Other way of advertising engine output?

[dudejo]

What if they displayed the vehicle speed at which the engine is running at its peak RPM?

For example, 150 hp @ 110 MPH.

Let's take a sample case. The latest model of the Dodge Ram HD has gas engines with equal or greater HP ratings than its Cummins diesel.

However, with everything else being equal, the diesel engine generates its peak HP at much lower RPMs, which would result in a lower top speed.

It would look something like this (the top speeds are fictional) :

5.7L Hemi (light load) : 385 HP @ 125 MPH

Ford 6.2L Gas (heavy load) : 315 HP @ 95 MPH

6.7L Cummins : 385 HP @ 70 MPH

 

[LMSCorvetteGT2]

...Yeah so what? I'm confused why to change from how it is

You're premise to advertise is only a one track mindset. First off at highway towing speeds the Ram shouldn't ever be doing 70 with the diesel. Also the power is at the lower end cause it's a diesel that only peaks a 5k rpm to begin with and you don't care about speed to begin with. Torque is the important figure, and no one buying a truck cares how much power you have when you're going a certain speed.

Also another reason why output advertising with speed in mind is bad, is because the power band (rpm range) is the true mark of how much torque or power you have at a given time. So if my car peaks at 6000rpm and I'm doing 65 as I shift to 3rd...why would that be wise to advertise 410hp @ 65-70 mph? Also every time I peak I'm doing so at different mph and not just a single one. Also it may be different from driver to driver, a person driving better than me could maybe achieve the same power but at a slightly lower mph before having to shift.

 

[Casey]

Weight also makes a car go slower or faster.

 

[dudejo]

...Yeah so what? I'm confused why to change from how it is

You're premise to advertise is only a one track mindset. First off at highway towing speeds the Ram shouldn't ever be doing 70 with the diesel. Also the power is at the lower end cause it's a diesel that only peaks a 5k rpm to begin with and you don't care about speed to begin with. Torque is the important figure, and no one buying a truck cares how much power you have when you're going a certain speed.

Also another reason why output advertising with speed in mind is bad, is because the power band (rpm range) is the true mark of how much torque or power you have at a given time. So if my car peaks at 6000rpm and I'm doing 65 as I shift to 3rd...why would that be wise to advertise 410hp @ 65-70 mph? Also every time I peak I'm doing so at different mph and not just a single one. Also it may be different from driver to driver, a person driving better than me could maybe achieve the same power but at a slightly lower mph before having to shift.

The indicated speed is what the vehicle can theoretically achieve when running in top gear. So, taking your example of 410 HP @ 65-70 MPH, that would be the fastest your vehicle can possibly go while the engine is making 410 HP.

Also, a lower speed indicates shorter gears, which means more power. If someone asks why they should buy the diesel, even though its output difference vs the gas engine is small, comparing the vehicle speeds will quickly show the diesel's advantage in power.

In the case of comparing equivalent cars, a higher top speed could indicate better potential fuel economy. Generally, that means the engine is running lower RPMs at highway speeds.

 

[LMSCorvetteGT2]

The indicated speed is what the vehicle can theoretically achieve when running in top gear. So, taking your example of 410 HP @ 65-70 MPH, that would be the fastest your vehicle can possibly go while the engine is making 410 HP.

Also, a lower speed indicates shorter gears, which means more power. If someone asks why they should buy the diesel, even though its output difference vs the gas engine is small, comparing the vehicle speeds will quickly show the diesel's advantage in power.

No it wouldn't not any more or any easier than the standard method to advertise such powers. Also the thing that you still neglect is that the power out for diesel first and for most is towing capacity which has more to do with what size truck and torque output you're getting than anything else. So power @ velocity isn't actually of much use since no one will care at what speed you get to to have full power, when the torque comes on at a lower rating. That was my first and most important point I was trying to convey about your post.

In the case of comparing equivalent cars, a higher top speed could indicate better potential fuel economy. Generally, that means the engine is running lower RPMs at highway speeds.

Really so let's take your idea and put it to the test.

I'll use a 488 GTB vs a Z06 Vette two cars in the same powerhouse and both force inducted, thus it can be said fuel economy will in cases of HWY velocity be effected in a beneficial matter compared to conventional NA.

So as you can see both have peak power round the same range and both have peak torque at slightly different ranges. The point being that the Ferrari and Vette (both seven speeds in manual/pdk form) may or may not have that big of a variation in gear ratio since both are claimed to be 200 mph cars. So the point is if you're trying to reach that max power output your not going to do so at highway speed, so what relevance to me or anyone interested in buying one over the other is it to tell us what speed they hit at peak power.

The peak power is going to be hit every time that driver gets into the 6500 range on both cars, however that speed isn't going to be the same. If I'm say drag racing or even track racing these and giving it full tilt these cars will experience 6.5k every time I go up the gears, but the velocity wont be the same. So again what does a relative velocity mean to it all?

Also how does your analysis really get rid of the mpg measure, yes gearing has an effect but once you get to the ideal velocity to start saving the electronics on board do the rest so long as the driver doesn't modulate much.

EDIT: most important part I forgot to add (shame on me) is that velocity has many factors and one of them in the case of cars is power, however it's not the end all end. And thus using it to be represented as such is wrong and misleading and basically gives a fictional idea of one car to another. Weight as @caseycar5 said is another factor. Coefficient of friction with the ground is another, so tires between the cars, air coefficient, and the coefficient of drag. As well as COG. All these things you're taking for granted all play into the reason a car hits a certain speed at a certain power.

 

[Imari]

Also, a lower speed indicates shorter gears, which means more power.

Shorter gears doesn't mean more power, it means shorter gears. The gearing has absolutely no effect on the power the engine puts out, it's a completely separate thing.

It has a big effect on how the vehicle is used though, which is why offroaders have low range boxes. I see no reason to conflate two wholly separate things, gearing and engine power. I mean, you can already calculate what you want very easily if you choose from the information given. Manufacturers give you engine power, gear ratios and wheel diameters, so if anyone cares then they can do it themselves. But I fail to see what sort of consumer would actually prefer this number to straight up power/torque.

Were this to somehow become a thing, I could see manufacturers sticking a ridiculously high top gear on vehicles that isn't intended for actual use, but is just there to boost this entirely theoretical number.

That's where this falls down, IMO. It's not even a real world testable value, the car doesn't have to be able to actually do it. You could get the same value as a Viper by taking the Viper drivetrain out and mounting it to a brick shed.

That, and that it assumes that everyone actually cares about speed. Ironically, the case that you used as an example, trucks, really don't care much at all. A truck is not a race car, the point is not to do 120 mph. The point is to move :censored:loads of weight all at once.

 

[Mikeybc]

I'd rather know what my engines characteristics are with HP and torque figures throughout a range of RPM's rather than be given a theoretical speed at a fixed (max HP) HP figure. I can't see how that tells you anything useful in real world driving. It seems pretty vague.

 

[VXR]

In instrumented tests, you will get a table showing mph per 1000 rpms, so for example, a longer geared car hitting 40mph for every 1000. However this is when you get into theoretical speed, as there's no way it's going to have a final drive that sees a six speed diesel achieving 200mph in top gear.

 

[LMSCorvetteGT2]

In instrumented tests, you will get a table showing mph per 1000 rpms, so for example, a longer geared car hitting 40mph for every 1000. However this is when you get into theoretical speed, as there's no way it's going to have a final drive that sees a six speed diesel achieving 200mph in top gear.

Unless Audi starts selling R18s

 

[dudejo]

I'll use a 488 GTB vs a Z06 Vette[...]

Corvettes have better mileage. While I can't speak for the newer 7-speed, their 6-speed has traditionally included an extremely tall 6th gear. Even before the introduction of cylinder deactivation, their MPG was easily comparable to engines almost half its displacement.

It has a big effect on how the vehicle is used though, which is why offroaders have low range boxes.

Maybe because the low drive gives them more power? This is also why some of them get engines like the Cummins 4BT, even if it's HP rating isn't particularly high. While the slower engine limits top speed, they have a lot more power to work with.

Were this to somehow become a thing, I could see manufacturers sticking a ridiculously high top gear on vehicles that isn't intended for actual use, but is just there to boost this entirely theoretical number.

They already do this with HP figures. For example, the current 4.8L engine in Chevrolet vans is rated at 280+ HP. However, you need to push the engine at 5500 RPMs to get this.

An old Ford 300 straight-six, while it can't run as fast, will make almost the same HP the 4.8L would at those slower RPMs.

I could replace 4.8L with the old Ford 300 and chances are, the average driver wouldn't notice.

 

[Imari]

CMaybe because the low drive gives them more power? This is also why some of them get engines like the Cummins 4BT, even if it's HP rating isn't particularly high. While the slower engine limits top speed, they have a lot more power to work with.

You need to get on Wikipedia and actually read up on what engine power is and how it works. It's not related at all to the gearing of the drivetrain.

What you appear to be getting confused with is torque at the wheels. That depends on the torque the engine produces, the gearing, and the wheel diameter(Edit: My bad, wheel diameter has nothing to do with torque at the wheels.). If you gear something low enough, you can pull a jumbo jet.

They already do this with HP figures. For example, the current 4.8L engine in Chevrolet vans is rated at 280+ HP. However, you need to push the engine at 5500 RPMs to get this.

What? How is having a revvy engine like bolstering a fake figure by sticking an entirely useless top gear on a car?

An old Ford 300 straight-six, while it can't run as fast, will make almost the same HP the 4.8L would at those slower RPMs.

Which is why power figures are quoted at a certain torque. Because everyone knows that an engine that produces the power peak early is likely to have torque curve that's heavily biased towards the low RPM range. Whereas screaming engines with peak power near the redline tend to have more flat torque curves.

That's a reasonably standard RX8 dyno. Torque is basically flat, power just climbs and climbs as the revs go up, what with power only being torque x rpm and all. That's what it feels like in the car too, it just pulls harder and harder the faster you go.

Compare that to your average diesel, where the torque comes in hard low down but the engine can't rev high enough to actually generate significant power with it. Because of how power is calculated. If a rotary was limited to 5500rpm it'd still feel the same driving it around every day*, but the power number on paper would be way down. To like ~150hp, according to that graph, instead of the ~220 it's usually at.

This is why we quote HP and torque, and we quote them at certain RPMs. Even that's a simplification, although if you know what you're talking about you can make reasonable assumptions about the character of the engine from just that information. I don't see what value you're bringing by obscuring how the engine behaves even more.

What does your figure tell you about the engines performance that the current HP and torque values do not?

Also, think about this. Why does an S2K rev to 9000, yet your Chevy 4.8 only goes to 5500? Why doesn't the S2K keep revving to 12000, and get more power? Why doesn't the 4.8 go to 9000? There are sports bikes that get to damn near 20k rpm, so why not do it with a car or truck?

*Mostly, there's a thing with rotaries where you really should flog them to redline at least every few days to clean the crap out of them. It's not really rough on the engine, and it (supposedly) stops junk building up and damaging your seals. But the point stands that you wouldn't miss the top end for daily driving.

I could replace 4.8L with the old Ford 300 and chances are, the average driver wouldn't notice.

Because an average driver isn't thrashing their engine to the max. Unless you're actually using that peak power, you're not going to notice that it isn't there. If someone is just cruising around town hauling shopping and the kids, you could replace it with a 2 litre inline 4 and they probably wouldn't notice either.

You know how some engines cut cylinders at cruise to save fuel? Why does that work? Because they're not needed, so the driver doesn't even notice that they're not firing. Ditto extraneous performance in general.

 

[dudejo]

What you appear to be getting confused with is torque at the wheels. That depends on the torque the engine produces, the gearing, and the wheel diameter. If you gear something low enough, you can pull a jumbo jet.

Ok, so we use different terms. I don't see how that changes anything. I just use power as a general term for overcoming resistance. Such as heavy loads like your jumbo jet example.

What? How is having a revvy engine like bolstering a fake figure by sticking an entirely useless top gear on a car?

What about existing cars with 8-speed transmissions? Is that not excessive? The only vehicles that really DO need that many gears are semi trucks.

What does your figure tell you about the engines performance that the current HP and torque values do not?

It tells me what happens after we run 9000 RPMs through all the multipliers.

Because an average driver isn't thrashing their engine to the max. Unless you're actually using that peak power, you're not going to notice that it isn't there. If someone is just cruising around town hauling shopping and the kids, you could replace it with a 2 litre inline 4 and they probably wouldn't notice either.

In what scenario would a half-ton van EVER need 280+ hp?

As for your other example, it's not the same. In my example, we're trimming away excess power in speed ranges the truck never needs to use.

In your example, you're losing power across the board. Not only will it be noticed by the average driver, your example vehicle would quickly gain a reputation as a gutless POS.

 

[VXR]

The 8/9/10 speed boxes allow them to fit a range of ratios to maximise acceleration in lower gears and economy in the higher ones don't they?

 

[dudejo]

The 8/9/10 speed boxes allow them to fit a range of ratios to maximise acceleration in lower gears and economy in the higher ones don't they?

For a daily driver, this is simply overkill. You get much higher complexity for marginal gains.

Also, you get a lot of needless shifting since the computer has to deal with more gears.

 

[Imari]

Ok, so we use different terms. I don't see how that changes anything. I just use power as a general term for overcoming resistance. Such as heavy loads like your jumbo jet example.

You should probably say that then, because "power" has a specific meaning when applied to engines.

Both power and torque have very specific meanings when applied to engines. Either specify that you're using them differently, or make up your own word. Dudejo-power or something. Then you can tell us exactly what Dudejo-power means, because we're not telepaths and we can't read your mind.

What about existing cars with 8-speed transmissions? Is that not excessive? The only vehicles that really DO need that many gears are semi trucks.

It's totally excessive. I didn't say that manufacturers don't boost other silly numbers. I'm just not for giving them more opportunities to do it.

It tells me what happens after we run 9000 RPMs through all the multipliers.

No, it doesn't. Because you're running the power peak RPM for the engine through all the multipliers.

I don't think you get how this math thing works.

In what scenario would a half-ton van EVER need 280+ hp?

Are you making my point for me or what?

As for your other example, it's not the same. In my example, we're trimming away excess power in speed ranges the truck never needs to use.

I really think you don't get how this math thing works.

You know that cars have multiple gears, right? There's no such thing as losing power at X speed, because if that's true then you just drop down a gear. Unless you're going to bang into the rev limiter, but gearboxes are generally designed better than that.

What the manufacturer is doing is building a torquey engine, but the way that is done generally means that it won't rev high. So you get good torque down low, you get to use a sensible set of gears so that the driver doesn't feel like they're in an 18 speed lorry, but you give up being able to rev the nuts off it. That's giving up power (in the traditional sense) at rev ranges that the driver won't use, for torque (which is what does the work anyway) at rev ranges that they will use.

If someone's driving around all day at 2-4krpm then they don't care what the engine does above that. That's not about speed, because you can easily be doing 70+ mph at well less than 4krpm in pretty much any car. It's about revs, and torque.

In your example, you're losing power across the board. Not only will it be noticed by the average driver, your example vehicle would quickly gain a reputation as a gutless POS.

Never driven a Hiace, eh?

Losing power across the board was the point. You don't miss 100% of the power you don't use. If someone tootles around town only using 100hp, then anything in excess of that won't be missed at any rev range. As you said, a half ton van doesn't need 280hp, so you can easily fit a smaller engine and still not have anyone notice the difference.

 

[LMSCorvetteGT2]

Corvettes have better mileage. While I can't speak for the newer 7-speed, their 6-speed has traditionally included an extremely tall 6th gear. Even before the introduction of cylinder deactivation, their MPG was easily comparable to engines almost half its displacement.

To bad .gov epa sites say differently and that both cars are exactly the same mpg. So that's a knock against your method of advertising.

 

[dudejo]

I really think you don't get how this math thing works.

Yes I do.

RPM * gear ratio * transfer case ratio * differential ratio * tire diameter = x MPH.

A lower top speed at y RPM = more wheel torque.

A HIGHER top speed at y RPM = less wheel torque.

Therefore, 100 HP @ 100 MPH has less wheel torque than 100 HP @ 50 MPH.

Which is the WHOLE point of displaying the freakin' top speed IN THE FIRST PLACE.

To bad .gov epa sites say differently and that both cars are exactly the same mpg. So that's a knock against your method of advertising.

Ferrari 488 GTB : https://www.fueleconomy.gov/feg/noframes/36942.shtml

Corvette C7 : http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=35318

I call absolute bull on your claim.

 

[Imari]

Therefore, 100 HP @ 100 MPH has less wheel torque than 100 HP @ 50 MPH.

I'm not sure about that. Speed says nothing about rpm. 100hp @ 5000 rpm gives you the same torque regardless of how fast you're going. The gear ratios can be equal all the way through to the wheels, which gives you the same torque at the wheels, and the only thing making the difference in speed could be wheel diameter.

Say that we've got two cars, identical engines, identically geared drivetrain. The only difference is the wheel sizes.

http://www.tyresizecalculator.com/tyre-wheel-calculators/tire-size-calculator-tire-dimensions

Car 1 has 185/50R13's on it, which by the handy calculator I linked above works out to 997 revolutions per mile. So if we assume that this car is doing 50mph, that'll be 49,850 revolutions per hour.

Car 2 has some really big wheels on it, 255/65R26's. Which is retarded, but people do all sorts of dumb stuff to their cars. The handy calculator says 539 revolutions per mile. So at 49,850 revolutions per hour (the cars are geared identically, remember) it would be doing ~92.5 miles per hour.

Well, I got close.

So you see, exactly the same torque at the wheels through exactly the same drivetrain from an engine with exactly the same power can end up at a hugely different speed, simply because I put great big donking wheels on Car 2.

If you want to take into account the size of the wheels, then you might as well start taking into account things like the weight of the car, and it's aero efficiency, and all the other things that actually make a difference. If you want to try and boil a car down to one holistic number, then be my guest. But what you've got so far isn't it, and it isn't even close.

Which is the WHOLE point of displaying the freakin' top speed IN THE FIRST PLACE.

And so why are you bringing speed into the equation? What useful information is given by saying 100hp @ 100mph that isn't already given by saying 100hp @ 6600 rpm?

Power as it's advertised now is purely a measure of the engine. What you're proposing is a composite number based on the engine, various gear ratios around the vehicle, and the tire diameter. Why is this composite number preferable to having all these numbers separately?

What does it tell you about real world performance that the current style of HP and torque figures do not?

You're too attached to this idea. It was interesting, but it doesn't work. Let it go.

 

[TexRex]

Sorry.

 

[LMSCorvetteGT2]

Ferrari 488 GTB : https://www.fueleconomy.gov/feg/noframes/36942.shtml

Corvette C7 : http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=35318

I call absolute bull on your claim.

That's nice you can call what ever you want, I used the actual Z06 numbers and not the C7 Stingray numbers. So call what ever you want but get your facts in order before doing so.

 

[Beeblebrox237]

You're too attached to this idea. It was interesting, but it doesn't work. Let it go.

This. This measurement isn't overly comparable and hides information about the engine that could be inferred from the accepted set of stats.

 

[dudejo]

What useful information is given by saying 100hp @ 100mph that isn't already given by saying 100hp @ 6600 rpm?

I already explained myself several times. I'm not doing it again.

100hp @ 5000 rpm gives you the same torque regardless of how fast you're going.

Is that why my car stalls every time I launch it in a higher gear than 1st?

BTW, doesn't the Z06 have a shorter top gear than the base model Corvette?

 

[TenEightyOne]

Weight also makes a car go slower or faster.

Not necessarily, it makes it more difficult to accelerate or de-accelerate. This has been covered plenty of times.

 

[LMSCorvetteGT2]

Not necessarily, it makes it more difficult to accelerate or de-accelerate. This has been covered plenty of times.

I think his point is if we go off of what the OP suggest two cars one heavy one lighter but with the same power will achieve this silly mph @ hp figure. Even though they have the same power but the mph is different because of the acceleration like you said.

 

[Tornado]

Even before the introduction of cylinder deactivation, their MPG was easily comparable to engines almost half its displacement.

To normally aspirated engines almost half of its displacement.

 

[dudejo]

I think his point is if we go off of what the OP suggest two cars one heavy one lighter but with the same power will achieve this silly mph @ hp figure. Even though they have the same power but the mph is different because of the acceleration like you said.

When did my opening post mention ANYTHING about weight influencing the speed?

Learn to read.

 

[Tornado]

I knew this thread reminded me of something.

 

[Exorcet]

A better way to advertise engine performance would be showing the powerband and gearing.

Power @ speed doesn't really mean anything, we have transmissions to decouple those two things.

 

[TenEightyOne]

I knew this thread reminded me of something.

So it does, how did @dudejo forget he'd always made this thread?!

He should

Learn to read.

 

[dudejo]

So it does, how did @dudejo forget he'd always made this thread?!

He should

At least my fame precedes me this time.