REVs at highway speeds
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REVs at highway speeds
hey guys I was just making sure my speedo is right. When doing 60-70 my revs are almost to 4k. That sounds high to me for only going 60-70mph. What is everyone else getting? Thanks much
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Scikotics
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Originally Posted by rdclark
You must have a stick. The auto revs lower at highway speeds, the ratios are different. That's why the xB auto is quieter and can get better gas mileage on road trips.
RichC
RichC
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From: Los Angeles
Originally Posted by hotbox05
3,000 at 60mph
3,500 at 70mph
4,000 at 80mph
3,500 at 70mph
4,000 at 80mph
On a level surface my AUTO xB can hold 80mph @ 3,000 - 3,300 rpms
But going uphill is another story....
-THE DON
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All you gotta do is turn-off overdrive and were at comparable rpms.... I haven't had a problem yet even driving over the altamont pass, turn off the o/d and it keeps on chuggin away and thats with 4 people too
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Yeah, I agree. I live in Pacifica so I only drive on the highways and off skirts of the city. I do work downtown SF though and I love driving to work. I look forward to driving to work. Its fun. I have a 89rx7 and its great but the Xb is like a go-cart. So much fun to drive.
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Team Sushi
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Yeah. . . 1-2MPG for a 0-60 a full second faster is a good trade off for me.
The whole fuel issue isn't that huge of a leap. . . but if you actually prefer auto, then there's no arguing with that. But for me, the manual is already slow enough. If it were ANY slower, I wouldn't have bought the car.
The whole fuel issue isn't that huge of a leap. . . but if you actually prefer auto, then there's no arguing with that. But for me, the manual is already slow enough. If it were ANY slower, I wouldn't have bought the car.
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Team Sushi
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Another thing that is deceiving about the revs, is that the manual puts more power to the ground (as there is less parasitic loss without a torque converter). Usually, manuals are both faster and have higher MPG, but Toyota decided to give us ultra short gearing, which compensates for the higher efficiency.
In our case, the auto does get better MPG, but not by much at all.
In our case, the auto does get better MPG, but not by much at all.
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From: Suburban Philadelphia
Yeah, I would not normally saddle an engine this small with an automatic; all my previous small cars have been sticks.
But in the case of the xB it seemed like the auto had been so well-optimized for the engine, with a minimal (50lb I think) weight penalty, that the only real cost would be the price of the transmission itself (which is not trivial, something like 6% of the sticker price). For me, driving mostly in the city with a bad knee, it was a no-brainer.
RichC
But in the case of the xB it seemed like the auto had been so well-optimized for the engine, with a minimal (50lb I think) weight penalty, that the only real cost would be the price of the transmission itself (which is not trivial, something like 6% of the sticker price). For me, driving mostly in the city with a bad knee, it was a no-brainer.
RichC
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I know this is a little late for this thread.. but I didnt want to repost the same question.. I know the scion says it redlines at like 6500 or so.. but my question is when Im going up those daunting hills and trying to maintain 80 with my overdrive off, Im doing about 5k-5500 the whole time with an auto.. The car seems to do it ok, but it worries me that Im going to blow my engine or something. Is the engine supposed to maintain that? I just hate going 80 down hill and 40 up hill with the OD on... but I would hate it even more if I chunked my block.
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Heh. Well, Edlin, you could try just maintaing the legal speed up those hills instead. 
Seriously, the engine is fairly comfortable at 5K, but like any mechanical device, the more strain you put it under the more chance there is for it to fail. Engineering 101...
Once again I will post this...
Seriously, the engine is fairly comfortable at 5K, but like any mechanical device, the more strain you put it under the more chance there is for it to fail. Engineering 101...
Once again I will post this...
Code:
====
(tire rev per mile) * (final ratio) * (top gear ratio) = (engine RPM at 60MPH)
For the stock xB automatic those numbers are:
880 * 4.15 * 0.70 = 2556.4 RPM
====
Just using the stock tire size, the differential ratio, and the top gear ratios of
the xB with manual or auto transmission I come out with these figures, plus
or minus maybe 10 RPM...
AUTOMATIC:
2560 RPM @ 60 MPH
2990 RPM @ 70 MPH
MANUAL:
3070 RPM @ 60 MPH
3580 RPM @ 70 MPH
====
Gear / Ratio C150 5MT U340E 4AT
1st 3.54:1 2.84:1
2nd 1.90:1 1.55:1
3rd 1.31:1 1.00:1
4th 0.96:1 0.70:1
5th 0.81:1 –
Reverse 3.25:1 2.34:1
Final Drive 4.31:1 4.15:1
Stock tire revolutions per mile = ~880 (Varies by tire make, size, wear, etc.)
The torque converter is a locking torque converter that locks (no slippage)
while cruising in either 3rd or 4th gear for highway efficiency.
====