TUNING GUIDE – #Audi-RS4-B7
One of the best loved RS models ever made, the B7 RS4 has even greater potential with some careful tuning…
AUDI RS4 B7
Launched in 2006, the B7 RS4 was a revelation. It featured an all-new aluminium 4.2 V8, which revved to 8000rpm and delivered a claimed 414bhp. But there was more to this car than a sweet engine. The rest of it made equally exciting reading. A proper non-electric steering system which gave great feedback, a sweet 6-speed manual, and it handled fantastically well too. Add to this the understated, muscular looks and it’s clear why they sold so well. But, as ever, there’s plenty you can do to make these great cars even better. We spoke to some of the UK’s top Audi tuners to find out what you need to know…
Being naturally aspirated, the 4.2 V8 is never going to deliver huge gains, unless you go forced induction (see later). That said, there’s a lot you can do to make the most of what you’ve got, remove some restrictions and create a car that drives better. The direct injection 4.2 FSI is a light, high-revving and compact unit with lots of character. Performance is strong, although the factory quoted 414bhp (420PS) is rather optimistic. 380bhp is a far more realistic figure, so bear in mind you’re starting from a lower level before you begin tuning. delivers smooth and gutsy power and revs to 8,000rpm. A 0-62mph of 4.7sec and top speed of 170+mph (delimited) is very respectable.
Before embarking on any tuning work, there are some known issues that you may need to take care of first.
The first is the build up of carbon in the inlet manifold/intake ports. This is more likely on cars that are not revved to the redline often, where oil builds up around the inlet valves. It can be fixed with a simple, but labour intensive, carbon clean. Specialists such as #MRC-Tuning
and others can carry this out for £500-800. The build up leads to a loss of power due to the restriction caused and B7s can be down to 350bhp or even more. There’s no point chasing higher power figures if your car isn’t even making stock power!
There have bee cases of bits of carbon (which is very hard) breaking up and ending up inside the cyliders, leading to engine failure. If it’s suffering from rough idling, get it checked out as this can be caused by failed breathers, lambdas, or solenoids – again essential before you begin tuning it. Vacuum leaks can occur, which also manifest themselves as rough idling, hesitation under load and may throw up fault codes (not all cars). It’s worth borrowing or investing in a fault code reader such as a Vagcom unit to check the health before you start hunting for extra power. An engine suffering from vacuum leaks and carbon build up could be down to as little as 300bhp. Coilpacks are known to fail, which again will show as poor running issues. Finally with running issues, early cars were subject to an ECU recall to cure a lumpy idle, so check that this has been carried out before you spend money chasing the problem in other areas. Oil coolers were fitted as standard, which is great from a performance perspective, however, the pipes can corrode, leading to leaks, so check for any fluid around the cooler, which can lead to catastrophic engine failure if not fixed. An uprated cooler from the likes of Forge Motorsport is a very wise upgrade as this will resist corrosion.
A solenoid opens a set of flaps at 5,000rpm for the exhaust, but these are known to stick shut due to vacuum issues, solenoid or corroded bush in the exhausts worn actuator rods, broken flap arms and carbon build up. The other issue (that is different to exhaust flaps and operate under different conditions) are the inlet manifold flaps. These can have worn actuator rods, broken flap arms, and carbon build up. These are only used on idle for better mixtruer for emmsions. These are not like dual runner manifolfds for torque/ power gains. Again, it’s not the end of the world, but it is another labour intensive (and therefore costly) job to remove them. Most RS4 owners get this done, along with the carbon clean and an ECU remap as a whole package. At this point it makes sense to have a performance exhaust fitted as a remap will be needed if the lambda sensors do not have 400 cell cats before them.
Not only will a larger bore, freer flowing exhaust system allow the engine to breathe better, it will also transform the sound it makes. There are many systems available, from Milltek who have about every option available for whatever sound you want and Scorpion, to some truly evil sounding non resonated systems from Capristo and AWE. You can go for a simple cat back set-up; a full system with high flow downpipes and sports cats, or go the whole hog and fit a de-cat system. This will create the most gains, but will need swapping come MoT time.
Be careful with aftermarket induction kits as these can change the calibration of hte maf and this needs to be corrected in the remap to correct mixture and any part throttle hesitations. Any increase in airflow from these can be negated by them being open and sucking in hot air from the engine bay. A quality inlet system with carbon fibre air box from the likes of AWE, Gruppe M, APR and others will help to feed the engine more effectively, while again making a nice noise as it sucks in air on the throttle. They look great in the engine bay.
NA tuning will never give huge gains and for many, just getting the factory quoted figures will be enough. For significant gains, you’ll need to consider forced induction. Several supercharger kits have been produced for the 4.2 V8 including units from APR, PES and TTS Performance, but the TTS kit is the only one currently available. All offer a full bolt-on solution that includes cooling system, all pipework, brackets, inlet manifold, pulley, belts, hoses and fuel pumps. With the correct mapping, a supercharged B7 RS4 can make up to around 600bhp, depending on fuel, conditions, map and other variables. You’ll need a decent budget though. A fully installed TTS kit retails for £11,400 plus fitting and mapping.
The 6-speed manual gearbox is a strong and reliable unit and should stand up to big power upgrades, although an uprated clutch such as a #Sachs
unit will be required. Stock clutches should last to around 40k miles, but hard used or tuned cars will wear their faster. A quick shift can improve the throw with #JH-Motorsports
Although a far cry from the weaknesses found with the C5 RS6, the RS4’s adaptive suspension can still throw up issues. If dammer fails it’s around £250, plus £140 for hydraulic lines, so it makes sense to upgrade to coilovers. KW Variant 3s are one of the best systems available, offering a multitude of adjustability, from nice and compliant for the road, to a harder set-up for track. A drop of around 30-35mm will provide the best ride characteristics, although you can go lower if you accept a compromised ride. As with all suspension upgrades, a full geometry set-up is vital to get the most out of it.
As ever air -ride system are available, and depending on your viewpoint are either a great solution to a problem or a complete waste of time on an RS4. Air-Lift Performance, and AirRex offer systems for the B7 platform, with companies such as Plush Automotive able to install them.
The B7 RS4 came with 9x19in alloys as standard with an ET29 (although 18s were an option). With 255/35 rubber, they suit the car, but many people will want to upgrade. A set of lighter 19s makes sense as any reduction from the unsprung mass makes s big difference to the way the car handles. There are several respected brands to look out for depending on your budget. At the top of the tree is stuff like ADV.1, Avant Garde, HRE and Vossen offering a multitude of stunning, forged wheels from the US. The optimum size is 9x19in for handling, but we’ve seen cars with 10x20in fitted (although this will take some work). BBS and OZ are all well suited to the RS4, as well as high-end Audi-specific MTM and ABT models. OEM items such as the A8 RS4 look, B8 RS4 (with spigot rings) and C6 RS6 also work well and there are literally hundreds of more ‘style-focused’ designs from the likes of Rotiform.
As you’s expect the RS4 came with decent stoppers. The 365mm discs and 8-pot Brembo calipers do a great job on the road, stopping the 1650kg car with ease. If it’s been used hard, then discs can warp, developing a lip, which will create judder under braking. With OEM discs and pads up to £2k from a main dealer, this it the time to upgrade to performance items. Brembo and Performance Friction offer larger 380mm steel discs, with pads, for around £1200. For hard use on track, then some bigger brakes that resist heat build-up are a wise move. AP racing, Brembo and MovIt all make kits for the RS4. We’ve also seen Porsche Cayenne brakes used – if they can stop a lardy big SUV, they’ll have no trouble with an RS4, and add braided lines.
The ultimate brake upgrade is a set of carbon ceramics (an option on the RS4). If they’re off an S8 or R8 they’ll need adapting to fit, but will offer serious, fade free stopping power, create very little dust and look amazing to boot. Figure on around £3,500+ for a used set on eBay or advertised on popular forums. Also look at the highend MovIt carbon kits.
The outside is bang on the money. Wide arches give the B7 a muscular look and with deep vents to the front bumper and trademark oval tailpipes at the rear, they look great. But there are things that can be improved upon if you so wish.
If your RS4 didn’t come with the Black Optic pack, then you’ll have chrome window surrounds, front grille surround and roof rails (avant only). These can easily be wrapped to a matt black finish or even painted. The RS4 is pretty stealthy anyway, but some owners removed the RS badges for the ultimate wolf in sheep’s clothing - although those that know will still spot the wide arches, front bumper and oval tailpipes. Many people choose a full wrap, to make their RS stand out, but also to offer protection. There are a number of approved 3M dealers that can transform your car in a day from around £1200.
There’s also plenty of carbon available to liven up your B7, from the likes of Carbon Goodies.co.uk, including front lower splitter, to badges, wheel centres, B and C-pillar covers, and boot strip. A few RS4s have popped up with vented bonnets, particularly supercharged cars, which run quite hot. The effectiveness is debatable as air flow is a complex area, but they certainly look mean.
If you’re fortunate to have an RS4 with the wing back Recaro sports seats, then lucky you – cos these are some of the finest seats ever made. If not, you can fit a set, but factor on at least £2k (assuming you can find a set). With early B7 interiors getting on for nine years old now, they do tend to wear, so a retrim is a good option. A full front and rear seat retrim in leather and or Alcantara, including door cards, starts from around £3k rising to £5k+ if you want the pillars, gear gaiter, dash and centre console doing – a significant outlay, but it will make your car feel like new inside. OEM steering wheels had a silver plastic bottom section that can also wear and perhaps isn’t in keeping with the high-end feel to the car. A replacement flat bottom wheel with carbon section can be sourced, although you’ll need to budget at least £500, plus another £200 or so to have it fitted. Companies such as Awesome GTI can do this, but it’s quite involved making sure the multi function buttons all work correctly. A later spec B8 RS4 wheel is another option, but again this would be around £1000 fitted.