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 rpm question
#1066033
11/10/13 08:35 PM
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Joined: Feb 2011
Posts: 288
OP
Mudrunner
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I would like to know for the 4cy 5 speed guys,at hiway speed,say 55-60....what rpm are you turning and post tire size also. Mine seems kinda high at 60 mph.
1991 Montero RS 
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Re: rpm question
[Re: SledgeHammer]
#1066034
11/10/13 09:21 PM
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Joined: Sep 2011
Posts: 628
Rock Warrior
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I would like to know for the 4cy 5 speed guys,at hiway speed,say 55-60....what rpm are you turning and post tire size also. Mine seems kinda high at 60 mph. With 31's around 3000-3200rpm. Remember these trucks have 4.62 axle gears, and it's on purpose. My best mileage ever in my Raider was 19mpg at 55mph in 4th gear for about 2 hours, fully loaded with all my belongings. Also the KM145 has a weak 5th gear, so I stay out of it most of the time for the sake of transmission life. Plus with 31's who needs overdrive. Its only useful around 70mph, which I only rarely do. Also keep in mind that 3000rpm is loafing for most 4cyl motors ;-)
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Re: rpm question
[Re: geocrasher]
#1066035
11/11/13 12:43 AM
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Joined: Feb 2005
Posts: 7,458
Trail Leader
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Revolutions at 60 mph (at a 1:1 ratio - 4th gear) by tire size and gear ratio: ![[Linked Image]](http://i236.photobucket.com/albums/ff112/rxinhed/44290ee2-5732-4b92-ba80-6b2445564d46_zpsb2b67016.jpg) This should help.
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Re: rpm question
[Re: SledgeHammer]
#1066036
11/11/13 01:27 AM
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Joined: Dec 2007
Posts: 2,348
Body Damage is Cool
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I would like to know for the 4cy 5 speed guys,at hiway speed,say 55-60....what rpm are you turning and post tire size also. Mine seems kinda high at 60 mph. What making you think it's high?
89 SWB, V-6 5SPD, OME Shocks, 16.5X37's, 2"BL, SR axle, Gen2 brakes, Lincoln w/Superwinch
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Re: rpm question
[Re: SledgeHammer]
#1066037
11/11/13 01:53 AM
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Joined: Nov 2008
Posts: 1,435
Body Damage is Cool
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I have an excel spreadsheet with the KM145. V5MT1, Aisin AX5 and Aisin AX15, with 4.22, 4.626 & 4.88 rear ratios - input tire size and get RPM in all forward gears from 5 to 80 mph in 5 mph increments. If anybody wants a copy let me know and I'll post a dropbox link.
- '83 Might Max: IG @83mmax
- '88 Raider: my OG
- '89 Raider: rescued
- '92 RS M/T: sold
- '93 SR: sent to crusher
- '05 Montero LTD: sold
- '18 PHEV: wife's daily
- '14 OL GT
- http://www.tuffpans.com
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Re: rpm question
[Re: Mudraider]
#1066038
11/11/13 10:23 PM
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Joined: Feb 2011
Posts: 288
OP
Mudrunner
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I would like to know for the 4cy 5 speed guys,at hiway speed,say 55-60....what rpm are you turning and post tire size also. Mine seems kinda high at 60 mph. What making you think it's high? at 55mph..in 5th gear with 30's it says 3500
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Re: rpm question
[Re: SledgeHammer]
#1066039
11/12/13 12:21 AM
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Joined: Feb 2005
Posts: 7,458
Trail Leader
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Your math needs to be rechecked.
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Re: rpm question
[Re: SledgeHammer]
#1066040
11/12/13 03:38 AM
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Joined: Nov 2008
Posts: 1,435
Body Damage is Cool
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I would like to know for the 4cy 5 speed guys,at hiway speed,say 55-60....what rpm are you turning and post tire size also. Mine seems kinda high at 60 mph. What making you think it's high? at 55mph..in 5th gear with 30's it says 3500 Check this: DropBox - Gear Ratio RPM MPH Calculator (Excel or OpenOffice)
- '83 Might Max: IG @83mmax
- '88 Raider: my OG
- '89 Raider: rescued
- '92 RS M/T: sold
- '93 SR: sent to crusher
- '05 Montero LTD: sold
- '18 PHEV: wife's daily
- '14 OL GT
- http://www.tuffpans.com
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Re: rpm question
[Re: rxinhed]
#1066041
11/12/13 05:15 PM
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Joined: Feb 2011
Posts: 288
OP
Mudrunner
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Your math needs to be rechecked. who's math?
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Re: rpm question
[Re: SledgeHammer]
#1066042
11/12/13 06:04 PM
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Joined: Sep 2011
Posts: 628
Rock Warrior
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at 55mph..in 5th gear with 30's it says 3500 Unless your axles have 5.29's in them (incredibly unlikely) your tach or speedo is simply off. Speedo is easiest to check with a GPS, or even a passenger with a stopwatch and an open road, milepost markers and some basic math.
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