wrc chirp
01 April 2007, 08:38 PM
#32
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02 April 2007, 05:31 AM
#34
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Now there in lies the rub 
He won't be able to get a lot of boost with a 34mm restrictor, just like ALL restricted cars, even WRC cars. Review the data log of any car with 34mm restrictor and you will notice one thing. As rpm increases, boost drops. That is the principal by which a restrictor works.
The sound he is enquiring about is created mainly by the anti-lag, but you might be surprised to learn that the restrictor (design, shape and length of the trumpet) also plays a part. On one Group A GT4 that I mapped, the turbo had to be swapped, and the new turbo had a different length trumpet, and let's just say that car got nicknamed "Tweety Bird"
It chirped before, but man that thing would chirp high pitched and loud after the change.
Anyways on to your question. I noticed you haven't fitted the restrictor yet, but that is one of the things that is responsible for the sound. As you lift off the throttle, the anti-lag strategies will start. Basically the throttle on the car will never be truly closed with anti-lag. It works by allowing extra air to enter the engine on closed throttle (which really isn't fully closed), coupled with significant retarding of the ignition advance and some extra fueling. This makes that extra air into very hot exhaust gas which makes it fast, which in turn spins the turbine. This creates positive pressure before the throttle plate, but at the same time the small bypass opening is still a restriction, which in turn means the air tries to exit back out the compressor. The restrictor itself by it's trumpet style design, acts like a whistle/megaphone, changing the pitch and volume of this pulsing/surging. Without the anti-lag this would be a single noise, similar to the sound of a car without a blow valve, if the throttle is suddenly closed while on boost. Without anti-lag, the throttle closes completely the pressure builds in the intake before the throttle butterfly until it tries to escape the only way left, back out the compressor, but that's it, a single short duration noise, because there is no extra exhaust gas trying to keep the turbine spinning while off the throttle. With anti-lag, it's a push pull fight that continues until the throttle is again opened, which results in positive pressure just waiting behind the throttle plate for instance response when the throttle is re-opened.
The level and tone of the chirp will also be affected by how aggressive the anti-lag is setup. There is one driver here who likes the anti-lag so aggressive the car actually 'pushes' in a corner. The more throttle opening and more retard you use, the more aggressive the anti-lag, but the faster things will wear.
I'd wait until you get the restrictor, to see if you get the nosie, but don't be consumed by the need for the noise. Tune the anti-lag to suit your driving style, and budget.
<looks up>
crap I'll shut up now.
He won't be able to get a lot of boost with a 34mm restrictor, just like ALL restricted cars, even WRC cars. Review the data log of any car with 34mm restrictor and you will notice one thing. As rpm increases, boost drops. That is the principal by which a restrictor works. The sound he is enquiring about is created mainly by the anti-lag, but you might be surprised to learn that the restrictor (design, shape and length of the trumpet) also plays a part. On one Group A GT4 that I mapped, the turbo had to be swapped, and the new turbo had a different length trumpet, and let's just say that car got nicknamed "Tweety Bird"
It chirped before, but man that thing would chirp high pitched and loud after the change. Anyways on to your question. I noticed you haven't fitted the restrictor yet, but that is one of the things that is responsible for the sound. As you lift off the throttle, the anti-lag strategies will start. Basically the throttle on the car will never be truly closed with anti-lag. It works by allowing extra air to enter the engine on closed throttle (which really isn't fully closed), coupled with significant retarding of the ignition advance and some extra fueling. This makes that extra air into very hot exhaust gas which makes it fast, which in turn spins the turbine. This creates positive pressure before the throttle plate, but at the same time the small bypass opening is still a restriction, which in turn means the air tries to exit back out the compressor. The restrictor itself by it's trumpet style design, acts like a whistle/megaphone, changing the pitch and volume of this pulsing/surging. Without the anti-lag this would be a single noise, similar to the sound of a car without a blow valve, if the throttle is suddenly closed while on boost. Without anti-lag, the throttle closes completely the pressure builds in the intake before the throttle butterfly until it tries to escape the only way left, back out the compressor, but that's it, a single short duration noise, because there is no extra exhaust gas trying to keep the turbine spinning while off the throttle. With anti-lag, it's a push pull fight that continues until the throttle is again opened, which results in positive pressure just waiting behind the throttle plate for instance response when the throttle is re-opened.
The level and tone of the chirp will also be affected by how aggressive the anti-lag is setup. There is one driver here who likes the anti-lag so aggressive the car actually 'pushes' in a corner. The more throttle opening and more retard you use, the more aggressive the anti-lag, but the faster things will wear.
I'd wait until you get the restrictor, to see if you get the nosie, but don't be consumed by the need for the noise. Tune the anti-lag to suit your driving style, and budget.
<looks up>
crap I'll shut up now.
02 April 2007, 07:45 PM
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Uhmmm, okay, well, I'll just live with my non restricted, non ALS car chirping like mad!
1.5 bar ought not to be a problem at 3500rpm, even with a restrictor. And in my experience, almost every TD05 turboed car running around 1.5 bar in the midrange makes plenty of noise on liftoff without a dumpvalve fitted. Although it's most noticeable on cars with FMICs fitted as there is more air to get rid of. If you fit a trumpet style restrictor then I can imaging more noise with it fitted, horns have that effect!
Paul
1.5 bar ought not to be a problem at 3500rpm, even with a restrictor. And in my experience, almost every TD05 turboed car running around 1.5 bar in the midrange makes plenty of noise on liftoff without a dumpvalve fitted. Although it's most noticeable on cars with FMICs fitted as there is more air to get rid of. If you fit a trumpet style restrictor then I can imaging more noise with it fitted, horns have that effect!
Paul
Now there in lies the rub He won't be able to get a lot of boost with a 34mm restrictor, just like ALL restricted cars, even WRC cars. Review the data log of any car with 34mm restrictor and you will notice one thing. As rpm increases, boost drops. That is the principal by which a restrictor works.
The sound he is enquiring about is created mainly by the anti-lag, but you might be surprised to learn that the restrictor (design, shape and length of the trumpet) also plays a part. On one Group A GT4 that I mapped, the turbo had to be swapped, and the new turbo had a different length trumpet, and let's just say that car got nicknamed "Tweety Bird" It chirped before, but man that thing would chirp high pitched and loud after the change.
Anyways on to your question. I noticed you haven't fitted the restrictor yet, but that is one of the things that is responsible for the sound. As you lift off the throttle, the anti-lag strategies will start. Basically the throttle on the car will never be truly closed with anti-lag. It works by allowing extra air to enter the engine on closed throttle (which really isn't fully closed), coupled with significant retarding of the ignition advance and some extra fueling. This makes that extra air into very hot exhaust gas which makes it fast, which in turn spins the turbine. This creates positive pressure before the throttle plate, but at the same time the small bypass opening is still a restriction, which in turn means the air tries to exit back out the compressor. The restrictor itself by it's trumpet style design, acts like a whistle/megaphone, changing the pitch and volume of this pulsing/surging. Without the anti-lag this would be a single noise, similar to the sound of a car without a blow valve, if the throttle is suddenly closed while on boost. Without anti-lag, the throttle closes completely the pressure builds in the intake before the throttle butterfly until it tries to escape the only way left, back out the compressor, but that's it, a single short duration noise, because there is no extra exhaust gas trying to keep the turbine spinning while off the throttle. With anti-lag, it's a push pull fight that continues until the throttle is again opened, which results in positive pressure just waiting behind the throttle plate for instance response when the throttle is re-opened.
The level and tone of the chirp will also be affected by how aggressive the anti-lag is setup. There is one driver here who likes the anti-lag so aggressive the car actually 'pushes' in a corner. The more throttle opening and more retard you use, the more aggressive the anti-lag, but the faster things will wear.
I'd wait until you get the restrictor, to see if you get the nosie, but don't be consumed by the need for the noise. Tune the anti-lag to suit your driving style, and budget.
<looks up> crap I'll shut up now.
He won't be able to get a lot of boost with a 34mm restrictor, just like ALL restricted cars, even WRC cars. Review the data log of any car with 34mm restrictor and you will notice one thing. As rpm increases, boost drops. That is the principal by which a restrictor works. The sound he is enquiring about is created mainly by the anti-lag, but you might be surprised to learn that the restrictor (design, shape and length of the trumpet) also plays a part. On one Group A GT4 that I mapped, the turbo had to be swapped, and the new turbo had a different length trumpet, and let's just say that car got nicknamed "Tweety Bird"
It chirped before, but man that thing would chirp high pitched and loud after the change. Anyways on to your question. I noticed you haven't fitted the restrictor yet, but that is one of the things that is responsible for the sound. As you lift off the throttle, the anti-lag strategies will start. Basically the throttle on the car will never be truly closed with anti-lag. It works by allowing extra air to enter the engine on closed throttle (which really isn't fully closed), coupled with significant retarding of the ignition advance and some extra fueling. This makes that extra air into very hot exhaust gas which makes it fast, which in turn spins the turbine. This creates positive pressure before the throttle plate, but at the same time the small bypass opening is still a restriction, which in turn means the air tries to exit back out the compressor. The restrictor itself by it's trumpet style design, acts like a whistle/megaphone, changing the pitch and volume of this pulsing/surging. Without the anti-lag this would be a single noise, similar to the sound of a car without a blow valve, if the throttle is suddenly closed while on boost. Without anti-lag, the throttle closes completely the pressure builds in the intake before the throttle butterfly until it tries to escape the only way left, back out the compressor, but that's it, a single short duration noise, because there is no extra exhaust gas trying to keep the turbine spinning while off the throttle. With anti-lag, it's a push pull fight that continues until the throttle is again opened, which results in positive pressure just waiting behind the throttle plate for instance response when the throttle is re-opened.
The level and tone of the chirp will also be affected by how aggressive the anti-lag is setup. There is one driver here who likes the anti-lag so aggressive the car actually 'pushes' in a corner. The more throttle opening and more retard you use, the more aggressive the anti-lag, but the faster things will wear.
I'd wait until you get the restrictor, to see if you get the nosie, but don't be consumed by the need for the noise. Tune the anti-lag to suit your driving style, and budget.
<looks up>
crap I'll shut up now.
02 April 2007, 10:56 PM
#39
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1.5 bar ought not to be a problem at 3500rpm, even with a restrictor. And in my experience, almost every TD05 turboed car running around 1.5 bar in the midrange makes plenty of noise on liftoff without a dumpvalve fitted. Although it's most noticeable on cars with FMICs fitted as there is more air to get rid of. If you fit a trumpet style restrictor then I can imaging more noise with it fitted, horns have that effect!
I think at this stage future responses on this subject would be pointless, so I look forward to your reply, and will gladly give you the last word.
02 April 2007, 10:58 PM
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02 April 2007, 11:02 PM
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I'll bear that in mind. What do you recommend I do about running 2.6 bar? Or perhaps the 150shot of nitrous?
Actually, I'd suggest you don't live with that. If your car is 'chirping like mad' and you are not using anti-lag, then you need to install a BOV, or if you have one, install one that flows more. I remember back when I had my GT4, I was running 1.2 to 1.3 bar, and the car never came with a BOV standard, so on closed throttle I'd get a loud nasty surge sound, which sounded nothng like chirping. We all know what that sound is, and it's not good for the turbo. Very shortly I installed a BOV. Hopefully you already know this, but it makes no sense to not use a BOV if you are not using anti-lag. With anti-lag, the associated noises mean you are sacraficing turbo life for a performance benefit, but without it, you're sacrificing turbo life for virtually no gains.
1.5 bar at 3,500 rpm shouldn't be a problem for most 34mm restricted cars, but using that logic, you would be saying that all restricted cars somehow always lift throttle at 3,500 rpm or below. If they lift at 5,500 rpm boost would probably be down to 1.1 to 1.2 bar, and if they lift at 6,500 rpm probably down to 0.9 to 1.0 bar.
I think at this stage future responses on this subject would be pointless, so I look forward to your reply, and will gladly give you the last word.
1.5 bar at 3,500 rpm shouldn't be a problem for most 34mm restricted cars, but using that logic, you would be saying that all restricted cars somehow always lift throttle at 3,500 rpm or below. If they lift at 5,500 rpm boost would probably be down to 1.1 to 1.2 bar, and if they lift at 6,500 rpm probably down to 0.9 to 1.0 bar.
I think at this stage future responses on this subject would be pointless, so I look forward to your reply, and will gladly give you the last word.
02 April 2007, 11:04 PM
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03 April 2007, 02:20 PM
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Paul, he obviously has no idea who you are or what you do so let him get on with it.
Ralph
04 April 2007, 06:31 PM
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just took intercooler out to inspect the pipe underneath which goes to the turbo and is split at the base of where the dump valve hose is. would this effect the noise at all?
04 April 2007, 06:56 PM
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Yes you effectively have a permanently open VTA dumpvalve! Replacing that hose should not only give you more chance of getting it to chirp, but it should make more boost and power too!
Get it fixed!
Get it fixed!
04 April 2007, 10:42 PM
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WTF is this thread all about - A stage rally car and the guy wants a specific sound from the engine.... is he for real? I think that if he ever gets onto a stage the chirp sound will be the last thing on his mind.
Don't forget to get a hammer or something to clunk the side of the tunnel when you engage 1st gear to make it sound like a dog box
PS - blanking off your dump valve will destroy your turbo if you fit an aggressive anti-lag, prepare yourself for BIG bills....... and all for a 'noise'
FFS - I can't stop laughing
All IMHO of course
GroupNGC8
Don't forget to get a hammer or something to clunk the side of the tunnel when you engage 1st gear to make it sound like a dog box
PS - blanking off your dump valve will destroy your turbo if you fit an aggressive anti-lag, prepare yourself for BIG bills....... and all for a 'noise'
FFS - I can't stop laughing
All IMHO of course
GroupNGC8
05 April 2007, 05:54 AM
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GroupNGC8 is correct that in most cases aggressive anti-lag will lead to more expenses, but again it's not written in stone. In my previous post I mentioned a driver who liked the anti-lag so aggressive that the car would 'push' off throttle. That car won Group N 3 years in a row, and won group N in our international stages rally 3 years in a row as well. Actually someone from your side of the pond, Ollie Clark, would be familiar with Barry Gale's (the car driver/owner) car and Rally Barbados, as he competed here in the event in 2004 if memory serves me right. I informed Barry that turbo life could suffer significantly with such an aggressive anti-lag (and no blow off valve) but he didn't mind, yet that turbo lasted 3 years, which I still find amazing. Bear in mind though, that stages in the U.K., will be longer than here, so your cars will do more 'work' in a year. The point I'm making is that his objective was to win at the risks of higher costs. On the other hand their is another guy here in Group N who wants be competetive, but fun is his main goal, so being No.1, while always wanted, isn't his priority. Barbados allows switched anti-lag that uses a solenoid (kicker) valve in Group N, and the same way you like the chirp, he likes the sound of roving idle (switched anti-lag with fixed throttle opening), so that's how I set it up for him. It does sound cool, and he enjoys it, which I see nothing wrong with at all.
As for Ralph's post, well I'm trying to figure out how he knows so much about me. I mean he must, because his comment would only be logical if he knew my background. Actually it still wouldn't be logical. You see, it really doesn't matter who I am, or who Paul is, what matters is the content of the posts in a thread. Paul chose not to post a decent reply, but to reply with 'smart a--' remarks and an ample supply of exclamation marks. This could have taken a totally different 'tone' had Paul's reply, been something like this hypothetical example, "Actually we did a lot of testing and found that while not as good for the turbo, the blow off valve still costs time going from open to closed throtle and back to open, so if your sport doesn't..........." I can think of dozens of people in motorsport and the automotive field that I have had debates with and sometimes I'm right, and sometimes after discussion, I'll say, "Ooops, you're right, I didn't think about the fact that the intake........", and sometimes we agreed to disagree. It was mature debate and discussion, with a key ingredient that seems to be missing on a lot of forums...respect.
marcyt21 I don't think it will give you the sound you are after, but I hope replacing your hose gives you it. I am happy to be wrong, if it results in a positive outcome. I definitely need to side with Paul on this point, fix it and you'll stop throwing out perfectly good boost.
It's time to step off the soap box and once again slip into the shadows. It's way to violent in here.
Dennis
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