3500 rpm on the highway normal?

[Mafty]

maybe its because i went from an auto car to a standard. but going about 120 on the highway in 5th my car is pretty well fixed on 3500 rpm. is that normal? or does it lower once it breaks in a bit?

[bhrm]

normal

if you slow down to 100km/h you save a ton of gas and reach 6.6-7L/100km instead of 8-8.5L/km

[Xerox]

maybe its because i went from an auto car to a standard. but going about 120 on the highway in 5th my car is pretty well fixed on 3500 rpm. is that normal? or does it lower once it breaks in a bit?

I don't think the gear ratio will change after break-in :chuckle
If you know the gear ratios you can do the math to figure out if that RPM is with-in spec...any math nerds here?

[b3GS]

you're RPM is not going to change once the car 'breaks in'

the gear ratio is what it is

[bhrm]

makes you wish there was a 6th gear and wonder how much more gas could be saved.

[kaval]

Drive slower :p haha

Welcome to TM3!!!!

[whiteomega]

on an automatic 5-speed, 3500rpm / (0.692*3.863) = 1310 rpm on the transmission output shaft; assuming a tire size of 205/50/17, that's a tire circumference of 2.00053 m; so in one minute, the tire rotates 1310 times, so you travel 1310 *2 = 2620 m; or 2.62 km. 60 minutes x 2.62 km = 157 km/h..

keep in mind this is with current figures for gear ratios on mazda's website; they may well have changed from previous years.

the lowest speed i can get at 3500 rpm (again using mazda's current figures) is 134 km/h (205/55/16 tires using the GS 5MT gear ratios)..what year is your car?

Edit: using the manual 5-speed gear ratios, 3500 rpm works out to around 135 km/h, just in case you were wondering.

[bhrm]

on an automatic 5-speed, 3500rpm / (0.692*3.863) = 1310 rpm on the transmission output shaft; assuming a tire size of 205/50/17, that's a tire circumference of 2.00053 m; so in one minute, the tire rotates 1310 times, so you travel 1310 *2 = 2620 m; or 2.62 km. 60 minutes x 2.62 km = 157 km/h..

keep in mind this is with current figures for gear ratios on mazda's website; they may well have changed from previous years.

the lowest speed i can get at 3500 rpm (again using mazda's current figures) is 134 km/h (205/55/16 tires using the GS 5MT gear ratios)..what year is your car?

Edit: using the manual 5-speed gear ratios, 3500 rpm works out to around 135 km/h, just in case you were wondering.

my head really hurts.

[Garu]

on an automatic 5-speed, 3500rpm / (0.692*3.863) = 1310 rpm on the transmission output shaft; assuming a tire size of 205/50/17, that's a tire circumference of 2.00053 m; so in one minute, the tire rotates 1310 times, so you travel 1310 *2 = 2620 m; or 2.62 km. 60 minutes x 2.62 km = 157 km/h..

keep in mind this is with current figures for gear ratios on mazda's website; they may well have changed from previous years.

the lowest speed i can get at 3500 rpm (again using mazda's current figures) is 134 km/h (205/55/16 tires using the GS 5MT gear ratios)..what year is your car?

Edit: using the manual 5-speed gear ratios, 3500 rpm works out to around 135 km/h, just in case you were wondering.

Holy crap, who do you work for???

[whiteomega]

Holy crap, who do you work for???

just bored @ work.

the math is actually on the web if you go hunting for it. (http://www.carbibles.com/transmission_bible.html)

[x_o_k_x]

I assume its 4 speed, since I get the same going 120kph at around 3500 rpm. It sucks cuz my old altima has 4 speed and I go 120 at 2500rpm

[loganm3]

I have been wondering about this as well, as I'm on the highway a lot. Is there a way to change the gear ratio for 5th?

[whiteomega]

change the ratio?

not really, unless you want to rip the transmission apart; you'd have to strip it down and swap the last gear out. you could also swap out the final drive while you're at it. the cost and effort of doing this is not worth the result, IMO

[MikeyGT]

hm.. thats weird... i have an auto and when i drive at 120km/h...my rpm usually sits at 3000 .. depending on the wind and elevation, it goes as high as 3200 but never 3500.

Hope that helps.

[Noisy Crow]

You would liekly be better off seeing if you could get a used six-speed transmission from a Speed3... although those ratios are optimized for the fairly narrow power-band off the turboed engine.....

[x_o_k_x]

hm.. thats weird... i have an auto and when i drive at 120km/h...my rpm usually sits at 3000 .. depending on the wind and elevation, it goes as high as 3200 but never 3500.

Hope that helps.

Yeah same here I think thats what he means. I havent drove mine since last summer, trying to remember what it was.

[Fuman]

change the ratio?

not really, unless you want to rip the transmission apart; you'd have to strip it down and swap the last gear out. you could also swap out the final drive while you're at it. the cost and effort of doing this is not worth the result, IMO
depending on how the transmission is made, the final drive but be at the end of the transmission as well, lol. For Integera, my friend had to dismantle the entire transmission, just to put in the ITR final drive

[Wild Weasel]

hm.. thats weird... i have an auto and when i drive at 120km/h...my rpm usually sits at 3000 .. depending on the wind and elevation, it goes as high as 3200 but never 3500.

Hope that helps.

If your speedometer says 120 km in 5th gear, your rpm will always be the same. Perhaps it's downshifting to 4th when you're seeing these higher values...

[SP33D 3]

normal

if you slow down to 100km/h you save a ton of gas and reach 6.6-7L/100km instead of 8-8.5L/km

my speed gets 6.8L/100km at 130km/h:bana2

[Flagrum_3]

maybe its because i went from an auto car to a standard. but going about 120 on the highway in 5th my car is pretty well fixed on 3500 rpm. is that normal? or does it lower once it breaks in a bit?

Unless Mazda changed the final gear ratio between 05' & 08', your engine rpm is excessive for 120kph, when I run at a steady 3500rpm I'm cruising close to 140kph, probably 138kph to be more precise, but hard to tell with our speedometers.

Incidently at 120kph my engine revs at a touch under 3000rpm.


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[wingnut12]

120 mph = ~ 3250 so that sounds about right with the 5 speed. Not much you can do about that. The joys of small engines. The power has to come from somewhere.

[Wild Weasel]

my speed gets 6.8L/100km at 130km/h:bana2

Is that from your own calculation or is that what the little readout on the dash says?

[whiteomega]

depending on how the transmission is made, the final drive but be at the end of the transmission as well, lol. For Integera, my friend had to dismantle the entire transmission, just to put in the ITR final drive

yep. basically way more work than it's worth unless you really, really wanted to do it.

just a note to those who think their RPM is varying when you go up a hill: on a manual transmission with the clutch engaged, the wheels, transmission, and engine are physically linked together; your rpm should never change as long as your speed is constant, even if you're going up a hill.

this is not true with an torque converter-equipped automatic transmission, since there is no direct coupling between the engine and the wheels; so in this case, yes, your engine can rev higher without actually increasing your speed, but it won't be a significant difference from a manual (500 rpm probably) unless your transmission is shot :)

[Mafty]

hmm shitty, lol my auto car cruised at 130 doing like 2500. im not an impatient driver, i just dont like doing 100, i drive a lot and like getting there in a relativley quick pace. and i was driving between 120 and 130 getting around 3200-3500.

[tweak_s]

Unless Mazda changed the final gear ratio between 05' & 08', your engine rpm is excessive for 120kph, when I run at a steady 3500rpm I'm cruising close to 140kph, probably 138kph to be more precise, but hard to tell with our speedometers.

Incidently at 120kph my engine revs at a touch under 3000rpm.


_3


.

I think that it might be the gear ratios then..

My 07 2.3L is exactly at 3250 for 120km/h (as wingnut said) :whoa.... If thats the case.....mazda what the hell? lol.

[Mafty]

oh ya i forget to mention mines a 2.3 so maybe that has something to do with it

[SP33D 3]

Is that from your own calculation or is that what the little readout on the dash says?

thats what the readout says, but its around the same when i did calculations, but i've never done it with a full tank.... only for a 2 hour drive

[alhope34]

The 6 speeds also hang just below 3000rpm at 120km/h, too.

I've seen 7.6 L/100km average on the first few hundred km's going to Niagara Falls and back, since break-in was over best highway economy I've seen was 7.8 L/100km, but mostly I get 8-8.2 L/100km. I find that weird because all city bumper to bumper I'll see no more than 10.5 L/100km, even if I punch the gas every chance I get. I've seen it get to 11L ONCE, and that was up north all fun twisty hilly farm roads.

[Wild Weasel]

thats what the readout says, but its around the same when i did calculations, but i've never done it with a full tank.... only for a 2 hour drive

I've always found the readout to be far too ambitious. It's always been off for me by at least 1L/100/km so generally over 10%.