Has anyone made a flat 4 before?

[91z4me]

I have never owned or ridden in a flat engined vehicle but have found myself very intrigued recently by them, both the Porche flat 6s, Corvair flat 6's, and also the Subaru 3.0 and 3.3 flat 6's.

Has anyone ever made a flat 4, a flat 6 with 2 cylinders chopped off? Would this design not be as or more stable than an I4 or a boxer 4 (like the Subaru 4's)?

What about flat 8s, they sound like they would be very well balanced and be as low as flat 6's and they would have more area of combustion?

Would not a flat 4/6/8 engine architecture be the most cost/engineering effective series of engines to build and package? Why aren't/haven't there been more out of the V (play on out of the box, I know it is not funny my bad) engine designs and if so what were they? I know of the Wankel rotor and the Miller cycle derivitives of Otto cycle engines.

Just looking to expand my knowledge of cars a little bit.

If it amuses you to answer or discuss feel free if not then let it slide. Thanks for listening to my rambles.

[Drew Dowdell]

I have never owned or ridden in a flat engined vehicle but have found myself very intrigued recently by them, both the Porche flat 6s, Corvair flat 6's, and also the Subaru 3.0 and 3.3 flat 6's.

Has anyone ever made a flat 4, a flat 6 with 2 cylinders chopped off?  Would this design not be as or more stable than an I4 or a boxer 4 (like the Subaru 4's)?

What about flat 8s, they sound like they would be very well balanced and be as low as flat 6's and they would have more area of combustion?

Would not a flat 4/6/8 engine architecture be the most cost/engineering effective series of engines to build and package?  Why aren't/haven't there been more out of the V (play on out of the box, I know it is not funny my bad) engine designs and if so what were they?  I know of the Wankel rotor and the Miller cycle derivitives of Otto cycle engines.

Just looking to expand my knowledge of cars a little bit.

If it amuses you to answer or discuss feel free if not then let it slide.  Thanks for listening to my rambles.

uhm.... Subaru's boxer 4 is a flat 4. It's just a different way of saying the same thing.

It's the same distinction as a Wankel engine compaired to a Rotary engine.

[91z4me]

uhm.... Subaru's boxer 4 is a flat 4.  It's just a different way of saying the same thing.

It's the same distinction as a Wankel engine compaired to a Rotary engine.

I thought subbies was vertical pistons that were split making it a || || || || design and that the crank case was all weird about it. Am I wrong?

Edit: Just looked it up and I'll be damned it is a true flat 4. Kinda cool is that the only one of its kind out there?

Edited May 20, 2006 by 91z4me

[Drew Dowdell]

I thought subbies was vertical pistons that were split making it a || || || || design and that the crank case was all weird about it.  Am I wrong?

Edit:  Just looked it up and I'll be damned it is a true flat 4.  Kinda cool is that the only one of its kind out there?

Hardly

edit: ugh.... while the flat-4 page I directed you to looks fairly acurate.... I clicked on the Wikipedia entry for the V16... and they call the V16 in the Cadillac Sixteen a Northstar V16.... which it isn't.

Edited May 20, 2006 by Oldsmoboi

[91z4me]

Hardly

edit: ugh.... while the flat-4 page I directed you to looks fairly acurate.... I clicked on the Wikipedia entry for the V16... and they call the V16 in the Cadillac Sixteen a Northstar V16.... which it isn't.

Hmm...So lots in the past but very few now.

[Satty]

Subaru used to advertise that their boxer engines had a lower center of gravity than an I4, which makes sense. The downside, I assume, would be that a boxer engine would be comparatively wider. There also may be some NVH differences, but I haven't ridden in a Subaru that was in good shape, so I cannot really say that they're smoother or rougher than a comparable I4. Boxers (at least Subarus) also have rather strange sounding exhausts.

[Hudson]

Kinda cool is that the only one of its kind out there?

Volkswagen has offered them for....um...nearly 70 years. Italians made them as well.

[91z4me]

Volkswagen has offered them for....um...nearly 70 years. Italians made them as well.

I knew you would come into this thread you seem to like 'different' cars and technologies.

Are there any modern flat engines besides Porches and Subbies?

As far as length of an I4 vs a boxer I would imagine the boxer is shorter because the cylinders can overlap a little because they are on opposite sides of the crankshaft.

The engine would be wider but not wider than a transversly mounted engine.

[Drew Dowdell]

I knew you would come into this thread you seem to like 'different' cars and technologies.

Are there any modern flat engines besides Porches and Subbies?

As far as length of an I4 vs a boxer I would imagine the boxer is shorter because the cylinders can overlap a little because they are on opposite sides of the crankshaft.

The engine would be wider but not wider than a transversly mounted engine.

a subi engine isn't mounted transversly.

[loki]

prolly a few have been made for motorcylces since there have been flat 6's

like honda has made..

?

[Drew Dowdell]

BMW bikes are horizontally opposed.

[balthazar]

91z4me As far as length of an I4 vs a boxer I would imagine the boxer is shorter because the cylinders can overlap a little because they are on opposite sides of the crankshaft.

Cylinder bores do not and cannot overlap on the same side of the engine for obvious reasons. There would not be a bore spacing difference (and thusly an overall front-to-rear dimension difference) --all else being equal-- between a 'flat' design and a V design. Height & width would differ greatly, tho.

The engine would be wider but not wider than a transversly mounted engine.

90-degree IBC V-8s are nearly square F-t-R vs. width (slightly longer than wide). A Corvair flat 6 is definately wider than it is F-t-R- go to 4-cylinders and the difference grows.

Tucker proposed a mid-engine flat six driving each rear wheel off the ends of the crank with torque converters at each wheel. That powertrain program was supplimented by another more-conventional rear-engine flat 6- data is scarce on exactly how well the first worked but then again; development had hardly started.

In modern, smaller cars, flat 6s do not add to packaging efficiency, in general. The main 'advantage' is a greatly reduced height, but when is this a primary concern for packaging? 90-degree V-type offer the most compact dimensions for a given cylinder count & displacement range.

[thegriffon]

BMW bikes are horizontally opposed.

Some BMW bikes are horizontally opposed. The R-series have boxer engines, but not the K-series.

[thegriffon]

91z4me As far as length of an I4 vs a boxer I would imagine the boxer is shorter because the cylinders can overlap a little because they are on opposite sides of the crankshaft.

Cylinder bores do not and cannot overlap on the same side of the engine for obvious reasons. There would not be a bore spacing difference (and thusly an overall front-to-rear dimension difference) --all else being equal-- between a 'flat' design and a V design. Height & width would differ greatly, tho. …

Depending on the angle of the V and the crank design a boxer engine can be shorter than a V-engine with the same number of cylinders. Not much shorter, not more than half a bore-spacing. Height, width, balance and commonality with another engine are the primary reasons for choosing a particular block angle, sometimes even for an I4. Hence the popularity of 90 degree V6s and V10s based on 90 degree V8s, instead of the more natural 60 and 72 degrees. Edited May 21, 2006 by thegriffon

[balthazar]

I clicked on the Wikipedia entry for the V16... and they call the V16 in the Cadillac Sixteen a Northstar V16.... which it isn't.

Fixed.

Also fixed: Cadillac V-16 entry.

[balthazar]

Depending on the angle of the V and the crank design a boxer engine can/ be shorter than a V-engine with the same number of cylinders. Not much shorter, not more than half a bore-spacing. Height, width, balance and commonality with another engine are the primary reasons for choosing a particular block angle, sometimes even for an I4. Hence the popularity of 90 degree V6s and V10s based on 90 degree V8s, instead of the more natural 60 and 72 degrees.

That angle of this possible V-type engine would have to be so narrow that the bottoms of the bores would interfere with bores on the other bank, requiring increased bore spacing and a longer crank. Sure, this is possible in theory, but even a 45-degree V-type doesn't encounter this problem. I am not aware of a V-type IC automotive engine with a degree of less than 45.

[Sixty8panther]

To add to all of the info Balthazar mentioned there's one

more huge benefit for flat or "boxer" engines: lower

center of gravity. This is esp. beneficial to cars like the

Porsche 911 & WRX.

& BTW, as you've probably figured out, the VW/Porsche

flat four (pancake motor) is also a "boxer". It's just 6 of

one and half dozen of another. The legendary Porsche

917 had a flat (boxer) 12 cylinder motor, depending on

the tuning & boost from the turbos they made huge

horsepower... as much as 1100-1300.

There's been a few other exotic boxer engines. The 80s

Ferrari Testarossa was a great example of this.

[Newbiewar]

I clicked on the Wikipedia entry for the V16... and they call the V16 in the Cadillac Sixteen a Northstar V16.... which it isn't.

Fixed.

Also fixed: Cadillac V-16 entry.

yea i just checked as well... and if my memory serves me correctly it was 2 LS6's crammed together?

[Hudson]

Depending on the angle of the V and the crank design a boxer engine can be shorter than a V-engine with the same number of cylinders. Not much shorter, not more than half a bore-spacing.

A horizontally opposed engine is a vee engine...with a 180-degree bank angle. Except at particular angles (due to the width of the head) will a vee engine of less than 180-degrees be wider than a flat engine. The two designs should be the same length (assuming all internal dimensions are the same, there's no reason why bore spacing couldn't be the same), but a flat engine is just about as wide as you're going to get.

That angle of this possible V-type engine would have to be so narrow that the bottoms of the bores would interfere with bores on the other bank, requiring increased bore spacing and a longer crank. Sure, this is possible in theory, but even a 45-degree V-type doesn't encounter this problem. I am not aware of a V-type IC automotive engine with a degree of less than 45.

Volkswagen has a series of vee engines (V5 and V6) that are designed with 15-degree bank angles.

[thegriffon]

A horizontally opposed engine is a vee engine...with a 180-degree bank angle. Except at particular angles (due to the width of the head) will a vee engine of less than 180-degrees be wider than a flat engine. The two designs should be the same length (assuming all internal dimensions are the same, there's no reason why bore spacing couldn't be the same), but a flat engine is just about as wide as you're going to get.

Volkswagen has a series of vee engines (V5 and V6) that are designed with 15-degree bank angles.

The new 3.6 L RV6 is supposed just over 10 degrees. From memory Rover was at one stage wrking on a narrow-angle V6, but the KV6 seems wider, if a little lop-sided or a V6. Edited May 22, 2006 by thegriffon

[balthazar]

A horizontally opposed engine is a vee engine...with a 180-degree bank angle.

Is an inline six also V-type with a zero degree bank angle?

Thos VW engines with 10 or 15-degree banks must have increased bore spacing to the point of almost making them comparable to an inline. What was the supposed advantage of building them so narrow??

[Hudson]

Thos VW engines with 10 or 15-degree banks must have increased bore spacing to the point of almost making them comparable to an inline. What was the supposed advantage of building them so narrow??

The "inline vee" six-cylinder Volkswagen engines are said to be about as long as a four-cylinder inline engine.

[Drew Dowdell]

Is an inline six also V-type with a zero degree bank angle? 

Thos VW engines with 10 or 15-degree banks must have increased bore spacing to the point of almost making them comparable to an inline. What was the supposed advantage of building them so narrow??

near the smoothness of an I6 in the space of an I4.

[balthazar]

We must not be talking 'apples-to-apples'. Something is radically different to allow such close spacing on such a narrow bank angle.

The only way I can see to make a 15-degree V-6 with the same size bores as a comparison inline 4 and have the block be shorter is to have long rods & very short strokes to avoid bore/piston interference. This runs counter to the target optimum bore/stroke ratio, tho with electronics I suppose a great deal is possible.

Again- VW isn't building smart-sized cars for these V-6s- what is the packaging problem these motors answer? Because if the overall dimensions aren't at least 20% smaller, the engineering dollar could've been spent much better, elsewhere.

Any links to a cut-away drawing?

[Hudson]

We must not be talking 'apples-to-apples'. Something is radically different to allow such close spacing on such a narrow bank angle.

The only way I can see to make a 15-degree V-6 with the same size bores as a comparison inline 4 and have the block be shorter is to have long rods & very short strokes to avoid bore/piston interference. This runs counter to the target optimum bore/stroke ratio, tho with electronics I suppose a great deal is possible.

Again- VW isn't building smart-sized cars for these V-6s- what is the packaging problem these motors answer? Because if the overall dimensions aren't at least 20% smaller, the engineering dollar could've been spent much better, elsewhere.

Any links to a cut-away drawing?

Have you ever changed the spark plugs on the "back" bank of a V6 on a transversely-mounted engine? It's not fun. The narrow bank angle allows for more space around the engine for crash protection, serviceability, and ease of assembly.

[Drew Dowdell]

We must not be talking 'apples-to-apples'. Something is radically different to allow such close spacing on such a narrow bank angle.

The only way I can see to make a 15-degree V-6 with the same size bores as a comparison inline 4 and have the block be shorter is to have long rods & very short strokes to avoid bore/piston interference. This runs counter to the target optimum bore/stroke ratio, tho with electronics I suppose a great deal is possible.

Again- VW isn't building smart-sized cars for these V-6s- what is the packaging problem these motors answer? Because if the overall dimensions aren't at least 20% smaller, the engineering dollar could've been spent much better, elsewhere.

Any links to a cut-away drawing?

Balthy, check out this page.

[76ChevyTrucker]

That's confuzzling there....someone remind my WHY you'd want a "W" configured engine anyway? Why don't we just strap a Rolls Royce Merlin inverted V12 in there and call it a day?

[Drew Dowdell]

That's confuzzling there....someone remind my WHY you'd want a "W" configured engine anyway?  Why don't we just strap a Rolls Royce Merlin inverted V12 in there and call it a day?

Packaging.

They managed to get an 8-cylinder into the nose of a Passat and have it actually suitible for production.

[balthazar]

Thanks for the link, Oldsboi.

This pic supports exactly what I was saying: the bores on one bank (separated by 15 degrees) have to be shifted in order to not interfere with each other. It's pure physical mechanics.

So the 15-degree V-6 is about as much longer than the inline 4 as the traditional V-6 is shorter- all because of bore spacing. I can see how it could provide some packaging answers in some situations, but it still hardly seems worth the engineering millions & increased complexity/cost.

Edited May 24, 2006 by balthazar

[Drew Dowdell]

Thanks for the link, Oldsboi.

This pic supports exactly what I was saying: the bores on one bank (separated by 15 degrees) have to be shifted in order to not interfere with each other. It's pure physical mechanics.

So the 15-degree V-6 is about as much longer than the inline 4 as the traditional V-6 is shorter- all because of bore spacing. I can see how it could provide some packaging answers in some situations, but it still hardly seems worth the engineering millions & increased complexity/cost.

You're thinking about it from the wrong angle. Think about trying to package an I-6 transversly.

The I6 is, mathmatically, the most harmonicly balanced engine setup <for automobiles>. This is where BMW gets their reputation for "turbine like" smoothness.

VW is attempting to have the same smoothness in a smaller package. By using a 15 degree angle, they get very very very close to the harmonic balance of an I6 while getting the packaging closer to an I4.

Plus, they only use two camshafts on their V6.

[Satty]

Plus, they only use two camshafts on their V6.

Yeah, I got to that part of the page and was like "wow" thats just awesome.

[Sixty8panther]

Have you ever changed the spark plugs on the "back" bank of a V6 on a transversely-mounted engine? It's not fun. The narrow bank angle allows for more space around the engine for crash protection, serviceability, and ease of assembly.

Yes... I agree. Transverse mounted motors & FWD suck.

The FWD STS's North* makes a 2005 Impala or what

have you seem downright accessible by comparison. In

any case the stupidest thing about new VWs is that the

,otor on them is mounted well ahead of the front axles

& therefore wayyy out front. Nice weight distribution.

[Hudson]

Yes... I agree. Transverse mounted motors & FWD suck.

Qualify that. Transverse engines and FWD vee engines suck to work on. Inline engines are nice. Chrysler's early 2.2L FWD were among the easiest cars EVER to work on. The oil filter is presented right up front. The 2.2L's design with both the intake and exhaust on the firewall side allowed for easy access to the spark plugs and most other parts of the engine. Add a second bank of cylinders and suddenly you'd rather have root canal surgery than change the spark plugs in your car.

[91z4me]

Have you ever changed the spark plugs on the "back" bank of a V6 on a transversely-mounted engine? It's not fun. The narrow bank angle allows for more space around the engine for crash protection, serviceability, and ease of assembly.

I did it on an LQ1, that is right I had to take off the FREAKING upper intake manifold. Who thinks of crap like that anyways?

Wanted to add the new 3.5 Duratec V6 has to do the exact same thing.

[Carguy]

VW with their 15 degree now 10 degree narrow angle V6's wanted to offer a V6 in several of their models that were built to handel I4's only. Becides extensive modification to the platforms of these models to allow them to use say an AUDI V6 they decided to design a new line of Engines. Its a smart move on their part really when you think about it. To bad there weight distribution LIKE MOST OTHER FWD CARS is SO HORRABLE! Then they WENT OVERBOARD with their GERMAN OVERENGINEARING with the SO CALLED but MISSLEADINGLY NAMED W line of Engines! (W) would make you think its got 2 crank shafts even though it DOES NOT!

Edited May 24, 2006 by Carguy