Different Engine Design Attributes

[еÏ]

Aight, the title pretty much defines my question. I've heard about the I6, F6 and 45* V12 being the smoothest engines. And then recently i heard something about the design of the V10, but I forgot what they said. Can someone give me a link to a site that explains the different designs and there pros/cons. Or better yet, someone post there favorite design and why they like it. Thanks very much, adios.

[Porsche]

Flat 4/6

Nothing beats Porsche ingenuity, or the sound of a Flat motor, I can hear a Subaru or Porsche from a mile away.

I dunno other than the sound, it's a rarely used desing, but it has worked well for those who use it. It has a lower CG and Subaru says something about it going under the passenger compartment rather than through.

In a sentence, I love em' since they are just so mechanically exotic.

[FYRHWK1]

inline motors are probably at the top when it comes to actual motor performance, the 6's are naturally balanced, each piston/rod has it's own main journal so once you've determined a firing order the position can be placed perfectly across the crankshaft. Out of all designs inline engines have the most power is transferred from the combustion pressure to the crank journal so there's a plus as well.

They do have the problem of extremely heavy cranks and unless slanted, the full weight of the internals being directly above the crank, which would explain why you dont see them revving as high as other similar displacement motors. They're also massive dimensionally, forget fitting it in anything but a sportscar with an extremely long engine bay and they've got a high center of gravity.

My personal favorite is the typical 90* V8, small enough to fit in any space, and can be extremely large volume wise without taking upmuch room. They're also naturally balanced so there aren't any balance shaft issues either.

[2strokebloke]

Horizontally opposed engines offer a good low center of gravity, make distinctive noise, and when six cylinders are used offer great smoothness, they're also relatively compact in length.

But my favorite engines are 2-strokes. Without any valves, or cams, or timing gears, they're mechanically simple, and mechincally quiet. They have very smooth torque and good power output for their size, and they're light compared to 4-stroke engines.

[pod]

i persanally like the h6 or the i6 the flat 6 is ballenced well and doesnt have to work agenst gravity the inline 6 has to be one of the best engines around for power

[Deakins]

Originally Posted by FYRHWK1

My personal favorite is the typical 90* V8... ...They're also naturally balanced so there aren't any balance shaft issues either.

Where do you get this stuff from?
I would love to hear you explain it..

[454Casull]

The 90 degree V8 is NOT naturally balanced (I assume you mean harmonic-free).

I6s, V12s, and all flat/boxer engines are completely balanced. Wankels are pretty smooth too.

[454Casull]

http://autozine.kyul.net/technical_s...ne/smooth1.htm

[WarPigs]

Originally Posted by 454Casull

http://autozine.kyul.net/technical_s...ne/smooth1.htm

That explained a lot, thanks.

[FYRHWK1]

Originally Posted by 454Casull

The 90 degree V8 is NOT naturally balanced (I assume you mean harmonic-free).

I6s, V12s, and all flat/boxer engines are completely balanced. Wankels are pretty smooth too.

Oh really? which 90* V8 have you ever seen use a balance shaft? 90* V8s with the proper counterweight designs are naturally balanced, yes they still use a harmonic balancer on the front of the crank, as every motor should because tooling isn't perfect, it only dampens the vibrations that arise from that.

Where do you get this stuff from?

knowledge, get some.

[ivymike1031]

Originally Posted by FYRHWK1

they still use a harmonic balancer on the front of the crank, as every motor should because tooling isn't perfect, it only dampens the vibrations that arise from that.

Um, guys, I hate to keep beating the same horse over and over again, but this one just won't seem to die. A "harmonic balancer" is correctly called a torsional vibration damper, and it is used to damp torsional vibrations of the crankshaft. These vibrations have little (nothing that I can think of) to do with rotational imbalance, and everything to do with the firing pressure of the cylinders, the firing order, the dimensions of the crank, and the mass of the slider assys. I'd go so far as to say that rotational imbalance is never considered at any point in the selection of a tv damper.

Haven't we gone over this a few dozen times before?

[SaabJohan]

The 90 degree two plane V8 uses counterweights on the crank to cancel out some unbalanced forces.

A flat engine isn't the ideal for a low center of gravity, a wide angle V engine is this is because of the exhausts will need some space, and you can't use to tight bends if you don't want to lose power. But a wide angle V engine gives other problems (balance is one) that's why we find 90 degree V10 engines in F1.

A flat- or inline engine doesn't have any more problems with high speed more than other engines do. But high performance inline engines are however not made that large since it would have given them a very long crankshaft.

Inline and flat engines should have an advantage when it comes to mechanical strength since they will have forces in fewer directions.

The inline engine have a little higher center of gravity, but one should remember that much of the weight in an engine is around the crankshaft.

For a given displacement fuel consumption and power tend to increase with the number of cylinders when the reliability drops. In racing therefore different engines have been used for different races, for about ten years ago F1 teams (the ones with most money) could use a V12 on tracks when a powerful engine was needed and for durability a V10 or V8 engine. Mercedes had also different engines for the CLK-GTR and CLK-LM (Le Mans).

[454Casull]

Originally Posted by SaabJohan

The 90 degree two plane V8 uses counterweights on the crank to cancel out some unbalanced forces.

A flat engine isn't the ideal for a low center of gravity, a wide angle V engine is this is because of the exhausts will need some space, and you can't use to tight bends if you don't want to lose power. But a wide angle V engine gives other problems (balance is one) that's why we find 90 degree V10 engines in F1.

A flat- or inline engine doesn't have any more problems with high speed more than other engines do. But high performance inline engines are however not made that large since it would have given them a very long crankshaft.

Inline and flat engines should have an advantage when it comes to mechanical strength since they will have forces in fewer directions.

The inline engine have a little higher center of gravity, but one should remember that much of the weight in an engine is around the crankshaft.

For a given displacement fuel consumption and power tend to increase with the number of cylinders when the reliability drops. In racing therefore different engines have been used for different races, for about ten years ago F1 teams (the ones with most money) could use a V12 on tracks when a powerful engine was needed and for durability a V10 or V8 engine. Mercedes had also different engines for the CLK-GTR and CLK-LM (Le Mans).

I thought the F1 V10s were 72-degree?

[SaabJohan]

Originally Posted by 454Casull

I thought the F1 V10s were 72-degree?

They were, and some are still. But the leading F1 teams have switched to 90 degree V10 engine because of their lower center of gravity. Renault tried a wider angle but this was quite unsuccessful since this caused several design problems (poor balance, powerloss and some reliability problems).

[TekPhobia]

This page has lots of good info about the smoothness of cylinder layouts:

http://www.e31.net/engines_e.html

-Tim