why the move to small engines ?

[anonymous-user]

Remember that most car manufacturers design their cars to appeal to the majority of customers, not a typically PHer.

[willmagrath]

Yup, it's simple: 2004 330ci, 218 g/km co2, 31 mpg and 230hp
2014 golf gti, 148 g/km co2, 44mpg and 220hp
Done

[jamieduff1981]

Inkyfingers said:

Remember that most car manufacturers design their cars to appeal to the majority of customers, not a typically PHer.

People like me aren't the typical PHer. The typical PHer buys by numbers rather than by emotion. PH is the place where a PHer is second most likely to be told how to buy a sensible diesel car with the best residual value (and that's if he/she is lucky and isn't told to invest in a rental property portfolio first) - second only to one's mother.

[DrDoofenshmirtz]

The stupidly long fleet manager pleasing service intervals probably won't help either.

[Debaser]

delboy735 said:

Just as an aside, how many people on here genuinely check the CO2's when purchasing another vehicle ?? Have to admit, it's never been a consideration for me.........yet

You need to think about CAFE, which isn't really about the end consumer.

[BL Fanboy]

If I compare 125 bhp from a 3 cylinder 1 litre eco-boost engine vs say, an older low tech 115bhp 2 litre engine why would I infer greater longevity from the lower bhp per litre engine?

If car engines are tested for durability at the design stage as sold as a consumer product to last at least a usual minimum amount of time why would I care or know. Perhaps old low tune engines are just not operating anywhere near their ability?

[BL Fanboy]

jamieduff1981 said:

People like me aren't the typical PHer. The typical PHer buys by numbers rather than by emotion. PH is the place where a PHer is second most likely to be told how to buy a sensible diesel car with the best residual value (and that's if he/she is lucky and isn't told to invest in a rental property portfolio first) - second only to one's mother.

What? You're not seriously suggesting that I cant get richer beyond all my wildest dreams by virtue of being a self styled property guru. There cant be a better feeling in the world than growing rich off the back of mere "workers" and pricing out youngsters and families with my borrowed money.........

[xRIEx]

jamieduff1981 said:

Inkyfingers said:

Remember that most car manufacturers design their cars to appeal to the majority of customers, not a typically PHer.

People like me aren't the typical PHer.

And neither are you the typical 'majority customer', which was Inkyfingers's point.

[DJP]

BL Fanboy said:

If I compare 125 bhp from a 3 cylinder 1 litre eco-boost engine vs say, an older low tech 115bhp 2 litre engine why would I infer greater longevity from the lower bhp per litre engine?

It's an interesting question.

I suppose as a gut reaction, I'd say that a bigger engine producing similar power would be dissipating the internal forces over more components / larger surface areas so that everything would be less stressed.

Eg. Big-ends and main bearings would have a larger surface area, the piston to cylinder contact area would be larger etc. etc. while handling similar forces.

The bigger engine would also have more metal to carry away the heat of combustion, so cooling would tend to be less critical.

Of course that may not all be the case (and, even if it is, modern materials technology may mean the the smaller lump is simply made of more resilient materials. After all, the environment inside a diesel engine is much harsher and they seem to last OK).

[xRIEx]

DJP said:

BL Fanboy said:

If I compare 125 bhp from a 3 cylinder 1 litre eco-boost engine vs say, an older low tech 115bhp 2 litre engine why would I infer greater longevity from the lower bhp per litre engine?

It's an interesting question.

I suppose as a gut reaction, I'd say that a bigger engine producing similar power would be dissipating the internal forces over more components / larger surface areas so that everything would be less stressed.

Eg. Big-ends and main bearings would have a larger surface area, the piston to cylinder contact area would be larger etc. etc. while handling similar forces.

The bigger engine would also have more metal to carry away the heat of combustion, so cooling would tend to be less critical.

Of course that may not all be the case (and, even if it is, modern materials technology may mean the the smaller lump is simply made of more resilient materials. After all, the environment inside a diesel engine is much harsher and they seem to last OK).

AIUI, the 1.0 Ecoboost has a long stroke which reduces the force form the conrod acting on the crank pin.

[Shurv]

My expectation is also for these small, highly strung engines, to start detonating on a regular basis. Time will tell.

[zeppelin101]

DJP said:

Eg. Big-ends and main bearings would have a larger surface area, the piston to cylinder contact area would be larger etc. etc. while handling similar forces.

You know that bearing sizes are flexible irrespective of engine size?

The aim is lowest friction possible with durability. So you use the smallest bearing size you can (for any application) which will survive all the durability sign off tests.

If that means you need to beef the mains / big ends up to maintain durability at the expense of some friction - that will take priority.

Modern engines utilise things like offset cranks and wrist pins to reduce loading on the pistons / bearings / bores to enable friction improvements which also has some other benefits in running (such as longer expansion strokes).

It's not as simple as saying "well this engine has less hp per litre so it must be less stressed" a st design is a st design regardless of how much performance it generates and that's the key factor - the design of the components to deal with the stresses involved.

[anonymous-user]

Shurv said:

My expectation is also for these small, highly strung engines, to start detonating on a regular basis. Time will tell.

Hot hatches, producing over 100hp/litre, have been around for over a decade now, and many have now done 150,000+ miles, quite happily (including my wife's, recently sold Golf GTI).

As Zeppelin says, good design and maintenance will offset most of the issues we might have associated with "stressed" engines.

The other good point, is that when they do go pop, they are likely to be cheaper to fix than a bigger engine.

Edited by anonymous-user on Monday 1st September 14:33

[98elise]

Shurv said:

My expectation is also for these small, highly strung engines, to start detonating on a regular basis. Time will tell.

Engines have been getting higher and higher BHP per litre for decades. Engine reliability has been getting better and better with each generation of engines. There is no reason to think that this generation will be any worse.

Manufacturers will have tested the engines over hundreds of thousands of miles.

[Ozzie Osmond]

Never forget that a 4-pot is lighter than 6-pot. It's lighter because it's got less material in it. Materials cost money. So to put it another way, the smaller the engine the cheaper the car will be to build.

[xRIEx]

Inkyfingers said:

The other good point, is that when they do go pop, they are likely to be cheaper to fix than a bigger engine.

I don't know about fixing, but comparing costs of crate engines the 1.0 Ecoboost is significantly more expensive than the 1.6 Sigma.

[anonymous-user]

xRIEx said:

I don't know about fixing, but comparing costs of crate engines the 1.0 Ecoboost is significantly more expensive than the 1.6 Sigma.

The OPs question was a general comparison between turbocharged 4 cylinder engines, and normally aspirated 6 cylinder ones. Comparing two individual engines from one manufacturer isn't really a fair comparison.

[Grayedout]

All this smaller engines with a smaller sump charge and higher power output and higher turbo temperatures along with longer drain intervals means the oils are having to work harder and harder !

Summation of this is always follow the manufacturers recommendations and don't be fooled into saving a few quid by using a lower quality oil !

[delboy735]

Inkyfingers said:

xRIEx said:

I don't know about fixing, but comparing costs of crate engines the 1.0 Ecoboost is significantly more expensive than the 1.6 Sigma.

The OPs question was a general comparison between turbocharged 4 cylinder engines, and normally aspirated 6 cylinder ones. Comparing two individual engines from one manufacturer isn't really a fair comparison.

IMHO....which counts for nothing really, but ....small turbo, frenetic, on the edge, like a terrier on crack.....V6 non turbo, smooth, relaxed and never really strained, like a golden retriever !!

[ORD]

delboy735 said:

Inkyfingers said:

xRIEx said:

I don't know about fixing, but comparing costs of crate engines the 1.0 Ecoboost is significantly more expensive than the 1.6 Sigma.

The OPs question was a general comparison between turbocharged 4 cylinder engines, and normally aspirated 6 cylinder ones. Comparing two individual engines from one manufacturer isn't really a fair comparison.

IMHO....which counts for nothing really, but ....small turbo, frenetic, on the edge, like a terrier on crack.....V6 non turbo, smooth, relaxed and never really strained, like a golden retriever !!

Or, even better, a flat six purring along very quietly until you press the loud pedal and it growls and roars up to the redline.

For the sake of 5-10mpg, you'd be crazy to want a turbo 4 over a 6, but that is the way the market is going.

As for longevity, I would only observe that requiring an engineer to hit a lot of difficult targets must lead to increased risk-taking and compromise.

I imagine that the guys would say "You want 350bhp from 2 litres and bugger all CO2? Sure. I can do it. But it wouldn't be how I would start given a choice".