Speaking of rpms..... on another note, I searched the archives for comments
on what "red line" would be for an inline (typically a 235 or a 261) and
what "normal" highway rpms might be to maintain reasonable engine longevity.
I only found one, two message thread that stated 3000 rpm driving on the
highway should be perfectly fine on a regular basis, with red line probably
at about the 3500 to 4000 rpm range. Any other opinions in this regard?
I have a fresh rebuild and want to treat it nice......
Thanks,
Allen in Seattle
'50 3100
----- Original Message -----
From: ROGER GLEASON <rogerg@maverick.facil.uconn.edu>
To: <oletrucks@autox.team.net>
Sent: February 03, 2000 6:49 AM
Subject: Re: [oletrucks] tire size
Ok here I go getting myself in trouble again!
I'll try to explain this...RPM=V / C X GR
Where V = Speed in MPH
C = Circumference of tire in feet
GR = Gear ratio
tire circ. = (27"x Phi = 85"...divide by 12"/ft = 7.07ft.)
(For those who don't know circ.= Phi or 3.14159 X Diameter)
So for example... RpM= 55mph X 5280 ft/mi =290400ft/hr
now divide 290400mph by 60 min/hr and you get 4840ft/min
Now go to the formula RPM = V / C X GR
Soooo.... RPM = 4800 ft/min / 7.07 ft X 4.10 = 2784 RpM
So... I get Close to what you get... Looks like you did it right...
Remember 3000 rpm for a 235 is pretty fast I don't think they can do
much more than 4000 and red line for a stocker is probably 3800
These are power house work horse engines not race engines and were
designed when speed limits on roads were max 40 mph. I always kept my
older much used AD's at 50 MPH as it seemed to me as you with yours
that at 55 it was screaming. If My calcs are wrong someone please
straighten me/us out...
Rogerg
51-3100 AD STocker
> From: MLayton324@aol.com
> Subject: [oletrucks] tire size
> RPM = V / D x GR x 334.2
> Where:
> V = vehicle speed in mph
> D = effective tire diameter
> GR = gear ratio (e.g., for my truck, 4.10 rear x .70 overdrive = 2.87)
>
> the above formula on the chevy truck sit does not seem to work out what
am
> i doing wrong
>
> 55 mph/ 27 inch tire is 2.03 2.03 x 4.10(gear ratio) x 334.2 equals
2781
> which is supposed to be rpms at 55
>
> if i was only turning 2800 at 55 i would be estatic i cant even get it
to
> 55 without feeling like its gonna blow help??
>
>
> thanks mike layton
> 50 3100
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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