Engine Power Vs. Engine Displacement Vs. Engine Configuration

[Gtek-i]

Everything depends...CVT also changes a lot of things too...but definetely not a V8, a Boxer 4 or I-4 maybe. it all depends on the setup.

[Slicks]

I wonder why people voted for V8 when part of the poll question is "best gas mileage"....

I voted for a V6 when I thought of how much power can be squeezed out of one and it sure have better gas mileage than V8.

re-read it, he doesnt ask which would get best gas milage, he asks if it would be effected.
Either way anyone who voted is purely guessing, there is no answer like I said there are far to many variables.

[lightweight]

re-read it, he doesnt ask which would get best gas milage, he asks if it would be effected.
Either way anyone who voted is purely guessing, there is no answer like I said there are far to many variables.

Actually the poll question itself doesn't make sense, as we have no idea what the best cmpromise is.

Usually when a manufacturer designs an engine, takes into account what the future buyers of the product would prefer. The buyer preferences determine what is the best compromise. Sales figures prove a well thought design.

But this poll has no such reference, so i guess everyone starts posting about his/her dream engine

[NSXType-R]

Thanks for the input. I though the V-8 would produce the most power but when I think about it the I-4 (or every other engine for that matter) would produce the same because the V-8 would have smaller cylinders and the other engines would make it up with larger cylinders. So confused...

[deffenbaugh03]

It is easier to fit 4 valves in a flat head, which far outweighs the power gained from a hemi.

I didn't know they had 4 valve per cylinder engines back in the days when flat heads were common. I'll admit though i do not know too much about flat heads. I just thought they had always been 2 valve per cyl.

[henk4]

I didn't know they had 4 valve per cylinder engines back in the days when flat heads were common. I'll admit though i do not know too much about flat heads. I just thought they had always been 2 valve per cyl.

I think there is some confusion here, Hootetc was referring to the shape of the combustion chamber which can be hemispheric ar a bit flat. What you are talking about are side valve engine which resulted in flat cylinder heads as there was nothing on top of the cylinders. These type of engines never came with four valves per cylinder as far as I know, but I am always prepared to stand corrected.

[deffenbaugh03]

Yea I am a bit confused here. You're right I am talking about the flat heads with valves to the side of the cylinders, but what other kind of flat heads are there? And about the type of head you are referring too that you're saying is a bit flat are you talking about the pentroof hemi?

[henk4]

Yea I am a bit confused here. You're right I am talking about the flat heads with valves to the side of the cylinders, but what other kind of flat heads are there? And about the type of head you are referring too that you're saying is a bit flat are you talking about the pentroof hemi?

just a shape a little bit flatter than the hemi

[h00t_h00t]

How far back are you talking about if you meant engines with side valves?!

I thought you were talking about modern Hemis.

[deffenbaugh03]

just a shape a little bit flatter than the hemi

So do you mean kind of like a small cone (which i thought was referred to as a pentroof hemi and i thought most modern cars use these, am i wrong?), or do you mean just a smoother spherical head that's not a full hemisphere it is just squished in a bit so its height is not the same as it's radius?

[KnifeEdge_2K1]

But with a lot of small cylinders there would be more surface area which means it would be less thremodynamically effecient wouldn't it?

Surface area causes heat loss which equates to lost power

I understand with that reasoning used for Hemi's though. Hemi's are better than flats because hemi's have less surface area than a flat head would. Therefore they are more thermodynamically effecient.

yes. this also means more friction loss cuz of having more area, but with smaller pistons you can have a shorter con rods which means higher rpm and thus more power

[KnifeEdge_2K1]

Actually, these goals are contradicting each other.
The best economy will be achieved with the I-4, whereas the most power will be achieved with the V8.

Less cylinders mean less friction losses, leading to a better mpg figure.

More cylinders mean less reciprocating mass, leading to more revving capability.

it would actually be more mass, but as i said in my prev post, the distance they travel per rotation is less, so hence piston speed goes down and rev limits are increased

[Kooper]

Being a fan of the inline 6 I just had to vote for it.

Maybe not the most power, or the best fuel use (though you might argue that fuel-use vs. displacement for these types of engines are at or below average).

What you do get is a great sound and smooth and adequate power.

Mmm, come to think of it, the Boxer 6 also has some great sounds...

A draw between the I6 and Boxer 6 for me.

[h00t_h00t]

So do you mean kind of like a small cone (which i thought was referred to as a pentroof hemi and i thought most modern cars use these, am i wrong?), or do you mean just a smoother spherical head that's not a full hemisphere it is just squished in a bit so its height is not the same as it's radius?

Thats what I was talking about.

[hightower99]

I believe I6 is the way to go becuase it is mechanically more efficient with lower frictional and vibrational losses than any of the other configurations and if packaging is a problem then go for VR6.

The best ratio of bore to stroke is 1:1 so you dont want too many or too few cylinders and if they are all gonna be 2L then a 6 cylinder will fit nicely (roughly 75mm bore and stroke).