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  #1  
Old 10-21-2019, 04:39 PM
Esa1178 Esa1178 is offline
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Mein Auto:
Transmission swap

Since my 1997 4cyl Z3 labors at 3500 rpm in 5th @ 80 mph/130 mph, I was wondering if it would benefit from a transmission swap? Around 1997 were there 6 gear manuals in the 3 series and is that transmission compatible with a 97 Z3? At the end of the day if there was a swap would the engine benefit and not be so labored?
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  #2  
Old 10-21-2019, 05:22 PM
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vintage42 vintage42 is offline
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Quote:
Originally Posted by Esa1178 View Post
Since my 1997 4cyl Z3 labors at 3500 rpm in 5th @ 80 mph/130 mph, I was wondering if it would benefit from a transmission swap?...
Is this car new to you?
The 1.9 does not have a lot of torque, which is what you are asking for at 3500 rpm.
Flooring the 1.9 at 3500 rpm is too low to open the DISA valve to the shorter intake tract, which opens at 4000 rpm for more HP.
So if you want to accelerate at 80 mph, downshift to 4th and take it up to 6500 rpm.
Or if that does not suit your driving style, get a 6-cylinder with the torque you expect.

It is likely than any transmission swap to give you more rpm's at 80 mph could rev limit the top speed, if that should be of concern.
BMW optimized the gear ratios for the best performance that could be obtained from the 1.9.

Last edited by vintage42; 10-21-2019 at 05:30 PM.
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  #3  
Old 10-21-2019, 05:45 PM
Esa1178 Esa1178 is offline
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Thanks for your reply. Yesterday I was going from A to B for about 80 miles. I was in cruise at 80 mph and the rpms remained at 3500. Shouldn't the ramp be lower at that constant speed? Say 3000 ? I just felt like the car was labouring at 80.
Oh and yes, I just purchased the car a few weeks back.
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Old 10-22-2019, 05:36 AM
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vintage42 vintage42 is offline
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Quote:
Originally Posted by Esa1178 View Post
... I was in cruise at 80 mph and the rpms remained at 3500. Shouldn't the rpm be lower... Say 3000 ? I just felt like the car was labouring at 80...
I don't know about what the rpms "should" be. BMW optimized the gear ratios for the engine. If the car was laboring at 80, see what it feels like at 100. That's the fastest I have gone and it had some left. Top speed is probably 120.
https://fastestlaps.com/models/bmw-z3-1-9

Last edited by vintage42; 10-22-2019 at 05:42 AM.
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  #5  
Old 10-22-2019, 08:20 AM
[email protected] tgilbert@embarq is offline
terry2001z3
Location: columbia city IN
 
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yes they had 6 speeds for the 01 and 02 z3,and may be one from a z4 might work .but I don't know if any of them will bolt up .if you like driving at the higher speeds have you thought of a rear gear change?
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Old 10-22-2019, 05:21 PM
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vintage42 vintage42 is offline
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Mein Auto: 1997 BMW Z3 1.9 5MT
Quote:
Originally Posted by [email protected] View Post
yes they had 6 speeds for the 01 and 02 z3... .if you like driving at the higher speeds have you thought of a rear gear change?
The 4-cylinder 1.9 ended in 1998 (for the US market), so those 6-speed transmissions are for a much more powerful 6-cylinder engine, if they even bolt up to a 1.9. Their ratios would not match the torque and power of the 1.9.

A higher differential gear ratio will provide more acceleration, but will run the engine out of rpms before it can reach 120 mph.

A lower gear ratio would lower the rpms at 80, which is what the OP wanted, but would prevent the engine from making enough rpms to reach 120 mph.

Last edited by vintage42; 10-22-2019 at 05:22 PM.
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  #7  
Old 10-22-2019, 09:24 PM
[email protected] tgilbert@embarq is offline
terry2001z3
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are the z3 cars governed at 120mph? I will not get to that speed,, just asking.
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  #8  
Old 10-23-2019, 04:45 AM
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vintage42 vintage42 is offline
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Quote:
Originally Posted by [email protected] View Post
are the z3 cars governed at 120mph? I will not get to that speed,, just asking.
No governor. The 4-cylinder listed as having a top speed of 127mph.
https://fastestlaps.com/models/bmw-z3-1-9
The 3.0 is listed as 155mph:
https://fastestlaps.com/models/bmw-z3-3-0i
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  #9  
Old 10-23-2019, 02:29 PM
zed3coupe zed3coupe is offline
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Quote:
Originally Posted by [email protected] View Post
yes they had 6 speeds for the 01 and 02 z3,and may be one from a z4 might work .but I don't know if any of them will bolt up .if you like driving at the higher speeds have you thought of a rear gear change?
Not sure if you are talking about a possible automatic transmission but no Z3 came with a 6 speed manual in the US not even S54 powered Ms
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  #10  
Old 10-26-2019, 11:06 AM
FINZ FINZ is offline
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Quote:
Originally Posted by Esa1178 View Post
Since my 1997 4cyl Z3 labors at 3500 rpm in 5th @ 80 mph/130 mph, I was wondering if it would benefit from a transmission swap? Around 1997 were there 6 gear manuals in the 3 series and is that transmission compatible with a 97 Z3? At the end of the day if there was a swap would the engine benefit and not be so labored?
Do some searching and there are several threads on 6 speed swaps. E46 and euro e36. I think you would drop about 400 rpm at that speed.
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  #11  
Old 10-26-2019, 01:04 PM
[email protected] tgilbert@embarq is offline
terry2001z3
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Originally Posted by zed3coupe View Post
Not sure if you are talking about a possible automatic transmission but no Z3 came with a 6 speed manual in the US not even S54 powered Ms
my mistake I thought that was a up grade.
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