optimal 2f rpm range for highway cruising

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Oct 20, 2005
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I drive a hour plus both ways daily to work, all steady speed interstate but for 4 or so miles. I drive at 3000 rpm which puts me at 68mph and (barely) keeps me from being a speed bump for the left lane traffic. 3000 sounds fairly wound up for this engine.

Obviously this is 75% of the recommended redline for this engine. While I appreciate short excursions near redline while shifting; does anyone run their 2f routinely at 75+% rpm? I'm talking about an hour or more, steady cruise, And yes, I've read the recent rpm discussion about running through the gears.

And what is the group's experience on best rpm/fuel efficiency for this engine?

cruise on
 

Cruiserdrew

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3000 is my absolute upper limit, but I've done it for 6 hours in a row numerous times. I now have an overdrive 5th gear so most highway cruise is closer to 2500 rpm. I think you are fine, but these old trucks don't like to be rushed.
 
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on the hwy, i'm runnin 3200 rpms
35's and 4.88's 4 spd
i'll max out at 3500 on a uphill shift,i never touch the red line

idealy,i'd prefer to keep it below 3k for optimum gas mileage ;)

"I AM SLOWER TRAFFIC"
 
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2badfjs said:
on the hwy, i'm runnin 3200 rpms
35's and 4.88's 4 spd
i'll max out at 3500 on a uphill shift,i never touch the red line

idealy,i'd prefer to keep it below 3k for optimum gas mileage ;)

"I AM SLOWER TRAFFIC"
What speed do you figure you are running at 3k? I'm thinking about doing 4.88's.
 
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I routinely cruise at about 2400-2500 rpms in my 83 FJ60, which, in combination with my 5 speed, and 31 in tires (aired to 40psi), gives me a 68-70mpg ground speed, with minimal road noise. The engine (relatively fresh rebuild), still has a lot to give if I need to push it, but, if I stay within these limits, I routinely get 17.5 mpg.
 

Mark W

 
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If you're looking for what the engine will put up with... 3000 is good for years and years of miles and miles. If you are looking at what the engine will be happiest with for the longest period, slower is better. Just above idle would be good. ;) If you are looking for the "best" highway cruise RPM to keep the engine happy and still actually move you down the road, then I have to agree with what Jim has to say inthe thred linked above. About 2300-2600. It'll be a slow ride thought.


Mark...
 

Mike S

 
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About 2500 RPM at cruise. The 5th gear and 31" tires help a lot.

M
 
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so like 55-65....I know with 4.56s and 35s its dead stock. So, I am sure with 4.88s ya got a bit of an underdrive...which would be fun on the trails :)
 
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Mike S said:
About 2500 RPM at cruise. The 5th gear and 31" tires help a lot.

M[/QUOT

personally i always run my 60 on highway speeds about 2500 and 2600 rpm's, i think that's the normal range for me.

does the 31's help that much with the 5speed tranny? also i think i'm going to buy some 31's cause right now i'm running 30'sx9.50 and they're way to small.
is there some diference between the 30'sx9.50 and the 31'sx10.50 on the driving and highway speeds with my 4speed tranny?

P.S: i'm buying those 31's for the moment cause in a year i'm going 35's and right now i don't have the money to buy them
 
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Mike S

 
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The OD 5th gear is a huge help, the 31's help a bit with 'rubber overdrive'.

Bigger tires get you to thinking about gearing, and the balance point for me was 31" to 33" tires. Any thing taller, and I would be looking for lower gearing. Depends a lot on how and where you drive. The FJ60 is no miracle at highway speeds in the mountains, and this is where you will notice the negative effects of taller tires.

One way to get a little more out of your cruiser is to wash and WAX it. ;)

M
 

87CRUSR

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Just a bit below 3000 rpms is my preference to keep her from screaming at me.
 
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OK I'm lovin the look of a 5sp and 31", mid 2's for rpm seems reasonable. If I got 17.5 mpg, I'd have to check if a couple of cylinders were dead
anybody can check rpm for 70mph/5sp/32"? I think that's the future
 
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Pig RPM's with OD

I've got a '71 Pig with F, 4-sp, 4.11's, and 4-sp t-case with a funky but effective OD unit. Engine is bone stock, and even with the 33's, the engine produces enough HP at around 2400 rpm for me to cruise effortlessly (if it's relatively flat) on the highway with the 27% OD at 70-75 mph. At that engine speed, it's actually a pleasure to drive.
 
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