Not mercedes as such but V6 v Straight 6 engines, pros and cons ???

[poormansporsche]

Just always wondered the reasoning behind each say build cost, fuel consumption, space in the bay and power etc etc ????


Cheers

Brett

 

[DSM10000]

V6 was the choice for front wheel drive applications as it was a much more compact than a in-line 6 and often shorter than an in-line 4 cylinder, a V6 has higher torsionally stiffness in the crankshaft and camshaft(s)than a straight 6 but because of the "odd" number of cylinders per bank do suffer from dynamic imbalance that often requires balance shafts to improve smoothness.

An in-line six engine is in perfect primary and secondary mechanical balance without the use of any additional balance shafts.

You can go into a lot more detail on the pros and cons of each from an engineering perspective.

I forgot to add: You will find a lot of heavy duty engines in trucks, marine applications, earth movers etc use straight 6 diesels as here space is not an issue but smoothness, simplicity and ease of access for maintenance is easier with the in- line engine type as well as providing superior low down torque I believe?

 

[carat 3.6]

A straight 6 will cost more to build than a v6, but will normaly have a live of up to twice as long.

Also up untill recently, many perfomance engines were built as straight 6's due to their better suitability.

 

[redbaron]

Just always wondered the reasoning behind each say build cost, fuel consumption, space in the bay and power etc etc ????


Cheers

Brett

given your username shouldn't you have asked about flat sixes too?

 

[219]

I guess a flat six is just a V6 with an angle of 180 deg between the banks rather than 60 or 90 .

 

[redbaron]

I guess a flat six is just a V6 with an angle of 180 deg between the banks rather than 60 or 90 .

no so, if that were the case then a 911 would sound like a v6.. which it doesn't... firing order or exhaust layout must be different?


here we go:-

Flat-six engine - Wikipedia, the free encyclopedia

 

[dan1502]

Reading that got me wondering why I sold my old Porsche a while back. That said, I've owned a flat six and a straight six and now want to scratch the V8 itch (I don't mind missing out the V6).

 

[juux]

V6 was the choice for front wheel drive applications as it was a much more compact than a in-line 6 and often shorter than an in-line 4 cylinder, a V6 has higher torsionally stiffness in the crankshaft and camshaft(s)than a straight 6 but because of the "odd" number of cylinders per bank do suffer from dynamic imbalance that often requires balance shafts to improve smoothness.

An in-line six engine is in perfect primary and secondary mechanical balance without the use of any additional balance shafts.

What he said

There is an additional problem in this green day and age for I6s in that they are usually (slightly) less thermally efficient than V6s, meaning more CO2/less MPG.

All things considered, you'd have to be a very brave/silly/niche manufacturer to consider an inline six nowadays. Sad, as they are truly lovely.

 

[poormansporsche]

given your username shouldn't you have asked about flat sixes too?

Although its my username the important bit is the poormans not Porsche as this suggests I don't have a Porsche just a Porsche wannabe ! Funnily enough I have never liked or wanted a Porsche and have zero interest in how they work

 

[Dieselman]

I guess a flat six is just a V6 with an angle of 180 deg between the banks rather than 60 or 90 .

A flat engine is always smoother due to removing one order of vibrations.

 

[Dieselman]

There is an additional problem in this green day and age for I6s in that they are usually (slightly) less thermally efficient than V6s, meaning more CO2/less MPG.

that is possibly true, but I can't really see it being so as the V6 has 4 end cylinders, the I6 only has two.

The real reason is length of the engine, an I6 won't fit in many engine bays.

 

[Charles Morgan]

My SM is a V6, but my instinctive preference after many years is for an inline six, and the noise they make plus the balance and smoothness is all part of the joy.

 

[brigadier]

Can't beat the straight-6 for smoothness.

 

[st4]

BMW use straight sixes for both petrol and diesel, can't be that much of a dinosaur of an engine. I used to have a BMW with an i6 petrol. Was wonderful.

 

[brucemillar]

Loving the straight six in my 300te. Sounds great at all speeds and pulls smoothly through the range.

My V6 (C240) blew up for no apparent reason and without any warning. Up until then I liked it. But it is not as smooth and not as nice a sound.

 

[DSM10000]

My previous car was a Saab 9-5 with the Saab modified GM 3litre V6 petrol with a 54 degree bank angle, it was not particularly smooth but the asymmetric turbo gave excellent low down torque and it had a rather nice howl above 4000 rpm.

 

[Dryce]

The real reason is length of the engine, an I6 won't fit in many engine bays.

That was always my understanding.

And as the larger cars move to turbocharged 4 pot units then that will make it harder for the likes of BMW to justify the compromises to make enough length in the bays for a 6 pot inline.

 

[blue gnome123]

Hi Juux

Apparently it's much easier to twin (even triple) sequential turbo charge a i6 than a V6. Hence the BWM twin/triple sequential turbo charged V6 diesels. I ready a report where a MB engineer said that this is why they don't twin turbo charge their V6 diesels.

 

[Red C220]

The smoothest car I've ever owned was a SIII Jag XJ6 4.2 I6.

It was like wafting around in your own lounge, lovely.

 

[Will]

As above.

The smoothest and most refined cars I have owned were also amongst the oldest/highest mileage/cheapest.

A couple of M103 engined 300TEs with circa 200k each, and an old Daimler Sovereign Series III 4.2 - just silk smooth