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?
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.."
Quote from: m1tch;802166I 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?
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.
What are your thoughts on silencer choice for wastegate buddy, straight through or otherwise?
Quote from: jetpilot;802171What 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
Massive silencer:
(http://t3.gstatic.com/images?q=tbn:ANd9GcTtyuGHjr6JbIXHO-VZVFMLZLToA_3w8mMV6jYLCLgNBsW8lehgcvg7OqjB)
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
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 :)
could you not make your down pipe larger to compensate for the back pressure and then plumb the WG back into the exhaust?
Quote from: clive;802185By 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.
Quote from: Grant Monkhouse;802194could 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.
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.
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!
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?
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 :)
Quote from: Brett;802503Out 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?
Was plumbed in to point in the direction of flow to try to keep disruption to a minimum
Presume the join was flush into the main exhaust? No protrusions?
Also, was power down in general, or only at certain rev/boost/throttle?
Quote from: Brett;802673Presume the join was flush into the main exhaust? No protrusions?
Also, was power down in general, or only at certain rev/boost/throttle?
You presume correctly. It was as good as it could be after much thought was put into it before any work began.
Jets got the charts I can\'t remember specifics but I run a screamer now which, at some point Will have its own silencer.
It\'s a black art!
Do you think it would make a difference plumbing the Return pipe in as far back as possible? (maybe mid pipe area?) or maybe put a dent just before the Return into the Downpipe to cause a low pressure spot as close to the end of the return as poss to help reduce Transition Turbulence at speed?
Be great to have a dyno that you could play on :)
Quote from: Grizzly;802762Do you think it would make a difference plumbing the Return pipe in as far back as possible? (maybe mid pipe area?) or maybe put a dent just before the Return into the Downpipe to cause a low pressure spot as close to the end of the return as poss to help reduce Transition Turbulence at speed?
Be great to have a dyno that you could play on :)
ye would be trying all kinds of shiz if i had my own dyno!!!
Quote from: Grizzly;802762Do you think it would make a difference plumbing the Return pipe in as far back as possible? (maybe mid pipe area?) or maybe put a dent just before the Return into the Downpipe to cause a low pressure spot as close to the end of the return as poss to help reduce Transition Turbulence at speed?
Be great to have a dyno that you could play on :)
Interesting thought and concept, however, not being au fai with the darker art of exhausts and tuning, would the exhaust flow not be constant throughout the entire length of it, or are you suggesting that it then has less time to exit to actually interfere with the flow?
So, would it not be best, just before the back box with the introduction of a y pipe?
Seems to me the safest option, cost wise, would be to silence the screamer pipe as you are guaranteed a result!
The only reason i could see is if the exhaust acts as a venturi and and sucks the gas out of the w/gate when it opens causing it to oull out too much gas before the controller has time to adjust it,or boosted gas from the wastegate may affect the parth partially of the escaping exhaust gas and gas a dropin flow,
probably wrong but the first makes sense.,,
maybe this is less likely on a turbo with a top boost controller/wgate
It\'s purely and simply to do with flow. If for eg. only half the engines gases are passing through a 3" system because of the rest diverted through the WG once plumbed back in that 3" system is now having to flow twice the volume. We all know the best exhaust for a turbo engine is no exhaust at al......
Quote from: stylus350;802824It\'s purely and simply to do with flow. If for eg. only half the engines gases are passing through a 3" system because of the rest diverted through the WG once plumbed back in that 3" system is now having to flow twice the volume. We all know the best exhaust for a turbo engine is no exhaust at al......
Correct :Thumbs-up
Quote from: stylus350;802824It\'s purely and simply to do with flow. If for eg. only half the engines gases are passing through a 3" system because of the rest diverted through the WG once plumbed back in that 3" system is now having to flow twice the volume. We all know the best exhaust for a turbo engine is no exhaust at al......
So i am with you know, hence why larger wastegates flow better...
I always wondered why wastegates were different sizes, sorry to sound daft :)
I think a silenced screamer is def the way forward then :)
Quote from: BlitzBoy;802831Correct :Thumbs-up
Yaaaaay! It\'s like getting a pat on the head from a wise uncle :)
Quote from: jetpilot;802835So i am with you know, hence why larger wastegates flow better...
I always wondered why wastegates were different sizes, sorry to sound daft :)
I think a silenced screamer is def the way forward then :)
That\'s what Im doing dude :)
eventually.