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FITTING BIMODAL VALVES INTO WALKINSHAW CATBACK ON VF SV6 WAGON

crew chief

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To my way of thinking if you take a standard muffler that has two outlets, fit bimodals, you have taken a quiet exhaust and made it quieter.......

I did it the other way and fitted bimodal mufflers its louder when open and quiet closed
 

stooge

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I disagree with that, mine works well.

the bimodal design has one outlet running through the baffles and one that is a straight through pipe design and it is the straight through pipe that the valve is on which can turn on and off the straight through pipe which changes the volume like in this picture.
d60b86399c80602978054e541e20d213.jpg


a twin outlet standard muffler typically has one inlet and the baffles on both of the outlets are the same like in this picture.
twnout.jpg


putting a valve to close one pipe on a standard muffler will just force everything to come through the one open pipe.
i guess that could have a small effect on lowering the sound but i would not expect that to be too great because you are pushing the same volume of air/noise through 1 baffle instead of being split between 2.
 

Not_An_Abba_Fan

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My question would be what do you want to achieve?

Do you want the same effect as a bi-modal muffler? IE quiet when closed, loud when open? If so, the effect of fitting the valve to a ordinary muffler will vary depending on the muffler, to have the proper effect you need a bi-modal muffler.
 

lmoengnr

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A bi modal valve on a standard DPE muffler works well to reduce the noise.
My neighbor will back me up on that.
 

Not_An_Abba_Fan

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Which is why I said it would varying effects depending on the muffler. Some it will work, others it won't.
 
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I can get HSV bimodal mufflers from planet parts. Walkinshaw perth will fit the valves. Brett ( the owner) said something about remanufacturing the mufflers for bimodal if I go with the Walkinshaw (DPE) mufflers I have on the car now.
 

Jackel

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Are the mufflers from the DPE system bimodal mufflers?
They said they have bimodal mufflers with the vacum set up or they can weld my current bimodal valves into the DPE system which is the electric set up used with Mylink.
When they provide the mufflers for the valves to be welded in are they specific bimodal mufflers or just a standard muffler?
 
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I had the valves fitted just before Christmas. It is noticeably quieter with the valves closed. Really happy with workmanship done by Walkinshaw Perth.
 

kleanphil

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Pretty sure bimodel mufflers are designed with a bypass route for back pressure to be released the other side of the butterfly valve
 
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