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-   -   What are your RPMs at 80? (http://www.camaro5.com/forums/showthread.php?t=303223)

Scooter11 06-21-2013 01:59 PM

What are your RPMs at 80?
 
So on my latest road trip, I found myself at a bit over 2,000 RPMs when at 80 in 6th (only when passing of course :D)

Just wondering what you guys are all seeing at that speed? I know gearing is the main factor here, so I think my 2.73 gears have something to do with this low number. What about SS, ZL1 guys?

cornerspeed92 06-21-2013 02:02 PM

i think like 1800

Scooter11 06-21-2013 02:05 PM

Quote:

Originally Posted by cornerspeed92 (Post 6698237)
i think like 1800

Ok, so you have 2 more cylinders and 3.45 gears (correct me if I'm wrong) so that seems to make sense at the moment

KKreme15 06-21-2013 02:06 PM

Quote:

Originally Posted by Scooter11 (Post 6698250)
Ok, so you have 2 more cylinders and 3.45 gears (correct me if I'm wrong) so that seems to make sense at the moment

3.93

Scooter11 06-21-2013 02:08 PM

Quote:

Originally Posted by KKreme15 (Post 6698255)
3.93

OK, so 1LE has 3.93, LS has 2.73, what does a stock SS and ZL1 have?

TooCool5 06-21-2013 02:15 PM

3.27 and I see just over 2,000

KKreme15 06-21-2013 02:15 PM

Quote:

Originally Posted by Scooter11 (Post 6698266)
OK, so 1LE has 3.93, LS has 2.73, what does a stock SS and ZL1 have?

Manual ZL1 has 3.73, I believe the auto is 3.23

cornerspeed92 06-21-2013 02:26 PM

Quote:

Originally Posted by Scooter11 (Post 6698250)
Ok, so you have 2 more cylinders and 3.45 gears (correct me if I'm wrong) so that seems to make sense at the moment

Sorry, my bad, i missed what i thought i read:facepalm:my gears are actually 3.91

Scooter11 06-21-2013 02:27 PM

Quote:

Originally Posted by cornerspeed92 (Post 6698330)
Sorry, my bad, i missed what i thought i read:facepalm:my gears are actually 3.91

That's cool, I don't know why that # popped in my head :noidea:

meissen 06-21-2013 02:35 PM

1LS, manual trans, about 2200-2500 at 80mph

NYYFan325 06-21-2013 03:00 PM

Pretty sure I'm around 2K (I know @ 60 I'm around 1400, so I'm just guess here lol)

snymat68 06-21-2013 03:02 PM

Wheel size also comes into play here.

mikeyg36 06-21-2013 03:09 PM

A bit over 2k I think.

E.T. 06-21-2013 03:19 PM

I'm somewhere in the 2K range at 80mph, probably at least 2300 or more. I have 3.70 gears.

littlecammi 06-21-2013 03:55 PM

Quote:

Originally Posted by Scooter11 (Post 6698229)
What are your RPMs at 80?

I'm not that old yet, but I don't expect to move very fast when I am that age.

firedrop 06-21-2013 08:52 PM

like 2100-2300

BubbaSS 06-21-2013 09:48 PM

4.10 gears 2400-2500 rpm +/-

Dez 06-21-2013 10:42 PM

I'm pretty sure it's around 2000 RPM at 80

snymat68 06-21-2013 11:31 PM

These numbers are for my '13 1LS M6 with 18" wheels. Change out the bold numbers for your own and recalculate.

The math...

KNOWNS
A = Vehicle Speed (in mph)
B = Wheel Radius (in inches) measured from the wheel center to the ground
C = Rear Differential Ratio (ie 3.27)
D = Transmission Gear Ratio (ie .84)

VEHICLE - Convert MPH to in/min
(80mi/1hr) x (5280ft/1mi) x (12in/1ft) x (1hr/60min) = 84,480 in/min

WHEEL - Convert radius to circumference
C = 2πr = (2) x (π) x (13.75in) = 86.39 in = 86.39 in/1 rev

WHEEL - Convert in/rev to RPM
(84,480in/1rev) x (1rev/86.39in) = 977.89 RPM (at the wheel)

RPMs - Work it backwards through the drivetrain
(Wheel RPM) x (Differential Ratio) x (Transmission Gear Ratio) = Engine RPM
(977.89) x (3.27) x (.84) = 2,686 RPM

Scooter11 06-21-2013 11:32 PM

Quote:

Originally Posted by littlecammi (Post 6698630)
I'm not that old yet, but I don't expect to move very fast when I am that age.

:facepalm: :sm0:
Thanks everyone else :thumbup:

Scooter11 06-21-2013 11:36 PM

Quote:

Originally Posted by snymat68 (Post 6700303)
These numbers are for my '13 1LS M6 with 18" wheels. Change out the bold numbers for your own and recalculate.

The math...

KNOWNS
A = Vehicle Speed (in mph)
B = Wheel Radius (in inches) measured from the wheel center to the ground
C = Rear Differential Ratio (ie 3.27)
D = Transmission Gear Ratio (ie .84)

VEHICLE - Convert MPH to in/min
(80mi/1hr) x (5280ft/1mi) x (12in/1ft) x (1hr/60min) = 84,480 in/min

WHEEL - Convert radius to circumference
C = 2πr = (2) x (π) x (13.75in) = 86.39 in/rev

WHEEL - Convert in/rev to RPM
(84,480in/1rev) x (1rev/86.39in) = 977.89 RPM (at the wheel)

RPMs - Work it backwards through the drivetrain
(Wheel RPM) x (Differential Ratio) x (Transmission Gear Ratio) = Engine RPM
(977.89) x (3.27) x (.84) = 2,686 RPM

Wow, that's really useful! It reminds me of AP Physics though :fear:
Thanks :w00t:

snymat68 06-21-2013 11:59 PM

Yeah, no prob. I also have a spreadsheet that I whipped up one day when I was bored that tells me the vehicle speed for any given combination of engine rpm and gear. :headbang:

Comrando 06-22-2013 03:59 AM

If I was passing I wouldn't be in 6th.

http://www.camaro5.com/forums/pictur...ictureid=64838

See my album page for more charts.
Misc

My program: Engine Speeds

Scooter11 06-22-2013 09:20 AM

Quote:

Originally Posted by Comrando (Post 6700684)
If I was passing I wouldn't be in 6th.

Wow! What program is this, or did you make it completely yourself? Very neat :w00t:

(Oh and I only said the passing thing so I wouldn't get flak from people for cruising at that speed, but I do :smiling1:)

pmandeep 06-22-2013 10:12 AM

I think I am right in between 2-2.1k @ 80mph.


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