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...

[Krikkit]

I think the origin of the phrase is more important - that it's easy to get more power out of a big engine. Modern engines defeat that with good engineering, turbocharging etc, but it's still easier to get 300hp out of a big V8 than a small V6/boxer 6.

[C.A.R.]

I guess there is little 'replacement for displacement' in typical engineering terms, if you had to design an engine with half the capacity but were not allowed to use forced induction or variable valve timing then it would be both difficult and in all likeliness un-roadworthy and unreliable, with a very peaky powerband and a lumpy idle.

If you count FI and VVT as 'engineering' then yes, your argument becomes a lot more valid. But then would a higher displacement engine with FI/VVT surely have more power?

Subtract that engineering wizardry and I think there is a lot of sense in the statement regarding displacement...

[Gooly]

I always took the particular phrase as referring to the torque, reliability and tuneability of a big unstressed engine. You are right in that there certainly is a replacement for displacement when it comes to raw power but a big unstressed engine has a few advantages. Take the S54 vs LS3, both around 340BHP stock i think? But the LS3 is much lower maintenance, and much more tuneable. Dont get me wrong, I'd take the S54 over the LS any day of the week but theres no denying the benefits of the big displacement V8.

[sjwb]

Point of order Mr Chairman.
The correct saying is. "There's no substitute for cubes."
Simpler and rolls off the tongue.

[cspan]

sjwb said:

Point of order Mr Chairman.
The correct saying is. "There's no substitute for cubes."
Simpler and rolls off the tongue.

I thought it was "There ain't no..." but yes, agreed.

[Rakoosh]

Sure if you're just talking power + torque...

but if you're playing top trumps and errr the category is displacement then there really is no replacement for displacement!

[GroundEffect]

Increasing displacement is the easiest way to get more power. There's nothing fundamentally wrong with doing that if you can accept the package and weight penalty.

[Fartgalen]

I always liked this one :-

[Benbay001]

OP, you are being sensible. Stop it.

[cspan]

There is a replacement for displacement - and that's forced induction, no? However, it is difficult to replicate that "big engine feel" (particularly in a relatively small bodied car) through other methods. Yes I guess at the root of it it's really just torque, response (and the noise), but...

Question: if I gave you a 1.0 turbocharged 3 cylinder and an NA V6, with similar outputs and dyno curves, do you think you'd have a preference for one over the other?

[Mastodon2]

The phrase should probably read "There's no replacement for displacement if you want a torquey, lazy engine that must be naturally aspirated".

[Happy Jim]

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

[TameRacingDriver]

cspan said:

Question: if I gave you a 1.0 turbocharged 3 cylinder and an NA V6, with similar outputs and dyno curves, do you think you'd have a preference for one over the other?

I would. And it would be the V6 every time for driving pleasure. However, as an every day car, I'm not so sure it would be.

My 350Z has a lovely engine, smooth, sounds great, lots of torque, very pleasurable to use. However, 20 MPG on SUL hurts if you're using it regularly.

If someone came along and gave me a 2.0T with as much power and torque, but with half the running costs, I'd be thinking pretty seriously about it if I had to use it every day.

However, if money is no object, then there is no comparison TBH.

[buggalugs]

If the question is can the overall driving experience of a big engine be replicated by a smaller one I think the answer is still no.

I think a modern 3.0 can feel like a 4.0 from a decade or so ago minus the noise maybe, but then you could say a modern 4.0 trumps a 3.0 so that's that really.

[Dr Interceptor]

There's nothing quite like being on a long incline behind slow moving traffic and squeezing in the right foot slightly to open the taps on a big 7.2l V8.

The way a big engine just pulls so effortlessly is ludicrously addictive.

I've owned small forced induction engines (Mini Cooper S R53, and the current derv Fiesta), but give me a big old V8 any day.

That being said, I can appreciate the engineering aspect. The 'little' 4.3l V8 in the Merc E-Class is a fantastic engine - lightweight, aluminium, set low down in the engine bay... combined with huge brakes and 265 width rear tyres - the way that puts its power down is quite something.

[ikarl]

like for like engine, there is no replacement for displacement

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

[RichardD]

Gooly said:

... Take the S54 vs LS3, both around 340BHP stock i think? But the LS3 is much lower maintenance, and much more tuneable. Dont get me wrong, I'd take the S54 over the LS any day of the week but theres no denying the benefits of the big displacement V8.

LS3 is 430 not 340. (and 480 with the different factory camshaft option). Probably weighs less too, being alloy vs iron.

Edited to add, you probably meant LS1, which would be 350bhp standard (but doesn't take too much effort to add another 100bhp)

Edited by RichardD on Thursday 21st February 13:34

[robinessex]

Have a gawp !!!!!!!!!!!! 1000 cu inch 2150bhp

http://www.pistonheads.co.uk/gassing/topic.asp?h=0...

Is this enough for you ?

[chris182]

As others have said, yes it is possible to create the same peak power from a smaller engine with FI, variable cam timing etc but it never feels the same as having big displacement and there are many downsides too such as complexity and reliability.

The obvious example that springs to mind is the Mitsubishi evo, very high specific output but all the descriptions I have read indicate that they are dog slow off boost and when on boost they suck fuel as fast as any V8 while also having lots of turbo lag.