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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-

what are your rpm's @ 70mph?

  • Thread starter Thread starter CDQICKGT
  • Start date Start date Jun 10, 2010
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CDQICKGT

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Jan 25, 2006
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fort hood, tx
Jun 10, 2010
#1
  • Jun 10, 2010
  • #1
Just outta curiosity what rpms is everyone turning @ 70mph? when i bought my 89 hatch i was told it had 4:10's in it.( havent pulled the cover of to check yet)... at cruising speed im pulling around 3k. i have never had 4:anything in the gear dept as ive always been partial to 3:73. how much MPG could i gain from a geat swap with my T5?Right now im not gettin crap for mpg.
 

87GT Drop Top

Member
May 1, 2009
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South Florida
Jun 10, 2010
#2
  • Jun 10, 2010
  • #2
Sounds about right for 410s. I have 373 and I'm around 2700-2800 rpms. I just put in a new trans will a .58 5th instead of a stock .68, but haven't been on the highway yet. You don't have to pull the cover to check the gear ratio. Just jack up the rear of the car. Then mark the drive shaft so you can count how many times it goes around. Spin the rear wheels by hand 1 revolution and count how many time the driveshaft goes around. If it's 410s it shound go around just over 4 times.
 

MAC'n89Blckstng

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Jun 11, 2003
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Jun 10, 2010
#3
  • Jun 10, 2010
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your mileage is going to suck regardless. With my z spec trans and my 4.10s I'm at about 2300 at 70.
 

aar0s

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Dec 20, 1998
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Jun 10, 2010
#4
  • Jun 10, 2010
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heh, im at about 1800 with my 2.73's and auto trans. I guess that about the only good thing about 2.73's is the low rpms at highway speeds.
I have some 3.55's that im waiting to get put in. if i have to wait much longer im going to do it myself and that will surely end badly!
 

CDQICKGT

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Jan 25, 2006
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fort hood, tx
Jun 10, 2010
#5
  • Jun 10, 2010
  • #5
87GT Drop Top said:
Sounds about right for 410s. I have 373 and I'm around 2700-2800 rpms. I just put in a new trans will a .58 5th instead of a stock .68, but haven't been on the highway yet. You don't have to pull the cover to check the gear ratio. Just jack up the rear of the car. Then mark the drive shaft so you can count how many times it goes around. Spin the rear wheels by hand 1 revolution and count how many time the driveshaft goes around. If it's 410s it shound go around just over 4 times.
Click to expand...

Guess you relly do learn something everyday.... thanks
 

CDQICKGT

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fort hood, tx
Jun 10, 2010
#6
  • Jun 10, 2010
  • #6
aar0s said:
heh, im at about 1800 with my 2.73's and auto trans. I guess that about the only good thing about 2.73's is the low rpms at highway speeds.
I have some 3.55's that im waiting to get put in. if i have to wait much longer im going to do it myself and that will surely end badly!
Click to expand...

Its not that bad....Ive done plenty and the only thing that sucks about doing it at home is torqing that pain in the A** crush sleeve.
 
K

Kerpal

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Aug 9, 2004
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Jun 10, 2010
#7
  • Jun 10, 2010
  • #7
I'd like to know what RPM people are running at 70 with 3.55's or 3.73's too...
 

SScott

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Apr 23, 2004
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Alabama
Jun 10, 2010
#8
  • Jun 10, 2010
  • #8
MAC'n89Blckstng said:
your mileage is going to suck regardless. With my z spec trans and my 4.10s I'm at about 2300 at 70.
Click to expand...

me 2
 

CDQICKGT

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fort hood, tx
Jun 11, 2010
#9
  • Jun 11, 2010
  • #9
SScott said:
me 2
Click to expand...

Hey man, where is millbrook at? i grew up and lived in dothan before i joined the army.
 

SScott

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Apr 23, 2004
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Jun 11, 2010
#10
  • Jun 11, 2010
  • #10
About 10 miles north of Montgomery. Been through Dothan many times! I also used to live outside Fort Worth... I've been stalking you =)
 

NIKwoaC

中國製造
15 Year Member
Oct 31, 2006
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Jun 11, 2010
#11
  • Jun 11, 2010
  • #11
Off the top of my head, my T5 + 3.73 equipped car runs 2200~2300 at 70.

Keep in mind that you can easily estimate RPMs just by doing a little math. For example, lets say my car runs exactly 2250rpm @ 70mph with 3.73s, and I want to know what it would be with 3.55s. 3.55/3.73=0.952. 2250*0.952=2141rpm. Ta-da!
 

Shaolin Crane

Banned
Oct 6, 2008
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Kommiefornia
Jun 11, 2010
#12
  • Jun 11, 2010
  • #12
NikwoaC said:
Off the top of my head, my T5 + 3.73 equipped car runs 2200~2300 at 70.

Keep in mind that you can easily estimate RPMs just by doing a little math. For example, lets say my car runs exactly 2250rpm @ 70mph with 3.73s, and I want to know what it would be with 3.55s. 3.55/3.73=0.952. 2250*0.952=2141rpm. Ta-da!
Click to expand...

DUDE! you're hurting the reupation of fox owners, we're supposed to be uneducated hicks that think that "stang is a gratest evar"
 

NIKwoaC

中國製造
15 Year Member
Oct 31, 2006
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Jun 11, 2010
#13
  • Jun 11, 2010
  • #13
Shaolin Crane said:
DUDE! you're hurting the reupation of fox owners, we're supposed to be uneducated hicks that think that "stang is a gratest evar"
Click to expand...

Haha, sorry, sorry, I will try to dumb down my posts in the future.
 

lancec2c30

Member
May 14, 2008
570
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16
Washington
Jun 11, 2010
#14
  • Jun 11, 2010
  • #14
Gear Ratio Calc
 

1987LXragtop

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Jan 26, 2008
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Just outside Philly PA
Jun 11, 2010
#15
  • Jun 11, 2010
  • #15
70 mph is speeding here

that and my speedometer isnt plugged in.
 
6

65coupe408w

Member
Mar 26, 2010
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Jun 11, 2010
#16
  • Jun 11, 2010
  • #16
around 2000rpm with 3.70 gear (9inch) and a Gforce T5 .58 OD
 

CDQICKGT

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Jan 25, 2006
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fort hood, tx
Jun 11, 2010
#17
  • Jun 11, 2010
  • #17
These 4.10's are just irritating the piss outta me. Ive never had them in ANYTHING before, and as soon as i can get them out i will never look back. I start off from a light and it seems like i shift 3 times before i clear the other side of the intersection. I do love the second gear effortless starts though. Ive always ran 3.73's but im thinking about doing some 3.55's in this one(never had them figure ill give them a try.) Im about to drive from ft hood,tx to ft jackson south carolina round trip and i dont wanna turn 3k+ there and back.
 

bentley429isBAC

10 Year Member
Jul 23, 2009
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CT
Jun 12, 2010
#18
  • Jun 12, 2010
  • #18
3200 rpm
 

aar0s

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Dec 20, 1998
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Jun 12, 2010
#19
  • Jun 12, 2010
  • #19
noob question but whats the OD gearing on an AOD?
 

KENS89LX

Member
Mar 12, 2006
302
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Cross lanes Wv
Jun 15, 2010
#20
  • Jun 15, 2010
  • #20
In my 89 with stock tranny and 3.55 its 1900-2000 rpms.
 
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