40 replies to this topic

[zac510]

Is there some funny business going on with the throttle in this Audi engine? Can't say I've noticed Audi with this configuration in the past.

http://www.leftlanen...27&idg=1&idi=18

Dressed in light blue on the RHS bank.

Beautiful intake trumpets too.

[desmo]

If I'm seeing what I think I'm seeing in that cutaway, those are some odd throttles indeed.

[Fat Boy]

To me it looks like 2 conventional throttles at the far end of the plenum. The blue 'toggles' look like something to keep intake velocity up at low speeds. My guess is that it move flush with the rest of the runner at a certain RPM/load.

[Hans Derbe]

that aren't normal throttles but tumble plates. the 2 regular throttles sit in the manifold at the back of the engine(where the black plastic covers are visible).

hans

/edit
not fast enough...
/edit

[12.9:1]

"Constant Velocity" think S U

[KABA]

They probably are unusual because of the direct gasoline injection.

[zac510]

Originally posted by Fat Boy
To me it looks like 2 conventional throttles at the far end of the plenum.

I didn't notice those there - you're definitely right, the electronic actuators on the side show them quite clearly as the throttles.

Is the tumble required due to the straight onto the back of the valve nature of the intake port ?

[imaginesix]

My 17-year old car has equivalent valves called Swirl Control Valves in Nissan-speak. They are supposed to promote fuel atomisation at low engine speeds by increasing the speed of airflow into the cylinders. Is this not the same thing but with different valve shapes (my car has conventional butterflies)?

[zac510]

Probably similar principles but the inline Nissan engine is a completely different port shape. These look a different to the KA24/CA18 type too; when they are retracted they would offer much less restriction.

[Ben Wilson]

Their effect on resonance tuning would be interesting to know, they almost look like 2 stroke reed valves...

edit - I just noticed the actuator (middle of the motor above the crank). That looks like a vacuum diaphram? Passively controlled?

[Powersteer]

Sort of like Toyota's TVIS system where it closes one of two intake route per cylinder. The blue throttle looks as if it guides the air on to the upper part of the port and the second, dark colour throttle, keeps it flowing that direction and prevents it from flowing back to the lower port area. Seems like they do this simply to cut intake port volume for low rpm so when the rpm goes up they could make for an even larger port.

[imaginesix]

So it is very different indeed from swirl valves that I am familiar with. Those are supposed to increase atomisation by generating high-speed turbulence (vortices?) in front of the injectors. On the other hand these appear to be purposely designed to maintain smooth aiflow, which would make sense since the injectors are in the cylinders so port turbulence isn't going to have very much effect on atomisation.

So what are they for? Perhaps to allow the potential for lean-burn operation by directing the airflow in the cyclinders such that fuel is concentrated around the spark plug in time for ignition? This is 100% guesswork, of course.

[Supercar]

A little bit off-topic here:

http://www.leftlanen...di-r8-2007-2008

"Audi has unveiled the 2008 R8 — its first ever mid-engine sports cars. Sales will begin in the first half of 2007 for the United States and Europe. The car has a 420 horsepower high-revving V8 engine and all-wheel-drive. It uses the mid-engine Lamborghini Gallardo platform, and will somewhere between $80,000 and $110,000 — positioning it squarely against the BMW M6, Porsche 911, and Aston Martin Vantage."

I am so mad! I think $80,000 is a B.S. Last time I checked that was the price for an Audi RS4. If it is anywhere near $80K I am going to the dealership tomorrow. My guess it will be about twice as much. Although 420 HP *is* the same HP as the RS4. Hmmm... Maybe it will be somewhat, dare I say, affordable??

[zac510]

£55000? They'll be running out the door faster than 997s!

[Andy Donovan]

It's quite a looker isn't it? If it really is that price, I think they could be selling quite a few. I've not been convinced by Audi's recent huge grill look, but this car manages to pull it off with aplomb (an under-used word in my opinion, aplomb).

[Powersteer]

Originally posted by Supercar
I am so mad! I think $80,000 is a B.S.

I agree. I will be shocked if it would sell cheaper than a 911. It going to be much more than 55,000 pounds. From Audi owning Lamborghini I would say this car is targeted directly at the market just below the Gallardo which would still be very costly, maybe just below 100,000 pounds. Murcielago is a 600+ horsepower option, Gallardo 500+ horsepower and the R8 the 400+ horsepower. The car would be a blast though, it already looks it. So far this is the most futuristic car I have seen for production. The Audi RS4 is already spectecular so a mid-rear engine, two seater and lower car with a lot larger wheels should be really exciting. I wonder if that engine is directly off the RS4 which would have these port controlling devices.

[Powersteer]

On the subject of throttle, are barrel throttle giving the right results in testing? It seems Cosworth are using them on the Caterham CSR 260 but not on the 200 and Engine Developments Judd on thier new pride and joy, the GV5 S2(courtesy of mulsannescorner.com)

Engines that are uding barrel throttle:

Caterham Ford Cosworth
Judd GV5 SP2
Panoz-Zytek V8 AER P32 T V8

Probably with the increasing constraints of the rule book, this technology might creep into Formula One sooner or later. It seems to provide an undistubed air flow at full throttle. It might also work very well with a sequential injector that has one of its injectors outside the intake runner. I think Judd got it perfect, keeping it intergrated withthe head so it can be mounted as close as possible to the intake.

[desmo]

Barrel throttles were actually prevelant in F1 ten years back or so. I'm not sure if anyone is still using them, butterflies seem to be the new orthodoxy.

[McGuire]

Originally posted by Powersteer
Probably with the increasing constraints of the rule book, this technology might creep into Formula One sooner or later. It seems to provide an undistubed air flow at full throttle.

No real advantage there to a barrel or slide valve. If greater airflow is desired, just make the conventional butterfly valve a few percent larger. It will still be lighter, use less space and cause fewer problems overall.

[McGuire]

Originally posted by desmo
Barrel throttles were actually prevelant in F1 ten years back or so. I'm not sure if anyone is still using them, butterflies seem to be the new orthodoxy.

The sharp edge of the throttle blade is a beautiful fuel shear area.

[Powersteer]

Originally posted by McGuire
No real advantage there to a barrel or slide valve. If greater airflow is desired, just make the conventional butterfly valve a few percent larger. It will still be lighter, use less space and cause fewer problems overall.

True but I was thinking more in the line of aerodynamics.

[Andrei]

The R8 will cost somewhere in the range of 100.000 - 120.000 euros, also with the 10 cylinder engine that will hit the market in a couple of month.

[EfiOz]

Getting back on topis, the blue bits are the deflectors that switch between the long and short rams in the intake manifold. They are actuated by the black vacuum canister at the front of the engine.

The engine is basically a FSI V8 version of the Gallardo V10.

[Ben Wilson]

I can see long runners, but I can't make out any short ones.....

[EfiOz]

You can sort of see them on the closest side to you and it's not very apparent on the farther side. Basically the flap diverts the intake from the "short" runners which go straight up and down to another passage that runs across the manifold and uses the opposite cylinders ram inlet, thereby extending the length.

[Powersteer]

Originally posted by EfiOz
Getting back on topis, the blue bits are the deflectors that switch between the long and short rams in the intake manifold. They are actuated by the black vacuum canister at the front of the engine.

The engine is basically a FSI V8 version of the Gallardo V10.

What you are saying is the Audi RS4 uses a version of the Gallardo engine? Thats totally new to me.

[Ben Wilson]

Originally posted by EfiOz
You can sort of see them on the closest side to you and it's not very apparent on the farther side. Basically the flap diverts the intake from the "short" runners which go straight up and down to another passage that runs across the manifold and uses the opposite cylinders ram inlet, thereby extending the length.

I'm still not seeing it - I can see a flow divider after the flap which looks like it is there to stop the air 'falling' off the back of the flap.

Looking at the sectioned runner on the left of the picture, I can't see any way the air can be diverted either to or from it. There are plugs opposite the flaps (I assume so you can get the screws in), and a small hole just below the trumpet, but other than that they look pretty much solid to me.

I can see something under the valley cover behind the flap actuator, but I can't for the life of me work out what it is..

[desmo]

I'm not seeing short (or long) intake runners either. Those look as others have noted like devices to control port velocities or turbulence. I've read DI spark engines like a lot of turbulence.

[zac510]

Originally posted by desmo
I'm not seeing short (or long) intake runners either. Those look as others have noted like devices to control port velocities or turbulence. I've read DI spark engines like a lot of turbulence.

Neither do I see it.
I recall there is a small section on DI in the Bentley Speed 8 Sportscar book (Bamsey, was it?). I'll get it out and have a look tonight.

[zac510]

I checked the book last night and Baretsky does indeed mention that more 'tumble swirl' is required for the direct injection to create a 'homogenous burn'. I paraphrase because the book is at home and I am at work!
There was no mention of engine speeds or port velocities but perhaps it could be extrapolated from the various peak torque and peak rpm figures in the book.

[Hans Derbe]

here is an map with the positions of the tumble flap. it's only closed in low load, low rpm conditions to increase tumble for better charge mixture and more stable combustion. this map is from an audi a8 4.2l v8.

hans

[GSX-R]

Gut.

Any BSFC maps ?

[imaginesix]

Originally posted by Hans Derbe

That graph suggests there are in fact two intake tracts, unless I am reading too much into 'lang' at low RPM and 'kurz' at high RPM?

'Tumbleklappen' is just funny, it sounds like an Anglo trying to invent a German word

[Hans Derbe]

Any BSFC maps ?

No, sorry.

That graph suggests there are in fact two intake tracts, unless I am reading too much into 'lang' at low RPM and 'kurz' at high RPM?

The normal 4.2l V8 in the Audi A8/Q7 has indeed a switchable runner system. The more powerfull version in the RS4 has fixed runners as has the RS8 engine.



"Tumbleklappen" sounds strange. A correct german word would be "Ladungsbewegungsklappen"....

Hans

[EfiOz]

My stuff up. It lloks awfully similar to the Gay Yardie manifold but it is different in operation.

[AndrewNystrom]

Since its a FSI-engine, it doesnt work like the regular throttle.

Im not so good at english to explain this, but this is what i know :
There are 2 "throttles" in the regular 2.0 FSI engine, and the intake has a divider,
where one of the throttles, makes the air only go the upper way in the intake.
This is to get a better tumble-effect in the cylinder, where
the air gets "rotated" down to the piston. To get this to work, everything needs to be perfect
with the pistons is designed aswell.
The first throttle then opens wide to to get the effect better, and then the valve
shuts, and the direct injector inserts fuel (at 40-120bar) above the air thats in the cylinder, right
under the ignition, and then the ignition goes off, and the fuel and air "explodes", and
this also makes the cylinderwalls run cooler.

then there is 2 or 3 more modes that this operates at, which way it operates is determinated
by the revs.

hope you understand anything ive written in by bad english.

[AdamLarnachJr]

Almost like a reed valve setup?

[knighty]

about barrel throttles........I have designed bothe barrel and butterfly systems.........and a butterfly system is preferable for the followings reasons:-

1) much lighter
2) progressive driving charicteristics

barrel throttles are out of fashion in the professional race industry now days.......everyone played with them, but went back to butterflys.........Renaults last 2 championship willing F1 engines use butterflys - need I say more.........believe me - barrels might look trick - but they are nothing special

[McGuire]

Cosworth has a new engine or two with barrel throttles. I have no idea what they were going for.

[desmo]

I think its been a good few years since a barrel throttled engine has won an F1 championship. All the recent Ferrari cars have been butterfly throttled, though they dallied with slide throttles in the late '80s.

[Powersteer]

All Ford Duratec Cosworth crate engines are barrel throttle. The only advantage I can see is intake aerodynamic and that too only applies during full throttle so probably better for smaller engines that run longer on full throttle than part throttle.