Shouldn't a 6 cylander engine get better gas mileage than a 4 banger?

[waggy]

Originally posted by: Ktulu

Originally posted by: waggy

Originally posted by: Accipiter22
To achieve a certain speed, say on flat terrain, a 6 cylander would have to work less than a 4 cylander, correct? So why not get better gas mileage?

have not read the thread.

but with this logic sholdnt say a 12 cylander be better? etc? wouldnt we all be driving 24+?

So then wouldn't a 3 CYLANDER be even better than a 4?

i guess not according the OP's logic.

 

[Ktulu]

Originally posted by: waggy

Originally posted by: Ktulu

Originally posted by: waggy

Originally posted by: Accipiter22
To achieve a certain speed, say on flat terrain, a 6 cylander would have to work less than a 4 cylander, correct? So why not get better gas mileage?

have not read the thread.

but with this logic sholdnt say a 12 cylander be better? etc? wouldnt we all be driving 24+?

So then wouldn't a 3 CYLANDER be even better than a 4?

i guess not according the OP's logic.

but i'm not talking about his logic.

According to the rest of you guys smaller is better. So then wouldn't a 3 CYLANDER be better than a 4 CYLANDER?

 

[thomsbrain]

Originally posted by: theNEOone
wow.....just wow.


=|

 

[waggy]

Originally posted by: Ktulu

Originally posted by: waggy

Originally posted by: Ktulu

Originally posted by: waggy

Originally posted by: Accipiter22
To achieve a certain speed, say on flat terrain, a 6 cylander would have to work less than a 4 cylander, correct? So why not get better gas mileage?

have not read the thread.

but with this logic sholdnt say a 12 cylander be better? etc? wouldnt we all be driving 24+?

So then wouldn't a 3 CYLANDER be even better than a 4?

i guess not according the OP's logic.

but i'm not talking about his logic.

According to the rest of you guys smaller is better. So then wouldn't a 3 CYLANDER be better than a 4 CYLANDER?

now wouldnt that depend on the size of the vehicle? a smaller 2 seater (smart car) arent they 3 cylanders?

 

[Accipiter22]

Originally posted by: iwantanewcomputer
i don't know anything about the relationships of torque produced, cylinder number, and fuel consumption of an internal combustion engine, but i am going to post something I just made up based on my limited scientific knowledge that sounds technical.

lol

 

[Accipiter22]

Originally posted by: Ktulu
Why is everyone jumping down the OP's throat about this. I don't think the idea is so far fetched for instance the Silverado with either the 4.3L v6 or the 5.3L v8 get the same gas mileage. According to most people here this should be impossible. But my guess is the 5.3L has to work far less than the v6. I'm not saying I'm right but it's is certainly an interesting idea.

I was also thinking of my own car, a malibu...I have a 4 cylander, and apparently the 6 gets better mileage. Apparently Chevy 4 cylanders often get worse gas mileage than 6's in similar models

 

[Eli]

Originally posted by: Zenmervolt

Originally posted by: fbrdphreak

Originally posted by: DivideBYZero

Originally posted by: Zenmervolt
6 cylinder has higher internal friction and while it does make more power, it takes more fuel to make that power.

At 60 mph, most cars only need about 20 hp. Drag increases with the square of speed, so to double speed you need 8X the power (2X power to double speed times 4X the power to overcome the drag associated with the higher speed), so a car that needs 20 hp to go 60 mph would need 160 hp to go 120 mph, which is roughly on track with where a 160 hp car would be hitting top speed (actually, it's over-estimating the required HP slightly as 160 hp should carry a car to about 130-135 mph).

So, at cruise speed, if the 4-cylinder is making 25 hp at 3,000 RPM while the 6 cylinder is making 35 hp at 2,000 RPM, the 4-cylinder is still using less fuel.

Even if both engines were sending 25 hp to the transmission at the same RPMs as above, the 6-cylinder is still using more fuel because of higher internal friction. (E.G. the 4-cylinder may only need to make 27 hp total to send 25 hp to the transmission while the 6-cylinder, due to greater friction, needs to make 30 hp total to send 25 hp to the transmission.)

ZV

:thumbsup: First decent, honest, non-flame response.

In threads like these there are a few select responses I look for, I don't bother reading the rubbish other idiots post. Zenmervolt is one of the few people whose responses and opinions I trust :thumbsup:

The thing that most people don't realise is that, all else being equal (and most modern engines are pretty close to one another in terms of overall efficiency, close enough to fudge a simple explanation anyway), fuel consumed is dependant upon power produced. If both engines are similarly efficient, then a 100HP V8 (regardless of displacement) should have similar fuel consumption to a 100HP I4 (again, regardless of displacement). (Note that if both engines are indeed similarly efficient and produce the same amount of power, in actual practice their displacements should end up to be similar.)

The reason that in some cases the V8 has better mileage is due to torque curves. If the I4 absolutely needs to be spinning at 3,000 RPM or above while the V8 can live just fine at 1,500 RPM, then the V8 will probably show better mileage. The I4 at 3,000 RPM will be making more HP than the V8 at 1,500 RPM and so will use more fuel than the V8. The V8 can take advantage of gearing and by doing so spin at a low enough RPM on the freeway to actually produce less HP (but more torque) than a smaller, less powerful (in terms of peak power) I4 engine spinning at higher RPM.

In most cases, the lesser overall power of the I4 is enough to keep it making less power at a given speed, but there are times when a V8 is geared right that it can achieve some very good mileage numbers on the freeway.

ZV

:thumbsup: