Inline vs. Flat vs. Regular


Twist
09-02-2001, 11:30 AM
I know that the Skyline has an inline six and that you can have several other variations of valves (inline, flat and regular). I was wondering what the advangtages and disadvantages of each are. I've only heard of flat design and have no idea of what it really looks like. Inline, from what i've heard, offers a more direct tranferance of power, while the standard design takes up less space. Am I wrong?

hermunn123
09-02-2001, 01:48 PM
i assume when you say, regular, you mean V configuration?? inline's are balanced perfectly and dont need counterbalances, same with flats. v's and flats need more room and require twice as many parts=heavier. inlines are the best

V.S.
09-02-2001, 02:52 PM
I've always thought V's were the easier to package and cheap alternative, hence their use in many cars(and being refferred to as "regular" by original post). If not, why are V's used in so many vehicles?

hermunn123
09-02-2001, 03:05 PM
just because a lot of companies use V's doesnt make them the best. i dont know everything about different configurations. all of the stuff i wrote was off the top of my head. i can find some more stuff out about it. give it a couple hours and we'll have a lot of good replies. maybe texan will show up :)

V.S.
09-02-2001, 08:54 PM
I never said nor implied V was the "best". Just that what you said didn't seem right because there *must* be economic factors(size, weight, and cost) behind a certain engine configuration being so widely used. I'll go further in regard to your post and say that not all types of inline/flats are perfectly balanced.


In response to the original post: Inline is just a straight row of cylinders with the crankshaft at one end. V(what you consider regular?) is two banks of cylinders with less than 180 degrees between them, joining at the crankshaft. Flat is two banks of cylinders on opposite sides of the crankshaft.

If you just imagine a group of cylinders inline as opposed to being in a "V", its easy to see the V will generally be easier to package.



What do you mean by "a more direct transferance of power"?


I feel stupid for not remembering this before I wrote ^.

Just go look at http://www.howstuffworks.com/engine2.htm

olds88
09-02-2001, 09:06 PM
what are you refering to as flat??? the head@valvetrain or the way the pistons are positioned in the engine. well any ways way back when the first motors were deemed "flatheads" this was due to the valves being located in the block insted of the heads.later ohv engines became more popular due to the increased flow ability of the valves being directly above the cylander than located off to one side. as the "boxer"or opposed cylander engines go (primaraly used by porche&vw) i couldent tell you if one can get more power than a v or inline. but with the opposed cylander engens it allowed for better air cooling.

V.S.
09-02-2001, 11:13 PM
By "flat" I was referring to "boxer" engines. I knew about the possible mis-understanding you brought up, but I figured explaining it to Twist would over-complicate the matter.

Hudson
09-03-2001, 12:41 AM
Originally posted by hermunn123
i assume when you say, regular, you mean V configuration?? inline's are balanced perfectly and dont need counterbalances, same with flats. v's and flats need more room and require twice as many parts=heavier. inlines are the best

Okay...there are a few problems here.

Inline engines are not necessarily balanced perfectly. You've never heard of vibrations from four-cylinder? Many inline-fours have counterbalance shafts to deal with this. And straight-eights are notorious for harmonic vibrations.

Theorectically, a "perfectly balanced" engine depends on the number of cylinders. For an "Otto-cycle" (4-stroke) engine, "balance" is achieved by placing the cylinders in banks angled at differing degrees. Fours are best at 180 (flat, horizontally opposed, boxer). Sixes should be at 120-degrees. Eights at 90-degrees. Twelves at 60-degrees.

"VEE" engines are best for their packaging. They are the most compact of the setups. Most companies use this design for engines six-cylinder or larger.

Inline engines take up additional length but are typically narrower than Vee engines. Most odd-cylinder engines use this design, almost all fours, and a few sixes.

Flat engines are quite wide but feature a low center-of-gravity. Old air-cooled Volkswagens and Porsche six-cylinders as well as Subarus and some Lancias used this design. Ferrari used the horizontally-opposed design on some older twelves.

No one design is the best. Each design has its applications.

Twist
09-03-2001, 11:07 AM
Thanks for all the info on the engine types. and yes i refer to v as regular. The name escaped me when I was writing. I wnated to know this when I was reading the Road and Track comparison section at the back of every mag. They just labeled some engines I or F (Inline or Flat). I know Porsche and Subaru both use the flat design. And the Skyline GT-R uses an inline configurarition. That was about all I knew. Thanks again. :D

hermunn123
09-03-2001, 06:13 PM
i was thinking of v6's or inline 6's or flat 6's. i just thought he meant 6 cylinders for some odd reason.

Hudson
09-03-2001, 10:29 PM
Originally posted by hermunn123
i was thinking of v6's or inline 6's or flat 6's. i just thought he meant 6 cylinders for some odd reason.

But Inline is not necessarily the best format for sixes. V6s are usually lighter and almost always more compact, for example.

hermunn123
09-03-2001, 10:39 PM
how can V6's be lighter?? they require more parts, therefore more weight.

Hudson
09-04-2001, 12:06 AM
More parts...like camshafts (in the case of OHC engines) and heads? Doesn't an inline engine require a LONGER camshaft or head than a Vee? Vee engines typically use less block material than an inline engine. Intake and exhaust manifolds are more compact (typically).

TheMan5952
09-04-2001, 01:36 AM
I have a Slant 6 all it is, is a I-6 tilted over 30 degrees.

It allows the Intake manifold to have a Ram effect because of the long runners, and it allows Good under hood room.

hermunn123
09-04-2001, 04:33 PM
you're so smart Hudson. BTW, do you want all your old car magazines??

Porsche
09-04-2001, 04:40 PM
Dosen't one engine design also allow etter Turbo and Supercharging? I think it's Inline engines. My personal preference is the "Boxer' Flat engine because of it's rarity and unique design. What about "W' engines, Nobody's discussed that? what are some of there advantages of the others besides More Cylinders in (Relatively Speaking) Less Space?

Twist
09-04-2001, 06:52 PM
I listed all the ones I knew (inline, vee, flat). I've never heard of "W." I am curious tho... What cars are they in?

Hudson
09-05-2001, 11:45 AM
Originally posted by Porsche

Dosen't one engine design also allow etter Turbo and Supercharging? I think it's Inline engines. My personal preference is the "Boxer' Flat engine because of it's rarity and unique design. What about "W' engines, Nobody's discussed that? what are some of there advantages of the others besides More Cylinders in (Relatively Speaking) Less Space?

"W" engines, radial engines, rotary engines, and the like are "fringe" types and are very rare.

Volkswagen introduced the "W" engine by merging two of it's narrow-angle Vee (VR) engines onto one crankshaft, giving it, technically, four banks of cylinders. Volkswagen has also demonstrated a "W" with three banks. VW concepts have included the W18 (three banks of six), W16 (two VR8s), W12 (two VR6s), and W10 (two VR5s). The only one currently in production is the W12 in the Audi A8 6.0.

Radial engines you've seen, but rarely in automotive applications. Remember seeing old bi-planes in movies or airshows? Radial engines have their cylinders around a central crankshaft. Usually in odd-numbers, radial engines have had 7 or 9 cylinder typically. Sometimes (again, in aircraft applications), multiple radial engines are linked by their crankshaft creating more powerful powerplants.

Rotary engines, or Wankel engines), don't have cylinders. The "figure-eight" shaped combustion chamber has a triangular "rotor" that compresses the fuel for power. Rotaries make excellent power for their "displacement" and are amazingly smooth. They're not very fuel efficient and have been notorious for their wear, although modern ones are better on both points.

Twist
09-05-2001, 05:01 PM
If you learn to work on rotaries then you can work at any garage in world. Those RX-7 engines (the ones that made it to the US and thus the older models) are notorious for their wear and tear tendencies. Doesn't diminish their raw power, tho...

MaxRX7
09-06-2001, 02:28 PM
My choice:

1-inline 6 (I-6)
2-rotary
3-H or flat
4-V
5-I-4

Hudson
09-06-2001, 03:37 PM
RX7:

I could never rank so them generically like that. There were plenty of inline-6s that I wouldn't take unless forced. There are some fours that are worlds better than many Vees (even V8s). The simple layout of the engine means nothing to me. The specific engine means everything.

FenrisOIF
01-26-2005, 08:10 AM
Well, Hudson, you've hit most all of your points on target. I thought I'd add some info about Flat (horizontally opposed, if you want to be really technical) engines. Opposing engines are used almost exclusively among general aviation, and being a pilot, I've seen a lot of them, in use and torn apart.

First, you're very wrong, hermunn, when you say that flat and v engines are heavier. The flat four is actually one of the lightest configurations out there, being the reason it is so incredibly successful in airplanes.

Porche engines are air cooled opposers, which makes them very lightweight, and have been used extensively in engine swaps in airplanes. The Suberu engines are liquid cooled. The advantages to either is that liquid cooled engines have thicker blocks, and can withstand much higher performance tunes, particularly boost from turbo and superchargers, but all that adds sophistication and, more importantly, weight. Air cooled ones are much lighter.

Also, different configurations of engines, inline/vee/opposing and so on, have different torque/horsepower virtues. Opposing engines usually generate a much higher amount of torque due to the fact that A) the pistons don't have to work with/against gravity constantly, B) being directly opposite one another, the pistons generate a more direct application of torque. Thus, they have very broad powerbands, similar to a V-8. Inline engines aren't naturally balanced, I tore apart a straight four out of an Eclipse to find that it had siezed up a balance shaft. They do, however, have lower rotational momentum, which makes them easier to rev up to higher RPMs. This gives them a very narrow powerband, requiring more frequent gear shifting. V engines seem to be a moderate between the two.

Another thing to consider is their shape. A flat four is only two cylinders long, and very low-centered, but also the widest type of engine. Both opposing and V engines are half as long as their number of cylinders. The W-12 that Hudson mentioned, like in the new Bently Continental GT is only three cylinders long, but a very wide -and- tall engine, giving it the large front end. Beutiful car though. V-12's and Straight-6's are generally the longest types. V-12's are known to run the smoothest of any type of engine.

There is my rant on engine configurations. Enjoy.

bjdm151
01-26-2005, 02:22 PM
Fenris,

Stop digging up posts from 4 years ago, these are all dead subjects

SaabJohan
01-26-2005, 06:46 PM
Well, Hudson, you've hit most all of your points on target. I thought I'd add some info about Flat (horizontally opposed, if you want to be really technical) engines. Opposing engines are used almost exclusively among general aviation, and being a pilot, I've seen a lot of them, in use and torn apart.

First, you're very wrong, hermunn, when you say that flat and v engines are heavier. The flat four is actually one of the lightest configurations out there, being the reason it is so incredibly successful in airplanes.

Porche engines are air cooled opposers, which makes them very lightweight, and have been used extensively in engine swaps in airplanes. The Suberu engines are liquid cooled. The advantages to either is that liquid cooled engines have thicker blocks, and can withstand much higher performance tunes, particularly boost from turbo and superchargers, but all that adds sophistication and, more importantly, weight. Air cooled ones are much lighter.

Also, different configurations of engines, inline/vee/opposing and so on, have different torque/horsepower virtues. Opposing engines usually generate a much higher amount of torque due to the fact that A) the pistons don't have to work with/against gravity constantly, B) being directly opposite one another, the pistons generate a more direct application of torque. Thus, they have very broad powerbands, similar to a V-8. Inline engines aren't naturally balanced, I tore apart a straight four out of an Eclipse to find that it had siezed up a balance shaft. They do, however, have lower rotational momentum, which makes them easier to rev up to higher RPMs. This gives them a very narrow powerband, requiring more frequent gear shifting. V engines seem to be a moderate between the two.

Another thing to consider is their shape. A flat four is only two cylinders long, and very low-centered, but also the widest type of engine. Both opposing and V engines are half as long as their number of cylinders. The W-12 that Hudson mentioned, like in the new Bently Continental GT is only three cylinders long, but a very wide -and- tall engine, giving it the large front end. Beutiful car though. V-12's and Straight-6's are generally the longest types. V-12's are known to run the smoothest of any type of engine.

There is my rant on engine configurations. Enjoy.
I think you should stay with aerodynamics and not go into engines...

...pistons not have to work against gravity :screwy:

Moppie
01-26-2005, 09:55 PM
Im closing this.

Its 4 years old, a dead topic, and we don't want any of those anti-gravity pistons escaping.

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