boxer engine capacity?

[anonymous-user]

just wondering after seeing the new 4.0 RS3 LE porsche, is it right that the boxer engine capacity is limited to 4.0 litres.... and why?

Will porsche have to stay at 4.0 litres for all future 911's.??

[v8will]

I have never heard of that, maybe it is just a packaging issue with 6 cylinders? I know Ferrari made larger capacity 12 cylinder flat engines but the actual cylinder capacity would have been smaller

[busta]

For that particular Porsche engine block perhaps 4 litres is the limit, but there's no reason why you couldn't build a bigger one if you made a bigger block.

[anonymous-user]

v8will said:

I have never heard of that, maybe it is just a packaging issue with 6 cylinders? I know Ferrari made larger capacity 12 cylinder flat engines but the actual cylinder capacity would have been smaller

the Ferrari was actually a flattened v12 not true boxer..

The reason I asked was this was why ruf moved to a v8..

[Si_steve]

black pipebandit said:

the Ferrari was actually a flattened v12 not true boxer..

The reason I asked was this was why ruf moved to a v8..

If the cylinders are flat (opposed)then it's a boxer/flat engine reguardless of what it was previously.

On the original subject of capacity limitations, I see no reason why a boxer engine should be limited to a 4 litre capacity. Space within an engine bay, maybe but thats not really what the questions about.

[busta]

There is an optimum piston size for any engine and a limit to how big you can sensibly go whilst still keeping good characteristics for a road car- hence why you don't see many 4 cylinder car engines over 2.2 litres or six cylinder engines over 3.6 litres. As far as I'm aware this has very little to do with the engine configuration though.

[WhoseGeneration]

black pipebandit said:

just wondering after seeing the new 4.0 RS3 LE porsche, is it right that the boxer engine capacity is limited to 4.0 litres.... and why?

Will porsche have to stay at 4.0 litres for all future 911's.??

Nope.
Boxers are, arguably, the ideal configuration, just that they are more expensive to produce and package in a world of mainstream fwd.

[ZeeTacoe]

busta said:

There is an optimum piston size for any engine and a limit to how big you can sensibly go whilst still keeping good characteristics for a road car- hence why you don't see many 4 cylinder car engines over 2.2 litres or six cylinder engines over 3.6 litres. As far as I'm aware this has very little to do with the engine configuration though.

Really 6 cylinders over 3.6 litres? Better ask cummins about all those ISBs

[Si_steve]

ZeeTacoe said:

Really 6 cylinders over 3.6 litres? Better ask cummins about all those ISBs

The volvo FH16 engines are 6 cyl 16 litres, which is good for low rpm/high torque applications, But for a road going petrol car...not so good. But I see your point.

[busta]

ZeeTacoe said:

Really 6 cylinders over 3.6 litres? Better ask cummins about all those ISBs

Not really a car engine though is it, and it's a diesel. I was going to use the cummins engine of an example that you could go to a higher capacity on a given number of cylinders but the characteristics of the engine change dramatically from that of a typical car engine- high torque, slower reving engines are not best suited to high end 911s!

If you want to take it to extremes, boat engines go to massive cubic metre capacities on 6 cylinders...

[E30M3SE]

Si_steve said:

black pipebandit said:

the Ferrari was actually a flattened v12 not true boxer..

The reason I asked was this was why ruf moved to a v8..

If the cylinders are flat (opposed)then it's a boxer/flat engine reguardless of what it was previously.

On the original subject of capacity limitations, I see no reason why a boxer engine should be limited to a 4 litre capacity. Space within an engine bay, maybe but thats not really what the questions about.

A true Boxer engine has two opposed pistons reaching TDC at the same time.

A flat they reach TDC half a crank rev apart.

[Puddenchucker]

E30M3SE said:

Si_steve said:

black pipebandit said:

the Ferrari was actually a flattened v12 not true boxer..

The reason I asked was this was why ruf moved to a v8..

If the cylinders are flat (opposed)then it's a boxer/flat engine reguardless of what it was previously.

On the original subject of capacity limitations, I see no reason why a boxer engine should be limited to a 4 litre capacity. Space within an engine bay, maybe but thats not really what the questions about.

A true Boxer engine has two opposed pistons reaching TDC at the same time.

A flat they reach TDC half a crank rev apart.

Hopefully, these make the difference easier to understand.

A flat (180 degree V) engine: http://www.youtube.com/watch?v=IEgXUt1PSgg

A boxer engine: http://www.youtube.com/watch?v=j_g_K0nyGHQ&fea...

[Si_steve]

Splitting hairs now :P haha I kid, I kid. Either way I dont think it makes much difference in reference to the original topic. Always told in college to call them a horizontaly opposed engine anyway, any other answer would fail an exam. Same as the shock absorber/damper common mistake that most people make.