Why don't cars display total revs?

cruizer101

So as the title says why don't cars display total revs, if it was displayed alongside the total mileage it would give a good indicator of how the car has been driven.

E.g. If a car drove 10,000 km in 5th at 100 km/h at 2000rpm that would be 12,000,000 total revs.
If a car drove 10,000 km in 4th gear at 50 km/h at 1500rpm that would be 18,000,000 total revs.
If a car drove 10,000 km in 3rd gear at 33km/h at 1500rpm that would be 27,000,000 total revs.

That gives mileage to revs ratios of 1:1200, 1:1800, 1:2700.

By looking at this ratio it gives a good indicator of how the car was driven and the actual engine wear.
I often wondered why timing belt and many other service items are based on mileage.
I know my examples are extreme and the reality will be a combination of this but I think it is still relevant, and in this day and age I reckon all that would be needed is update of software to record it the sensors and all that are there.

jimgoose

Not a bad idea. In fact, it's already been patented:

http://www.google.com/patents/US9008947

vintagevrs

A similar idea would be what they have on plant and farm machinery, a running time clock. Would give a similar indication. You could compare two cars with 100k miles but one has 30% more time clocked up. Similar to the revs, and something maybe more people would understand.

jimgoose

vintagevrs wrote: »

A similar idea would be what they have on plant and farm machinery, a running time clock. Would give a similar indication. You could compare two cars with 100k miles but one has 30% more time clocked up. Similar to the revs, and something maybe more people would understand.

It would be tasty to have total engine spins and running hours logged in the ECU and available under core powertrain OBD-II, so them as are interested can access the data with cheap little scanners.

cruizer101

jimgoose wrote: »

Not a bad idea. In fact, it's already been patented:

Ah feck, filing date Oct 6, 2014, I had thought of this years ago, tis amazing the kind of stuff you can patent.

Hadn't realised plant machinery had that, makes sense, a digger sits there digging not moving about.

vintagevrs

cruizer101 wrote: »

a digger sits there digging not moving about.

Black_Knight

Taxi's would be interesting to see. Might help with the sale of start/stop technology too.

HandsomeDan

At lower ratios there is less loading, so despite the extra revs the wear difference is not as great as you might think. A doubling of revs/kilometer doesn't mean a doubling of wear, in other words.

BMJD

The counter would go mental when VTEC kicks in yo!

LawlessBoy

Or someone with a rotary engine

Bruthal

cruizer101 wrote: »

E.g. If a car drove 10,000 km in 5th at 100 km/h at 2000rpm that would be 12,000,000 total revs.

The speed would be irrelevant really. 10,000km in 5th gear will be 12,000,000 revs.

Fred Swanson

This post has been deleted.

millington

Would only be useful for comparing 2 cars with the same engine, gearbox, diff, wheel & tyre size as all affect the RPM/speed ratio.

StereoSound

The granny next door revving the car to 7k rpm reversing out the driveway at 0.5kph.

gctest50

You get a version of this with generators, service it more often if its running 60Hz ( American etc power stuff) instead of 50Hz

60Hz = 1800rpm 50 = 1500rpm

unless tis all fancy with CVTs inverters n stuff

MojoMaker

cruizer101 wrote: »

E.g. If a car drove 10,000 km in 5th at 100 km/h at 2000rpm that would be 12,000,000 total revs.
If a car drove 10,000 km in 4th gear at 50 km/h at 1500rpm that would be 18,000,000 total revs.
If a car drove 10,000 km in 3rd gear at 33km/h at 1500rpm that would be 27,000,000 total revs.

Back to school for a maths refresher for you I think

ironclaw

MojoMaker wrote: »

Back to school for a maths refresher for you I think

10,000jm / 100kmh = 100 hours -> 6000 mins

6000mins @ 2000rpm = 12,000,000 Total

10000km / 33kmh = 303 hours -> 18180 mins

18180 mins @ 1500rpm = 27,270,000 Total

Unless I've done something wrong there, its correct.

Although I see absolutely no benefit to this. It makes sense on a static-ish piece of machinery e.g. A Generator but for a car, with a lifetime perhaps many multiples of a generator, with service intervals, varying road conditions and maintenance, its an entirely useless metric in my opinion. In this example it would be skewed as the faster you drive for longer, the less revs total you will have, ideally you'd want to minimise your time at lower revs, so you benefit by driving harder in the acceleration phase to maintain a longer time at lower revs at the top end (Obviously some sweeping generalisations there) You're also assuming all cars are equal, an enthusiast loved RX8 would have astronomical Rev Totals, whilst a cruising motorway diesel might have nothing at all but an owner who filled it to the brim with dodgy fuel weekly.

Sh1tbag OToole

Pity opensource ECU's are not more common. They could record all sorts of interesting stuff

*Total distance traveled by each piston
*Number of sparks per spark plug (with reset for when you change them)
*Number of rotations for each wheel
*Distance traveled in each gear

From the sensors that are already fitted in every car you should be able to derive a whole lot more statistics than you can get from the ECU but feck it cars are made to be consumer-friendly so they hide or don't bother calculating the real interesting numbers. It would be fierce handy for identifying dodgy fuel and parts that will need replacing soon

gctest50

You can get/make dataloggers

http://www.comap.cz/products/detail/id-mobile-logger

• 8 Binary inputs
• 11 Configurable analog inputs
• 1 x Frequency input for RPM measurement
• 2 x Impulse inputs
• Communication Interface RS485, 2xCAN, J1939
• Running-hours meter, number of starts counter, battery voltage measurement
• Integral fuel consumption measuring

ironclaw

One of the issues there is the pure volume of data. The newest Airbus generates a couple of Terabytes of info each time it flies. Your average consumer car, whilst not completely comparable, would easily be able to generate a few GBs every week or so, depending on how you drive. You need to 1) store all that data and 2) process it. Both are significant challenges, the processing especially. To get a really good picture of a car, you would need a really good mathematical model and the horsepower to process it. Telsa I believe are doing this, but its by upload over night to a central server farm and there user base isn't too big yet. There are privacy issues there as well. Systems exist to do this in industry but its not really worth mining to the company. Cars needs parts at some stage, its of no benefit to a manufacturer to know when its needed precisely as supply chains and rough estimates from past experience are accurate enough.

All told, good idea, but we're not quite at stage were its feasible at a consumer level in my opinion.

Bruthal

StereoSound wrote: »

The granny next door revving the car to 7k rpm reversing out the driveway at 0.5kph.

A total revs counter won't show that.

Fred Swanson

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Fred Swanson

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Jayop

I wouldn't be able to let the missus drive anymore, she's flat out at 60mph in 4th gear.

gctest50

Fred Swanson wrote: »

This post has been deleted.

they all have that






20meg original here :


www.blog.caranddriver.com/wp-content/uploads/2012/04/Alfa_Midair_Rod-DeeBaldwin-HIRes-NoCallout.tif

H3llR4iser

I honestly can't see the point of it; An engine is designed for a certain range of RPMs which are safe to use - better still,it's usually a good idea to actually use the whole range. There's a reason manufacturers put a limiter - it's where things begin to be a bit unsafe (normally involving valve recall and possible impacts with the piston head).

Every single car I ever owner I have used the full range of the engine - note I never had a diesel car. Now, that doesn't mean bombing at every traffic light and always changing up at 7000rpm, but driving fluently without being worried about "never go above X rpm!" where X is a totally made up number - 2000, 3000, 3500, you pick. It means going to a lower gear if, for example, the car is struggling a little bit going on a steep uphill struggle and yes, why not, every now and then even pushing near the redline (or wherever the torque dies off, which on some engines happens way before redlining) if conditions/traffic allow. Never had a single issue, considering I always kept proper, even preemptive maintenance - at least the fluids should always be kept reasonably fresh.

Actually, I swear it kept the engine in a more reactive and "elastic" state; I did on a couple of occasions drive different examples of the same car I owned, which the owners used to drive with the "egg under the pedal", and they invariably felt sluggish.

It was the same for my current car - when I got it, it had been on "school bus duty" for a couple of years, start stop driving afraid of building rev. It felt sluggish as hell, but nothing a couple of Italian tune-ups didn't cure.

I might or might not recall this correctly, but I seem to have a foggy memory about one of the Twin Spark Alfas I had (might have been the 155) explicitly saying on the owner's manual to use the full torque curve. That 155 was unfortunately scrapped when I left Italy, but the engine was still pristine - it lived on to power another 155, even with nearly 250k in its "career".

Now, I would actually be more wary of an engine that was constantly driven at low RPMs. Most people, especially the ones driving diesels, have a nasty tendency to lug the engine down - e.g. trying to go uphill in 5th, or accelerating from near idle RPMs in a relatively high gear. That form of driving is actually putting the highest possible load on every single engine component, increasing the level of metal fatigue. With a "total rpm counter", that kind of driving would actually seem good.

And then there's grandma doing 17kph in 1st at 7300rpm with her left foot half down on the clutch. That's a completely different story.

aidanki

would it not be better have something record the average miles per gallon since car and say the miles per gallon over the last 10 trips greater than 20miles

give a v good idea if the ****e has been driven out of the car

tractors and plant by the way have moved away from recording hours at a certain engine rpm to recording simply running hours, Im not sure why

I do have another question - lets say 2 of the same model engine one tuned to 150hp and another to 170hp both engines are well capable of this power btw, both are driving generators in a factory, thus loads vary a bit so up and down, but every now and then they hit peak power for 10-15min intervals, however both are full revving at all times, thus they have done the v same number of revolutions in 10k hours

both engines are serviced on time

which is more worn after 10k hours operation ?, the lubrication should be doing its job and protect them, thus are they equally worn

the crankshaft will be more tired I guess in the 170hp setup but how about the bearings etc, should the lubrication protect them from wear and tear so both sets are equally worn

Most of the engine wear happens on cold starts (the colder the worse the wear is) and while the engine is warming up. Apart from gross driver error (change to 1st at 100 km/h) or overloading the engine prolonged times at track etc. the condition of engine is much dictated by number of cold starts.

Of course engine will be damaged if oil changes are neglected. But the worse kind of driving you can do is to idle the engine for prolonged times when it's cold and then drive for a few hundred meters to the train station and then back 5 days a week. 10 cold starts a week and no chance for moisture to ever evaporate from the oil.

cruizer101

Bruthal wrote: »

The speed would be irrelevant really. 10,000km in 5th gear will be 12,000,000 revs.

I know the speed is irrelevant but thought it makes it bit clearer

ironclaw wrote: »

Unless I've done something wrong there, its correct.

Yeah I didn't think there was any glaring errors fair enough I did bit of rounding on the 33 km/h.

ironclaw wrote: »

Although I see absolutely no benefit to this. It makes sense on a static-ish piece of machinery e.g. A Generator but for a car, with a lifetime perhaps many multiples of a generator, with service intervals, varying road conditions and maintenance, its an entirely useless metric in my opinion.

H3llR4iser wrote: »

I honestly can't see the point of it;

Every single car I ever owner I have used the full range of the engine - note I never had a diesel car. Now, that doesn't mean bombing at every traffic light and always changing up at 7000rpm, but driving fluently without being worried about "never go above X rpm!" where X is a totally made up number - 2000, 3000, 3500, you pick. It means going to a lower gear if, for example, the car is struggling a little bit going on a steep uphill struggle and yes, why not, every now and then even pushing near the redline (or wherever the torque dies off, which on some engines happens way before redlining) if conditions/traffic allow. Never had a single issue, considering I always kept proper, even preemptive maintenance - at least the fluids should always be kept reasonably fresh.

Without breaking down the posts bit by bit, I would agree with a lot of what you are saying that a single measurement doesn't give you an full insight into how a car was driven. But a lot of the arguments could be used against mileage measurement as well.

Low mileage car may have been driven up and down to train station and rarely got a decent run, not good at all for the engine, but next user will know nothing of this will just see low mileage. Bar a full breakdown of complete driving history stored on ecu we can't know this, and that is not going to happen.

But given that ecu is constantly recording revs anyway it would be easy for it to just keep a running total, I see no harm in having more information when it is readily available.

gctest50

ironclaw wrote: »

........

Although I see absolutely no benefit to this. It makes sense on a static-ish piece of machinery e.g. A Generator but for a car, with a lifetime perhaps many multiples of a generator,...........

dunno about dat

Bruthal

ironclaw wrote: »

e.g. A Generator but for a car, with a lifetime perhaps many multiples of a generator,

Maybe for a small lidl/aldi generator for powering a drill in a field. But hardly for something like a €200k generator or the ones in generation stations etc.

ironclaw

Bruthal wrote: »

Maybe for a small lidl/aldi generator for powering a drill in a field. But hardly for something like a €200k generator or the ones in generation stations etc.

Well, a Micra and a €200k Merc are not exactly comparable either etc. Example was given in generalities. Also the maintenance contract on such a generation system along with the SCADA control systems & health checks, makes the comparison even less appropriate.

Bruthal

ironclaw wrote: »

Well, a Micra and a €200k Merc are not exactly comparable either etc. Example was given in generalities. Also the maintenance contract on such a generation system along with the SCADA control systems & health checks, makes the comparison even less appropriate.

Well a €200k car is not that likely to outlast the €200k generator by multiples of its lifespan.

Or a micra v a micra priced generator. Or maybe it does.