Huge power loss with cone filter

[EspenW]

Dynoed a RS2 and a rare S6+ this weekend, using a MRDyno unit (more advanced form of G-Tech that corrects for air resistance, temperature, barometric pressure, etc). The test is performed on the road, so the car is in its natural environment, with plenty of cooling air.
We tested the RS2 pre and post remap.
In standard form, it put down 250whp and 250ft-lb, after the remap ("360hp" chip that peaked at 1.7bar) it put down close to 280hp and 283ft-lb to the wheels. The measurements were taken in 2nd gear. 3rd and 4th would yield better numbers due to lower losses to inertia, with torque numbers suffering the most, due to lack of spool.
The S6+ with the 4.2L engine from the S8 puts out 326hp in stock form. It was previously tuned by one of the most reputable Audi tuners in Norway (chip, open cone filter and 3" race exhaust), with a promised power output of close to 400hp.
With the open filter, it put down 250hp and 215ft-lbs to the wheels. Not being a fan of open airfilters, I suggested to reverse tune it and put in the standard airbox with stock paper filter. It now put 255hp and 225ft-lbs to the wheels, with the power and torque curve elevated at all rpms. The biggest loss with the open filter was at approx 5000rpm, where it lost approx 15whp. With quattro, 15hp at the wheels is close to 20hp at the flywheel.

Graph # 1 shows the diference in power between cone filter and standard box
Graph # 2 shows the difference in torque
Graph # 3 shows 3 consecutive runs with stock airbox. The MRDyno unit has such good repeatability that consecutive runs will produce graphs that overlay pretty much perfectly, enabling the user to spot even minute gains or losses from mods and adjustments

[T2Andy]

would this be down to heat or restriction ,so you can pay upto £100 and loose power

[Jamo]

Depends on the filter / filter placement and if it had a cold air feed.

I'm not a fan but setup correctly they can be very good.

[Rusty]

Things are a little different on the road due to more air but generally it's accepted that a cone filter will not work better than an airbox unless you a) shield and feed it properly or b) the airbox is a restriction causing a loss in power. I don't like the sound of a cone on the S2 but I can imagine on teh V8 it's awesome so I'd happily lose 15bhp but not all the time

[Jamo]

Amazing same as this thread http://www.s2forum.com/forum/showthread.php?t=27869

[EspenW]

would this be down to heat or restriction ,so you can pay upto £100 and loose power

The open filter pulls more, but hotter air, so the end result is still fewer oxygen molecules. At very high rpm, the graphs get close, since the cone has better flow, and the airbox shows some restriction.
This cone filter setup had a cold air feed.
They need to be perfectly sealed from the engine bay heat in order to work.
Most cone vs. airbox tests are performed in a hot dyno room, and the cone proponents always claim that the cone will work better on the road. This test was performed on the road, with an ambient temp of 6degs.

[s2driveruk]

yep, pretty much confirms what i found when going from a cone back to airbox....

[EspenW]

Differences would have been even greater on a turbo with a red hot turbo and manifold heating the inlet air for the cone filter.
15whp maximum loss on this NA engine could easily translate to a 25whp maximum loss on a 20vT

[Rusty]

I bought the proper hoses to fit my cone filter and had a go today, car felt really flat (not a suprise as I'd not fitted any shielding). I'm going to have a play and see if I can make a decent heat shield and see if I can get it to perform as well as my drilled and hacked ABY box. Had a couple of ideas, one for use with a cone filter and one for use with the OE airbox to further insulate it. Shame that a proper cold air feed is such a PITA on the stock inlet

[PeteUr]

Keep us updated andy as this might have to be the route i'd go with one of my cars.

[Keeper of The Kitten]

I've always said any filter type should live inside an airbox! Ran cones on the Le Mans cars but they were in sealed airboxes and fed directly from the outside airstream, not from any source within the engine compartment.

[Rusty]

Yeah, that's the best way, shame that the sealed filters are serious money, BMC, K&N etc. Pity I can't get a bit 4" feed to the stock airbox without cutting the strut that supports the headlight. The silly Audi inlet routing of the inlet means that it's nearly impossible. Inner wing has been discussed in the past but then that's more cutting...

[Keeper of The Kitten]

I've considered right through the bonnet with that whole corner sealed by a vertical wall inside the engine compartment, with a rubber strip pressing on the inside of the bonnet ...but the front wing is high on my list of potential intakes.

[S2central.net]

Front wing is best technically I feel... just intuitively in how a sealed airbox could ingest huge amounts of lovely fresh air thru vents on the right wing. MTM and others have done this effectively - but its a fairly unsubtle modification.

Agreed 100% that the factory intake is a bit pants with that fingers width of an air gap beside the headlight that Hans & Franz decided was good enough at the time. Tis not unique to S2/RS2 as the V6 engined B4 has an equally weedy air intake that I am convinced strangles the motor.

[Rusty]

Cheap and easy mods:-

With the aux rad removed I've stretched the inlet duct over about 3" to capture as much of the air flowing through as it can, a simple and effective cable tie mod. I think that eventually the strut that supports the bonnet stay is going to be cut and a slither of pipe welded in place to guide some large ducting. That's a good next mod I think.

Inner wing mods:-

Could drill a faffing big hole in the inner wing and fit some 4" plastic pipe to the side of the stock airbox that can poke through, that would satisfy the cold air part for sure

I could of course leave my heavily drilled 'box in there and put a row of say 2" holes in the inner win for fresh air to flow through, problem is that it could of course just flow out, no uinder tray more than likely = area of low pressure due to air flow

As for a sealed airbox, I'd prefer to feed it from the front rather than the inner wing as the inner wing doesn't feel like an area of particularly high pressure with all that air flowing past, seems silly to go to all the hard work just to feed it air at a lower pressure, albeit colder...

A turbo heat shield that fits to the standard pipe heat shield and that cover the turbo is looking like a nice Sunday afternoon project, I'll get some 1mm ally and get bending

I think sorting a 3" or 4" feed from the OE position for a stock airbox is the neatest mod, can attach something suitable to the front for sure

Lots of ideas there, I'll get the measuring tape out and go play tomorrow I think.

Shame that I spent £35 on hose to get the cone filter on there just to remember how much it needs a shield, a further £15 on sheet ally and a day of palying and measuring (spread out over a bit) should yield another solution along the lines of the Dahlback effort but hopefully for a little less Krona.