[cornflakes]

Just an odd question i have but something i've been watching carefully over the years.

When you are cruising at a steady speed on the highway and your RPM needle is steady at around the 2.9 - 3.0 rpm, what speed are you travelling at in km/h?

Usually when the needle is at 3 (3,000 rpm) my speed is at 120 km/h or just slightly under it.


But sometimes i noticed when the needle is at the 3,000 rpm, my speed is at a tad lower to about 117km/h now.

[Focus man. Focus.]

Yeah at around 3K I am cruising at 120KPH. I guess it would all have to do with load as well. Wind resistance, traveling up or down hill, # of occupants, etc.

[Canadian ST]

X2 at 3000 rpm I'm going 119-120kph.

[NOS2Go4Me]

Fast enough to cause me some serious trouble on the side of the road with the right people :P ;)

That's one thing I don't miss... high cruising RPMs.

[Canadian ST]

NOS2Go4Me,Mar 23 2009, 03:04 PM Wrote:Fast enough to cause me some serious trouble on the side of the road with the right people :P ;)

That's one thing I don't miss... high cruising RPMs.
[right][snapback]283254[/snapback][/right]

We had an Escape for a couple of weeks last year, at 120kph its at 2000rpm I think?

[cornflakes]

when i check, i'm always driving straightaway (no uphill or down), no abnormally strong winds, and i'm the only person in the vehicle but I've noticed at 3K im at 117km/h when it used to be right at 120km/h (i remember because it's always a nice and even marker needle at the 3, needle at the 120).

Why would i have dropped 2-3 km/h? Needs tune up? Car just getting old?

(2004 and i'm at 73K km, regular oil changes every 5).

[NOS2Go4Me]

I'd say tire wear but I can't remember if lower O.D. makes the speedo faster or slower at a given RPM. If anything I think a smaller O.D. makes your speedo read TOO fast, ex. you're doing 100 KM/H indicated and you're really only going 95.

Could be anything... given that you're only 2.x % off from stock, I doubt the dealer would worry too much about it. Maybe clutch slip? I think I had a very similar experience in my old Bronco II before.

Nathan - I'm doing pretty much 100 KM/H @ 2000 RPM in my truck, but that might be out a tad because it's a converted cluster (metric install in a USDM vehicle before it was sold to me). I've paced a few cars and figure it's pretty close to bang on, and my GPS agrees with me that I can recall.

[NefCanuck]

Cruising @ 3,000 RPM? In the Fusion that's "pull over and hand your keys to the cops" territory (120km/h is barely 2,000 RPM)

NefCanuck

[ZTWsquared]

cornflakes,Mar 23 2009, 01:33 PM Wrote:Just an odd question i have but something i've been watching carefully over the years.

When you are cruising at a steady speed on the highway and your RPM needle is steady at around the 2.9 - 3.0 rpm, what speed are you travelling at in km/h?

Usually when the needle is at 3 (3,000 rpm) my speed is at 120 km/h or just slightly under it.


But sometimes i noticed when the needle is at the 3,000 rpm, my speed is at a tad lower to about 117km/h now.
[right][snapback]283251[/snapback][/right]

Funny you should ask this question today - I was out this morning answering the exact question for my new Fusion in preparation for doing the XCal math to accomodate the new tires and rims. At 3000 RPM the Fusion runs exactly 112 kph in 5th gear - confirmed by both speedo and GPS.

Unless your clutch / torque converter is slipping, your speedo should read the exact same speed at the same rpm assuming you're on the same tire / rim combo. Also: if it's an auto it could be the difference between a locked and an unlocked torque converter - which sometimes happens IIRC when you let the car decelerate and then get back on the gas ... the revs go up for a bit as the t.c. unlocks when you let off the gas, and then remains unlocked momentarily when you get back on the gas.

Wind and other external factors should have no impact whatsoever on the RPM (perhaps the throttle position to maintain that RPM, but not the revs themselves.

Underinflated tires will have the same effect as reducing the rolling circumference of your tire, but that would have the effect of increasing your indicated speed at the same RPM, as the wheel has to turn more times to travel the same distance compared to a wheel with a larger circumference - the more rotations in a given distance, the greater the indicated speed.

My bet is on the locking and unlocking of the torque converter.

[ZTWsquared]

NefCanuck,Mar 23 2009, 03:16 PM Wrote:Cruising @ 3,000 RPM?  In the Fusion that's "pull over and hand your keys to the cops" territory (120km/h is barely 2,000 RPM)

NefCanuck
[right][snapback]283264[/snapback][/right]

Oh the joys of V6 torque and a 5-speed auto ... with my setup 3000 RPM is just 112 kph !! Thank God 3500 is a really comfortable cruising rev in the 4-cyl Fusion.

[FocusGuy7476]

The SVT is at about 120kph @ 3000rpm, I set it to cruise between 2700 and 3000rpm for the best fuel mileage, and I still get passed by everyone on the highway here.

[NefCanuck]

ZTWsquared,Mar 23 2009, 03:23 PM Wrote:

NefCanuck,Mar 23 2009, 03:16 PM Wrote:Cruising @ 3,000 RPM?  In the Fusion that's "pull over and hand your keys to the cops" territory (120km/h is barely 2,000 RPM)

NefCanuck
[right][snapback]283264[/snapback][/right]

Oh the joys of V6 torque and a 5-speed auto ... with my setup 3000 RPM is just 112 kph !! Thank God 3500 is a really comfortable cruising rev in the 4-cyl Fusion.
[right][snapback]283266[/snapback][/right]

Uh 6 speed auto actually, which is why 3,000 RPM lands you in "heap 'o s**t" category.

NefCanuck

[faster_than_u]

3000rpm = 115 km/h for me

[Scorcher000]

3000RPM = 125KMH
2300RPM = 100KMH
I've messed with the SCT a bit
And it also depends if I have winters or summers

[NikiterZTS]

3000=115km/h in focus on winter tires
247k on the engine

i think it also depends on how you engine was tuned at the factory

[ZTWsquared]

NikiterZTS,Mar 24 2009, 12:05 PM Wrote:3000=115km/h in focus on winter tires
247k on the engine

i think it also depends on how you engine was tuned at the factory
[right][snapback]283315[/snapback][/right]

Nope - strictly a mechanical / mathematical thing based on transmission gearing, final drive ratio, and tire circumference.

Mechanical problems like slipping clutch or unlocked torque converter vs. locked t.c. could have an influence ... but otherwise it doesn't matter the size of the engine, the torque or the hp ... or its condition - the revs / kph will remain the same so long as those three factors remain the same.

A good analogy is the bicycle ... if the gearing and tires are the same, it doesn't matter who's riding it, the number of rpms per distance will remain the same.

[lgSPI]

with my SPI I'm usually around 115-118 km/h at 3000 RPM.

[Gabriel]

ZTWsquared,Mar 24 2009, 01:53 PM Wrote:

NikiterZTS,Mar 24 2009, 12:05 PM Wrote:3000=115km/h in focus on winter tires
247k on the engine

i think it also depends on how you engine was tuned at the factory
[right][snapback]283315[/snapback][/right]

Nope - strictly a mechanical / mathematical thing based on transmission gearing, final drive ratio, and tire circumference.

Mechanical problems like slipping clutch or unlocked torque converter vs. locked t.c. could have an influence ... but otherwise it doesn't matter the size of the engine, the torque or the hp ... or its condition - the revs / kph will remain the same so long as those three factors remain the same.

A good analogy is the bicycle ... if the gearing and tires are the same, it doesn't matter who's riding it, the number of rpms per distance will remain the same.
[right][snapback]283318[/snapback][/right]

I agree with you , just with one exception : tire circumference . It doesn't matter whether you're on low or high profile tires , if your tach says 3000 and you drive let's say 120 km/h the gear ratio stays the same and the transmission turns at constant rpms . Now if you have tires with lower profile than the manufacturer installed , at 3ooo rpm the speedometer will show you 120 km/h but in reality you will have less than 120 . And for higher profile tires , for same readings you will actually move at over 120 km/h . That is for a manual transmission . As for automatic , I don't know , I am european , I don't play with that s#%t .
My 03 Focus SVT reads around 3200 rpm at 120 km/h in 6th . Slightly more than the 03 ZTS I had before read in 5th .

[ZTWsquared]

Gabriel,Apr 5 2009, 03:26 PM Wrote:

ZTWsquared,Mar 24 2009, 01:53 PM Wrote:

NikiterZTS,Mar 24 2009, 12:05 PM Wrote:3000=115km/h in focus on winter tires
247k on the engine

i think it also depends on how you engine was tuned at the factory
[right][snapback]283315[/snapback][/right]

Nope - strictly a mechanical / mathematical thing based on transmission gearing, final drive ratio, and tire circumference.

Mechanical problems like slipping clutch or unlocked torque converter vs. locked t.c. could have an influence ... but otherwise it doesn't matter the size of the engine, the torque or the hp ... or its condition - the revs / kph will remain the same so long as those three factors remain the same.

A good analogy is the bicycle ... if the gearing and tires are the same, it doesn't matter who's riding it, the number of rpms per distance will remain the same.
[right][snapback]283318[/snapback][/right]

I agree with you , just with one exception : tire circumference . It doesn't matter whether you're on low or high profile tires , if your tach says 3000 and you drive let's say 120 km/h the gear ratio stays the same and the transmission turns at constant rpms . Now if you have tires with lower profile than the manufacturer installed , at 3ooo rpm the speedometer will show you 120 km/h but in reality you will have less than 120 . And for higher profile tires , for same readings you will actually move at over 120 km/h . That is for a manual transmission . As for automatic , I don't know , I am european , I don't play with that s#%t .
My 03 Focus SVT reads around 3200 rpm at 120 km/h in 6th . Slightly more than the 03 ZTS I had before read in 5th .
[right][snapback]284268[/snapback][/right]

I think we're saying basically the same thing ... which is why I mentioned tire circumference and not rim circumference ... as the profile gets lower the circumference of the tire will also get smaller (all other things being equal) ... bottom line being that when you reduce the circumference of the tire you cause the speedo to register higher.

[lowblackdub]

Kind of a related but separate question:

Are there replacement final drives for the Focus? Going from my ZX2 into my Focus is really a drag - the ZX2 transmission seems to keep the Focus in happyland as far as revs are concerned. My ZX2 @ 100kp/h would be turning 3000rpm and was a lot more lively around town.

My question is this: the ZX2 and the Focus share the Zetec engine (although configured differently). Does anyone know if a ZX2 transmission or at least the final drive bolt over to the Focus? I think it would make it a lot more fun!