Boxer breathing

[Rani]

During the coverage of Rally Mexico, everyone kept going on and on about how the Subarus lose less power high up in the mountains due to their boxer engines. Could someone please explain why that is?

[Daniel]

Perhaps there's some truth to that but I don't see why. The Subaru has the same sized restrictor as all the other cars and the same amount of air is going to get inside the Subaru engine as in a Citroen engine. Never make the mistake of trusting what Paul King says :crazy:

[Mark]

Same amount of air, but perhaps they make better use of the available air?

[jonkka]

Same amount of air, but perhaps they make better use of the available air?

Then the advantage should be the same everywhere, not just in Mexico.

[Daniel]

Then the advantage should be the same everywhere, not just in Mexico.

yes and Subaru don't have the best engine out of the bunch.

[SubaruNorway]

yes and Subaru don't have the best engine out of the bunch.

Who's that then? everyone seems to say that the Subaru has the strongest engine these days. Think maybe it has something to do with the short stroke on the boxer engine.

[Daniel]

Who's that then? everyone seems to say that the Subaru has the strongest engine these days. Think maybe it has something to do with the short stroke on the boxer engine.
I hate to use the nOObish evidence of Virtual Spectator but have you not seen how far Subaru's fall behind on fast straights? :confused:

[SubaruNorway]

I hate to use the nOObish evidence of Virtual Spectator but have you not seen how far Subaru's fall behind on fast straights? :confused:

Can't remember to have seen any comparisons like that for several years though

[Magnus]

I doubt that the boxer is that much worse then other designs when it comes to high altidtudes. In the end it is just a question of filling four cylinders with air using a pump, and that is a problem all the teams has in common.

[Rani]

So you guys really think it's all just a big myth? :confused:
I have heard this from every source between Eurosport and Israeli local coverage.
Doesn't anyone around here have any inside information about this?
Complementing Subaru's WRC engineering and design isn't very common these days.

[Mickey T]

i can't see any reason why that would be the case, but am staying at chris's house tomorrow night. will ask him for you

[gloomyDAY]

i can't see any reason why that would be the case, but am staying at chris's house tomorrow night. will ask him for you
http://www.o--rly.com/owl_orly.png

Ask him if he remembers the guy in Mexico with the blonde wig!
I was dressed up for the opening ceremony.

[grugsticles]

Basically it come down to the bore and stroke of the Subaru's engine, which allows the engine to rev more freely at higher altitudes.

[Glee]

If the boxer of the Subaru’s gains an advantage in high altitude, what about Jordan, where some of the stages are 400 meters below sea-level?

Quote: “This event features an unusually wide range of altitudes on the special stages, not far short of the range experienced in Turkey and Monte Carlo. In fact the highest stage will not go much above 1000 meters - but the lowest goes down to minus 400 metres - and most of the stages are below sea level.”

[Magnus]

I really do not undestand what this tumour hints at, I think it could be a misunderstanding from the beginning, since, as I pointed out, the basic problem is the same for everyone.

[SubaruNorway]

I really do not undestand what this tumour hints at, I think it could be a misunderstanding from the beginning, since, as I pointed out, the basic problem is the same for everyone.

Same for everyone, but less for the Boxer, get it? :p

[Daniel]

Same for everyone, but less for the Boxer, get it? :p

I'm sorry but you've not actually produced any evidence as to WHY the Subaru is supposedly better. I personally think red cars work better at high altitude due to oxidisation of the sun's gamma ray particles. But don't ask me to provide evidence :) My statement is all I have :p

[SubaruNorway]

now your just being dumb Daniel :laugh:

[Daniel]

now your just being dumb Daniel :laugh:
But at least I am being dumb on purpose :)

[leno]

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

[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-Performance-Tuning-3rd-practical/dp/1844253147/ref=pd_sim_b_img_1/103-0480864-4783849

[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.

[leno]

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.

wow! so that means wan.kle should be only 0,6 litre for wrc

[Daniel]

wow! so that means wan.kle should be only 0,6 litre for wrc

No :)

1L

1 (actual displacement) * 2 (FIA ruling on rotaries) * 1.7 (turbocharging) = 3.4

[urabus-denoS2000]

No :)

1L

1 (actual displacement) * 2 (FIA ruling on rotaries) * 1.7 (turbocharging) = 3.4

They can race those minicars you can only see in Japan!

OFF TOPIC:
Now I seriously think Mazda can be a serious competitor in the future.
1)Their ZOOM-ZOOM philosophy is ideal for rallying
2)Every new car is lighter than the car before it
3)The new Mazda 3 MPS will be ideal for group N.It will have 4WD with around 300 BHP.The only problem is that it will have a 2.5 liter engine,but that can be solved by putting a 2.0 liter on some market (just like Subaru did with the last generation Impreza9
4)They are showing some signs of waking up by their programmes is Australia ,etc.
5)They have announced their plan for a R2 Mazda 2 (we havent spokeen about it here).There are even some pictures.http://www.autosport.hr/images/stories/news/2008/02/29mrav.jpg

I would love to see Mazda back.

[Mirek]

That Mazda 2 is not R2. It is local Australian project of cheap rally car. Only the future will show if it can come to something more...

[urabus-denoS2000]

I know but they said could make one either in an S1600 (wich I doubt,its a dying class) or R2
The problem is that they dont have an appropriate engine

[Nenukknak]

Basically it come down to the bore and stroke of the Subaru's engine, which allows the engine to rev more freely at higher altitudes.

LOL, man if you don't know what you're talking about just don't say anything. At least Daniel did it on purpose.

As for my thoughts: I don't know, but I think it's just an urban myth.

[Mickey T]

chris thinks it's an urban myth as well.

i asked, and his take was that the suby engine is more tuned for mid-range, while the citroen and ford engines are revvier.

mexico, he reckons, just suits an engine with its performance in the mid range, and he doubts it has anything to do with altitude.

[leno]

chris thinks it's an urban myth as well.

i asked, and his take was that the suby engine is more tuned for mid-range, while the citroen and ford engines are revvier.

mexico, he reckons, just suits an engine with its performance in the mid range, and he doubts it has anything to do with altitude.

i belive him

[Gard]

chris thinks it's an urban myth as well.

i asked, and his take was that the suby engine is more tuned for mid-range, while the citroen and ford engines are revvier.

mexico, he reckons, just suits an engine with its performance in the mid range, and he doubts it has anything to do with altitude.

A slight contradiction here? Altitude will surely affect rewier engines more than engines tuned for midrange. so it will have much to do with altitude.

[Daniel]

A slight contradiction here? Altitude will surely affect rewier engines more than engines tuned for midrange. so it will have much to do with altitude.
What Chris is saying is that the engine is tuned better for the roads regardless of the altitude. As has been pointed out altitude has the same effect on all engines as they all get the same amount of oxygen into the engine.