Mark,
Variable inlets were used on the 90's M3 BMW's and in F1 until it got banned
they had variable inlets and exhausts.. lots of modern cars have butterfly
valves in the mufflers these days to let them be quiet down low and loud
when you step on it.. but in theory it sort of does the same thing..
increases flow at higher rpm when the engine breathes harder.
On 9 June 2010 06:02, Rense, Mark (GE Indust, ConsInd) <mark.rense@ge.com>wrote:
> Tom,
> Variable tuned exhaust has been used for years on high-performance
> motorcycles. Yamaha pioneered it with their EXUP system, now Honda and
> Kawasaki use it and BMW's new S1000 sportbike uses it (191 HP at the
> rear wheel, 440 lbs. wet). Furthermore, several of these bikes also
> employ variable intake tracts, with servos lengthening or shortening the
> velocity stacks inside the airbox depending on engine speed and load.
> Add variable valve timing, three-dimensional fuel and ignition mapping
> and these engines make 200HP per liter yet are docile around town. Ain't
> high tech cool?
>
> Bugz
>
> -----Original Message-----
> From: Thomas Witt
> Sent: Tuesday, June 08, 2010 2:24 PM
> To: tigers@autox.team.net
> Subject: Re: [Tigers] Headers versus Cast Iron Exhaust Manifolds
>
> Which brings me to the concept of variable exhaust. Just like there are
> multi valve engines that allow for good intake velocity and the ability
> to meet an added demand I'm surprised there aren't designs that follow a
> similar concept on the exhaust side. I'm thinking of a smaller primary
> exhaust pipe with a sprung flap that vents to a larger pipe secondary
> pipe on demand. Anyway, just thinking out loud.
> Tom
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>
--
Regards
Michael King
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