How come our cars don't come with a tachometer

folks, mbigh is playing around with the [me] tag, or whatever it is. His post is not directed to you.

First time it was funny.

 

<div class='quotetop'>QUOTE(prez1 @ May 14 2006, 07:52 AM) [snapback]255173[/snapback]</div>

CAN-view does that too. Current fuel gauge reading is 93% of full.

 

<div class='quotetop'>QUOTE(tochatihu @ May 14 2006, 03:18 AM) [snapback]255091[/snapback]</div>

So is every car when it rolls off the assembly line. It's when something goes wrong that gauges come in handy and give you early info that might save you from being stuck on the side of the road.

 

The Prius does not come with a tachometer because the Prius is equipped with an Electronically controlled continuously variable transmission (ECVT), meaning it has no gears.
A tachometer shows the level of RPMs your engine is running and helps drivers with a manual transmission know when to shift to keep them from blowing up their engine.
In average cars in 1st gear the RPS can rev up to about 5,000 but the car will only be moving about 10 to 15 mph, shift into 2nd gear and get up to 25 to 30 and so on... The higher your RPS the lower your fuel economy.
The Prius was equipped with the Electronically controlled continuously variable transmission to not only save on fuel efficiency but also to create a smooth ride.
The computer in the Prius controls the transmission in a way that maximizes its fuel efficiency by keeping the engines running at the lowest possible RPM level.
So to answer your question, the Prius has no tachometer because it has no gears. Simple yet elegant.

 

<div class='quotetop'>QUOTE(prez1 @ May 14 2006, 07:52 AM) [snapback]255173[/snapback]</div>

Know what you mean. The s2000 has digital blocks for gas gauge too, but looks like regular gas guage with many bars... unlike the Prius.

 

<div class='quotetop'>QUOTE(8AA @ May 6 2006, 08:55 AM) [snapback]250706[/snapback]</div>

I personally cannot stand it when I cannot tell how fast an engine is turning, especially if it's a loud four cylinder. I drove an automatic Yaris without a tach recently, and giving it gas often sent the engine spinning. I'd have liked some feedback concerning just how fast it was spinning, to help me figure out how much gas to give it.

A tach also helps if you manually shift the automatic, but this is admittedly not often.

 

Adding a tach is relatively trivial. The IGF lead common to all
four ignitors serves as the "coil" input, and you can basically
install any joe random aftermarket tach, set it for 4 cylinders,
and there you go. And it's very useful for determining power
output, per http://techno-fandom.org/~hobbit/cars/prius-curves.gif
which shows a fairly convenient mapping between kW output and 1000s
of RPM. Basically, get the RPM up above the 1000 or 1100 baseline
such that you're applying meaningful torque to the drivetrain, and
you're in a much more efficient region of operation. This is why
pulse-n-glide works so well.
.
_H*

 

Short answer to original question: a tach is not of much use or interest to most Prius drivers.

<div class='quotetop'>QUOTE(hobbit @ May 5 2006, 10:19 PM) [snapback]250624[/snapback]</div>

Those graphs are for the first generation Prius. See the original document at http://www.transportation.anl.gov/pdfs/HV/2.pdf The 2nd generation probably has somewhat different curves, and may also have a different control algorithm, one which keeps engine RPMs in their most efficient range.

 

It'd be nice if Canview were to have a nice graphic interface; an improvement on the standard; one which you could add things like tach/fuel/etc..

And it may be cheesy, but <on the mfd> a nice analog-look tach would be kinda nice.

 

<div class='quotetop'>QUOTE(mrbigh @ May 6 2006, 08:50 AM) [snapback]250752[/snapback]</div>

got here yesterday, as a matter of fact...will install shortly

 

erm.. no. The curves for the third-gens may depart in very minor
ways from those for the Classic, but the methodology of running the
engine is the same. Constant high torque, pretty much, and
regulation of *power* output [torque * RPM] by governing RPM.
Evidence: I watch my vacuum gauge more or less snap down to 2 or
3 in-Hg, indicating high load, and then watch it stay down there
while RPM wanders all over the place based on my demand. Vac lifts
up again only when there's very little demand [and that's when you
start running inefficiently]. Same scenario as "driving with load"
espoused by the hypermilers over on cleanmpg.com. [Which, by the
way, could use more clueful Prius people hangin' out on it...]
.
_H*

 

<div class='quotetop'>QUOTE(prez1 @ May 14 2006, 10:52 AM) [snapback]255173[/snapback]</div>

I just wish the gauge was more linear. With my first long trip with the Prius (just got it 3 weeks ago), it was 288 miles before the first bar dropped off and at 410 miles the 5th bar had dropped off. Took 7.3 gal to refill. BTW I got 57mpg actual for the 800 mile trip from York,PA to Warner Robins, GA.

 

Does the Prius have some sort of governor to keep the engine from redlining? I was doing about 95 MPH in the car the other day (don't lecture me, I usually drive the speed limit, often under it). The car didn't have tach and didn't know how fast I could really push it. If so, anyone know the max RPM?

 

<div class='quotetop'>QUOTE(bigdaddy @ Sep 29 2006, 09:46 AM) [snapback]325631[/snapback]</div>

yes it's governed at 5000 RPM continous. That is a function of the relationship between the planet carrier and the sun (MG1) gear. MG1 has a designed limit of 10,000 RPM and the HV Computer controls the speed.

 

Keep in mind that we technologically-curious drivers are not the target market for the Prius. The target market is people who just want to get from here to there in a clean and efficient car. They don't want to be bothered with dials and gauges. They don't want to be bombarded with information about the operating parameters of the car. They just want to drive it. And they want it to "feel" like an automatic (thus the way the prius mimicks an automatic when you take your feet off of both pedals.).

We are such a small piece of the market, that it's not worth it to Toyota to even include screens that other drivers could shut off, because then they'd have to put it in the owner's manual, and that would confuse the folks who don't want to think about that stuff.

As for CAN-View on the '06, Norm is one guy who does this as a hobby in his basement. He does not own an '06 to play with, and he does not have the means to get the necessary details. I imagine that if someone could give him all the technical specs, he could build a CAN-View for the '06.