Speed versus RPM - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 14 (permalink) Old 06-10-2007, 02:18 PM Thread Starter
 
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Speed versus RPM

At 100 Ks (64MPH) per hour I am at 3500 RPM in my 92 Spider in 5th gear
Does that sound right
I was passing a lot of cars at that speed and had the feeling I was going a bit faster than 64 MPH
14" wheels
Daydreaming or what
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post #2 of 14 (permalink) Old 06-10-2007, 02:25 PM
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1st gear @ 1000 rpm: 8.5 km/h
2nd gear @ 1000 rpm: 14.8 km/h
3rd gear @ 1000 rpm: 20.9 km/h
4th gear @ 1000 rpm: 28.8 km/h
5th gear @ 1000 rpm: 35.6 km/h
Take into consideration that your tach could be well off, so the above isn't gospel, just reference.


3500 @ 64mph sounds about right, and something right around 41-4200 at 74mph.




Darren
'84 manufacture ~ '85 MY Spider Graduate

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post #3 of 14 (permalink) Old 06-10-2007, 02:34 PM
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I refer to Alfa product bullettin PA381500000000 Jan 86 for Spider 115. USA Version Graduate, Veloce, Quadrifoglio. This is on page 36 (RPM vs Road Speed Graps for gears 1 thru 5)

Fifth gear, 100km/h, 2800rpm
Fourth gear, 100km/h, 3500rpm

My 87 Quad confirms these points.

I would take it that your 92 would follow the same curves, as such you are going faster than your spedo indicates.

From the same curve I reference 3500rpm in 5th gear is 130km/h

Best regards, Elio

Last edited by Elio Comello; 06-10-2007 at 02:38 PM. Reason: mistake
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post #4 of 14 (permalink) Old 06-10-2007, 02:34 PM
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5th gear = 22mph/1000rpm
3500 rpm = 77 mph

92 Spider Veloce
71 TwinSpark Spider - Soon to be 4 Sale
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post #5 of 14 (permalink) Old 06-10-2007, 03:15 PM
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The smart money is on both the speedo and the tach being off. Fortunately they're fairly easy to adjust. Details here:

http://www.alfabb.com/bb/forums/showthread.php?t=2902

Best to calibrate them independently rather than to use one to calibrate the other. Use a GPS for the speedometer and a digital voltmeter or engine analyzer with a tachometer function for the tach.

Tom

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1974 GTV
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Former: 1987 Milano Gold
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post #6 of 14 (permalink) Old 06-10-2007, 04:02 PM
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Quote:
Originally Posted by Paradiso View Post
5th gear = 22mph/1000rpm
3500 rpm = 77 mph
I think those numbers are for a 4.56 rear end. The newer Spiders have the 4.10.

[FONT="Comic Sans MS"]Ken Lee
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post #7 of 14 (permalink) Old 06-10-2007, 04:34 PM
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Paradiso is right on the money. 22.14mph per 1000rpm in 5th. 82-94 Spiders....manual only

The 4.56 is 20mph per 1000rpm in 5th. 81 and earlier spiders.

Best Regards,
John M

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1978 AR Spider Veloce 2000....the first and still here...Bianco
1984 AR Spider Veloce............the second & gone to the parts bin....Rosso
1992 AR Spider Veloce............the third and still here...Bianco
1991 AR 164L........................the fourth and traded on the SS....Rosso
1965 AR Sprint Speciale..........the fifth...in boxes....sold....Bianco
1978 AR Spider Veloce 2000....the sixth gone to be a parts car...slow black
1967 AR Giulia Sprint GT.........the seventh with Gregg and sold......Rosso
1993 AR Spider Veloce............the eighth with Gregg and still here....Verde Inglese
1982 Ferrari 308 GTSi.............the first and still here....Azzurro
1999 Ferrari 355F1 Spider........the second and still here....TdF Blue[/SIZE]
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post #8 of 14 (permalink) Old 06-10-2007, 05:12 PM
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Thanks for straightening me out

[FONT="Comic Sans MS"]Ken Lee
Alfa Dogs #13
Oakville, ON[/FONT]
73 GTV
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post #9 of 14 (permalink) Old 06-10-2007, 05:53 PM
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Now the million dollar question is what about an automatic spider? This I do no know.

Best Regards,
John M

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1978 AR Spider Veloce 2000....the first and still here...Bianco
1984 AR Spider Veloce............the second & gone to the parts bin....Rosso
1992 AR Spider Veloce............the third and still here...Bianco
1991 AR 164L........................the fourth and traded on the SS....Rosso
1965 AR Sprint Speciale..........the fifth...in boxes....sold....Bianco
1978 AR Spider Veloce 2000....the sixth gone to be a parts car...slow black
1967 AR Giulia Sprint GT.........the seventh with Gregg and sold......Rosso
1993 AR Spider Veloce............the eighth with Gregg and still here....Verde Inglese
1982 Ferrari 308 GTSi.............the first and still here....Azzurro
1999 Ferrari 355F1 Spider........the second and still here....TdF Blue[/SIZE]
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post #10 of 14 (permalink) Old 06-10-2007, 06:12 PM
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speed vs rpm

Let's not forget tire size in these computations.

Paul
76 Spider
71 Spider & many parts
67 BSA
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post #11 of 14 (permalink) Old 06-10-2007, 07:35 PM
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The Alfa Romeo publication (1986) linear charting graph for all 5 gears, for the USA version of the Gad, Veloce and Quad are for stock tires.

Of course if you are non stock you need to factor in the differences in tire diameter.

Hey John M on an automatic, the tach calibration would be optional, don't you think? If not you would need to calibrate it every time you changed AT fluid....

TTFN Elio
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post #12 of 14 (permalink) Old 06-13-2007, 11:09 AM
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Just putting your guys words into a graphical form (as my girlfriend calls me an "enginerd").
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post #13 of 14 (permalink) Old 06-13-2007, 11:23 AM
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This graphic plot is in the Alfa Spider Spec's for the model 115 (USA version) as mentioned in my reference in earlier post.

Nice Y=mX + b fellow enginerd.

TTFN Elio

Last edited by Elio Comello; 06-13-2007 at 11:24 AM. Reason: spelling
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post #14 of 14 (permalink) Old 06-14-2007, 10:28 AM
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The Spider automatic is a ZF 3-speed with no overdrive, so at freeway speeds it winds out noticeably higher.

[B]'91 Spider Veloce[/B]

[I]"Twenty years from now you will be more disappointed by the things you didn't do than by the things you did do."[/I] - Mark Twain
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