Piston Banks

[Matt]

I have a question for you technical people out there....
Which arrangement of pistons do you like the best and why, what benefits from each or no pistons such as the rotary engine in the RX8. Im curious if you know some of the advantages and disadvantages of each style. Heres what I know.

V
W
Inline
Boxer (good because less vibration and lower center of gravity)
Rotary (good because lots of horsepower out of small engine, not much torque though)

[vw12]

i chose W because it is compact yet capable of producing power to conventional V engines.

[SDNR]

I wonder could you tell me what production car was the first to offer a W engine.

[vw12]

i think the first W engine was in the volkswagen W12 coupe in 2001.

[martinbo]

Superb poll Matt!

I'm going to go with the left-field choice of the Boxer engine here of course. Ok, so I'm being a little too predictable eh?

Boxer engines have a great many virtues and only a few flaws.
Like you stated, Boxer engines have very little vibration courtesy of the horizontally opposed (and hence counter-balancing) piston arrangement. Boxer engines can hence be made much lighter (they're more rigid) because they don't require ancilliaries light counter rotating balancer shafts. Low CofG is a great plus too Matt, like you said.

Boxer engines have a short-stroke so smaller capacity NA engines can be a little short on torque, even though the spread is fairly even. But, the short stroke has many advantages: mean piston speed is lower and so with a little bit of engineering (like titanium con-rods in a GT3) they can be made to rev high without compromising reliability. Boxer engines just love to be turbocharged and the results are nothing short of spectacular.

Boxer engines' biggest drawback is the lack of application versatility. A transversly mounted in-line four is a far better packaging option for compact fwd cars for example. It's not like you'll ever see a great hot hatch like a Clio 182 with a boxer engine now eh? And, a straight six or V arrangement is better suited to rwd applications if the engine is mounted in the front. Boxer applications require very specialised and unconventional installations.

Other than that I believe a straight six to be one of the purest engine layouts around. Love em.

V's are great too, specifically because they're the only way to achieve truly large displacements and hence max power - see AMG's new 63 V8 and BMW's V10s by way of example. Obviously, such power comes at a price. V engines are expensive simply because they're bigger and more powerful.

[Kleemann_SL]

I choose for the boxer, I just love the sound of it. Its music in the ears!
And about performance, one word: "Porsche"

[Just_me]

I always loved the sound from a I6. The car is smooth and the sound is delicious. Forza I6 engines

[Alx]

I say the inline.

[The Artist]

V for me.. cause there is no sound like a V8 or a crazy V12 like the one in the ZOnda F..

[SDNR]

Originally Posted by vw12

i think the first W engine was in the volkswagen W12 coupe in 2001.

I was looking for some more info - I discovered that Audi were offering a W12 in the old A8 in 2000.

[Matt]

I also chose the Boxeer engine for the reasons Martinbro said above. Thanks for the technical insight! I learned some new things.

[wltsm]

I voted inline!

If it creates such engines such as the great one in the M3, what's not to like?

[Brookside]

the boxer engine configuration is superior engineering
(thanks for the info Martinbo) but.....
Inline.....BMW's inline 6's are works of art-
A little engine vibration works for me!!!

[martinbo]

Originally Posted by James

the boxer engine configuration is superior engineering
(thanks for the info Martinbo) but.....
Inline.....BMW's inline 6's are works of art-
A little engine vibration works for me!!!

It would be remiss of me to say that one layout is superior to another, I really just wanted to get across that a Boxer layout is my favourite because I identify with certain benefits that Boxer engines provide.

I'm almost dead certain that an in-line six is smoother (less vibration) even than a Boxer engine. They are fantastic in that respect. Did I mention that I'm an absolute fan of the M/S54 in the Z4 and M3 and the new N52 in the E90? Untouchable in their class for character and linear power delivery imo...

[warot]

Originally Posted by martinbo

It would be remiss of me to say that one layout is superior to another, I really just wanted to get across that a Boxer layout is my favourite because I identify with certain benefits that Boxer engines provide.

I'm almost dead certain that an in-line six is smoother (less vibration) even than a Boxer engine. They are fantastic in that respect. Did I mention that I'm an absolute fan of the M/S54 in the Z4 and M3 and the new N52 in the E90? Untouchable in their class for character and linear power delivery imo...

Not to mention are better for 50/50 weight ratio too. The 3.0 liter in the E90 is absolutely magnificent. That sound will play in my head over and over again.

That's my choice for "everday" car... But a V configuration is a must for performance purposes.

P.S. ROtary engines are such gas guzzlers

[martinbo]

Originally Posted by warot

Not to mention are better for 50/50 weight ratio too. The 3.0 liter in the E90 is absolutely magnificent. That sound will play in my head over and over again.

That's my choice for "everday" car... But a V configuration is a must for performance purposes.

P.S. ROtary engines are such gas guzzlers

Yes kinda, but when it comes to that 50:50 weight distribution inline engines aren't as ideal as a V layout as the engine is, obviously, longer. This necessitates a push far back into the engine bay, 3 series style. So warot, in this case it's the engine placement rather than its layout that achieves this distribution. What the inline 6 does do is concentrate the engine mass along the centre line of the car which probably goes someway to improving roll characteristics.

V engines are only good where displacement is the primary consideration. Which is just about in every performance car these days. So yes, in that respect I'm inclined to agree with you.

Rotaries. Nah. I'm follower of the piston faith.

P.S. your avatar picture, where was that taken? Main skidpan at Gerotek?

[warot]

Originally Posted by martinbo

Yes kinda, but when it comes to that 50:50 weight distribution inline engines aren't as ideal as a V layout as the engine is, obviously, longer. This necessitates a push far back into the engine bay, 3 series style. So warot, in this case it's the engine placement rather than its layout that achieves this distribution. What the inline 6 does do is concentrate the engine mass along the centre line of the car which probably goes someway to improving roll characteristics.

V engines are only good where displacement is the primary consideration. Which is just about in every performance car these days. So yes, in that respect I'm inclined to agree with you.

Rotaries. Nah. I'm follower of the piston faith.

P.S. your avatar picture, where was that taken? Main skidpan at Gerotek?

Ah yes very good point, you are full of knowledge. I always figured that BMW's inline is better for 50/50 weight balance rather than cornering abilities, but your argument makes perfect sense.

Sorry that I'm not so good with engine knowledge (I'm trying to learn as much as I can), but what is stopping from someone making an inline 12? Just curious.

P.S. Wow Martinbo, good eyes, I didn't think anyone in the world would ever notice that. I know that you've been at Gerotek numerous times but that's insane. So yes, our department (Analysis and Test Center... BMW) took 17 E90's to Gerotek and spent all day there. My avatar is a picture of a 320d going around the .. crap forgot the name... that big circle with the patch of water at the end to test aquaplanning... at 70 kmh.

[martinbo]

Originally Posted by warot

Sorry that I'm not so good with engine knowledge (I'm trying to learn as much as I can), but what is stopping from someone making an inline 12? Just curious.

You don't have to apologise. We've all got lots to learn and the only way is to ask questions. What this forum needs is an engineer who can explain technical concepts in layman's terms in much the same way as Jeff Daniels of EVO or Jake Venter of Car magazine does. I run out of answers pretty quickly when things get really technical.

To the best of my knowledge an in-line twelve is unfeasible for a number of reasons:
1. It's a nightmare to package such a long thin engine in any practicable application.
2. In-line engines are economically more expensive to engineer than a V engine of the same number of cylinders. An in-line engine block and crankshaft use more raw material in the manufacturing process. An in-line 6's crank is decidely longer and more expensive to engineer than an equivalent V crank.
3. From a torsional rigidity point of view a shorter crank is less prone to flex than a longer one. So in an in-line twelve, crank stiffness (or rather the lack thereof) would be a big problem. Needless to say a flexing or twisting crankshaft is a very bad thing.

Originally Posted by warot

P.S. Wow Martinbo, good eyes, I didn't think anyone in the world would ever notice that. I know that you've been at Gerotek numerous times but that's insane. So yes, our department (Analysis and Test Center... BMW) took 17 E90's to Gerotek and spent all day there. My avatar is a picture of a 320d going around the .. crap forgot the name... that big circle with the patch of water at the end to test aquaplanning... at 70 kmh.

Yup, I'm at Gerotek every six weeks all weekend in my capacity as instructor for Subaru, so I'm familiar with the facility. You're talking about the Dynamic Circle which is exactly as you say - to test aquaplaning.
Did you get to drive on the dynamic handling track? That's flippin awesome.

I remember being asked to instruct for the E90 and E65 facelift by Gerotek, unfortunately my SAP project commitments precluded me from attending. I would've loved to have been there given my enthusiasm for BMWs.

[Snake Vargas]

I suppose each type of engine layout has its own benefits, so I'm not such a fan over any other. Inline engines can be smooth (well, inline 4 engines sometimes aren't), boxer engines have all the benefits as Martin said , the V layout is good for space efficiency and reasonably simple construction, the W layout is more space efficient WRT (with respect to) number of cylinders and therefore swept capacity, but it does restrict the angle of the banks and also makes the block somewhat complex to engineer, and rotary engines are small and do have a low centre of gravity like the boxer engines.

I suppose I'm a fan of the boxer for the reason of engineering elegance - use the engine's own reciprocating mass to cancel out vibrations, and on the same plane so that it is most effective. That's just smart. Low centre of gravity etc. are just icing on the cake.

That said, I can understand why not many cars use the engine. It does make packaging difficult. So, my "everyman's choice" would be the V-layout. Compact and simple, efficient space WRT capacity.

[Matt]

Don't boxer engines tend to be heavier than regular engines? Oh yeah and people seem to forget that Rotary engines work off gaining momentum, which means they have a huge amount of horsepower per litre. Boxers also take up alot of horizontal room. Am I off. If so please correct...

I SAW MY FIRST M5 today......... They just got to America so it was a big deal for me.

[Snake Vargas]

I suppose the boxer engines might be a bit heavier. The way the cylinders are laid out means that you need more metal in the block to house them - in most other layouts, cylinders share cylinder wall/engine block material a bit more readily.

Not sure about rotaries though. The fuel consumption isn't great, and the seals between rotors and the engine wall has been a sore point in the past. Oil consumption can be high as well.

[martinbo]

Typically Boxer engines are lighter than their inline and V counterparts. The are inherently more rigid and thus require less metal for structural strength. I'm not absolutely certain about Porsche but I'm 99% of the understanding that all modern Boxer engines are made from aluminium alloy. Which makes them lighter still.

[Centurion]

I have voted for the boxter einge and Martin explained it all . On top of that the sound of a porsche is breath taking. I have heard the sound of a Murceilago and a 911 GT2, and in my ear the sound of the lambo was no way as sweet as the soung of the Porsche.