There is no replacement for displacement

[Captain Muppet]

Hello,

I'm not a fan of clichés, but sometimes they become clichés because they are true and it's a conversational short cut.

However sometimes they become clichés because they sound right and no one can be bothered arguing despite them making no sense. See my "handles like a kart" thread.

Over in the Viper thread this happened:

PascalBuyens said:

Contigo said:

Gotta love these "Lazy" engines, I mean an 8.0 V10 with only 450bhp

It blows the old adage "There's no replacement for displacement" right out of the water lol

I'd say it would not only confirm it, but cast it in stone, rather than 'blow it out of the water'?

I'm a big fan of logic, and the only thing needed to disprove the statement "there is no replacement for displacement" is to find a replacement for displacement, right?

So if we look at this data...

Cheburator mk2 said:

Hmm, let's see... the ORECA Le Mans cars as well as the Zakspeed N-ring 24hrs were around 620bhp... nigh on 40% more... consider they had to have restrictors too...

To get 40% more power the displacement did not increase by 40%.

There is a replacement for displacement, it's called engineering.

I know that someone is going to slag off tiny engines, and probably say something entirely valid like 160bhp 1.6 Vtecs don't have the same torque curve as a 160bhp 3.5 Rover V8. But in order for the cliché to be wrong we just have to imagine a 3.4litre engine that is not worse than the 3.5 litre one, and that's easy.

And then people are going to ask if making that 3.4 litre engine a 3.5 would make it better, and chances are it would, but bigger isn't always better because the extreme end of that argument is an engine that won't fit in a car, or do more than 100rpm, or burn petrol any more.

I'm not in any way knocking how much fun huge engines are, I like that you can gets lots of reliable power/torque for not much money. I even owned a deeply lovable 4.6 V8 for a while.

However it seems the cliché is wrong.

It'd be nice if people just said "I like big reliable engines" instead, but that doesn't rhyme or imply superiority over people with smaller engines than you, which are the two things that I suspect keep that stupid cliché alive.

Let the spelling corrections begin...

[Captain Muppet]

Happy Jim said:

You're missing the engineering point here. As the internal combustion engine is an Air Pump then the statement can only be true, any "engineering" is merely making more use of the available air, and simply increasing the size of the available air must be the easiest way to get more power (PS, as FI is "just" increasing the amount of available air, then all FI does is increase the effective displacement of the engine).

Simples

Jim

I like this bit: "simply increasing the size of the available air must be the easiest way to get more power". Yes it is, up to a point. But unless it's the only way, which it isn't, the cliche is still false.

Also you said "simples".

[Captain Muppet]

Just for all those who missed it in the OP and started talking about highly tuned tiny engines not being as good as huge simple engines:

Captain Muppet said:

I know that someone is going to slag off tiny engines, and probably say something entirely valid like 160bhp 1.6 Vtecs don't have the same torque curve as a 160bhp 3.5 Rover V8. But in order for the cliché to be wrong we just have to imagine a 3.4litre engine that is not worse than the 3.5 litre one, and that's easy.

[Captain Muppet]

ikarl said:

like for like engine, there is no replacement for displacement

Like for like engine they are the same displacement. Unless you mean if you increase the displacement with a given level of technology you get more power, in which case yes, no one is even toying with pretending that isn't true. More is more.

ikarl said:

Easy enough saying that if you turbo this or supercharge that the engineering can replace the displacement, but if you increase the displacement and then turbo it or supercharge it, you get more

But you also get "more" if you keep the displacement the same and reduce piston skirt friction, or any one of a thousand other things. And as we only need one of these things to be true in one case just once for prove the absolute statement "There is no replacement for displacement" wrong then I think the logical part of the discussion has to be pretty much done already.

[Captain Muppet]

Gaz. said:

The cliche isn't false - I say this as someone with a pair of engines with over 100bhp/litre and owned many turbocharged cars.

More is more. Why can't you have a 7.0 litre V8 rev to 8000 rom, or supercharge it? Or the naughtiest cams you can get away with?

I could get my S2000 up to 450bhp with a supercharger, but a 6.3 litre LS3 starts at 430bhp....

What displacement increase do you need to get your S2000 to 450bhp from 240bhp?

[Captain Muppet]

300bhp/ton said:

Captain Muppet said:

Gaz. said:

The cliche isn't false - I say this as someone with a pair of engines with over 100bhp/litre and owned many turbocharged cars.

More is more. Why can't you have a 7.0 litre V8 rev to 8000 rom, or supercharge it? Or the naughtiest cams you can get away with?

I could get my S2000 up to 450bhp with a supercharger, but a 6.3 litre LS3 starts at 430bhp....

What displacement increase do you need to get your S2000 to 450bhp from 240bhp?

I would guess something like 14psi of boost or more, so effectively forcing twice the amount of air into the engine making it when running under boost a 4.0 litre engine.

This is no different to filling a dive tank with O2 by compressing it thus allowing you to carry more for a given physical displacement.

So using a device to make it seem like it's more capacity is the same as giving it more capacity? Yet somehow not a substitute for more capacity.

Lets assume I have no problem with that. I do, but getting agreement will never happen.

So moving on: What if you add a low friction coating to your pistons, machine away the side of the cam bearings that don't see any load and replace your hydraulic tappets with shim and bucket. What you've done is reduce frictional losses. For the same capacity, and even the same air going in to the engine, you are getting more out of it. It's not as cheap, or simple, as just making the engine a tiny bit bigger, but it has the same effect (apart from it also reduces your fuel use, which we can ignore because no one cares).

[Captain Muppet]

300bhp/ton said:

kambites said:

As I said, the shape of the torque curve, and the responsiveness of the throttle matters; the capacity only matters in how it effects these things and how it effects the weight of the engine.

But how do you significantly affect the torque curve, especially at low rpms without doing something to displacement?

I'll try to ignore your use of "rpms" and just say "variable inlet manifold".

[Captain Muppet]

quiraing said:

Across the same rev-range you could never achieve the same torque from a small hi-spec stressed 1.6 or 3-litre, (or whatever), against maybe a lazy 7.2 V8.

But could you make a 7.1 V8 better than a lazy 7.2 V8? Yes. Thus cliche is wrong.

[Captain Muppet]

300bhp/ton said:

doogz said:

300bhp/ton said:

But surely a variable inlet manifold isn't allowing more low rpm/revs torque, it just means you don't strangle it once you have it spinning quicker.

No, the clue is in the name.

http://en.wikipedia.org/wiki/Variable_length_intak...

Ta. But all it's doing is allowing you to optimise it for different rpm ranges. You could have a static intake manifold optimised for max low rpm torque and it'd be just as effective at that rpm range.

But without a VIM your won't also meet your power target. So you'd need a bigger engine to make the same torque and power, unless you had a VIM.

[Captain Muppet]

300bhp/ton said:

Captain Muppet said:

quiraing said:

Across the same rev-range you could never achieve the same torque from a small hi-spec stressed 1.6 or 3-litre, (or whatever), against maybe a lazy 7.2 V8.

But could you make a 7.1 V8 better than a lazy 7.2 V8? Yes. Thus cliche is wrong.

But could you make a 7.2 V8 better than a lazy 7.1 V8? Yes. Thus cliche is right.

You only need one bit of data to prove that a statement isn't true.
You can't prove it's true using one bit of data.

[Captain Muppet]

300bhp/ton said:

Captain Muppet said:

300bhp/ton said:

kambites said:

As I said, the shape of the torque curve, and the responsiveness of the throttle matters; the capacity only matters in how it effects these things and how it effects the weight of the engine.

But how do you significantly affect the torque curve, especially at low rpms without doing something to displacement?

I'll try to ignore your use of "rpms" and just say "variable inlet manifold".

What if it already has an intake manifold design to make the most torque at low rpms it just doesn't perform so well at higher ones. How then do you make more torque at low revs?

I'm not going to go through the entire history of engine tuning with you bit by bit. But variable compression ratio or converting to 2-stroke would do it.

It is possible to build an engine with a given limit of capacity that is better than an engine of equal or greater capacity that has a lower level of technology. This disproves that there is no replacement for displacement.

You can also get more out of an engine for a given level of technology by increasing the capacity. Obviously. No one has pretended otherwise.

[Captain Muppet]

JamesK said:

You're all boring!!! A good biggun ALWAYS beats a good littlun. This is true with any comparable intervention, be it money, design, equipment. The end.

I'm assuming you're married to a fat bird.

[Captain Muppet]

300bhp/ton said:

Captain Muppet said:

But without a VIM your won't also meet your power target. So you'd need a bigger engine to make the same torque and power, unless you had a VIM.

So no replacement for displacement then

There is no replacement for comprehension.

[Captain Muppet]

300bhp/ton said:

Captain Muppet said:

You only need one bit of data to prove that a statement isn't true.
You can't prove it's true using one bit of data.

I'm not sure saying do something to one engine and not another is really proving a statement isn't true though.

Take the same engine in two different displacements, Rover K Series maybe, 1.6 and 1.8

You can easily get the 1.6 to out perform the 1.8 by doing many of the things cited in this thread. But do those same things to the 1.8 and it will always make more power and torque than the 1.6

There may be alternative tuning methods to attain greater performance, but all other things equal there is no replacement for displacement.

Oh absolutely, if you change the statement by adding clauses to it you can make it true.

[Captain Muppet]

300bhp/ton said:

Captain Muppet said:

It is possible to build an engine with a given limit of capacity that is better than an engine of equal or greater capacity that has a lower level of technology. This disproves that there is no replacement for displacement.

Curious, but how does it disprove it?

I just don't understand how this isn't simply an alternative, rather an replacement?

I would like to continue this discussion with either an alternative 300bhp/ton or a replacement 300bhp/ton.

[Captain Muppet]

minime68 said:

But the topic is about displacement not bigger turbos. You can say " well a turbo can replace displacement". No it cant. Lets say with a smaller FI engine, you make the same power as bigger N/A engine. The NA engine will have a much better power curve. I'm too lazy to write a whole write-up on it so ill copy and paste this which explains what I'm trying to say.

Cool, lets hope the second sentence of your cut&paste doesn't massively undermine your argument by suggesting there is a replacement for displacement...

minime68 said:

"There is no replacement for displacement. Let me correct myself: there is one: Cubic dollars.

[Captain Muppet]

300bhp/ton said:

Captain Muppet said:

300bhp/ton said:

Captain Muppet said:

It is possible to build an engine with a given limit of capacity that is better than an engine of equal or greater capacity that has a lower level of technology. This disproves that there is no replacement for displacement.

Curious, but how does it disprove it?

I just don't understand how this isn't simply an alternative, rather an replacement?

I would like to continue this discussion with either an alternative 300bhp/ton or a replacement 300bhp/ton.

I guess I must need English lessons. Sorry, not being difficult, I just don't get it.

al·ter·na·tive (ôl-tûrn-tv, l-)
n.
The choice between two mutually exclusive possibilities.

replacement [rɪˈpleɪsmənt]
n
a person or thing that replaces another.

An alternative to displacement is something that isn't displacement.
A replacement for displacement is something that isn't displacement.

I'm at my limit of language skills, at this point it'd be much easier for me to design and build you a pair of engines and take them to a dyno.

[Captain Muppet]

minime68 said:

It gets tricky when you compare two different designs and engine components. Especially when you compare diesel vs petrol.

Yes, it's much easier and simpler when you have two engines of identical physical geomtetry and identical displacement one of which produces more power and torque because it's internal friction has been reduced, or because it has a more sophisticated ECU map, or because of any of the other things you can do to improve it which aren't increasing the displacement.

Which isn't to say increasing the displacement doesn't also work, it just isn't the only thing that works.

[Captain Muppet]

minime68 said:

Captain Muppet said:

al·ter·na·tive (ôl-tûrn-tv, l-)
n.
The choice between two mutually exclusive possibilities.

replacement [rɪˈpleɪsmənt]
n
a person or thing that replaces another.

An alternative to displacement is something that isn't displacement.
A replacement for displacement is something that isn't displacement.

I'm at my limit of language skills, at this point it'd be much easier for me to design and build you a pair of engines and take them to a dyno.

So what you want us to discuss/compare is, for example:

Engine 1: 2.0L Turbo 4 Cylinder engine @300BHP?

Engine 2: 4.6.0L NA V8 @300BHP?

No, I'd be fine with you just reading the OP and having a little think about it.

From page 2:

Captain Muppet said:

Just for all those who missed it in the OP and started talking about highly tuned tiny engines not being as good as huge simple engines:

Captain Muppet said:

I know that someone is going to slag off tiny engines, and probably say something entirely valid like 160bhp 1.6 Vtecs don't have the same torque curve as a 160bhp 3.5 Rover V8. But in order for the cliché to be wrong we just have to imagine a 3.4litre engine that is not worse than the 3.5 litre one, and that's easy.

[Captain Muppet]

300bhp/ton said:

Captain Muppet said:

al·ter·na·tive (ôl-tûrn-tv, l-)
n.
The choice between two mutually exclusive possibilities.

replacement [rɪˈpleɪsmənt]
n
a person or thing that replaces another.

An alternative to displacement is something that isn't displacement.
A replacement for displacement is something that isn't displacement.

I'm at my limit of language skills, at this point it'd be much easier for me to design and build you a pair of engines and take them to a dyno.

I guess there is a degree of semantics going on.

But my take is, 'no replacement for displacement' simply means a small engine won't do this.

Which is generally true. Sure you can do many things to make a small engine perform better, but none of them will truly mimic the same power delivery of a large displacement n/a engine.

Every engine is more than just it's PEAK hp figure.

If your take on "no replacement for displacement" is that "a small engine won't do" then that is fine, because what this thread is about is what those words actually mean when placed in that order, rather than what that phrase stands for as a philosophy.

What if you take a 400bhp 7.2 litre NA V8, and make a fractionally shorter stroke and smaller bore 7.1 litre NA V8. If it is possible to get the same 400bhp (and torque curve) by improving things that aren't the displacement then you have replaced that displacement with engineering.

Hell a very lightly tuned 7.1 litre NA V8 might even sound, feel, look and taste the same as a 7.2 litre V8. You don't even have to change the cams, or timing, or exhaust to do it.

If Mythbusters want to pay for it I'm happy to do the work to disprove that there is "no replacement for displacement".

Again, this thread is about is what those words actually mean when placed in that order, rather than what that phrase stands for as a philosophy.