rec.autos.simulators

by **Mar** » Tue, 18 Feb 2003 21:03:22

> It's the turbo. More accurately, it's the wastegate bleeding off excess
> boost. I used to own a slightly modified '86 Buick T-Type that ran the
> 1/4 mile in the mid-12 second range and in it, you could hear the
> wastegate operating when you let off the gas. The Buick had a fairly
> large (by today's standards) aftermarket turbo and wastegate so the
> sound was more pronounced than it is in a factory stock turbo car.

Yes, it's the wastegate flutter. I was almost run over by a modded
(are any not?) Renault 5 Turbo "Raider" on my way to work that sounded
just like this!

Regards,

Mark

by **Steve Smit** » Tue, 18 Feb 2003 21:10:14

What a marvellous thread! Might help zero in on the definitive answer,
Dave, if you described when, exactly, the chirp occurs. Stephen F. is
right; WRC cars--real and virtual--are a delightful collection of chirps,
bangs, boinks, clunks, pops, growls, whizzes, and screeches.

by **Gunnar Horrigm** » Tue, 18 Feb 2003 21:30:20

> > Even tho it's at least a week delayed now, we still get pretty thorough
> > race recaps of the World Rallye Championship. In many of the exterior
> > shots of the cars you can hear them chip/squeak as they navigate the
> > corners. What is the cause of this noise? Springs? Brakes?
> > dave henrie

> Its the wastegate on the Turbo its as they come off the throttle and IIRC -
> a valve released pressure from the turbo system to stop it trying to 'push'
> the fuel/air mix into the cylinders after the driver has come off the
> throttle

that's how one of the team mechanics explained it sometime in the
previos season. IIRC he also said the waste gate on WRC turbos are in
the engine intake, since they run at warp 10 continuously.

--
Gunnar
Cougar#02748 #31 SUCKS#015 Tupperware MC#002 DoD#0x1B DoDRT#003 DoD:CT#4,8 Kibo: 2
myk, trygg og god.

by **Stephen F** » Tue, 18 Feb 2003 21:33:19

Not to mention the hooting and hollering of Jeff Gordon when he goes upside
down...

> What a marvellous thread! Might help zero in on the definitive answer,
> Dave, if you described when, exactly, the chirp occurs. Stephen F. is
> right; WRC cars--real and virtual--are a delightful collection of chirps,
> bangs, boinks, clunks, pops, growls, whizzes, and screeches.

> > Even tho it's at least a week delayed now, we still get pretty
thorough
> > race recaps of the World Rallye Championship. In many of the exterior
> > shots of the cars you can hear them chip/squeak as they navigate the
> > corners. What is the cause of this noise? Springs? Brakes?
> > dave henrie

by **ctrlaltdelete3** » Tue, 18 Feb 2003 23:00:46

> > I'm fairly certain it is the turbo. I remember it most prominently on the
> > Audi Quattro's that were run in the late 80's Trans Am. The sound was also
> > heard in the CART Indy cars, but not to the same degree. What little Ralley
> > car footage I see, I hear the same thing on all the Turbo assisted cars.

> It's the turbo. More accurately, it's the wastegate bleeding off excess
> boost. I used to own a slightly modified '86 Buick T-Type that ran the
> 1/4 mile in the mid-12 second range and in it, you could hear the
> wastegate operating when you let off the gas. The Buick had a fairly
> large (by today's standards) aftermarket turbo and wastegate so the
> sound was more pronounced than it is in a factory stock turbo car.

Yes Todd, you are correct. It's more pronounced on the rally cars
'cause they use the misfire/bang bang/anti lag system. Info. here:
http://www.rallycars.com/Cars/bangbang.html

by **ctrlaltdelete3** » Tue, 18 Feb 2003 23:07:58

> Even tho it's at least a week delayed now, we still get pretty thorough
> race recaps of the World Rallye Championship. In many of the exterior
> shots of the cars you can hear them chip/squeak as they navigate the
> corners. What is the cause of this noise? Springs? Brakes?
> dave henrie

Hi Dave, what you are hearing is the turbo blow off. It's more
pronounced on WRC cars 'cause they use the anti-lag/bang bang/misfire
system (tho not unique to WRC cars). Check out this article for info:
http://www.racesimcentral.net/

hope this answers your question

ot: would you happen to know the "secret" project SBDT is currently
*** up??? :)

cheers

mike

by **Dave Henri** » Wed, 19 Feb 2003 01:23:21

Boy that is tough...it's only heard on the trackside cameras. I think
I notice it the most on slower corners I assumed it was the suspension
working. The trouble is...because of camera/microphone placement it is not
always easy to tell the exact status of the car. Do they drift through off
throttle? Or do they keep some trail braking going? I'm pretty sure I
don't hear it much on the hand-brake turns so I'm assuming it is when the
throttle is off or relaxed.
dave(here birdy birdy)henrie

by **Leo Landma** » Wed, 19 Feb 2003 07:06:53

Actually they use 3 diffs: front, rear and one in between. But the sound is
the turbo wastegate.

Bye,
Leo

by **KWS** » Wed, 19 Feb 2003 08:16:17

Hi Dave,

This excerpt is from the Subaru Impreza Owners Group website...

"...the main advantage of the blow off valve is to reduce stress upon the
turbo blades when you lift off of the accelerator to lets say change gear.
The turbine is still spinning and thus pumping gas into the input...but the
engine is off power. So what to do with the excess. A blow off valve set to
a certain pressure releases this excess. A vent to atmosphere allows it to
go to air giving the characteristic pfffft, a recirculating one feeds it
back into the input of the turbo thus keeping the system pressurised. When
you hit the accelerator the vented system then needs to momentarily build up
the pressure again whilst the recirculating system doesn't.

Without a BOV the turbine can actually stall or air is drawn back through
the wastegate in the wrong direction. The turbine is spinning but there are
no exhaust gases coming out of the engine, so it either stalls or draws
airthrough the wastegate from the exhaust side.This is the chirp you hear on
the WRC cars. The stress on the bearings is quite substantial and in a
completely different direction to that which the turbo is designed. The
turbo in the WRC cars has a 360 degree bearing surface to counter this (and
the turbo is changed and refurbished per rally if not sooner), the road
going turbo does not."

Regards,

KWS

by **Jussi Koukk** » Wed, 19 Feb 2003 16:30:17

something like this:

So they are saying that the recirculating system is some sort of
perpetual-motion machine? I wonder why they don't use it in WRC cars
or in tuned up street machines if it actually reduces lag... :P
--
- JKo -

by **Larr** » Thu, 20 Feb 2003 03:04:54

That's what I thought. Suspension, or maybe body parts.

Larry

> Yeah, that's a good question actually.. I really noticed it last year,
> especially with the Peugeot! Also, I noticed that the in-car camera in the
> Peugeot the whole thing sounds like it whistles really loudly, I'm
guessing
> it is the turbo, although I don't know much about cars.

> I always just assumed that the little chirps and squeaks were from the
> suspension or even the brakes. If someone makes a modern day WRC game
> (pleeeaaaaaaaaseee), I'd love to be able to hear these same noises during
> replays.

> Mike
> http://mikebeauchamp.com

> > Even tho it's at least a week delayed now, we still get pretty
thorough
> > race recaps of the World Rallye Championship. In many of the exterior
> > shots of the cars you can hear them chip/squeak as they navigate the
> > corners. What is the cause of this noise? Springs? Brakes?
> > dave henrie

by **skee..** » Thu, 20 Feb 2003 09:16:52

I seem to remember the announcers mentioning this on the first race of
the year at Monte Carlo. One of the drivers was at the starting line
revving the engine and it was chirping away. He mentioned that it was
the turbo waste gates making the noise.

>> It's most likely the turbo blow off valve... it releases the pressure
>> from the intake manifold when the driver lifts his foot off the
>> accelerator. AFAIK the only game that has this modelled is netKar
>> (Supra TT).
>> --
>> - JKo -

> But isn't the turbo waste=gate a popping noise? pop pop this is more
>like a bird chirp or a metal on metal squeak. Do the turbos really sound
>like that?
>dave henrie

by **Jussi Koukk** » Thu, 20 Feb 2003 19:09:18

Have you tried netKar? It has a Toyota Supra TT (Twin Turbo) that has
this nice pfffft/chirp sound when you lift your foot off the
accelerator =)

http://driving.multiplayer.it/netkar/home.htm
--
- JKo -

by **Dave Henri** » Sun, 23 Feb 2003 14:30:06

uhhh no...why do you ask? :)
(you think they'd trust me to keep my yapper shut??)
dave henrie

rec.autos.simulators

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

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OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?

OT: Why do WRC cars chirp?