RPM per gear...MPH when upshifting

[BATTLERATTLER]

Let's just assume everyone is upshifting at 3000 RPM. I'd like to take a survey of how many miles per hour everyone is getting per gear. For instance, I'm around this(I feel like something is off on my car):
1st gear: 0-15mph
2nd gear: 15-40mph
3rd gear: 40-50mph
4th gear: 50-60mph
5th gear: 60+mph

[bobdavisnpf]

I don't always shift at 3000, but:
1st gear: 0-15mph
2nd gear: 15-30mph
3rd gear: 30-40mph
4th gear: 40-55mph
5th gear: 55+mph

Generally I like to keep my perceived workload on the engine as light as possible for a given power demand. Uphill I shoot for 2600-3500 rpm; On level roads, 2200-2800 rpm; downhill, 1600-2500 rpm. In higher gears I'm at the higher end of the range - for instance 3rd gear level road 2300-2600 is ok, but 4th gear level road 2600-3000 is better because the increased wind resistance = more work for the engine.

Engine size and car weight contributes to this estimation too, though. My 325i convertible, at 3000 lb with a 2.5L M20, is a heavier car with a larger engine. A 320is, at 2600 lb with a 1.8L M10 engine, I would run with a little bit higher rpm. A 325i coupe, at 2600 lb with a 2.5L M20, I'd run at even a little lower rpm than I do now.

Overall condition factors into this also. My engine and drive train is in good shape (160K miles, top-end rebuild 40K miles ago, new timing belt & seals 4K ago, a little bit of ping at fast idle, burns a quart of oil in about 4K miles, a little bit of shake in the steering wheel around 45-65). If it was in worse shape, I'd drive with a lighter foot, run a bit higher rpm, and keep my top speeds down below 65mph.

[BATTLERATTLER]

OK, thanks, I guess I'm not that far off. But what concerns me is that at 75-80 mph, I'm at 3000rpms or more. It's got an S14 2.0L engine with a supposed top speed of 140-155mph, so I'm a little puzzled by why she's struggling so hard with speed. I know it's not the differential. Any thoughts anyone?

[bobdavisnpf]

more numbers because you got me interested and I don't know when to quit...

I'd expect you to be turning 3400-3600 rpm at 75-80 mph, and 6400 rpm at 141 mph.
From automobile-catalog.com
A 1989 320is sedan with stock engine (S14 2.0L), gearbox, diff and tires (195/65R14), at 3000 rpm:
gear mph
1 18
2 27
3 37
4 52
5 66
At 75 mph in 5th gear, you'd run 3424 rpm; at 80, 3652 rpm.
ref: http://www.automobile-catalog.com/ca...bmw_320is.html

My 1989 325i convertible with stock engine (M20 2.5L), gearbox, differential and tires (195/65R14), at 3000 rpm:
gear mph
1 15
2 26
3 41
4 57
5 70
ref: http://www.automobile-catalog.com/ca...nvertible.html
This is pretty much exactly what I'm seeing, so for my car at least, their simulation is accurate.

You may also consider where you get your readings, and the accuracy of your speedometer. My speedo is "optimistic" by a few perecent; not sure but yours might be also. It's easy to verify if you've got radar-display signs in good working condition around town: find a good one in a 40mph zone that'll display mph at 35-40, get it to show you 37, check your dash for speed and rpm. When I get a good sign to show 41, I'm doing 3000 rpm in 3rd and my speedo is showing 43.

[BATTLERATTLER]

Thanks man, that's great information. I guess I'm not that far off...though I need to test it out. The guy I bought it from told me he changed the differential but it turns out it is stock. I'm not sure if he meant the prop shaft or not, he didn't speak English. But hey, thanks a ton, that really helps me out.

[E30ISLIFE]

i've found this a while ago on a dutch forum when i was trying to figure out what rpm's i would be doing at what speed depending on which differential i would buy for my car:

http://www.e30forum.nl/forum/viewtopic.php?f=63&t=2237

hope it can help you out a bit.

[thejlevie]

An M20B25 engine will be a lot happier if you run up above 4k before shifting. I generally avoid loading the engine below 4k and frequently hit 6k when accelerating.

[MauiM3Mania]

An M20B25 engine will be a lot happier if you run up above 4k before shifting. I generally avoid loading the engine below 4k and frequently hit 6k when accelerating.

Your words are even more appropriate for the OP who has a S14B20... that engine loves/lives to rev.