Do V6 engines rev quicker than an inline 6?

[ford man xf]

Would it be fair to say that a V6 engine will make revs quicker than an inline 6 engine, mainly due to the lighter crankshaft in a V6 needing less inertia to spin?

[Grippy]

If you're referring to Falcon I6's not revving quickly, it's due to their long stroke.

[ford man xf]

Originally Posted by Grippy

If you're referring to Falcon I6's not revving quickly, it's due to their long stroke.

No, I mean just in general terms, I know the Falcon has a long stroke and is good for its low down torque. It's when you freel the weight difference of a V6 crank and an inline 6 crank you can really feel the difference in weight.

[Windsor220]

Generally yes because inline engines have long strokes and heavy running gear but if they were built with the same bore/stroke ratio there probably wouldnt be much difference.

[ford man xf]

Originally Posted by Windsor220

Generally yes because inline engines have long strokes and heavy running gear but if they were built with the same bore/stroke ratio there probably wouldnt be much difference.

So crank weight doesn't really come into the equation? I know people will lighten flywheels, this would be the same principle though wouldnt it?

[chevypower]

Agreed, it's more about the length of the stroke. But RPM doesn't tell the whole story RPM only measures crank speed, not piston speed. So an engine with a 2'' stroke at 4,000 rpm has a piston speed the same as an engine with a 4'' stroke at 2,000 rpm. I liken it to riding a bike. If you want to ride fast, you use a short stride in your legs. If you want to ride up a steep hill, you stretch out your legs using the long stroke as leverage. Except pistons have a fixed stroke length

[BradEL]

It's definitly not just falcon engines, a lot of the bmw i6 engines are slower to rev than say an Audi v6

[Windsor220]

Originally Posted by ford man xf

So crank weight doesn't really come into the equation? I know people will lighten flywheels, this would be the same principle though wouldnt it?

Yeah it does but not sure by how much.

[commodorenutt]

Too many variables to say it's a blanket rule.
Stroke, reciprocating mass, and lots of other things come into play.

Holden (buick) V6s don't exactly rev fast.....

The additional weight of the crank is only a small factor - it's dynamic rotational mass is with a relatively small radius, so this has less bearing on the rotational speed change as the pistons & rods that are moving much further (and changing directions).

Even the widths of the rings, coatings on the piston skirts, and the block material on the bore surface can all affect how quickly it will rev, but to a smaller degree than say lightening the flywheel.

As others have noted, the stroke plays a large part, as that is where the reciprocating mass comes from. A lot of straight 6s have long strokes, and most modern V6s - for various reasons, are heavily under square with very short strokes in comparison.

Usually these under square engines produce noticeably less torque, so they have to be revved more to perform (Holden's Alloytec is the perfect example, as too many Toyota engines).

But while it may be an observation of most current engines, it's certainly not a blanket rule that can be applied.

[FPV GTHO]

I don't think there would be much difference. I think the crank twist of the I6 would be a bigger issue. A V6 will have a lighter crankshaft but also will need balance shafts to be smooth. So you've got a more naturally balanced heavy crank vs a lighter, rougher crank.

[XR Martin]

Originally Posted by BradEL

It's definitly not just falcon engines, a lot of the bmw i6 engines are slower to rev than say an Audi v6

What makes you think its not related to gear ratios?

[Franco Cozzo]

That's half the problem with the I6, to me they feel like they rev out slow but its the gearing, to me I feel like they're geared too long, they really need 3.9s IMO when all you have is just NA engine.