Planet 9

NLS8520 · #1 06-06-2009, 01:24 PM

I was reading some information regarding flat 6 engines and came across this info on wiki talk.

"a flat-6 configuration consists of two straight-3 engines laying on their side and connected to the same crankshaft"

Would you describe a flat 6 motor along these lines or would you not agree with that description of a flat 6?

Follows is the rest of the paragraph.

"Now, a flat-6 configuration consists of two straight-3 engines laying on their side and connected to the same crankshaft. In the horizontally-opposed or boxer configuration, the two halves are mirror images of each other and the directly opposing pistons are moving toward each other or away from each other at the same time. So, while one three-cylinder bank is trying to rock clockwise, the other other bank is trying to rock counterclockwise, and the two motions cancel each other. Hence the engine is in perfect primary balance. Straight-3 engines have no secondary imbalances, so all you are left with is an intrinsic tertiary vibration caused by the fact there are only three cylinders firing per crankshaft revolution, and as I said, tertiary vibrations are not much of a problem."

**bretster** · #2 06-06-2009, 06:01 PM

I think the description is technically accurate; although, I've never heard it worded "2 straight 3 engines laying on their side..."

NLS8520 · #3 06-06-2009, 06:21 PM

Originally Posted by bretster

I think the description is technically accurate; although, I've never heard it worded "2 straight 3 engines laying on their side..."

I agree, the wording sounds off, is that a Golden Retriever in your Avatar?

Krazed1 · #4 06-06-2009, 06:28 PM

How about a horizontally opposed 6 cylinder...

NLS8520 · #5 06-06-2009, 08:09 PM

Originally Posted by Krazed1

How about a horizontally opposed 6 cylinder...

That it is! Dont forget Flat 6, Boxer 6 or a horizontally opposed 6 cylinder engine. The thing is I have never heard someone say that flat-6 configuration consists of two straight-3 engines laying on their side and connected to the same crankshaft. I suppose that is more or less true, but what do you guys think?

**ed1** · #6 06-06-2009, 08:58 PM

I think its demeaning.

NLS8520 · #7 06-06-2009, 09:30 PM

Originally Posted by ed1

I think its demeaning.

I have to be honest with you, and being a former Porsche Boxster owner, I also felt it demeaned a unique, storied and wonderful sounding engine. I think that is what bothered me in the first place. But when you think about it is he wrong in what he is saying?

chas365 · #8 06-06-2009, 09:43 PM

I don't mind his explanation analyzing the layout as two straight-threes to help illustrate his vibration analysis. But he's wrong. He says that one bank is torquing clockwise while the other bank is torquing counter-clockwise. The direction of the engine torque depends solely on the crank rotation- both banks torque in the same motion. Both banks just work their forces directly against each other, rather than trying to 'blow out the bottom end'.
IMHO

P987 · #9 06-07-2009, 12:14 AM

Originally Posted by chas365

I don't mind his explanation analyzing the layout as two straight-threes to help illustrate his vibration analysis. But he's wrong. He says that one bank is torquing clockwise while the other bank is torquing counter-clockwise. The direction of the engine torque depends solely on the crank rotation- both banks torque in the same motion. Both banks just work their forces directly against each other, rather than trying to 'blow out the bottom end'.
IMHO

I agree, he probably means to say the horizontal 6 is more balanced than a V6 or an inline 6.

gtscayman · #10 06-07-2009, 05:21 PM

Don't get too worked up about the comparison to 2-3 cylinder engines. The three cylinder engine is used as a dynamic basis for the straight six, vee six and flat six, as well as the various 12 cylinder configurations. If you can understand the dynamics of a three cylinder in line engine, it makes it easier to understand the explanations of the differing six and twelve cylinder engines. Nothing more, nothing less. Gotta walk before you can run, as they say!

sixisenuff · #11 06-07-2009, 09:33 PM

Flat 6's aren't the only configuration with inherent balance...In-line 6 engines are also inherently balanced. They're much better than Vees unless the Vee is a V-8. Inline 6's are expensive to produce because of the long heads and blocks, but they're very smooth. Even the old Chevy inline-6 was really smooth. My 3 liter BMW M3's 6 was also creamy smooth all the way up the tach.

The nice thing about boxers (I also have a 2 cylinder boxer). Is that the weight stays nice and low. A big part of the magic of the Cayman is that engine sitting in the center of the car with such a low CG. Boxer 6's are great. Can you imagine a rear engined car like a 911 or VW with a taller engine? It would be pretty horrid.

The negatives of a flat 6 are things we're familiar with...wiffs of smoke out the exhaust on start-up, difficulty of getting at certain components for service, stuff like that. They can be inconvenient at times, but they sure are nice.

Boxer engines are just plain lovable. Look at VW's long run with the bug. People are willing to pay a bit extra to have a Subaru over a Honda or Toyota because the handling and the drivability are so nice...and those are just lowly 4s. I'm willing to bet a bunch of Subaru fans are ex VW bug fans.

My boxer twin is mounted in a BMW R1200RT motorcycle. It does everything well. Has 110 HP, weighs about 520 lbs, has bags for storage, a nice fairing to keep you out of the wind, plenty of ground clearance for good lean angles and that nice, smooth opposed twin feel. It also has gobs of engine braking which can be used effectively to steer the bike around fast corners.

The low CG is another big bonus for a touring bike. Makes it easy to flip from side to side in the esses....when it's not loaded with gear up high on the bike. I pack light.

Another great example is the Honda Gold Wing. Wanna know why those things are still around and seem to never change? Because they're so great, that's why. Boxer six. Low CG. Massive power and easy to handle because it's not top heavy like competing bikes with Vee engines and even inline 4s. I think it has a ground clearance problem and a weight problem, but I LOVE the Wing's Flat 6 engine!

When they talk about German engineering, well, there's a point to it, but the real thing going on with the Cayman is the placement and design of the engine. It's brilliant. The Porsche precision is just icing on a really good cake.

Anyone got balance shafts on their engines? I've got an Aprilia 60 degree Vee Twin with two of them. It idles like a Harley except there's no vibration through the bars. What a strange thing. Then you've got the Mitsubish inline 4s and turbo 4s that don't vibrate. Mitsu invented the balance shaft. It's really a great idea that more companies should use. Honda uses them on it's inline 4 for the Accord and Element. Those are inherently unsmooth configurations that work very nicely now.

There are many ways to skin a cat, eh?

-Six

NLS8520 · #12 06-08-2009, 09:11 PM

Originally Posted by gtscayman

Don't get too worked up about the comparison to 2-3 cylinder engines. The three cylinder engine is used as a dynamic basis for the straight six, vee six and flat six, as well as the various 12 cylinder configurations. If you can understand the dynamics of a three cylinder in line engine, it makes it easier to understand the explanations of the differing six and twelve cylinder engines. Nothing more, nothing less. Gotta walk before you can run, as they say!

Great point, and very well said!

casualsurfer · #13 06-08-2009, 09:18 PM

nobody talking about subys? great flat 4/6 engines and probably the only other mfg. besides porsche to do this kind of engine regularly.

NLS8520 · #14 06-08-2009, 09:29 PM

I am enjoying everyone's opinion on my original post, and also like hearing your opinions on boxer engine's in general. its amazing what Porsche has done with boxer motor's over there history. Please keep your opinions coming!

gtscayman · #15 06-09-2009, 06:35 PM

Originally Posted by casualsurfer

nobody talking about subys? great flat 4/6 engines and probably the only other mfg. besides porsche to do this kind of engine regularly.

Subies rule! Well, next to Porsches!

NLS8520 · #16 06-11-2009, 10:42 PM

Originally Posted by sixisenuff

Flat 6's aren't the only configuration with inherent balance...In-line 6 engines are also inherently balanced. They're much better than Vees unless the Vee is a V-8. Inline 6's are expensive to produce because of the long heads and blocks, but they're very smooth. Even the old Chevy inline-6 was really smooth. My 3 liter BMW M3's 6 was also creamy smooth all the way up the tach.

The nice thing about boxers (I also have a 2 cylinder boxer). Is that the weight stays nice and low. A big part of the magic of the Cayman is that engine sitting in the center of the car with such a low CG. Boxer 6's are great. Can you imagine a rear engined car like a 911 or VW with a taller engine? It would be pretty horrid.

The negatives of a flat 6 are things we're familiar with...wiffs of smoke out the exhaust on start-up, difficulty of getting at certain components for service, stuff like that. They can be inconvenient at times, but they sure are nice.

Boxer engines are just plain lovable. Look at VW's long run with the bug. People are willing to pay a bit extra to have a Subaru over a Honda or Toyota because the handling and the drivability are so nice...and those are just lowly 4s. I'm willing to bet a bunch of Subaru fans are ex VW bug fans.

My boxer twin is mounted in a BMW R1200RT motorcycle. It does everything well. Has 110 HP, weighs about 520 lbs, has bags for storage, a nice fairing to keep you out of the wind, plenty of ground clearance for good lean angles and that nice, smooth opposed twin feel. It also has gobs of engine braking which can be used effectively to steer the bike around fast corners.

The low CG is another big bonus for a touring bike. Makes it easy to flip from side to side in the esses....when it's not loaded with gear up high on the bike. I pack light.

Another great example is the Honda Gold Wing. Wanna know why those things are still around and seem to never change? Because they're so great, that's why. Boxer six. Low CG. Massive power and easy to handle because it's not top heavy like competing bikes with Vee engines and even inline 4s. I think it has a ground clearance problem and a weight problem, but I LOVE the Wing's Flat 6 engine!

When they talk about German engineering, well, there's a point to it, but the real thing going on with the Cayman is the placement and design of the engine. It's brilliant. The Porsche precision is just icing on a really good cake.

Anyone got balance shafts on their engines? I've got an Aprilia 60 degree Vee Twin with two of them. It idles like a Harley except there's no vibration through the bars. What a strange thing. Then you've got the Mitsubish inline 4s and turbo 4s that don't vibrate. Mitsu invented the balance shaft. It's really a great idea that more companies should use. Honda uses them on it's inline 4 for the Accord and Element. Those are inherently unsmooth configurations that work very nicely now.

There are many ways to skin a cat, eh?

-Six

Great to see your passionate about Boxer motor's!

xmatt · #17 06-11-2009, 11:12 PM

Until I pull the trigger on a Cayman, I have a flat-6 in my other car -- proper placement in the back too: