| Pesca 555 | 11-27-2001 12:26 PM |
Name that sound!
I was watching the Australian WRC this past weekend on NASCAR-vision :( Very nice footage, and I think that they are catching onto the fact that the fans want to hear more "sounds".
Speaking of sounds... All you Rally-maniacs, answer me this. I've always been wondering, what on earth is that chirping sound that I hear when the WRC cars are under braking and also taking corners? Is that the brakes? The Differentials? The tires? Sounds like Flipper, the dolphin (ke-ke-ke-ke....) :confused:
Speaking of sounds... All you Rally-maniacs, answer me this. I've always been wondering, what on earth is that chirping sound that I hear when the WRC cars are under braking and also taking corners? Is that the brakes? The Differentials? The tires? Sounds like Flipper, the dolphin (ke-ke-ke-ke....) :confused:
| Porter | 11-27-2001 12:31 PM |
The sound you're hearing is the wastegate modulating at high speed under pressure. The sound is known as "wastegate chatter". Most WRC cars do NOT have a blow off valve.
Or, you could do a search... this is about the 20th time someone has asked this question in the past 6 months. :p
I'm not trying to be crabby... :lol:
Or, you could do a search... this is about the 20th time someone has asked this question in the past 6 months. :p
I'm not trying to be crabby... :lol:
| Pesca 555 | 11-27-2001 12:43 PM |
:( Sorry, didn't mean to ask a stupid question. It's my first time here on the Motorsports BB. I will now go and hide under the Northwest i-Club rock... :lol:
Wastegate clatter? :confused: I have a turbo (non-soob) car, but I've never heard anyting REMOTELY close to that sound. Granted it's a totally different animal all together, but it's very curious...
I'll do an archive search, too. Thanks.
Wastegate clatter? :confused: I have a turbo (non-soob) car, but I've never heard anyting REMOTELY close to that sound. Granted it's a totally different animal all together, but it's very curious...
I'll do an archive search, too. Thanks.
| Porter | 11-27-2001 12:56 PM |
It's an external wastegate.
Search for posts by Johnfelstead on the subject "wastegate".
Search for posts by Johnfelstead on the subject "wastegate".
| Pesca 555 | 11-27-2001 01:33 PM |
DOH!!!
Thaks for the search criteria - found the info I need.
I didn't realize the topic was that big. Should have done a search before. :eek:
Got it. It's the wastegate :cool:
Now, back to life.
I didn't realize the topic was that big. Should have done a search before. :eek:
Got it. It's the wastegate :cool:
Now, back to life.
| Porter | 11-27-2001 01:44 PM |
No problem. It wasn't a dumb question at all. Ask, and ye shall receive. :D
| Pesca 555 | 11-27-2001 01:54 PM |
Thanks!
And receive, I did. :D
Good information by John - myths debunked and technical information galore. I love this BB. :cool:
Thanks again :)
Good information by John - myths debunked and technical information galore. I love this BB. :cool:
Thanks again :)
| Shik | 11-27-2001 04:55 PM |
[quote]It's an external wastegate. [/quote]
Actually, I believe the WRC Impreza does indeed use an internal wastegate, it may vent externally, but all the pictures I've seen of the WRC motors have internal wastegates.
However, it is actuated differently then a standard turbo car with the typical boost solenoid. But if you found Mr. Felstead's post, you know about it already :)
You can see here(what looks to be) the internal wastegate actuator in gold.
[img]http://www.c-t-l.co.uk/firefox/WRC%2001/turbo.jpg[/img]
Actually, I believe the WRC Impreza does indeed use an internal wastegate, it may vent externally, but all the pictures I've seen of the WRC motors have internal wastegates.
However, it is actuated differently then a standard turbo car with the typical boost solenoid. But if you found Mr. Felstead's post, you know about it already :)
You can see here(what looks to be) the internal wastegate actuator in gold.
[img]http://www.c-t-l.co.uk/firefox/WRC%2001/turbo.jpg[/img]
| TampaWRX | 11-27-2001 07:10 PM |
I want a chattering wastegate! Wish there was a way to mount one on a street Scooby for reasonable $$$. :(
| Shik | 11-27-2001 09:14 PM |
Disable or remove the BOV and vent the wastegate to the atmosphere(aka dump tube), you'll hear it :) May not be super good for your turbo, but you'll hear it.
| Pesca 555 | 11-27-2001 09:19 PM |
Wastegate to the... ATMOSPHERE??? :eek:
| gumby647 | 11-27-2001 10:35 PM |
Do you have any more of those pics?
I think that is the most beautiful intake manifold I have ever seen.
I think that is the most beautiful intake manifold I have ever seen.
| Porter | 11-28-2001 09:23 AM |
Yeah Pesca... wastegate to atmosphere. Instead of routing it down into the exhaust again, it gets its own little exhaust tube. Some people even put a glasspack on there to keep the noise down a little. It's LOUD!
You'll need more boost than the WRX runs stock to make it sound good though...
You'll need more boost than the WRX runs stock to make it sound good though...
| Greg555 | 11-28-2001 09:25 AM |
YO
It is the blow of valve that does it. Trust me on this one. Crank your boost to 25 psi and you will get a very similar sound. There is so much boost that every time you close your butterfly your BOV has to open few times to let all the air out.
And yes, the air has to go out to atmosphere, otherwise you will not hear it.
Greg
It is the blow of valve that does it. Trust me on this one. Crank your boost to 25 psi and you will get a very similar sound. There is so much boost that every time you close your butterfly your BOV has to open few times to let all the air out.
And yes, the air has to go out to atmosphere, otherwise you will not hear it.
Greg
| Porter | 11-28-2001 09:55 AM |
Greg... that's pretty funny since the WRC cars HAVE NO BLOWOFF VALVE.
:D
:alien:
:D
:alien:
| Greg555 | 11-28-2001 12:11 PM |
Whatever. I will not argue because I don't know for sure. All I know is few Prorally lancers that are running high boost (ex. Burke)are making very similar sound and it is coming from BOV :)
| Porter | 11-28-2001 12:21 PM |
I'm not sure about ProRally. It's very possible. A BOV can make a similar sound.
The WRC cars don't have a BOV though.
The WRC cars don't have a BOV though.
| Pesca 555 | 11-28-2001 12:24 PM |
Boy, I have MUCH to learn about this Rally stuff (see note below my ID...."Scooby Newbie") :alien:
Please note that with an open element filter (ie. my non-soob), you can hear LOTS of different sounds (ie. compressor whine, Bypass valve, etc...)
Since i am a newbie, I am allowed to ask STUPID questions :p right? So here goes. If, for instance, you want to LIMIT (why?) your boost to a certain amount, wouldn't a BOV in fact help? Any boost above, say 34psi would simply "blow off"... Boost limiting for purposes of narrowly-tuned induction, Air Mass Meter (MAF for Soobs) limitation, etc???
I, for one, hate the sound of BOVs. Sounds like a leak of some sort in the motor. I like tight sounding motors for my cars. Supercharger whine is a good sound, too. Straight-cut gears sound good too (for the first 3-minutes or so, and after that, it's just TORTURE).
Please note that with an open element filter (ie. my non-soob), you can hear LOTS of different sounds (ie. compressor whine, Bypass valve, etc...)
Since i am a newbie, I am allowed to ask STUPID questions :p right? So here goes. If, for instance, you want to LIMIT (why?) your boost to a certain amount, wouldn't a BOV in fact help? Any boost above, say 34psi would simply "blow off"... Boost limiting for purposes of narrowly-tuned induction, Air Mass Meter (MAF for Soobs) limitation, etc???
I, for one, hate the sound of BOVs. Sounds like a leak of some sort in the motor. I like tight sounding motors for my cars. Supercharger whine is a good sound, too. Straight-cut gears sound good too (for the first 3-minutes or so, and after that, it's just TORTURE).
| Porter | 11-28-2001 12:35 PM |
Pesca, what you're referring to is best controlled by a wastegate.
John Felstead or another of the techie gurus could explain it better, but that's essentially what a wastegate is designed to do... limit boost very precisely by controlling the pressure across the turbo.
What you're hearing in the WRC clips is the wastegate modulating OPEN/CLOSED at very high speed to limit boost precisely to a set value. That's what makes the chirping sound.
John Felstead or another of the techie gurus could explain it better, but that's essentially what a wastegate is designed to do... limit boost very precisely by controlling the pressure across the turbo.
What you're hearing in the WRC clips is the wastegate modulating OPEN/CLOSED at very high speed to limit boost precisely to a set value. That's what makes the chirping sound.
| Pesca 555 | 11-28-2001 01:00 PM |
Porter,
Understood - John went into detail (and a lot of it) about the WG chatter, and it makes sense. I have an external WG on my non-soob, too, so i know what he's talking about. However, a pressure controlled BOV would "also" limit boost that gets past the butterfly, instead of fancy WG actuators and solenoids.
Just wondering if TWO mechanical boost controllers (ie. WG/BOV) would aid in the performance, if both of them were tuned correctly (say, recirculate blow-off into intake route, instead of atmosphere) which is standard on my non-soob.
Understood - John went into detail (and a lot of it) about the WG chatter, and it makes sense. I have an external WG on my non-soob, too, so i know what he's talking about. However, a pressure controlled BOV would "also" limit boost that gets past the butterfly, instead of fancy WG actuators and solenoids.
Just wondering if TWO mechanical boost controllers (ie. WG/BOV) would aid in the performance, if both of them were tuned correctly (say, recirculate blow-off into intake route, instead of atmosphere) which is standard on my non-soob.
| Porter | 11-28-2001 01:11 PM |
Just incidentally... what is your non-soob? External wastegate? Hmmmm.... :confused: ;)
| Pesca 555 | 11-28-2001 01:20 PM |
Not a soob, but a saab turbo :devil:
The external WG is aftermarket, as the OEM internal one was too resrictive. But i don't drive it nearly as hard enough to create WG chatter :(
The bypass valve - also called the "Hooter Valve" - because it ...er, "hoots" (no, it doesn't have exceptionally large breasts) is an OEM Bosch unit. Damn blast! It's not a GReddy-HKS-Apex-technogizzmo from Japan! It recirculates instead of er, blowing off... Pretty effective.
The external WG is aftermarket, as the OEM internal one was too resrictive. But i don't drive it nearly as hard enough to create WG chatter :(
The bypass valve - also called the "Hooter Valve" - because it ...er, "hoots" (no, it doesn't have exceptionally large breasts) is an OEM Bosch unit. Damn blast! It's not a GReddy-HKS-Apex-technogizzmo from Japan! It recirculates instead of er, blowing off... Pretty effective.
| Porter | 11-28-2001 02:02 PM |
NICE!
I used to have an '89 900 SPG 3-door that I blew up at 24psi, it was around 300hp. Best car I ever had. I just killed the tranny in my '87 900S at 174k miles.
:devil:
I used to have an '89 900 SPG 3-door that I blew up at 24psi, it was around 300hp. Best car I ever had. I just killed the tranny in my '87 900S at 174k miles.
:devil:
| Pesca 555 | 11-28-2001 02:12 PM |
Good gawd!
If you can produce 300ps on the SPG, you need to come back to Saabdom. The most recent dyno champion among the Seattle SAAB Club was 238ps (270lb/ft) on an MY88 SPG with T03/T04 hybrid turbo, external wastegate, Spearco FMIC, Aquamist water injection, Jacobs ignition, RRFPR, and a 3" trubo-back exhaust (to name a few). No, that was not my 900.
But we're getting off topic here.
Can you tell me a little ore about the exhaust tube for the atmospheric Wastegate? Very intriguing... do they make tiny glass-pacs specifically for this purpose?
But we're getting off topic here.
Can you tell me a little ore about the exhaust tube for the atmospheric Wastegate? Very intriguing... do they make tiny glass-pacs specifically for this purpose?
| Porter | 11-28-2001 02:26 PM |
I have no idea... most of the ones I've heard of were homemade with a piece of fiberglass wrapped over holes cut in the tube, and another piece of metal welded around that..... No idea.
.....238ps??? ***? With that kind of modification he should be turning 300hp. Damn, dude! The Euro spec SPGs came with 200 STOCK! I did have an aftermarket ECU in it... the Group 6 full replacement. I won't go into all the rest, I ended up blowing the head gasket and warping the head due to poor tuning on my part. I'm older and wiser now (I hope). Sounds like the guy running 238ps is a boost chicken. The Saab I4 can handle very large amounts of boost when tuned properly.
Or did you mean 238 at the wheels? I'm referring to crank HP.
.....238ps??? ***? With that kind of modification he should be turning 300hp. Damn, dude! The Euro spec SPGs came with 200 STOCK! I did have an aftermarket ECU in it... the Group 6 full replacement. I won't go into all the rest, I ended up blowing the head gasket and warping the head due to poor tuning on my part. I'm older and wiser now (I hope). Sounds like the guy running 238ps is a boost chicken. The Saab I4 can handle very large amounts of boost when tuned properly.
Or did you mean 238 at the wheels? I'm referring to crank HP.
| Pesca 555 | 11-28-2001 03:19 PM |
238ps at the Wheels (tires, the drum of the dyno, what have you).
All those bells and whistles, and it still can't touch the WRX... Add to that, the weight of Swedish metal :eek: Great cars, really. The SPG was/is the quintessential classic Saab - dontcha just miss it?
I'm hanging on to my RS and my 900t. The best cars I've ever owned!
All those bells and whistles, and it still can't touch the WRX... Add to that, the weight of Swedish metal :eek: Great cars, really. The SPG was/is the quintessential classic Saab - dontcha just miss it?
I'm hanging on to my RS and my 900t. The best cars I've ever owned!
| Shik | 11-28-2001 07:49 PM |
Guys, the BOV opens when it sees vacumn, so getting it to "blow off" at a certain boost psi is really impossible the way they are originally designed right now.
Not to mention it would be hell on a turbo since it would spin as fast as it possible could all the time. The wastegate allows the turbine wheel to maintain a certain pressure letting exhaust bypass it. If a BOV regualted boost, the turbine wheel would constantly spin with nothing allowing it to slow down. Probably wouldn't last very long;) IMHO, standard wastegates and they way they are actuated on a street car do a pretty damn good job of controlling boost
And Pro Rally Lancers are a far cry from WRC cars. They do use BOV's and they do sound very cool, but it is totally different then the "chirping" heard from the WRC cars.
Gumby, I'll post the link to all the pictures that Jay_UK took of the 2001 WRC car when it was still in prototype form I believe, just have to find it again :)
Not to mention it would be hell on a turbo since it would spin as fast as it possible could all the time. The wastegate allows the turbine wheel to maintain a certain pressure letting exhaust bypass it. If a BOV regualted boost, the turbine wheel would constantly spin with nothing allowing it to slow down. Probably wouldn't last very long;) IMHO, standard wastegates and they way they are actuated on a street car do a pretty damn good job of controlling boost
And Pro Rally Lancers are a far cry from WRC cars. They do use BOV's and they do sound very cool, but it is totally different then the "chirping" heard from the WRC cars.
Gumby, I'll post the link to all the pictures that Jay_UK took of the 2001 WRC car when it was still in prototype form I believe, just have to find it again :)
| Pesca 555 | 11-28-2001 08:00 PM |
I'm not a BOV advocate, but I have to disagree to the fact that the BOV opens when there is vaccuum.
The basic principle of a BOV, AFAIK, is that the pressure built up between the compressor and the throttle body is released at a set psi level. No vaccuum there, right?
The turbine does slow down, and the pressure in the intake is not a "brake" per se, so a BOV wouldn't inhibit the turbine from slowing down because the compressor has no air mass to bite against.
brain pain... need to go rent more coffee.
The basic principle of a BOV, AFAIK, is that the pressure built up between the compressor and the throttle body is released at a set psi level. No vaccuum there, right?
The turbine does slow down, and the pressure in the intake is not a "brake" per se, so a BOV wouldn't inhibit the turbine from slowing down because the compressor has no air mass to bite against.
brain pain... need to go rent more coffee.
| Shik | 11-28-2001 08:33 PM |
[quote]is that the pressure built up between the compressor and the throttle body is released at a set psi level[/quote]
Nah, no set psi level or anything for a BOV, just negative pressure.
[quote]The turbine does slow down, and the pressure in the intake is not a "brake" per se, so a BOV wouldn't inhibit the turbine from slowing down because the compressor has no air mass to bite against. [/quote]
Ya lost me totally :lol:
If a BOV was the ONLY boost control(if it could be made to work), which I assumed is what you were asking, and there is no wastegate, the more exhaust going through the turbo, the faster the turbo would spin. If there was no way of some exhaust bypassing the turbo, it would simply continue to spin until it killed itself, as long as there was exhaust coming out of the engine. It wouldn't matter what was going on on the intake side.
I think I may have what you said confused a bit, so don't take what I'm saying too seriously :)
Nah, no set psi level or anything for a BOV, just negative pressure.
[quote]The turbine does slow down, and the pressure in the intake is not a "brake" per se, so a BOV wouldn't inhibit the turbine from slowing down because the compressor has no air mass to bite against. [/quote]
Ya lost me totally :lol:
If a BOV was the ONLY boost control(if it could be made to work), which I assumed is what you were asking, and there is no wastegate, the more exhaust going through the turbo, the faster the turbo would spin. If there was no way of some exhaust bypassing the turbo, it would simply continue to spin until it killed itself, as long as there was exhaust coming out of the engine. It wouldn't matter what was going on on the intake side.
I think I may have what you said confused a bit, so don't take what I'm saying too seriously :)
| Pesca 555 | 11-28-2001 09:11 PM |
Forced induction 101
Shik,
I stand corrected :)
You'll need to correct me if I am wrong - be gentle, it's my first time :lol:
Negative pressure: Are you referring to the negative pressure that is created withing the intake manifold (between the butterfly and the combustion chamber)? Okay, that makes sense. :cool:
The reason for my confusion was mixing up "Pop-off" valves (from old dragsters and Cargo-hauling rigs) that are positive pressure activated, and BOVs. Sorry for the mixup. :(
However, the compressor would not continue to spin out of control, because the revolution is dictated by the turbine side of the world.
As for adjustability of the BOV, I'm almost positive that the amount of negative pressure it requires to pull the plunger up is adjustable to a certain degree. Otherwise, it WOULD create a problem like you described.
...but my BOV (bypass valve) on my non-soob releases the blow-off back into the intake (between the MAF and compressor), so there is no loss nor surges in psi.
Are we kosher? :)
I stand corrected :)
You'll need to correct me if I am wrong - be gentle, it's my first time :lol:
Negative pressure: Are you referring to the negative pressure that is created withing the intake manifold (between the butterfly and the combustion chamber)? Okay, that makes sense. :cool:
The reason for my confusion was mixing up "Pop-off" valves (from old dragsters and Cargo-hauling rigs) that are positive pressure activated, and BOVs. Sorry for the mixup. :(
However, the compressor would not continue to spin out of control, because the revolution is dictated by the turbine side of the world.
As for adjustability of the BOV, I'm almost positive that the amount of negative pressure it requires to pull the plunger up is adjustable to a certain degree. Otherwise, it WOULD create a problem like you described.
...but my BOV (bypass valve) on my non-soob releases the blow-off back into the intake (between the MAF and compressor), so there is no loss nor surges in psi.
Are we kosher? :)
| Rebellion | 11-29-2001 10:45 AM |
the stock WRX uses the same kind of "blow off" valve.. the bypass recirculating type. I've replaced mine w/ the GFB which will do 50/50 recirculation/atomosphere or full atmosphere. (I just can't figure out how to get it to go 50/50 with the equipment I got).
| Pesca 555 | 11-29-2001 11:59 AM |
Rebellion,
Agreed - here is an aftermarket version... for the WRX (not the WRC monster of a soob) [url]http://www.stratmosphere.com/wrx.htm[/url]
However, the comments by Shik and Johnfelstead seem to indicate that they (SWRT) use no form of pressure releasing contraptions for those times the driver slams the throttle butterfly shut, therefore causing the wastegate chatter to compensate...
Shik, would you mind enlightening me with some information on the presence (or lack thereof) of a recirculating bypass valve?
Thanks :)
Agreed - here is an aftermarket version... for the WRX (not the WRC monster of a soob) [url]http://www.stratmosphere.com/wrx.htm[/url]
However, the comments by Shik and Johnfelstead seem to indicate that they (SWRT) use no form of pressure releasing contraptions for those times the driver slams the throttle butterfly shut, therefore causing the wastegate chatter to compensate...
Shik, would you mind enlightening me with some information on the presence (or lack thereof) of a recirculating bypass valve?
Thanks :)
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