Dump valve - I'm not a chav!

[dgannon]

Guys,

I'm not into the dump valves you get on jap cars...

After hearing the sound of the Audi S1 rally car dump valve, i want one!

It makes a kind of fluttering noise which just sounds awesome. I'd guess someone is going to tell me you either can't buy them or they only work on cars with seriously high bhp??

If you can buy them, where from?

cheers,
Dave

 

[Dandle]

Guys,

I'm not into the dump valves you get on jap cars...

After hearing the sound of the Audi S1 rally car dump valve, i want one!

It makes a kind of fluttering noise which just sounds awesome. I'd guess someone is going to tell me you either can't buy them or they only work on cars with seriously high bhp??

If you can buy them, where from?

cheers,
Dave

You cant get that noise on your car without seriously lowering the engine and turbo life. The noise it makes is due to compressor stall(the flutering noise) and antilag firing fuel into the exhaust manifold to keep the turbo spinning while there isnt enough exhaust gases.

 

[10blazin]

damn dandle you seem to know your stuff ...............

 

[dgannon]

Fair enough, that's some interestin stuff, thanks Dandle

Dave

 

[Lee_R]

I've only ever heard 1 road legal car with anti lag and that was an Escort Cossie running 550bhp, it was mental and has the WRC style flutter and the cute little squeek on change!

 

[Caesium]

Actually the fluttering noise is an external wastegate opening and closing, rally cars to not suffer from compressor stall, compressor stall occurs on vehicles with no dump valve due to build up of pressure in the compressor housing and associated pipework which the DV bleeds off. Compressor stall on a high performance engine like a rally car would very quickly lead to a sheared compressor shaft due to the torsional forces involved in one side of the turbo being driven and the other side in a stall.

In short, the chattering fluttering sound is a combination of the external wastgate opening and closing rapidly and the DV doing the same.

Antilag causes a crackling/banging sound out of the exhaust. and the injector is usually directly into the turbine housing. This is pretty rare now however as modern antilag systems divert the charge air from the compressor housing into the turbine side to keep it spinning up. Dumping fuel into the exhaust is very unreliable.

 

[smudge_don]

i thought a dump valve actually prolongs the life of the turbo anyway........

 

[S3Alex]

Antilag causes a crackling/banging sound out of the exhaust. and the injector is usually directly into the turbine housing. This is pretty rare now however as modern antilag systems divert the charge air from the compressor housing into the turbine side to keep it spinning up. Dumping fuel into the exhaust is very unreliable.

As you say,newer systems work using an air bypass system,whereas some of the older ALS systems work by retarding the ignition when you lift the throttle,and also open the idle control valve to allow some engine air flow whilst the throttle is virtually closed.
Fuel is burnt quite late in the ignition cycle,and continues into the exhaust phase,but there is no injector in the turbine housing.
The net result is higher exhaust pressures and gas flow,which keep the exhaust turbine spinning,but also massively raised exhaust temperatures,and typically a turbo from one of these systems might need to be replaced after each stage of a rally.

Having run one of these systems on the road,I can vouch for it almost eliminating lag,but it also makes the car extremely difficult to drive unless you have a clear road.

 

[warren_S5]

Will something like this go someway to creating the effect you are looking for? (This is for an S3, but they may do something similar depending on what your A3 model is)

http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=010202&product=FMFSITR

You'd need to buy something like this first:

 

[S3-Dan]

i dont know ANYTHING about how engines work but if u wanna cool noise get the forge uprated DV in the pic before my post by warren and a full CAI it kinda flutters doesnt it guys ? more of a WOOHOOHOO as u let of haha i think youll like it theres guys with videos on here that im sure they will send u if u wanna hear it oh and get the DV spacer i took mineoff as the noise is mega loud n did my nutts in after a while