What’s the conspiracy behind the lack of VR6 engines? Lol

[FakeCarGuy]

Am I the only one puzzled by the lack of VR6 engines in the car industry?

All of the benefits of an inline 6 in a more compact design than a V6… and the only downside is the unequal intake/exhaust manifold lengths - but that’s not something that seems to affect the Buggati Chiron’s W16 or Bentley’s W12… or any of VW’s previous VR6 engines… or even their new VR6 released in 2017 in China…

I just think it’s the obvious choice with 0 compromises on cost, simplicity, packaging, weight, balancing, robustness etc. for an ultimate sports car that is all about minimising size and weight whilst not sacrificing performance at the same time that packaging and simplicity needs to be maximised… not to mention that they still output the same exotic exhaust note associated with inline 6s and v12s.

V6s have similar advantages - but the VR6 does everything that the V6 does better, and without sacrificing any of the advantages of the I6 in the first place (which the V6 does)…

I mean, VW released a 2.5L VR6 Turbo in 2017 that makes 295hp and 500Nm (369ft/lb) of torque. Just try telling me that you couldn’t easily design a B58/S58 I6 competitor in a VR6 configuration…. And the best part is that such an engine would literally be able to fit into ANY car basically since it is perfectly suited for both transverse AND longitudinal mounting lol.

Like, if you replaced any v8 car with a VR6 then you could shorten the bonnet and increase cabin space, or just reduce the overall length of the car. Obviously people might want to buy a V8 simply because they like the iconic V8 - but wouldn’t it be far simpler and less expensive to design a very nice VR6 than all of these new 120degree V6s in these new supercars - all whilst being able to retain a more exotic sound (since people don’t generally seem to like the sound of V6s and apparently it takes more effort to get them to sound good. Don’t get me wrong - the QF Giulia, 296GTB, Artura, and MC20 all sound pretty good - but I honestly think that most people would prefer the sound of an old 3.2L EA390 VR6 when it’s turbocharged lol.

Am I just bonkers, or is anyone else in agreement and also confused?

[paradigital]

The one reason my Mk1 TT V6 is staying is the sound. I’d jump on a modern VR6 even a forced induction one, they just sound superb.

[C70R]

Put quite simply, unless your sole design goal was induction noise, a turbo 3 or 4 cylinder lump takes up barely any more space. They are typically more fuel-efficient and can make equal/better power for the same size and weight.

The VR6 was a fun oddity.

[FakeCarGuy]

C70R said:

Put quite simply, unless your sole design goal was induction noise, a turbo 3 or 4 cylinder lump takes up barely any more space. They are typically more fuel-efficient and can make equal/better power for the same size and weight.

The VR6 was a fun oddity.

I’m talking about sports cars… you wouldn’t argue that a 3 or 4 cylinder makes sense in an M3. An inline 3 or 4 needs complex work arounds to make equal/better power than an i6/vr6 simply because of balancing issues. Not to mention, more cylinders is better because you can distribute the power in more places.

Furthermore, BMW (and a bunch of other manufacturers) have kind of proven that you can make a 6 cylinder fairly efficient. The B58 beats a lot of 4 cylinder engines in terms of mpg and overall efficiency.

Small turbo charged inline 3 and 4 engines aren’t that efficient once you get them to start boosting. For example, a 2.0L i4 is gonna be less efficient making 140hp at 4000rpm than a 3.0L i6 making 140hp at 3000rpm. More displacement can genuinely help with more efficient cruising (to a certain extent).

[CABC]

I see your points.
one question: how long is the engine? shorter than an I6 obvs, but a little longer than a 4 I would have guessed?

[C70R]

FakeCarGuy said:

C70R said:

Put quite simply, unless your sole design goal was induction noise, a turbo 3 or 4 cylinder lump takes up barely any more space. They are typically more fuel-efficient and can make equal/better power for the same size and weight.

The VR6 was a fun oddity.

I’m talking about sports cars… you wouldn’t argue that a 3 or 4 cylinder makes sense in an M3. An inline 3 or 4 needs complex work arounds to make equal/better power than an i6/vr6 simply because of balancing issues. Not to mention, more cylinders is better because you can distribute the power in more places.

Furthermore, BMW (and a bunch of other manufacturers) have kind of proven that you can make a 6 cylinder fairly efficient. The B58 beats a lot of 4 cylinder engines in terms of mpg and overall efficiency.

Small turbo charged inline 3 and 4 engines aren’t that efficient once you get them to start boosting. For example, a 2.0L i4 is gonna be less efficient making 140hp at 4000rpm than a 3.0L i6 making 140hp at 3000rpm. More displacement can genuinely help with more efficient cruising (to a certain extent).

I think a of what you've mentioned there is factually inaccurate.

A small capacity turbo is absolutely more efficient over a normal driving cycle than an equivalent power (larger V6). That's why we're seeing a shift away from larger capacity engines to smaller turbo units.

Your point about different revs is largely irrelevant, because that's simply down to gearing rather than engines.

I'm not sure what the point about "distributing power" is all about either. That's not really a thing.

And finally, I can't recall any sports cars being fitted with VR6 engines. They were designed for advantageous FWD packaging, so not really relevant to sports cars...

[FakeCarGuy]

CABC said:

I see your points.
one question: how long is the engine? shorter than an I6 obvs, but a little longer than a 4 I would have guessed?

I believe they’re actually slightly shorter than an I4, since it’s more like 3 1/2 cylinders long. It’s wider of course, but that’s rarely ever an issue with engine packaging - especially when considering that it’s still FAR narrower than any other type of V engine. I believe (however I might be wrong) that they’re shorter too, simply because they don’t need a balancing shaft at the bottom - so the height (and thus centre of gravity) is lower than an inline 4 or 3 too.

Thinking about it, aside from the accommodations required to the intake and exhaust manifolds of a VR6 and the slightly wider dimension - the only other downside I can think of is the fact that the crank would be forced to only have 4 main bearings (as opposed to 7 compared to the inline 6), however a reduced number of main bearings is typically in any V configuration - and also, the crank itself would be almost half as long, so should be stiffer/stronger anyway.

[FakeCarGuy]

C70R said:

I think a of what you've mentioned there is factually inaccurate.

A small capacity turbo is absolutely more efficient over a normal driving cycle than an equivalent power (larger V6). That's why we're seeing a shift away from larger capacity engines to smaller turbo units.

Your point about different revs is largely irrelevant, because that's simply down to gearing rather than engines.

I'm not sure what the point about "distributing power" is all about either. That's not really a thing.

And finally, I can't recall any sports cars being fitted with VR6 engines. They were designed for advantageous FWD packaging, so not really relevant to sports cars...

No? I’m not talking about gearing. I’m talking about power-bands. A smaller displacement engine is inherently going to make less power at the same RPM as a higher displacement engine (when not factoring in FI), so you will therefore need to increase the RPMs to produce the same torque necessary to move a vehicle that has a smaller displacement - and thus use more fuel (with gear ratios equal). You can say that a turbo brings the torque curve down lower - and that’s fine, but you still need to match the amount of fuel to the extra air you are feeding the engine through boost. Essentially, 3L of air (or however much air) going into a 2L engine (which is what a turbo allows) will not be as efficient as a 3L engine using 3L of air to make the same power.

I’m not saying turbos don’t help with efficiency, because they do - but imo they’re simply a tool and aren’t a counter to displacement. Companies like Ferrari are still able to produce 800bhp 6+L N/A V12 engines that pass emission standards. Whether you make 400bhp from a heavily boosted 1.5L 3 cylinder or whether you make 400bhp from a 5L V8 - you’re still burning similar amounts of fuel and air to create 400bhp at full chat. A larger displacement is just inherently able to drink more fuel because it’s able to produce more power - but there’s hardly a difference between starting with 5L or slapping a fat turbo onto a 1.5L to force it to act like a 5L. Yes, a 5L will need more fuel to simply tick-over - but it will also produce much more torque (and thus power) at 1500rpm than the boosted 1.5L (so you don’t need to feed it additional fuel+air to do its job in the first place).

Guaranteed the real life difference between a 1.6L i4 turbo and a 3.0 N/A i6 is negligible (especially on the motorway). And in the same breath, the difference between the 1.0L i4 and 3.0L i6 is negligible also. The only time the smaller engine is genuinely more economical is when you drive like a granny because not much fuel is required to create the 60bhp of power made at 1500RPM in a 1L turbo - but no one drives a 1L turbo like that lol.

[AmyRichardson]

FakeCarGuy said:

Am I the only one puzzled by the lack of VR6 engines in the car industry?

All of the benefits of an inline 6 in a more compact design than a V6… and the only downside is the unequal intake/exhaust manifold lengths - but that’s not something that seems to affect the Buggati Chiron’s W16 or Bentley’s W12… or any of VW’s previous VR6 engines… or even their new VR6 released in 2017 in China…

I just think it’s the obvious choice with 0 compromises on cost, simplicity, packaging, weight, balancing, robustness etc. for an ultimate sports car that is all about minimising size and weight whilst not sacrificing performance at the same time that packaging and simplicity needs to be maximised… not to mention that they still output the same exotic exhaust note associated with inline 6s and v12s.

V6s have similar advantages - but the VR6 does everything that the V6 does better, and without sacrificing any of the advantages of the I6 in the first place (which the V6 does)…

I mean, VW released a 2.5L VR6 Turbo in 2017 that makes 295hp and 500Nm (369ft/lb) of torque. Just try telling me that you couldn’t easily design a B58/S58 I6 competitor in a VR6 configuration…. And the best part is that such an engine would literally be able to fit into ANY car basically since it is perfectly suited for both transverse AND longitudinal mounting lol.

Like, if you replaced any v8 car with a VR6 then you could shorten the bonnet and increase cabin space, or just reduce the overall length of the car. Obviously people might want to buy a V8 simply because they like the iconic V8 - but wouldn’t it be far simpler and less expensive to design a very nice VR6 than all of these new 120degree V6s in these new supercars - all whilst being able to retain a more exotic sound (since people don’t generally seem to like the sound of V6s and apparently it takes more effort to get them to sound good. Don’t get me wrong - the QF Giulia, 296GTB, Artura, and MC20 all sound pretty good - but I honestly think that most people would prefer the sound of an old 3.2L EA390 VR6 when it’s turbocharged lol.

Am I just bonkers, or is anyone else in agreement and also confused?

I'd go the other way.

- The I6 is "right"; from a refinement perspective it can't be improved upon - and all with zero wizardry. It's only downside is packaging. That it could have rigidity issues (either for engine speed or structural use) isn't relevant to road cars.

- V6s either make serious refinement compromises (see new Alfa V6 or the old SM V6 - fruity and interesting, but audibly more than a little "off") or add a load of complexity (balance shafts, split journals) to get something acceptably close to I6 refinement. But if you want the sort of package that works in the most cars then it's probably choice #1.

Whether a VR configuration repressents the worst or best of all worlds depends on your perspective. I suspect they came into VW-world as a novelty and persisted in (as W-engines) because they lack a proper, rwd 'big car' platform.

[IJWS15]

Cost.

Why design and build a v5/6 when you can get the same output from a turbo version of a four you already have.

I had a 4 cylinder 1.8t Passat 20 years ago with exactly the same power and torque that the v5 put out for much more money.

[Megaflow]

IJWS15 said:

Cost.

Why design and build a v5/6 when you can get the same output from a turbo version of a four you already have.

I had a 4 cylinder 1.8t Passat 20 years ago with exactly the same power and torque that the v5 put out for much more money.

^ What he said. Cost is almost always the answer to any question regarding the automotive industry.

[FakeCarGuy]

I'm a bit confused by people the people in this thread to be honest. We all know what a VR6 is, right?

There technically shouldn't be any additonal cost to design a VR6 compared to an inline 4/3, since a VR6 technically IS an inline engine - since it only has 1cylinder head. It's distinctly different from a 'true' V engine that has 2 cylinder heads. The cost to design a VR6 is essentially the same as an inline 6, and thus it's marginally different from an inline 4 or inline 3 also.

The arguments here don't make sense because companies ARE developing V6s, V8s, H6s, H4s etc. - and my point is simply that a VR6 is actually the more cost-effective option than any of these whilst also being easier to package, less complex, and more capable of producing large amounts of power.

I'm not arguing that all inline 4s or inline 3s should be replaced with a VR6, so i have no idea where that's come from. What world do you guys come from where every single car is a 4/3cyl econo-box?

Edited by FakeCarGuy on Saturday 11th March 17:30

[FakeCarGuy]

AmyRichardson said:

I'd go the other way.

- The I6 is "right"; from a refinement perspective it can't be improved upon - and all with zero wizardry. It's only downside is packaging. That it could have rigidity issues (either for engine speed or structural use) isn't relevant to road cars.

- V6s either make serious refinement compromises (see new Alfa V6 or the old SM V6 - fruity and interesting, but audibly more than a little "off") or add a load of complexity (balance shafts, split journals) to get something acceptably close to I6 refinement. But if you want the sort of package that works in the most cars then it's probably choice #1.

Whether a VR configuration repressents the worst or best of all worlds depends on your perspective. I suspect they came into VW-world as a novelty and persisted in (as W-engines) because they lack a proper, rwd 'big car' platform.

Yeah, the whole point of the post is to address the I6's packaging issues. I wholeheartedly agree that I6s are amazing from an isolated perspective of "what's the best engine?" - but that's without considering the constraints they cause around the design of the car that it goes into.

Therefore, my point is simply that a VR6 allows 99% of the advantages of the I6, whilst getting rid of the I6's only disadvantage: packaging.

And thus, I don't understand your point about V6s, as that is exactly my point also. A VR6 is even better packaged and simpler than a V6, since a VR6 remains balanced and doesn't have 2 cylinder heads - thus I can't understand WHY the V6 seems to be the '#1 choice' when it comes to an easily packaged 6 cylinder engine configuration when the VR6 exists and objectively beats it in absolutely every single angle of consideration.

[FakeCarGuy]

IJWS15 said:

Cost.

Why design and build a v5/6 when you can get the same output from a turbo version of a four you already have.

I had a 4 cylinder 1.8t Passat 20 years ago with exactly the same power and torque that the v5 put out for much more money.

That's like saying what's the point in a 600bhp V8 M5 when you can just boost the hell out of a Honda?...

Also, I hope you know that a VR6 is only marginally more expensive to design and build than an inline 4 since a VR6 essentially already is an in inline engine.

[spookly]

Not quite as balanced as an I6, so if you have room for an I6 I'd rather have that.

[Megaflow]

FakeCarGuy said:

I'm a bit confused by people the people in this thread to be honest. We all know what a VR6 is, right?

There technically shouldn't be any additonal cost to design a VR6 compared to an inline 4/3, since a VR6 technically IS an inline engine - since it only has 1cylinder head. It's distinctly different from a 'true' V engine that has 2 cylinder heads. The cost to design a VR6 is essentially the same as an inline 6, and thus it's marginally different from an inline 4 or inline 3 also.

The arguments here don't make sense because companies ARE developing V6s, V8s, H6s, H4s etc. - and my point is simply that a VR6 is actually the more cost-effective option than any of these whilst also being easier to package, less complex, and more capable of producing large amounts of power.

I'm not arguing that all inline 4s or inline 3s should be replaced with a VR6, so i have no idea where that's come from. What world do you guys come from where every single car is a 4/3cyl econo-box?

Edited by FakeCarGuy on Saturday 11th March 17:30

V6’s became a bit of a fad for a while, but they are being replaced with I6’s now. JLR, BMW and Mercedes are now all I6.

I used to be a cost engineer for an engine manufacturer and I reckon a VR6 block will be more expensive to make than an I6 because of the angled cylinder bores.

[Novexx]

Larger engines are not as efficient as small turbo units. Compare a V8 against an I3 with a fat turbo, before even considering revs, bands or whatever, the V8 could easily weight ~150Kg more, which sucks performance & power.

That a VR6 is as easy or nearly as easy to design or manufacture as an I3 or I4 is not correct.

I would still take any 6 pot over any 4 or 3 pot though!

[C70R]

FakeCarGuy said:

C70R said:

I think a of what you've mentioned there is factually inaccurate.

A small capacity turbo is absolutely more efficient over a normal driving cycle than an equivalent power (larger V6). That's why we're seeing a shift away from larger capacity engines to smaller turbo units.

Your point about different revs is largely irrelevant, because that's simply down to gearing rather than engines.

I'm not sure what the point about "distributing power" is all about either. That's not really a thing.

And finally, I can't recall any sports cars being fitted with VR6 engines. They were designed for advantageous FWD packaging, so not really relevant to sports cars...

No? I’m not talking about gearing. I’m talking about power-bands. A smaller displacement engine is inherently going to make less power at the same RPM as a higher displacement engine (when not factoring in FI), so you will therefore need to increase the RPMs to produce the same torque necessary to move a vehicle that has a smaller displacement - and thus use more fuel (with gear ratios equal). You can say that a turbo brings the torque curve down lower - and that’s fine, but you still need to match the amount of fuel to the extra air you are feeding the engine through boost. Essentially, 3L of air (or however much air) going into a 2L engine (which is what a turbo allows) will not be as efficient as a 3L engine using 3L of air to make the same power.

I’m not saying turbos don’t help with efficiency, because they do - but imo they’re simply a tool and aren’t a counter to displacement. Companies like Ferrari are still able to produce 800bhp 6+L N/A V12 engines that pass emission standards. Whether you make 400bhp from a heavily boosted 1.5L 3 cylinder or whether you make 400bhp from a 5L V8 - you’re still burning similar amounts of fuel and air to create 400bhp at full chat. A larger displacement is just inherently able to drink more fuel because it’s able to produce more power - but there’s hardly a difference between starting with 5L or slapping a fat turbo onto a 1.5L to force it to act like a 5L. Yes, a 5L will need more fuel to simply tick-over - but it will also produce much more torque (and thus power) at 1500rpm than the boosted 1.5L (so you don’t need to feed it additional fuel+air to do its job in the first place).

Guaranteed the real life difference between a 1.6L i4 turbo and a 3.0 N/A i6 is negligible (especially on the motorway). And in the same breath, the difference between the 1.0L i4 and 3.0L i6 is negligible also. The only time the smaller engine is genuinely more economical is when you drive like a granny because not much fuel is required to create the 60bhp of power made at 1500RPM in a 1L turbo - but no one drives a 1L turbo like that lol.

I'm actually going to dip out of this discussion, mainly because you don't seem to understand some very basics of automotive engineering.

[IJWS15]

Cost.

Why design and build a v5/6 when you can get the same output from a turbo version of a four you already have.

I had a 4 cylinder 1.8t Passat 20 years ago with exactly the same power and torque that the v5 put out for much more money.

[AmyRichardson]

FakeCarGuy said:

Yeah, the whole point of the post is to address the I6's packaging issues. I wholeheartedly agree that I6s are amazing from an isolated perspective of "what's the best engine?" - but that's without considering the constraints they cause around the design of the car that it goes into.

Therefore, my point is simply that a VR6 allows 99% of the advantages of the I6, whilst getting rid of the I6's only disadvantage: packaging.

And thus, I don't understand your point about V6s, as that is exactly my point also. A VR6 is even better packaged and simpler than a V6, since a VR6 remains balanced and doesn't have 2 cylinder heads - thus I can't understand WHY the V6 seems to be the '#1 choice' when it comes to an easily packaged 6 cylinder engine configuration when the VR6 exists and objectively beats it in absolutely every single angle of consideration.

There's no right answer, it's simply wrong to see the VR6 as a circle squared - it's another compromise amongst equal compromises. Keep in mind that the wonky ports need wider manifolds to "square" them, the VR6 isn't only a sneeze (or rather a cylinder offset) wider than an I6.

Cost-wise it's all about lobes, ports and valves - anything that needs machined or deburred - how all that stuff is configured in cast elements isn't really important - if it were nobody would have switched to V6s.

Refinement-wise its I6 and "the others", though the VR needs no mechanical help to attain decent balance etc.

Packaging-wise, it varies. The VR6 lives and dies on its virtues in transverse arrangements, in which its a good package - because it's neither very long nor pariculatly wide. But the six is dead in small, mass-market cars and are now invariably longitudinal engines in large cars; if you're VW that makes a short engine good, for everyone else its "what the hell" and an I6. Historically the transverse V6 was short lived (<30 years in wide application), existing alongside legacy (Cologne/PRV) engines and a single generation of newer V6s, many of which also served in longitudinal roles (e.g. Duratech as AJ6.)

Lastly, think of a modern engine bay on any car that still comes with a 6, is the block being +/- 150mm longer or +/- 80mm wider really an issue? Why not choose optimum - 120° hot vee or an I6.