active zaust on v8 project

[WabTheKing]

works like this, would this give more torque?

[Keeper of The Kitten]

The diagram and captions look ***** about face to me - surely the valve is closed at lower revs (forces system to use smaller bore) and open above 1700rpm (opens free flow path)???

__MDC__

[WabTheKing]

thats what i was thinking, found it on the miltek site

will have to look at the valve to see if its Normally Open or Normally Closed

[pastures16]

it looks like what we call an exhaust brake on our trucks when the brake pedal is pressed the exhaust brake comes on which slows the engine down thus helping with braking but your exhaust works the other way round might be all down to back pressure
what operates the valve a vacumn feed

[pastures16]

on another thought our scanias have a white smoke inhibitor which applys the exhaust brake to cut down emmissions for town or city use

[Audi_CQ]

Is there any likelihood that this system increases torque in the NA engine at lower revs? I think it might! Problem is, does the extra weight negate any gains made?

__MDC__

Why would extra back pressure increase torque?
This is just an old myth
Someone will propably claim that it has worked for them, but my opinion is that if it does, it's something wrong/bad design with another component in the engine. Can't imagine that Audi does a bad engine design and build an expensiv exhaust to compensate

[WabTheKing]

Why would extra back pressure increase torque?
This is just an old myth
Someone will propably claim that it has worked for them, but my opinion is that if it does, it's something wrong/bad design with another component in the engine. Can't imagine that Audi does a bad engine design and build an expensiv exhaust to compensate

what do think its purpose is then?

[pastures16]

have you asked mrc yet

[Audi_CQ]

what do think its purpose is then?

Noise regulations and comfort mostly. Maybe a few extra top end hp because of less pumping loss.

[WabTheKing]

so in your opinion is it a waste of time?

[Audi_CQ]

so in your opinion is it a waste of time?

Would be easier to make your own system with just a valve and pipe to bypass the mufflers at full throttle or boost higher then 1 bar or whatever you choose to trigger it with
In that way you could get low noise when cruising, and nearly zero back pressure at full attack. A bit loud when valve open maybe but...

[WabTheKing]

zero back pressure on an NA wont have much torque, IMHO you need some back pressure unless you have a nice turbo sat there - which i dont.........yet:mischeif:

[Mihnea]

That's a nice myth as Roger said it before!

Any engine will have more torque if tuned properly to take advantage of the lowest possible backpressure levels.

But after all, if you think you *need* back pressure, do it your way

zero back pressure on an NA wont have much torque, IMHO you need some back pressure unless you have a nice turbo sat there - which i dont.........yet:mischeif:

[Audi_CQ]

zero back pressure on an NA wont have much torque, IMHO you need some back pressure unless you have a nice turbo sat there - which i dont.........yet:mischeif:

The question you have to ask yourself here is why would back pressure get you more torque?

[WabTheKing]

That's a nice myth as Roger said it before!

Any engine will have more torque if tuned properly to take advantage of the lowest possible backpressure levels.

But after all, if you think you *need* back pressure, do it your way

ok well the exhaust which is fitted at the moment has very little back pressure, 3", into one box 8"x14" split into twin 3"
what sort of bhp/torque figures do you think you could get from the 4.2 32v abz engine running standard motronic ecu with minimal back pressure?