Screamer pipes

[jetpilot]

I have had a quick search with options and not much really came up!

I know my car drops about 20hp with the wastegate pipe plumbed back into the exhaust, so looking for options as want it to be ok for track days, so cant really run a screamer!

If i were to run a silencer on the screamer pipe, should it effectively be as silenced as possible, i.e not straight through, or would that restrict things, as its only venting air?

Is there a good way of plumbing back in without loosing too much power?

Has anyone tried one of the exhaust diverters?

[m1tch]

I have seen an FC running a silenced screamer pipe - basically an extra exhaust can under the car, perhaps the issue with the power drop is where the pipe is plumbed back into the downpipe etc as if its too high up it can disrupt the gas flow from the rest of the exhaust. I think someone suggested fitting a bike exhaust to it which are usually slimmer etc.

I am planning on fitting an exhaust diverter valve, but it won\'t be for track use as it will just be an open pipe out the side of the car with all the exhaust gasses unsilenced :rollin

Lol best solution is found here:

http://mazdarotaryclub.com/forums/showthread.php?t=63650

"Or just turn up the boost and less will be coming out the w/g. It will then be a lot quieter.."

[jetpilot]

I have seen an FC running a silenced screamer pipe - basically an extra exhaust can under the car, perhaps the issue with the power drop is where the pipe is plumbed back into the downpipe etc as if its too high up it can disrupt the gas flow from the rest of the exhaust.

Well this was my thinking, is there any science to this (i am sure there is) or just route it say halfway down the midpipe?

[stylus350]

It was plumbed into the bend in the pipe just before the mid silencer pointing in the direction of flow as I considered this the best way. Rear can was RB.

Sih has plumbed a separate silencer to the WG and I\'m going to go this way at some stage.

As long as the diameter of the pipework is a little bigger than the exit on the WG then I think you will be fine and not lose power at all with a separate silencer.

[jetpilot]

What are your thoughts on silencer choice for wastegate buddy, straight through or otherwise?

[stylus350]

What are your thoughts on silencer choice for wastegate buddy, straight through or otherwise?

Straight through as it\'s still part of the exhaust and if you introduce back pressure then may as well run it back in to the cars main system :Thumbs-up

[m1tch]

Massive silencer:

[clive]

By plumbing back in I see no reason to lose power,

My personal view is that if it\'s not plumbed in you will at times literally have sheet flame under the car which potentially could cause problems, next up is when the wastegate is open the car will be LOUD, indeed some cars that get through the static noise test to go on track, then get chucked off because of the screamer pipe making the car too loud.  

I have even tried a totally different route, if you look at the picture below you will see a small pipe along side the main tail pipe.

Took a day to bend up this screamer pipe to go from front to back a a 2 minute run to decide it sounded like a strangled 2 stroke moped, it was a horrible noise as opposed to the beautiful Rotary sound it made when I plumbed it back in :cool

Hope this helps

[jetpilot]

Well in my ltd knowledge the only reason i can think is the gases from the wastegate cause flow issues with the exhaust gases.

I would doubt it myself, but 20hp proven on a dyno is quite a lot to loose or gain for that matter

[Grant Monkhouse]

could you not make your down pipe larger to compensate for the back pressure and then plumb the WG back into the exhaust?

[stylus350]

By plumbing back in I see no reason to lose power,

My personal view is that if it\'s not plumbed in you will at times literally have sheet flame under the car which potentially could cause problems, next up is when the wastegate is open the car will be LOUD, indeed some cars that get through the static noise test to go on track, then get chucked off because of the screamer pipe making the car too loud.  

I have even tried a totally different route, if you look at the picture below you will see a small pipe along side the main tail pipe.

Took a day to bend up this screamer pipe to go from front to back a a 2 minute run to decide it sounded like a strangled 2 stroke moped, it was a horrible noise as opposed to the beautiful Rotary sound it made when I plumbed it back in :cool

Hope this helps

Like jetpilot said it was dyno proven on this engine.

could you not make your down pipe larger to compensate for the back pressure and then plumb the WG back into the exhaust?

This may well be an alternative route. The exhaust was 3" and had the Racing Beat back box and a decent mid silencer so scope for a less restrictive system that might flow all gases well enough.

[billybobbooth]

why not run the pipe with a small silancer next to your stock exhaust till the backbox the with a shallow angle plum it back in just before the backbox, either that or,
 
have two exhaust 1 being for the exhaust and the other for the screamer you can match the tail pipes so it wouldnt look odd, dont know about fd by fc there is loads of room to run a 3" and a say 2"-1.75" next to it.

[jetpilot]

Kind of very complicated way about combining the two options to probably the same effect of loss of hp when you plumb it back in!

and if i am putting a silencer on i would simply have it under the car rather than fab up a load of pipe to the back and then try to find somewhere for it to exit where it doesnt look odd!

[Brett]

Out of interest, what is/was the joint and angle like when you had it plumbed into the exhaust?
Was the 20bhp drop/gain at a certain rev range, or general trend?

[jetpilot]

It was changed before i bought it so it only vents to atmosphere now so not sure of its previous configuration, stylus might be able to offer more info on that and i will have a look at the dyno charts and report back