REVs at highway speeds

[BlangKang]

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

[hotbox05]

3,000 at 60mph
3,500 at 70mph
4,000 at 80mph

[jct]

thats about right, you'll get use to it in all in due time

[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

[whatmovesu]

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

I have a 5 spd and it rev 3000 @ 60 3500@70 3900-4000@80 are their any mods that would change your revs

[THE_DON]

Originally Posted by hotbox05

3,000 at 60mph
3,500 at 70mph
4,000 at 80mph

Wow, the 5-speed does rev higher!

On a level surface my AUTO xB can hold 80mph @ 3,000 - 3,300 rpms

But going uphill is another story....

-THE DON

[rxheaven1]

That sounds right. At first I was kinda worried, but then just got used to it. Its nice having a fairly high revving engine on the freeway. Does have its power advantages....considering there isn't much to play with.

[SmokingTires]

This is exactly why the automatic has better gas mileage on the freeway....4k @ 80mph vs 3k @ 80mph

[hotbox05]

it's ok i'll take the power and "fun" factor..

i love driving to tahoe in 5th gear passing all the auto and other slower 5 speed boxes. bwahahaha.

[SmokingTires]

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

[rxheaven1]

Well....I like to "drive" to work rather than "commute"....thats why I got the 5speed. Its just more fun for me. Nothing against auto....I just have more fun with 5spd.

[SmokingTires]

Agreed completely, but since I live in S.F. and have a 5 speed BMW when I'm not in the city, I much more prefer the auto

[rxheaven1]

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.

[xA_Factor]

Auto = 2900 rpm @ 70 mph.

[djct_watt]

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.

[MikeC]

Some of you make it sound like a toy car that is secondary to your "real ride". *envious*

[djct_watt]

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.

[rdclark]

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

[edlin]

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.

[Tomas]

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...

====

(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.

====