4L Inline 4 vs 4L V8? Or 4L inline 6 vs 4L V12?

[fleabag]

Aside from a smoother engine, what is the benefit of more cylinders if two engines are of the same displacement and basically have the same technology put into them? I mean why would a V8 have more power than an inline 4 if they're the same displacement? I can understand an inline 6 vs inline 4 with the same displacement, that an inline 6 would be more powerful because it doesn't need counterweights I believe since it's perfectly balanced, same with V12.

 

[sjwaste]

More cylinders to make the same displacement would mean a shorter stroke, if my visualization of the math is correct. Shorter stroke engines generally allow for higher RPM operation.

 

[woodie1]

1st thought - the V8 will have smaller pistons, valves, etc. allowing a much higher red line. More RPM = more HP.

 

[Howard]

more power, lower mileage

 

[fstime]

A shorter stroke generally means a higher rpm redline but if you were to take an engine and increase the stroke, the redline of the engine would most likely decrease but the piston speed would remain the same because the piston is traveling a longer distance every stroke.

That being said, i'm guessing the 4 cylinder will have the most torque but the lowest hp rating and the v12 would have the highest hp rating but a rev happy power curve. There are many variables to consider however.

 

[LordMorpheus]

Originally posted by: Howard
more power, lower mileage

Not always higher mileage for the less number of cylinders.

Ford had a straight six in their trucks for a whlie that was huge, and it got unbelievably bad mileage. Other than that I only hear good things about that engine, though.

 

[mwmorph]

The reason companies dont go high displacement, low cylinder count is reciprocating mass. A 4L 4 cylinder engine would shake out of its mounts at any decent RPMs because the moving mass becomes so large that it becomes hard to control.

A I6/I8(or 2 I6/I8 as a V12/V16) is perfectly balanced ad far as primary and secondary vibrations go. I8 are actually slightly smoother because of the power strokes are all balances against each other as opposed to an I6 (to eliminate odd order harmonic imbalance at low speeds), but most companies have trouble with the torsional vibration forces on such a long crank.

 

[Zenmervolt]

Originally posted by: LordMorpheus

Originally posted by: Howard
more power, lower mileage

Not always higher mileage for the less number of cylinders.

Ford had a straight six in their trucks for a while that was huge, and it got unbelievably bad mileage. Other than that I only hear good things about that engine, though.

The 300 CI Ford straight six still offered better mileage than the 302 V8 and the "bad mileage" comments have to account for the fact that it was pushing a truck with the frontal area of an aircraft hangar.

ZV

 

[thedarkwolf]

Originally posted by: Zenmervolt

Originally posted by: LordMorpheus

Originally posted by: Howard
more power, lower mileage

Not always higher mileage for the less number of cylinders.

Ford had a straight six in their trucks for a while that was huge, and it got unbelievably bad mileage. Other than that I only hear good things about that engine, though.

The 300 CI Ford straight six still offered better mileage than the 302 V8 and the "bad mileage" comments have to account for the fact that it was pushing a truck with the frontal area of an aircraft hangar.

ZV

1mpg better. The 302 made 40 more HP and 5 more ft-lbs of torque give or take depending on the year and versions. The 300ci revs more like a diesel and hits max HP at 3400rpms.

 

[boomhower]

Originally posted by: Zenmervolt

Originally posted by: LordMorpheus

Originally posted by: Howard
more power, lower mileage

Not always higher mileage for the less number of cylinders.

Ford had a straight six in their trucks for a while that was huge, and it got unbelievably bad mileage. Other than that I only hear good things about that engine, though.

The 300 CI Ford straight six still offered better mileage than the 302 V8 and the "bad mileage" comments have to account for the fact that it was pushing a truck with the frontal area of an aircraft hangar.

ZV

My step dad had an '85 that got 8-9MPG. The gearing didn't help any, I think I saw him use first gear twice. It took the term stump puller to the extreme.