we've owned from the early 00's...

2003 Vauxhall Astra SRi 1.8i - 3600rpm @70mph
2003 Ford Focus LX 1.6i - 3000rpm @70mph
2003 Ford Mondeo ST220 3.0 V6 - 3000rpm @70mph

Compare that with a brand-new Vauxhall Corsa I had last month with a 1.2 75bhp petrol engine that was doing just 2000rpm @ 70mph.

Are these lower speeds good for the engine? I understand at lower RPM's you have less internal frictional losses, the throttle plate will be open further meaning less pumping losses etc etc etc. But does an engine at a higher RPM but less load wear faster or slower than an engine spinning less but under a higher load. :unsure:

Edit...

Just thinking here. My first car was a 1998 Peugeot 406 with a 110bhp 2.1 Turbo Diesel engine. It would spin at 3000rpm at 70mph. The engine was out of puff by 4000rpm meaning top speed was about 110mph.

My current daily driver is a 2021 Vauxhall Insignia (Buick Regal) and it has a 1.5 3 cylinder 120bhp diesel engine. An almost direct modern equivalent of my first car. It does just 2000rpm at 70mph. Due to its longer gearing, with a long enough road will do 130mph! In the real world though, I don't think fuel economy is any better and the Peugeot could run on waste cooking oil!
 
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One of the reasons they use CVT for economy, they do very low rpm for speed. A manual Fit/Jazz is doing about 3,000rpm at 100kph, the CVT is doing 2,000rpm. You'd be changing gear all day in a manual at that ratio, the CVT just seamlessly goes to a lower ratio.
 
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Both my automatic 90's SL1 and SL2 Saturns revved pretty high at thruway speeds. I wanna say over 3400 rpms at 65..
I just assumed because the 90's engines had no power, so they geared them high to stay in the power? Fuel economy was "good" maybe low 30's.. But not great for the power/weight and slow accretion.

To put it in perspective, the forte pulls 37 plus on highway in 6th gear at around 2200 rpms... When you wanna have some fun, you can... But mileage drops a good 10 mpg if I exercise the RPMs with frequent shifting... I average 30 plus most of time though where the Saturns you had to "work" to get the 30 mpg.
 
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I have a 1984 Chevy Cavalier. It has a 4-speed manual transmission, code M19.

According to the data I can find (car has no tach to confirm), this has a 4.10 final drive ratio with a .81 4th gear ratio. With 24" tall tires, the calculators say that at 85MPH, the engine will be turning almost 4000RPM in 4th gear (top gear). (I thought it was interesting that I could shift into 4th at 25MPH without any complaint from the engine, but this short gearing explains why!)

Is this common for 1980s 4-cylinder vehicles? Given that, when they were designed, 55MPH was the fastest legal speed?

Does anyone know what the redline for the engine in this car is? It's a 2.0L "122" engine, code LQ5. I've been unable to find this info.
I'd say that's not unreasonably short. How much power does the engine produce, and at what RPM? It could be an overdrive gear even if the engine can't reach that RPM in top gear. If max power is reached at 6k RPM, the car would be travelling 127 ish mph.... redline is likely around 500 RPM over max power
 
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I’ve got a 1991 Toyota Previa running an engine very similar to the 22re. I’m not sure what the gearing is precisely but at 70mph on the speedo, it’s running at 3800rpm. At 190k miles, it ran without any noticeable issues, and wasn't maintained as well as I would have hoped by the prior owner. I don’t think higher rpm’s are a really an issue for engines - Maintenance is.
 
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When was the 55mph limit repealed? didn’t need to keep the rpm down, couldn’t drive fast anyhow.
 
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Outside the gearing question, but as far as the redline goes I'd say it's somewhere between 5500-6000. I couldn't find a picture of a 1st gen Cavi tachometer with the 2.0, only the V6, but the 2nd gen Cavi's tach has dotted lines from 5500-6k and then solid red. The 2.0 and 2.2 are mostly identical, so those numbers should be a solid bet.

My '00 GC has 3.73 gears and has NOT had it's TCM flashed with the 5-speed software upgrade, and I turn about 2300 RPM @ 70mph. My girlfriend's '02 GC that came from the factory with the 5-speed software turns a couple hundred less, maybe 2050-2100.
 
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We had a 77 rabbit 4MT. it had no tach, but at 60mph I remember hearing it sound like it was around 3000 rpm.

we had an 84 vanagon water box. Also no tach. I think it was probably geared the same. At 65 it seemed like it was well into 3k rpm. The one time I had it up to 70 it felt close to 4K. It needed to rev to get the power out, and the engine did it well.
 
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My folks’ 84 5 speed caravan couldn’t gave spun more than 1800 rpm at 60 mpg. (The only option that car had was a rear defroster. No ac, am stereo (!) radio, and no tach). But it was geared ver very tall.
 

brianl703

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I'd say that's not unreasonably short. How much power does the engine produce, and at what RPM? It could be an overdrive gear even if the engine can't reach that RPM in top gear. If max power is reached at 6k RPM, the car would be travelling 127 ish mph.... redline is likely around 500 RPM over max power

88HP @ 4800RPM, 110 lb-ft @ 2400RPM
 

brianl703

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When was the 55mph limit repealed? didn’t need to keep the rpm down, couldn’t drive fast anyhow.

In 1987 the FedGov allowed 65MPH Interstate speed limits in rural areas. I think the criteria was the population of the county the Interstate passed through.

In 1995 the 55MPH speed limit was repealed entirely.
 
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