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Chassis/Vehicle Dynamics Engineer
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Discussion Starter · #1 ·
We recently had an intake walnut blast and full carbon clean done on our 2012 Audi R8 V10 at 27,500 miles. We had noticed stumbles off idle and she was dumping a bit of carbon out on cold starts. Per pictures below, she was not as carboned up as I expected seeing many others (though I think they were mainly V8's) and we had done the Direct Injection Clean a few times, which seemed to have helped some. I discussed that here prior. We also do not use fuel with Ethanol and wait until even the oil is at full temperature before pushing her hard.

We had a Mustang AWD dyno run done prior to the intake carbon clean and then afterward for more objectively understanding the difference.

A couple of pictures of the carboned intakes first - definitely not as bad as others I have seen posted here.
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Partially Cleaned
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Cleaned Intake
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Pre Carbon Clean Dyno Curve is Dotted and Post is Solid. She gained 17 peak HP and 19 peak lb-ft of torque
Rectangle Slope Font Plot Parallel



This was an expensive process for 17 HP (injector seals and gaskets alone are just over $1000), but it was definitely noticeable by the following:
  • Acceleration improved noticeably throughout the rev range
  • More crisp throttle response in general
  • Off idle stumble went away
  • No more carbon coming from the exhaust on start up (this took a few cold starts to clean up after the intake cleaning)
  • The induction noise and exhaust noise is noticeably louder and more sharp - She is breathing much better
  • Throttle lift off burble happens a lot more often now - much more noticeable
You will note the HP and torque numbers in general seem low for the V10. However, Mustang AWD Dynos are known to be very conservative and this RWHP number of 459 HP represents just over a 12% loss from the 525 HP rating at the crank. (though this V10 has an AWE exhaust - no tune). This all seems reasonable for loss for an AWD system, but I don't know the exact loss numbers. (We found it to be about 7% on the RWD only '05-'06 Ford GT)

Dyno Runs and Cooling your transaxle
The standard Dyno cells are set up for front engine and cooling. The Transaxle oil cooler is at the right blade intake. I do not think that transaxle cooler got enough air/cooling on these 2 dyno runs with warmup as the new clutch (fully broken in) was glazed some and as a result the engagement felt soft at first and then gradually came back over about 150 miles of use. So beware of this potential issue if you go to a Dyno. Fortunately it was not a lot worse.
 

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We recently had an intake walnut blast and full carbon clean done on our 2012 Audi R8 V10 at 27,500 miles. We had noticed stumbles off idle and she was dumping a bit of carbon out on cold starts. Per pictures below, she was not as carboned up as I expected seeing many others (though I think they were mainly V8's) and we had done the Direct Injection Clean a few times, which seemed to have helped some. I discussed that here prior. We also do not use fuel with Ethanol and wait until even the oil is at full temperature before pushing her hard.

We had a Mustang AWD dyno run done prior to the intake carbon clean and then afterward for more objectively understanding the difference.

A couple of pictures of the carboned intakes first - definitely not as bad as others I have seen posted here.
View attachment 267031


Partially Cleaned
View attachment 267032


Cleaned Intake
View attachment 267033


Pre Carbon Clean Dyno Curve is Dotted and Post is Solid. She gained 17 peak HP and 19 peak lb-ft of torque
View attachment 267034



This was an expensive process for 17 HP (injector seals and gaskets alone are just over $1000), but it was definitely noticeable by the following:
  • Acceleration improved noticeably throughout the rev range
  • More crisp throttle response in general
  • Off idle stumble went away
  • No more carbon coming from the exhaust on start up (this took a few cold starts to clean up after the intake cleaning)
  • The induction noise and exhaust noise is noticeably louder and more sharp - She is breathing much better
  • Throttle lift off burble happens a lot more often now - much more noticeable
You will note the HP and torque numbers in general seem low for the V10. However, Mustang AWD Dynos are known to be very conservative and this RWHP number of 459 HP represents just over a 12% loss from the 525 HP rating at the crank. (though this V10 has an AWE exhaust - no tune). This all seems reasonable for loss for an AWD system, but I don't know the exact loss numbers. (We found it to be about 7% on the RWD only '05-'06 Ford GT)

Dyno Runs and Cooling your transaxle
The standard Dyno cells are set up for front engine and cooling. The Transaxle oil cooler is at the right blade intake. I do not think that transaxle cooler got enough air/cooling on these 2 dyno runs with warmup as the new clutch (fully broken in) was glazed some and as a result the engagement felt soft at first and then gradually came back over about 150 miles of use. So beware of this potential issue if you go to a Dyno. Fortunately it was not a lot worse.
Looks great! Are the injector seals and gaskets replacement required, as I’ve never heard anyone else mention this for their cleanings? Thanks


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I'll explain how the carbon gets on the intake valves. At part load, the inlet and outlet valves are open before the top dead center of the piston, which is referred to as valve overlap. At the same time, the tumble flaps are set to a low air flow, which creates an air roll in the cylinder. The disadvantage here is that the air roller also directs the cylinder contents via the inlet valve, as a result of which the residues of the exhaust gas are deposited on the valve. The more often the engine is operated in partial load operation, the more carbon is deposited on the inlet valve. The coal does not decrease until the inlet valve reaches a certain temperature, but this does not happen under partial load. If the tumble flaps are permanently open and it is like the 4S engine, less carbon is produced because the air roll is not available. I hope I was able to put it in an understandable way.

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Tom
 

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Here is a graphic from Audi that does not properly represent the intake valve carbonization problem. The air flow shown in red includes neither the overflow of the air via the inlet valve nor the sucking back of the exhaust gas from the exhaust manifold. Exhaust gas and fresh air mix and are directed to the inlet valve by the rotation.

The graphic on the left shows the condition as with the 4S engine and also the condition of the old V10 when the tumble flaps are open at full load.

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Tom
 

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Solid post. I also ran on a mustang, got 463/349 at 20k miles. Tune/exhaust. Different dynos Even of the same brand and variant can produce different numbers. I’m planning on getting cleaned at 31k miles and do a full injector service as well.
Tom: how does one achieve that the tumble flaps stay open the whole time, and wound things need to be recalibrated\tuned?
 

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The lower parts of the suction tube can be dismantled (red arrow) and the actuating shafts are attached to the vacuum socket with a lever arm, which is connected to the flaps by its contour. If the shaft is pulled out, the flaps no longer have a drive and can be removed from the gallery. The holes on the side of the flaps through which the shaft passes are enlarged with a drill to allow the shaft to rotate without operating the flaps. The flaps are then glued to the gallery with an adhesive and the full cross-section is always present. Disadvantage: It is no longer possible to return to the old function.

There are no diagnostic errors because the shaft actuates the potentiometer.

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As a comparison, 4S
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Tom
 

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What is the intended benefit of the tumble flaps anyway. And if faking out the potentiometers in their thinking the flaps are in a certain position they're not - what else happens with the combustion - (besides the now loss of a stratified charge and having a homogeneous one instead) and are there any other effects or unintended consequences?

Thanks for the great details - could we just take the flaps off the rod and leave them out completely rather than glue them in a fully open position?
 

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With the flaps open, the V10 / V8 runs perfectly under full load and, with the flaps firmly glued, even under partial load. You have to attach the flaps, otherwise the contour in the duct is bad and there will be flow losses without flaps.

If there is no negative pressure due to a defective non-return valve and the flaps cannot be opened, the check lamp indicates.

You can buy used parts here in Europe and then tweak them, but it's a waste of money because they say they don't need to be returned to their old condition.

Optimization is free and only requires glue.

Tom
 

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Yes I understand also but that seems a little risky, is it possible for the glue to break down and cause unintended consequences? No tuning parameters needed either? If this is solely to reduce carbon I frankly don’t find it worth it, even if there is benefit.
 

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Discussion Starter · #13 ·
Looks great! Are the injector seals and gaskets replacement required, as I’ve never heard anyone else mention this for their cleanings? Thanks


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I do not know if this is required, but replacement of seals and gaskets is often the practice when taking apart and reassembling. I did not discuss this with the shop that did this work and they automatically replace them, but I should have asked them about it. The transaxle cooling on the dyno was a far more concerning problem to me.

An experienced powertrain person could answer your question specifically.
 

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What does a good job is a window adhesive that won't come off in a hundred years.

Tom

Yes I understand also but that seems a little risky, is it possible for the glue to break down and cause unintended consequences? No tuning parameters needed either? If this is solely to reduce carbon I frankly don’t find it worth it, even if there is benefit.
 

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With the flaps open, the V10 / V8 runs perfectly under full load and, with the flaps firmly glued, even under partial load. You have to attach the flaps, otherwise the contour in the duct is bad and there will be flow losses without flaps.

If there is no negative pressure due to a defective non-return valve and the flaps cannot be opened, the check lamp indicates.

You can buy used parts here in Europe and then tweak them, but it's a waste of money because they say they don't need to be returned to their old condition.

Optimization is free and only requires glue.

Tom
Thanks - I LOVE this dialog to start with. I don't mean to get into an argument, but as a Fluids Flow engineer, I cannot fathom why the rod by itself causes any MORE or worse flow losses than the rod WITH anything else also attached and in the way - like the stationary flaps - THAT to me seems to have the MOST 'flow losses' when compared with ANY other cross-section in the duct other than a variably closed flap. Here's my order of INCREASING 'flow losses' in the duct :

1) Empty of anything - like the 4S - this would include 'filling in' the longitudinal holes that the rod passes through to eliminate cross-cylinder intra-flow (while this would NOT likely cause 'flow losses', the cross-flow would probably not be a good thing either). Whatever you use to do this probably has a better (less likely) failure rate (falling/flaking/peeling off) than on the flaps inside the duct.
2) The rod alone - which is probably sealed between cylinder ducts I would expect
3) The rod and the flaps opened to their most open position - presumably where you'd glue them
4) The rod and the flaps in any other position between #3 and closed
5) The rod and the flaps closed

This also presumes that the rod is 'in the way' fully across the duct at all times, and that the flaps have a center cross-section at least as large as the rod that they're on - Since you noted that a part of this mod is to increase or drill the flap holes out to allow the rod to rotate and not move the flap, it's reasonable to conclude both of these are true.

While I might trust an adhesive (so long as its rated for temperature AND fuel exposure - not sure window adhesive meets either) to hold these in place, putting that adhesive anywhere in the path to do so, would CERTAINLY add to the 'flow losses' (but would easily be BETTER than the flaps in ANY variably closed position), and have the added concern of falling/flaking/peeling off to be consumed in the engine while then that flap (and perhaps NOT the rest) would have some undeterminable semi-closed position that even the now-faked out potentiometer could not/would not recognize to warn you of. I'm not sure I'm too keen on that.

I might rather seek to rid the rod with flaps and find a way to fake-out the potentiometers (and maybe just taking the rods out can do that) and fill in the longitudinal holes with something appropriate.
 

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Discussion Starter · #17 ·
Hi

You don't have to worry about the gearbox (if it's the R-Tronic) because the R8 GT does not have active gearbox cooling.


Tom
Ours is not a GT and is a 6MT. So this comment of mine then is for any of the R8's with trans coolers like ours. She got too hot and glazed the clutch noticeably, as noted. Fortunately, not ruined.
 

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A connection to the inlet of each cylinder is always in the channel in which the shaft is embedded. The flap is rotatably mounted in a position in the gallery and the window adhesive holds the flap in position. The window adhesive from the automotive sector is temperature stable and also chemically resistant. It is also possible to completely glue the flap so that it becomes a unit with the gallery. There are no high temperatures in the intake port, as cold air is always sucked in when the engine is running and, with a direct injection engine, the resistant adhesive does not come into contact with fuel.
Problems are mentioned here that do not exist.
I don't think so, I did it successfully with glue too.;)

In addition, if the flaps are attached without a shaft drive and the function of the shaft on the potentiometer works, why should the ECU be optimized as well? that only costs money that ends up in the garbage can.

Tom
 

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I think I've been a bit misunderstood, we're cool - peace.
 
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