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2Addicts | BMW 2-Series forum Technical Topics B58 (M240i) Engine, Transmission, Exhaust, Tuning M240i Manual - When to shift gear and RPM Cruising

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      11-27-2018, 12:08 PM   #1
jules_78th
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M240i Manual - When to shift gear and RPM Cruising

For the Manual drivers here on their F22/23, for normal daily driving, at what RPM do you upshift in to hit that sweet spot of not lugging the engine given that our cars are Turbo and not over revving it to maintain low gas/longevity on our engines?

Also what RPM does everyone cruise at on the local roads? (Once in the Highway I'm on 6th gear when I'm over 80km, and RPM sits between 1500 - 2k). Local road speed here in Toronto are 60km, so I'm finding myself between 4th and 5th (mostly 5th) depending on my speed and sitting between 1500-1900, def under 2k RPM. Is that ok or should I be cruising on the lower gear and hitting a higher RPM?

Also on a few occasions I tried to follow the suggested gear change on the dash but I find that it's asking me to change gear much to early and I feel like its lugging the engine (doesn't matter if its comfort of sports mode, I find it to early). Wondering if this is just me or anyone else find it to early and ignore it?

This is for normal daily driving, which is on comfort mode.
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      11-27-2018, 01:39 PM   #2
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Following the gear change indicator is fine when you are at small throttle openings, if you are used to other 6-cylinder BMWs (as I was), the B58 is fine in one gear higher than you would think, when just cruising around. I've found that shifting into 3rd at 30km/h, 4th at 40km/h, 5th at 50km/h and 6th at 60km/h works well for good fuel economy if accelerating gently, without any lugging. This corresponds closely to the gear change indicator. Compared with the N54 in the 135i (which would be a gear lower than the B58 in the M240i), I'm seeing about 10.0 l/100km driving around town compared with 12.5 l/100km.
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      11-27-2018, 03:19 PM   #3
ScottSinger
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really good question. first, lugging UNDER LOAD is a lot different than cruising at a lowish rpm. Under load when going up a hill or carrying a heavy load, then low rpm will cause mechanical stress and that stress gets transmitted into the connecting rods and valves - exactly how that stress causes mechanical knocking, I don't know.

When you leave a lower gear to go to a higher gear the 1000 rpm drop was the traditional amount, Whether due to gearing and number of gears and most common speed traveled - how they created the 1000rpm number I don't know.

Shifting early for good fuel economy shouldn't have any relationship to engine damage. You could potentially shift too early but the car would bog.

I do this without really thinking about it. 1st to second -depending on conditions - 2000rpm, 2nd to third 2200 rpm, 3rd to fourth 2400 rpm. And I look at the dash upshift arrow and use that.

When I want speed I shift at the halfway point between maximum torque and maximum rpm, which feels about 3500 rpm.

Curious what others say

Last edited by ScottSinger; 11-27-2018 at 05:29 PM.
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      11-27-2018, 04:45 PM   #4
dradernh
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Quote:
Originally Posted by aerobod View Post
...6th at 60km/h works well for good fuel economy if accelerating gently, without any lugging.
Those are the circumstances when I shift into 6th gear with my manual transmission. It works just fine, both for me and for the car.

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Originally Posted by ScottSinger View Post
When I want sped I shift at the halfway point between maximum torque and maximum rpm, which feels about 3500 rpm.
I shift at 6,000 RPM for speed, but only on the track.

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Originally Posted by ScottSinger View Post
When you leave a lower gear to go to a higher gear the 1000 rpm drop was the traditional amount, Whether due to gearing and number of gears and most common speed traveled - created the 1000rpm number I don't know.
This chart shows that's still a good general rule for those of us with manual transmissions:

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      11-27-2018, 04:50 PM   #5
jules_78th
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I can't 100% say I fully know how to read that chart. Are you able to give a breakdown on how to read that chart?
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      11-27-2018, 05:11 PM   #6
dradernh
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Quote:
Originally Posted by jules_78th View Post
I can't 100% say I fully know how to read that chart. Are you able to give a breakdown on how to read that chart?
Basically, you take the speed shown at the intersection of gear and RPM (e.g., 4th gear at 5000 RPM = 102.3 MPH), and you then look to see at which RPM that speed appears in the column for the gear into which you're shifting.

An example:

1) You shift up from 4th gear at 5000 RPM to 5th gear while going 102.3 MPH.

2) You're still going ~102.3 MPH when you release the clutch in 5th.

3) You now look in the 5th gear column to see where 102.3 MPH appears.

4) You won't find 102.3 MPH as a discrete value in the 5th gear column; however, a bit of interpolation will show that 102.3 MPH is equal to ~4250 RPM in 5th gear. Therefore, the RPM drop in this example is ~750.

I'm not terribly good at explaining things like this, so I hope it makes sense.

Something possibly worth keeping in mind is that the more gears you have, and the closer together their ratios are, the less of an RPM drop you'll experience when going up or down to another gear.
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      11-27-2018, 05:15 PM   #7
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Quote:
Originally Posted by jules_78th View Post
I can't 100% say I fully know how to read that chart. Are you able to give a breakdown on how to read that chart?
For shifting at 1000 rpm increments and to get the speed with the tire circumference stated on top / start at top left corner then move over and down for each upshift
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      12-03-2018, 12:31 AM   #8
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When I'm just casually carting around town in downtown Toronto, I'm mostly in Comfort mode, and usually up shift between 1500-2500rpm for smooth drive and fuel economy. I find this range best to comfortably cruise but still have good torque at your disposal regardless of speed or hill inclines etc. You can definitely upshift 1-1.5krpm gears, but I find you'll end up downshifting a lot more often in the city. YMMV.
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      12-06-2018, 09:29 PM   #9
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I keep it under 4k rpm and take it easy on the boost until the oil is hot. That is all. After that, wring it out. I won't hold it above ~2k rpm unless I'm accelerating and planning to shift soon. Cruising speed = ~2k rpm, depending on what type of road I'm on. I don't know what it's like to drive a manual and shift early for better mpg. :
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