GruppeM just released ram-air system for B7 RS4

[chris5150]

You know what I like the way it looks, I dont really expect any power gain, that would be a bonus, Im more hoping it might make a nicer induction sound. I used to have a BMW CSL and the induction noise on that is fantastic.
On the other point yes they cannot extract more from a GTRS , but then that is Porsche's top tuned version of that power lump. A normal Carerra can indeed be played with to up the power, point being I think many of the cars about today are not necesarily tuned to where they could be due to cost etc. Who is to say the airbox on an RS4 is perfect?, it could be imrpoved possibly if Audi didnt build it to a cost...I dont know I am just hypothasizing.
Like I said I am a 'dodo' that has bought one, or rather put my name down for one, and yes its best part of 600 notes, and as Ive said Im hoping for a bit better induction noise, and I like the carbon look to match the other bits.
it seems on this subject its all got a bit silly on this thread, listen we wouldnt be driving £50k cars if we were being practical would we, so I dont really see that insults to people for spending £600 on an airbox for any reason is needed, play nicely now

[SR71]

Not that having a PhD in aerodynamics counts for anything but....

I'd be more confident Audi had done the CFD analyses than GruppeM!

If it were that easy surely MTM would have an induction kit out?

But I agree that aesthetics and noise are valid drivers of a purchase...albeit at that price, not for me!

My $0.02.

[tartan_rob]

SR71 - remember one thing about Audi and other manufacturers. They are mass producing these cars. Carbon takes a lot of time to lay up, cure and finish. Everything comes down to time and money unfortunately. If the trade off is a little performance, so be it...

[djcevo]

The RS4 4.2 would generate 465hp at 9000rpm....but its longevity would no doubt be affected. How does that work, because when I look at my byno print outs the BHP tails away over 7800 rpm!?!?!??!

[SR71]

Rob,

It is not the fact that it is carbon that makes any difference to its ability to flow though....

I'm speculating but it is just as easy to mould plastic isn't it?

To me, the fact that the existing intake has flaps etc etc means someone, somewhere has thought about the aerodynamics involved...

djcevo,

Your graphs tail off because 9000rpm was not a considered design point.

That said, I've heard in testing the car was run to these kind of rpms, albeit with issues relating to the dispersion of all the associated heat.

The above figure is theoretical i.e., 9000/8000 x 414 =~ 465.

My guess is that the intake is not designed to flow enough air at 9000rpm so its acting a bit like a restrictor on a WRC car at those insane rpms...

[tartan_rob]

SR71 - the material that the box is made from has an almost negligible difference on flow. The volume of air forced into the intake, and the max volume of air possible at slowest possible speeds gives an increase.

If you had a big air scoop the size of the front of the car (and forgetting about air resistance), this would not necessarily give the best power output. The volume and pressure of the air into the collector in relation to the velocity of the air as it enters the inlet manifold is more important.

I am not criticising at all, I just don't think Audi would have spent hard hours and money maximising the air into the car. EVERYTHING they do has to come down to profit margin amongst other things. Fact is that plastic moulds are MUCH cheaper than carbon and they both have their need, I suspect that other parts manufacturers such as GruppeM work in carbon as it is seen as being the best and certinaly lighter. Don't knock it just because Audi haven't done it.

Have you ever had a car remapped or changed anything for non-std? If so, enough said.

[SR71]

As I understand, a lot of what Audi learnt/learn at DTM with NA 4.0L engines has fed back into the B7 RS4.

These cars run with 2 28mm restrictors in their intakes. You can bet your ass that Audi have extracted maximum performance from the 4.0 bearing in mind this restriction by studying the internal fluid dynamics. The press release detailing the new R14 DTM car says as much.

This may be a "mass-produced" car but the donkey work has been taken care of by the race series.

It, therefore, costs very little to transpose the lessons learned across to the road car...which doesn't have any restrictors!

I personally, believe that Audi have probably spent a good deal of time optimising the intake....just my opinion. On a NA car that is one (of only a few) way you're going to affect the ultimate output.

I have tweaked cars in the past, but they've all been turbocharged. I've done so cognizant of the fact that, as a result, they've been more likely to go pop sooner rather than later!

Tuning NA cars is a different kettle of fish, and a £55K one at that....I like to think I'm paying for some serious technology already!

[t_urbo]

rs6.com have the same thread running which is worth a read...http://www.rs6.com/forum/showthread.php?t=14820

Chris you buying one for the aesthetics is fair enough but alex is pushing this product all the way and I see it that users on here are being sold a product that is well overrated.

So far we've been told it was in development for over 8 months, what the f**k does that mean?

We've been shown a graph that my 8 year old could have produced on her laptop.

Oh and the price which started out at over £1200 is now less than half that, some product that must be.........

How about GruppeM producing some actual Air Flow charts and AFR charts with specific dyno run dates/times and references.

[alex_123_fra]

rs6.com have the same thread running which is worth a read...http://www.rs6.com/forum/showthread.php?t=14820

Chris you buying one for the aesthetics is fair enough but alex is pushing this product all the way and I see it that users on here are being sold a product that is well overrated.

So far we've been told it was in development for over 8 months, what the f**k does that mean?

We've been shown a graph that my 8 year old could have produced on her laptop.

Oh and the price which started out at over £1200 is now less than half that, some product that must be.........

How about GruppeM producing some actual Air Flow charts and AFR charts with specific dyno run dates/times and references.

If you're trying to imply that I somehow have a vested interest in this, you couldn't be more wrong. I contacted gruppeM to ask whether they would produce an air induction system for the RS4, given my previous very positive experiences with their products on various other marques including a 996 GT3, Evo and CTR. They said they were developing it at the time (8 months into the process) so I left it at that.

After I had sold the RS4, they emailed me to say that they had completed it and it was ready for sale, hence why I posted. As I said, I merely did this to provide information which other people might find interesting and to give more modding options for the RS4. I am not affiliated with gruppeM in any way and have nothing to gain from this. I am not "pushing" the product in any way, I just find it interesting.

I felt that your pessimism about it and your accusation that it is "restrictive" just by looking at it (!) was quite presumptious. This is especially in light of the fact that gruppeM are very well respected in motorsport (and also by enthusiasts).

The price was on the original attachment and has not changed. As I said, it is in Japanese yen and you can use whatever calculator to convert it as you wish. One person did email them to ask whether a group buy would effect a cheaper price (which it did). Nothing wrong with any of that.

As far as you not liking the graphs, again, your choice. I'd imagine they produce a headline graph to attach to the product brief as not everyone is as interested in AFRs as you or me (believe it or not). If you or anyone else rings/emails them, I'm sure they'll give you as much info about it as you want.

This thread was started because I just wanted to share a modding option that came to my attention. I don't even have an RS4 any longer so I don't care who buys it or not. I suppose it can't be helped that, whatever forum one is part of, there will always be pessimists who try to shoot down everything you say and indirectly accuse you of having a vested interest.

[tartan_rob]

Alec - thanks.

Ultimately. Pay your money, take your pick.

On the DTM 4.0 front. Are you honestly saying the intake system on the RS4 is the same as the one out of the DTM car?

[SR71]

On the DTM 4.0 front. Are you honestly saying the intake system on the RS4 is the same as the one out of the DTM car?

Not at all....the RS4 doesn't have a restrictor to fight against for starters...

I'm saying that bearing in mind the fluid dynamicists have no doubt been working on the constantly evolving Audi DTM cars, it probably wasn't that expensive to recruit their expertise (and analytical tools) and employ it in the development of the 4.2.

The B7 RS4 4.2 is leading edge V8 technology.

It has pistons moving as fast as a F1 car; 92.8mm stroke at 8250rpm places the inertial loads on the pistons at their limit; it employs some pretty funky 34CrNiMo8 metallurgy as a result; the FSI paradigm wasn't designed on the back of a fag packet; the RS4 4.2 Self Study Guide claims:

The intake system of the RS4 engine was designed with emphasis on maximum flow control. Pressure loss is minimized by a large cross-sectional areas in the Mass Air Flow (MAF) Sensor G70 and air intake pipe in combination with a 90 mm diameter throttle valve.

To ensure a sufficient supply of air to the engine at high RPM, the power flap in the air filter is opened at engine speeds higher than 5000 RPM and at road speeds higher than 200 kph.
The power flap is opened and closed by a vacuum
actuator which is map-controlled by the ECM via the Intake Air Switch-Over Valve N335.

The sand cast aluminum (should be magnesium) intake manifold was designed specifically to match the sporty characteristic of the engine. In contrast to the basic engine, maximum torque is produced at higher engine RPM. At this engine speed, the intake manifold changeover valve would be switched to the short path for higher power output.

Audi knew what they were doing when they developed this engine....

Is is just ridiculous in my opinion to suggest that you will improve the overall performance of the car with this GruppeM product.

It may improve the performance at one particular test point, but since when was that of any use to anyone?

I'm bowing out of the discussion at this point.

Just my $0.02.

[tartan_rob]

SR71 - we have to politely agree to disagree.

[BigD]

Almost worried about chucking in my two cents…

I largely agree with SR-71… re the level of engineering, research, development and testing that marques like Audi and Porsche undertake for their performance models. Porsche has historically made such a good product (in comparison to other sports cars) based on the amount of information feedback from all the racing it is involved in, which it supports exclusively. Audi has been following suit for some time with DTM and LMP, FSI was developed on the R8 at lemans a car so successful and reliable that it very rarely retired from race due to mechanical breakdown and also had weight and I think inlet restrictors added to “even the fieldâ€

[s4woody]

Audi knew what they were doing when they developed this engine....

if thats the case then why do people on this forum bother to tune there cars..and why has MRC,MTM,QST etc etc been in business to do just that..
car maker's are good..but only at a price...

[hugy]

This topic is realy getting out of hand.I have put my name down for one and am realy looking forward to it.I dont expect any noticable power gains but I like the look of it.I would expect some increase in induction noise as I had a Gruppem ram air system in my E46 M3 and I loved it.So I think whoever is buying one has there own reasons for the purchase and they should enjoy it and not take it too seriously!