Manual/SMG 645ci/650i rpm at a certain speed
11-21-2008, 04:13 AM
#1
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Hi guys!
Can you report how many RPM your engine does at 90 MPH/145 kmh in 6th gear?
Maybe a picture with cell phone.
Like this:
http://snipurl.com/67d2i
It's quite important, thanks!
PS:
It would be the same if you have all RATIOS of SMG/manual transmission of 645ci/650i.
Can you report how many RPM your engine does at 90 MPH/145 kmh in 6th gear?
Maybe a picture with cell phone.
Like this:
http://snipurl.com/67d2i
It's quite important, thanks!
PS:
It would be the same if you have all RATIOS of SMG/manual transmission of 645ci/650i.
11-21-2008, 08:31 AM
#2
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My Ride: (USA) 645Ci, Silver Gray, Chateau, Cold Weather PKG, Premium Sound PKG, Sport PKG, Step, NAV [Std Equip in 645], HUD, Satellite (SIRIUS) Radio, Aux Input, Bluetooth enabled using iPhone 3GS w/ adapter cradle - Build date - 01/05, Baby delivered 2/24/05
Here is a chart for you. These are calculated and are against "TRUE" speed which may not be what is indicated by your speedometer so you need to know its error is at specific speeds. I can attest to the Auto numbers as they match my experience. 650 will be same as 645.
Formula for calculations is:
MPH = RPM/(Overall ratio[Final*Gear])/336*Tire Diameter
RPM = MPH x overall gear ratio (tranny x final) x 336 / tire diameter
This chart assumes OEM Sport package wheel/tire combo at 26.7 inch diameter at real wheel. So for 90MPH in 6th for Auto tranny, RPM should be = 2704: for manual it should be 3183.
Here is my speedo error chart, but yours could be different.
Formula for calculations is:
MPH = RPM/(Overall ratio[Final*Gear])/336*Tire Diameter
RPM = MPH x overall gear ratio (tranny x final) x 336 / tire diameter
This chart assumes OEM Sport package wheel/tire combo at 26.7 inch diameter at real wheel. So for 90MPH in 6th for Auto tranny, RPM should be = 2704: for manual it should be 3183.
Here is my speedo error chart, but yours could be different.
11-21-2008, 09:43 AM
#3
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Thread Starter
Thanks cobra!
With my 3.15 new ratio I have 4000 rpm at 110 MPH and I don't like it (too noise)
Often I travel @125 and I have too many rpm, so I thought 645ci had to be a different 6th ratio in the gearbox, but from your table the ratio seems the same (0.87).
So my 6th gear is still longer than the 645ci one.
With my 3.15 new ratio I have 4000 rpm at 110 MPH and I don't like it (too noise)
Often I travel @125 and I have too many rpm, so I thought 645ci had to be a different 6th ratio in the gearbox, but from your table the ratio seems the same (0.87).
So my 6th gear is still longer than the 645ci one.
11-21-2008, 05:45 PM
#4
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Originally Posted by AlexFW' post='727773' date='Nov 21 2008, 01:43 PM
Thanks cobra!
With my 3.15 new ratio I have 4000 rpm at 110 MPH and I don't like it (too noise)
Often I travel @125 and I have too many rpm, so I thought 645ci had to be a different 6th ratio in the gearbox, but from your table the ratio seems the same (0.87).
So my 6th gear is still longer than the 645ci one.
With my 3.15 new ratio I have 4000 rpm at 110 MPH and I don't like it (too noise)
Often I travel @125 and I have too many rpm, so I thought 645ci had to be a different 6th ratio in the gearbox, but from your table the ratio seems the same (0.87).
So my 6th gear is still longer than the 645ci one.
Well you could go to larger diameter tire or wheel/tire combo to reduce RPM for given speed, expecially if you are doing more crusing and not trying to do fast acceleration.
Why did you change to 3.15? - quicker acceleration?
11-21-2008, 10:42 PM
#5
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My Ride: 2008 650i convertible
jet black / saddle brown
6spd manual
sport pkg
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i dont do too much freeway driving, but i have a manual and can look - do you still need the info?
might be taking a road trip up the 5 for thanksgiving holiday
let me know
i'll hit 90 no problem
might be taking a road trip up the 5 for thanksgiving holiday
let me know
i'll hit 90 no problem
11-22-2008, 01:28 AM
#6
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Originally Posted by cobradav' post='728186' date='Nov 22 2008, 03:45 AM
Yes, tranny ratios the same. rear ratios different.
Well you could go to larger diameter tire or wheel/tire combo to reduce RPM for given speed, expecially if you are doing more crusing and not trying to do fast acceleration.
Well you could go to larger diameter tire or wheel/tire combo to reduce RPM for given speed, expecially if you are doing more crusing and not trying to do fast acceleration.
Why did you change to 3.15? - quicker acceleration?
Yes: with 2.93 it was too slow (74 MPH the 2nd and 110 the 3rd, for example). Especially on slopes with 3-4 people on board. Even the M5 (with 500HP) has shorter gear that manual/smg 545i.
11-30-2008, 11:44 AM
#7
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My Ride: 2008 650i convertible
jet black / saddle brown
6spd manual
sport pkg
premium sound
comfort access
heated seats
satellite radio
at 90MPH in 6th my tach reads *just* over 3100RPM's
maybe 3120 or so, as it's reading less than halfway to 3200.
maybe 3120 or so, as it's reading less than halfway to 3200.
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