Alfa Romeo Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
110 Posts
Discussion Starter #1
Sorry for such a banal question but can anybody out there who has a stock S4 Spider please tell me approx what RPM you are showing at 80mph? I used the very good thread (on this forum) to adjust my Tacho and just want to make sure it is close. At 80mph I am now showing 4100 rpm. Is that about what it should be?

PPS-to everyone with all the advice thanks you VERY much. I managed to fix the VVT issue and the entire flat spot issue on my S4. The low idle was in fact (I believe) an incorrect reading tacho!
 

·
Registered
Joined
·
2,513 Posts
Sorry for such a banal question but can anybody out there who has a stock S4 Spider please tell me approx what RPM you are showing at 80mph? I used the very good thread (on this forum) to adjust my Tacho and just want to make sure it is close. At 80mph I am now showing 4100 rpm. Is that about what it should be?

PPS-to everyone with all the advice thanks you VERY much. I managed to fix the VVT issue and the entire flat spot issue on my S4. The low idle was in fact (I believe) an incorrect reading tacho!
With the car in 5th gear, 185/70R14 tires and a 4.11:1 rear end, your RPM should have been: 3594.900684123614
 

·
But Mad North-Northwest
Joined
·
10,074 Posts
S4 Spider should be 22.14 MPH per 1000 RPM in 5th (Alfa TSB 40.93.03), so at 80 it should be ~3600 with stock tires as Douglas said. Did you set your tach using a digital tachometer and test it in the higher ranges? If so I'd get a GPS and verify the speedo accuracy.

How'd you end up fixing the VVT issue?
 

·
Registered
Joined
·
98 Posts
Not sure if it adds to a significant difference, but if the S4 has the phonedial alloys, the stock size is 195/60 x 15. The starfish Campys are 185/70 x 14 if the S4 was not a Veloce model.
 

·
Registered
Joined
·
2,513 Posts
Not sure if it adds to a significant difference, but if the S4 has the phonedial alloys, the stock size is 195/60 x 15. The starfish Campys are 185/70 x 14 if the S4 was not a Veloce model.
If he has the those tires, they are a little smaller in diameter and 80mph would put his car at 3609.7556456282577RPM
 

·
Registered
Joined
·
34 Posts
With the car in 5th gear, 185/70R14 tires and a 4.11:1 rear end, your RPM should have been: 3594.900684123614
If he has the those tires, they are a little smaller in diameter and 80mph would put his car at 3609.7556456282577RPM
Seems that your numbers would be affected a few zillionths by tire wear.
Could you please recalculate based upon the actual diameter of the tires .
Maybe you could do a detailed ANALysis taking into account each 0.001 of tire wear.
Thanks for your efforts. Details like this are so important, especially considering Alfa tachometers are known to be so accurate. :p:p
 

·
Registered
Joined
·
110 Posts
Discussion Starter #7
Thanks for the advice guys. My car has the original wheels, only ones offered on S4 here in the UK. I think they are what you call the phone dials. 3500/3600 is what I wanted, thats close enough anyway to tell me I need to adjust the back of the tacho again! Thanks for all the help.
 
1 - 9 of 9 Posts
Top