high rpm at 75 mph normal ?
#1
high rpm at 75 mph normal ?
i often complained how bad the mpg on this 85 euro auto is. around 13-16 mpg.
after fixing the cruise and finally sitting and watching the rpm against cruising speeds 3,000 rpm at 75-80 seems rather steep. may i assume the 4 speed auto is not a overdrive ?
is this normal ?
is there a better option manual maybe or is the gearing just as high in 5th gear?
this car is a poster child for a gear vendors overdrive unit but it just can not work .
after fixing the cruise and finally sitting and watching the rpm against cruising speeds 3,000 rpm at 75-80 seems rather steep. may i assume the 4 speed auto is not a overdrive ?
is this normal ?
is there a better option manual maybe or is the gearing just as high in 5th gear?
this car is a poster child for a gear vendors overdrive unit but it just can not work .
Last edited by tomshark; 08-16-2011 at 11:41 PM. Reason: i can not spell
#2
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4-speed auto is 1:1, no overdrive. Final drive increase slightly for S4 model I think, so my RPM at 80 mph is around 2700. This gets me 20 mpg nonetheless, so less than 18 mpg highway is indicative of rich running.
-Sean
-Sean
#4
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plus it has a looser torque convertor which allows the engine to rev more quickly as you start to pull away from a stop. The Euro 16 valve likes RPM.....at the expense of MPG
#6
thanks the info confirms what what i am seeing. i was under the impression it was a 4 speed overdrive .
the car is running very very well and a blast to drive .
i just have not seen those kind of rpms at hwy speed since muscle cars with 3.55 and up rear ratios
i really love driving and working on it but i hate righting a check to exxon /mobile everytime i take it out.
the car is running very very well and a blast to drive .
i just have not seen those kind of rpms at hwy speed since muscle cars with 3.55 and up rear ratios
i really love driving and working on it but i hate righting a check to exxon /mobile everytime i take it out.
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#9
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It's because the ROW/Euros have a 2.75 rear gear insted of the 2.20 USA. If you had a 5-spd auto or I had a 6-spd manual we'd have OD instead of 1:1 in top gear. Highway MPG would shoot way up.
#10
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Well, I'm doing 100kph(60mph) @ +/-1800rpm in my 84 AT in D... But I think my speedo is off by 5kph.
According to my calculations, it would give me 80mph @ +/-2400rpm. I will have to confirm that in real life...
As a side note, I did 210kph(130mph) @ 5000rpm in 3rd a few times - This I will not confirm - maybe.
According to my calculations, it would give me 80mph @ +/-2400rpm. I will have to confirm that in real life...
As a side note, I did 210kph(130mph) @ 5000rpm in 3rd a few times - This I will not confirm - maybe.
#13
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the tranny/diff info is stamped on the lower rear diff casing. if you get under the car from the rear the stamping is easy to find then we can determine what ratios you have from there.
do you shift the gbox manually? does it select all gears? whats the maintenance on the tranny?
do you shift the gbox manually? does it select all gears? whats the maintenance on the tranny?
#15
Three Wheelin'
The speedo & tach may or may not be accurate, but
you can do the math using the tire diameter,
gearing etc. & compare it.
http://www.jekylhyderacing.com/HeightofTires.htm
you can do the math using the tire diameter,
gearing etc. & compare it.
http://www.jekylhyderacing.com/HeightofTires.htm