| elemental | 10-27-2001 10:31 PM |
Rally car noise?
I think it's the transmission, or isn't it? Wrong forum if it isn't, but:
What's that noise that sounds like bird's chirping that comes from WRC cars when they shift?
What's that noise that sounds like bird's chirping that comes from WRC cars when they shift?
| ForceFed4 | 10-27-2001 11:22 PM |
Wastegate chatter. Search the motorsports forum for detailed description of how/why this happens, I don't have the technical knowlege to explain it, but a couple people there do.
| RallyImprezive | 10-28-2001 04:33 PM |
Kinda, it is actually the Blow of Valve . Sounds cool huh. The BOV is part of the turbo system that is placed in the intake side of the turbo after the actual turbo, and before the throttle body. When the throttle is slammed shut, the turbo is still trying to shove air into the engine. If there was no BOV, the internal pressure would cause the turbo to blow apart. (Worst case senario). SOO ya let off the gas, and the BOV releases the pressure and creates that noise. Not all Blow of valves make that noise tho...most just make a short whooshing sounds.
-Andy
P.S. In rally cars, you can usually hear the tranny too though. It sounds like a permanent whine that increases pitch as the car accelerates. I love that sound.
-Andy
P.S. In rally cars, you can usually hear the tranny too though. It sounds like a permanent whine that increases pitch as the car accelerates. I love that sound.
| elemental | 10-28-2001 05:10 PM |
rally cars don't have bovs... it would kind of defeat the purpose of the anti-lag system, dont u think?
| RallyImprezive | 10-29-2001 01:02 AM |
No no, A BOV is very important...you must have one. You are thinking of a Wastegate. A wastegate is on the exhaust side. And the anti-lag is on the exhaust side of the system. I would double check your false knowledge. Think about it for a minute, the purpose of an anti-lag is to keep the turbo spooled up right? So in a turbo system without a BOV, the sudden backpressure caused by the throttle body closing would stop the turbo's spinning....in a hurry. But the BOV lets out the access air ON THE INTAKE SIDE, so that it doesn't back up into the turbo....and the turbo keeps spinning. AND, the anti lag system, introduces raw fuel into the exhaust side of the turbo, which causes an explosion, which keeps the turbo spinning even when there isn't a whole lot of exhaust pressure. That way, when you get back on the gas, you don't have to wait for the turbo to spool back up again. Hence...anti-lag.
One more thing, if that chripping truly isn't the BOV (which it is) then where does that sound come from?
-Andy
One more thing, if that chripping truly isn't the BOV (which it is) then where does that sound come from?
-Andy
| elemental | 10-29-2001 01:20 AM |
a) you need a wastegate so you don't overboost and blow up the engine in short order
b) if the anti-lag system is to have the turbo make boost all the time (which is something you did actually get right), wouldn't the bov just release the pressurized air after the turbo did all that work to compress it?
and yes, i do believe forcefed4 was correct in saying that it is wastegate chatter, i read a little about it after i read his post and it is supposed to be a result of the super duper wastegate (obviously not what they call it) being able to so quickly let out exhaust gas
think about it
you're missing a big thing as well... the turbo incorporates exhaust gas and intake gas (air)... so your whole argument about one is on one side the other is on the other side doesnt necessarily mean that they don't affect each other, they do.
b) if the anti-lag system is to have the turbo make boost all the time (which is something you did actually get right), wouldn't the bov just release the pressurized air after the turbo did all that work to compress it?
and yes, i do believe forcefed4 was correct in saying that it is wastegate chatter, i read a little about it after i read his post and it is supposed to be a result of the super duper wastegate (obviously not what they call it) being able to so quickly let out exhaust gas
think about it
you're missing a big thing as well... the turbo incorporates exhaust gas and intake gas (air)... so your whole argument about one is on one side the other is on the other side doesnt necessarily mean that they don't affect each other, they do.
| JNasty | 10-29-2001 02:18 AM |
I think you both are right on parts. The sound is the BOV. When they lift off the throttle, there is pressure that has to be let out. So, the BOV lets it out. But, the anti-lag system throws more fuel in so that is keeps the turbo spooling. And, yes, the BOV is letting boost out that the turbo is making, but that's not the point. They don't care about the power it's making right then, just as long as when they get back on the throttle they have full boost, hence "anti-lag". The wastegate, like in all turbos, is just there to regulate a max level of boost. So, you guys were both kinda right. And, I also agree that trans whine is kick ass. I had an AWD Talon before the WRX and when it was real cold out sometimes, the trans would whine like crazy, it was kick ass. Prob not the best thing for the trans, but if you know DSMs, you'll know that they don't exactly have the best ones to start with, so who cares.
| grimlock | 10-29-2001 08:57 AM |
Jeez, somebody get the inimitable Mr. Felstead in here pronto.
Guys, if you're gonna be dumping fuel in the exhaust manifold to keep the turbine spinning, you've gotta have air to combust with it. Which means the throttle plate needs to be open. Which means you don't need the BOV if you're doing anti-lag.
Ross N.
Guys, if you're gonna be dumping fuel in the exhaust manifold to keep the turbine spinning, you've gotta have air to combust with it. Which means the throttle plate needs to be open. Which means you don't need the BOV if you're doing anti-lag.
Ross N.
| Tats | 10-29-2001 06:01 PM |
It is DEFINATELY an anti-lag system. Works real good but is tough on turbo's.
Tats.
Tats.
| elemental | 10-29-2001 06:53 PM |
hehe, the anti-lag system is easy to recognize, the series of pops of the combusting of gas/air mixture in the piping, what they're discussing is the high pitched bird-like sound that happens every once in a while.
| RallyImprezive | 10-29-2001 07:08 PM |
[url]http://www.rallycars.com/Cars/bangbang.html[/url]
I know I know...bangbang is a lame name for the ALS, but the description is good.
-Andy
I know I know...bangbang is a lame name for the ALS, but the description is good.
-Andy
| RallyImprezive | 10-29-2001 07:35 PM |
ok, here is where I stand. The anti-lag issue should be cleared up by now. The back-fire you hear on rally cars is the anti-lag system introducing raw fuel to the system. And that chirping noise, which also sometimes sounds like a bunch of air rushing out for a second is the BOV. The article I posted also mentions the use of the BOV but calls it a dump valve, which I hope we can all agree is just another name for a BOV. The article also states that with an anti-lag system, and ADDITIONAL bypass valve is utilized to let extra air/fuel mixture in...so (low and behold) the BOV is still used!
Also, I have been to a few Rallies, and heard the US Rally Subaru first hand. I was able to get a close look at the engine and noticed the BOV..and yes, Subaru uses an ALS.
I am 100% certain that the chirping is the BOV. Heck, SCC even has a long article about how a turbo works. Go read it.
By the way. I really hate being rude, and I am sorry if I seem offensive, but I am trying to clear up false information. If you can prove me wrong, with TRUE, un edited proof. Go for it. If I am truely wrong I certainly want to be corrected.
-Andy
Also, I have been to a few Rallies, and heard the US Rally Subaru first hand. I was able to get a close look at the engine and noticed the BOV..and yes, Subaru uses an ALS.
I am 100% certain that the chirping is the BOV. Heck, SCC even has a long article about how a turbo works. Go read it.
By the way. I really hate being rude, and I am sorry if I seem offensive, but I am trying to clear up false information. If you can prove me wrong, with TRUE, un edited proof. Go for it. If I am truely wrong I certainly want to be corrected.
-Andy
| RallyImprezive | 10-29-2001 07:42 PM |
BTW, reading previous posts, you don't HAVE TO HAVE a wastegate. It is possible to properly size your turbo so that it is not capable of creating more boost than you want. Wastegates are ceratainly very important if you have an over-sized turbo capable of making to much boost.
-Andy
-Andy
| elemental | 10-29-2001 07:48 PM |
here we go, from that john felstead guy:
[quote]
There is an awefull lot of bollix and misinformation floating around about dump valves. Must be the biggest single con by the tuning trade in the history of turbo tuning.
The reason car manufacturers fit BOV's is to prolong the life of the turbo, to allow them to get away with selling cars fitted with 300 degree thrust bearings.
Having a BOV on a turbo engine reduces throttle response, it allows boost that would be there to bleed away.
Fitting an aftermarket BOV that vents to atmosphere is bad news on an engine that uses a MAF sensor to meter airflow.
Removing a BOV from the system will give you better throttle response than having it there. Do this with a standard turbo and you will reduce its life.
If you want to run without a BOV to get better response then a good idea is to use an uprated turbo with a 360 degree thrust bearing. (I have run normal 300 degree bearing turbos without BOV's for over 12 months on track days and road without a problem.)
The only time it becomes esential to use a BOV is when you get to using turbos the size of an RS500 full race T4. Anything smaller than that and you do not have any problem whatsoever without a BOV.
No WRC car runs a BOV, WRC spec anti lag systems wont work with a BOV.
Turbo's of the size we use on our subaru's and cosworth's do not suffer from reverse pulses stalling the turbo, thats complete bollix. I have discussed this at length with WRC engine builders and they all agree this is not what happens.
The chatter is the sound of the exhaust gasses passing through the waste gate button in the turbo housing. You need very high exhaust gas speeds to cause the waste gate to chatter, this is something you only start to see when you run high boost. WRC engines run at 34PSI boost at low revs (3000rpm) and this is bled away as the revs rise to stop the air going supersonic as it passes through the 34mm turbo restrictor. This is why the chatter is more noticable at low speed transitions as the revs are lower and the boost is much higher on WRC cars.
The boost curve is far more conventional on my own engine, that gives 26PSI boost at 3300rpm and then only drops 3psi till 6000rpm so i get chatter right accross the rev range.
Do i use a BOV? NO
Do i need one? NO
Does my turbo have a 360 degree bearing? Yes
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
quote:
--------------------------------------------------------------------------------
I would not have thought the wastegate would open on lift off/overrun, but thats when the noise occurs.
--------------------------------------------------------------------------------
Thats exactly when you get the biggest opening of the wastegate, or should i say, the most agresive opening. This is where the ECU is trying to stop the turbo from producing boost as the throttle is closed and so the waiste gate is banged wide open to dump the exhaust gasses down the wastegate and bypass the turbo.
This is aided by the boost presure building up very quickly in the piping between the turbo and the throttle bodie as the throttle is snapped shut. One of the ways the waste gate is forced open so quickly is by the feed from the outlet of the turbo compresor being fed via a solonoid valve to the diaphram of the actuator. The efective presure that is available to do this is higher without a BOV as the boost is not being bled away via the dump valve.
Thats why, when you take the BOV away, the chatter is greater as the actuator is being fed with higher than normal presures and the waste gate bounces.
quote:
--------------------------------------------------------------------------------
John, I bow to your knowledge, and will you warranty my turbo if I blank my blow off valve off .....lol...
--------------------------------------------------------------------------------
errrmmmm nope Like i say earlier, taking a BOV away and blanking its pipes off will reduce the turbo life (although not by a huge amount), i have never seen this as a problem and always use 360 degree turbos that can stand the presures.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
You are quite correct in saying that keeping the turbo spinning is paramount to reducing lag. However your statement is implying that removing the BOV stops the turbo from spinning, it doesnt.
There is another factor to throttle response. That is what presure is in the system between the turbo outlet and the throttle butterfly when you open the throttle. If you have a BOV in the system, when you come off throttle the boost presure is bled away. What this means is that when you re-open the throttle buterfly the turbo has to build the boost back up.
You wont ever find a BOV on a competition engine except where you have huge turbo's running very high boost. The only cosworth that needs a BOV for example is an RS500 race spec engine running a large T4 turbo, in that app the BOV is there to protect the thrust bearing from being overloaded by such high presure/volume on throttle snapping shut. It isnt there for throttle response.
You wont find a BOV on a WRC engine either, in fact the anti-lag systems wont work with one installed.
BOV's on production engines are there purely for longevity of the turbo's, they reduce throttle response.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
[/quote]
[url]http://www.i-club.com/forums/showthread.php?s=&threadid=48843&highlight=wastegate[/url]
[url]http://bbs.scoobynet.co.uk/Forum9/HTML/001078.html[/url]
[quote]
There is an awefull lot of bollix and misinformation floating around about dump valves. Must be the biggest single con by the tuning trade in the history of turbo tuning.
The reason car manufacturers fit BOV's is to prolong the life of the turbo, to allow them to get away with selling cars fitted with 300 degree thrust bearings.
Having a BOV on a turbo engine reduces throttle response, it allows boost that would be there to bleed away.
Fitting an aftermarket BOV that vents to atmosphere is bad news on an engine that uses a MAF sensor to meter airflow.
Removing a BOV from the system will give you better throttle response than having it there. Do this with a standard turbo and you will reduce its life.
If you want to run without a BOV to get better response then a good idea is to use an uprated turbo with a 360 degree thrust bearing. (I have run normal 300 degree bearing turbos without BOV's for over 12 months on track days and road without a problem.)
The only time it becomes esential to use a BOV is when you get to using turbos the size of an RS500 full race T4. Anything smaller than that and you do not have any problem whatsoever without a BOV.
No WRC car runs a BOV, WRC spec anti lag systems wont work with a BOV.
Turbo's of the size we use on our subaru's and cosworth's do not suffer from reverse pulses stalling the turbo, thats complete bollix. I have discussed this at length with WRC engine builders and they all agree this is not what happens.
The chatter is the sound of the exhaust gasses passing through the waste gate button in the turbo housing. You need very high exhaust gas speeds to cause the waste gate to chatter, this is something you only start to see when you run high boost. WRC engines run at 34PSI boost at low revs (3000rpm) and this is bled away as the revs rise to stop the air going supersonic as it passes through the 34mm turbo restrictor. This is why the chatter is more noticable at low speed transitions as the revs are lower and the boost is much higher on WRC cars.
The boost curve is far more conventional on my own engine, that gives 26PSI boost at 3300rpm and then only drops 3psi till 6000rpm so i get chatter right accross the rev range.
Do i use a BOV? NO
Do i need one? NO
Does my turbo have a 360 degree bearing? Yes
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
quote:
--------------------------------------------------------------------------------
I would not have thought the wastegate would open on lift off/overrun, but thats when the noise occurs.
--------------------------------------------------------------------------------
Thats exactly when you get the biggest opening of the wastegate, or should i say, the most agresive opening. This is where the ECU is trying to stop the turbo from producing boost as the throttle is closed and so the waiste gate is banged wide open to dump the exhaust gasses down the wastegate and bypass the turbo.
This is aided by the boost presure building up very quickly in the piping between the turbo and the throttle bodie as the throttle is snapped shut. One of the ways the waste gate is forced open so quickly is by the feed from the outlet of the turbo compresor being fed via a solonoid valve to the diaphram of the actuator. The efective presure that is available to do this is higher without a BOV as the boost is not being bled away via the dump valve.
Thats why, when you take the BOV away, the chatter is greater as the actuator is being fed with higher than normal presures and the waste gate bounces.
quote:
--------------------------------------------------------------------------------
John, I bow to your knowledge, and will you warranty my turbo if I blank my blow off valve off .....lol...
--------------------------------------------------------------------------------
errrmmmm nope Like i say earlier, taking a BOV away and blanking its pipes off will reduce the turbo life (although not by a huge amount), i have never seen this as a problem and always use 360 degree turbos that can stand the presures.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
You are quite correct in saying that keeping the turbo spinning is paramount to reducing lag. However your statement is implying that removing the BOV stops the turbo from spinning, it doesnt.
There is another factor to throttle response. That is what presure is in the system between the turbo outlet and the throttle butterfly when you open the throttle. If you have a BOV in the system, when you come off throttle the boost presure is bled away. What this means is that when you re-open the throttle buterfly the turbo has to build the boost back up.
You wont ever find a BOV on a competition engine except where you have huge turbo's running very high boost. The only cosworth that needs a BOV for example is an RS500 race spec engine running a large T4 turbo, in that app the BOV is there to protect the thrust bearing from being overloaded by such high presure/volume on throttle snapping shut. It isnt there for throttle response.
You wont find a BOV on a WRC engine either, in fact the anti-lag systems wont work with one installed.
BOV's on production engines are there purely for longevity of the turbo's, they reduce throttle response.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
[/quote]
[url]http://www.i-club.com/forums/showthread.php?s=&threadid=48843&highlight=wastegate[/url]
[url]http://bbs.scoobynet.co.uk/Forum9/HTML/001078.html[/url]
| RallyImprezive | 10-29-2001 08:57 PM |
*sigh* I guess I stand corrected. So, sometimes you hear rally cars with what sounds like a BOV making that "shhhh" sound. Is that the wastegate also? And I have heard a BOV, on WRX's and Mitsu's, and the ones that vent into the air make a distinctive sound that I have heard rally cars in the WRC make. (In the WRC FIA review videos to be exact.) I am now very confused.
-Andy
-Andy
| RallyImprezive | 10-30-2001 02:47 AM |
Apology
I want to apologize to everyone. I am sorry that I was so incessant about the stupid noise thing. I thought I knew for sure what I was talking about...and it went to my head. I was wrong and I am sorry.
Ya wanna know where the noise comes from?!? Somewhere in yer' damn turbo system! OK!?!? :D ;)
-Andy
Ya wanna know where the noise comes from?!? Somewhere in yer' damn turbo system! OK!?!? :D ;)
-Andy
| bsquare | 10-30-2001 04:56 AM |
No clue what that chirp is, but I sure know a lot more, as always, after reading a felstead post. Now, how do I locate a turbo with a 360 thrust bearing?
Ben
Ben
| NickSTi | 10-30-2001 10:36 AM |
you mean the chirping isnt actually birds? :(
i thought they use birds in the turbo system. my world just shattered :(
i thought they use birds in the turbo system. my world just shattered :(
| STiShawn | 10-30-2001 11:38 AM |
I emailed SWRT for an answer, lets see what they say...
| Lurker | 10-31-2001 09:10 AM |
[QUOTE][i]Originally posted by NickSTi [/i]
[B]you mean the chirping isnt actually birds? :(
i thought they use birds in the turbo system. my world just shattered :( [/B][/QUOTE]
:lol:Buahahahahahahaha!:lol:
I thought that noise was the gravel gun shooting pebbles at onlookers...:devil:
[B]you mean the chirping isnt actually birds? :(
i thought they use birds in the turbo system. my world just shattered :( [/B][/QUOTE]
:lol:Buahahahahahahaha!:lol:
I thought that noise was the gravel gun shooting pebbles at onlookers...:devil:
| PURE EPI | 10-31-2001 04:18 PM |
cool cool cool
For a while I thought that the chirp was actually the brakes...:lol: can ya believe that? God!! I am one pathetic loser!!!:lol: :p
| p-car | 10-31-2001 05:26 PM |
deja vu
here we go again...:lol:
| SSJ Char | 10-31-2001 06:19 PM |
I thought it was the tranny. I just thought that the gears squeeled under pressure.
| bbbradley | 11-01-2001 07:12 AM |
I just assumed it was the suspension components creaking from the super stiff running gear... Of course up until this spring I had never heard a BOV venting.
/bill
/bill
| johnfelstead | 11-01-2001 07:05 PM |
too funny. :D
This topic comes up at least once a month in here.
It took me quite some time to get the knowledge i now have about these systems so dont feel bad about not understanding it all, it's quite complex.
I know the first time i heard Jimmy McRaes GroupA Cossie in the forests (god i am old hehe) i didnt have a clue what the waste gate chatter was. I thought it was the rear tyres, how wrong was that. :D:lol:
Some clubman level cars run BOV's because they dont know any better. Anything that has proper mapping and decent turbos runs without a BOV and runs full ALS that uses ECU controlled Buterfly bypass valves or stepper motor driven overides on the throttle butterfly.
I am out with our GroupA Escort Cossie tomorow/saturday on the last rally of the year for us. Wish us luck, last event we rolled it and knackered every single panel on the car and part of the rollcage. :eek:
If you want a competition spec turbo seek out a specialist near you. I have a few piccies of my GroupA turbo rebuild if you are interested.
This topic comes up at least once a month in here.
It took me quite some time to get the knowledge i now have about these systems so dont feel bad about not understanding it all, it's quite complex.
I know the first time i heard Jimmy McRaes GroupA Cossie in the forests (god i am old hehe) i didnt have a clue what the waste gate chatter was. I thought it was the rear tyres, how wrong was that. :D:lol:
Some clubman level cars run BOV's because they dont know any better. Anything that has proper mapping and decent turbos runs without a BOV and runs full ALS that uses ECU controlled Buterfly bypass valves or stepper motor driven overides on the throttle butterfly.
I am out with our GroupA Escort Cossie tomorow/saturday on the last rally of the year for us. Wish us luck, last event we rolled it and knackered every single panel on the car and part of the rollcage. :eek:
If you want a competition spec turbo seek out a specialist near you. I have a few piccies of my GroupA turbo rebuild if you are interested.
| In2Deep | 11-02-2001 01:15 AM |
Always! I'd love to see some pics. How are you guys doing in the standings?
| HiImZackJones | 07-21-2012 02:07 AM |
The reason
if you are talking about this sound.
[ame="http://www.youtube.com/watch?v=dmJH84FnQa8"]Straight Cut Gears - YouTube[/ame]
the gears are straight cut to handle more torque. Helical gears can handle it unless you have a large transmission. Straight cut allows to have a smaller transmission that can deal. Done and done.
[url]http://automotivethinker.com/transmission/straight-cut-gears-vs-helical/[/url]
Don't believe me? try gunning it in reverse. Yep, reverse is straight cut.
[ame="http://www.youtube.com/watch?v=dmJH84FnQa8"]Straight Cut Gears - YouTube[/ame]
the gears are straight cut to handle more torque. Helical gears can handle it unless you have a large transmission. Straight cut allows to have a smaller transmission that can deal. Done and done.
[url]http://automotivethinker.com/transmission/straight-cut-gears-vs-helical/[/url]
Don't believe me? try gunning it in reverse. Yep, reverse is straight cut.
| HiImZackJones | 07-21-2012 02:09 AM |
I am stupid.
I misread the original post that said something about birds chirping. Yes BOV.
| That guy in Maine | 07-21-2012 12:32 PM |
:unamused:
This was already solved. It's not the BOV it's wastegate chatter.
We know that gears make a droning noise because they're straight cuts.
This was already solved. It's not the BOV it's wastegate chatter.
We know that gears make a droning noise because they're straight cuts.
| CGMDan | 07-22-2012 02:31 AM |
Holy crap, I've seen it all now. Zack Jones, you win the award for the oldest thread bump in Nasioc history. You bumped an 11 year old thread!!:eek:
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