Boxer breathing

[N]

Lower centre of gravity is one reason why they keep the boxer engine.
I just spent half an hour searching for different engine spec, my goal was to compare a same cc and same compression ratio boxer v's straight 4 engine, but in the end, they had the same spec, same power and torque at same rpm and of course, this is something that you can tune, so it's not a very good comparsion.

I really don't have a good reason as to why would a boxer outperform a standard 4 cyl, maybe because it's better balanced, is there any real proof to this? except for guessing because Atkinson drove faster and Hirvonen...

[Gard]

So what are advantages and disadvatages of boxer engine?Why subaru dont change? what is so special?

The obious ones:
Longer intakes, 2+2 with180dgr and distance from ex valve to turbo

[Daniel]

Some advantages

http://www.irvinesubaru.com/enthu/theboxerengine.html

Also remember that the engine is shorter than a I-4 engine and also it is fairly symetrical so the car should be better balanced. The crankshaft is also shorter too which means it can be lighter.

Disadvantage?

Have you ever seen how wide a Subaru engine is in the car and how little room there is either side of it? This means (as someone has pointed out) that you end up with a fairly short stroke engine which has it's disadvantages

[Mirek]

Another big dissadvantage is that the engine is longitudinal and must be infront of front axle where it makes too much polar moment of innertia.

[OldF]

One possible reason is the intake manifold. Because Subaru has a boxer engine it has to have two intake manifolds with two cylinders per manifold compared to a normal four-cylinder engines manifold. In a four-cylinder row engines manifold where the air intake is at the either side of the manifold, the cylinder nearest the intake (from turbo) get 3-5% less air compared to the average and the outmost cylinder get 5-7% more air compared to average. If there is only two cylinders per manifold the air will possible be distributed more even between the cylinders. This would also be true at lower altitudes but maybe it’s still some difference at high altitudes where the density of the air is lower.

Wisdom from the book: Four-Stroke Performance by A. Graham Bell
http://www.amazon.com/Four-Stroke-Pe...480864-4783849

[leno]

Why noone use wa nkle engine? is it prohibited?

[Glee]

Why noone use wa nkle engine? is it prohibited?

Because Mazda isn’t in WRC…

I think there is a factor to calculate the volume of a ****el engine somewhere in the regulation.
(As a turbo engine of 2 litre is calculated as 3,4 (2,0 * 1,7= 3,4)

[Mirek]

I think that Wan.kel (why is it forbidden?) engine of that power and torque would be highly unreliable. The sealing faces of the triangle cylinder would be too stressed. The same about the central gear.

[leno]

Because Mazda isn’t in WRC…

I think there is a factor to calculate the volume of a ****el engine somewhere in the regulation.
(As a turbo engine of 2 litre is calculated as 3,4 (2,0 * 1,7= 3,4)

so 1,2 litre wa.kle woudl be not competitive with others

[Daniel]

so 1,2 litre wa.kle woudl be not competitive with others

Well you wouldn't be able to have a turbocharged wan kel 1.2. A normal 4 stroke engine had a power stroke per cylinder once every 2 times the crank turns. But a rotary has a power stroke each time. So to calculate the volume of a wan kel in FIA terms a 1.2 turbo rotary engine would be 1.2*2*1.7 so 4.08l.