B5 (8D) 98-05 Audi A4 Mods & Tuning Upgrades

"A4 (B5) Best Mods and Performance Upgrades"

Let's look at the best A4 mods and tuning upgrades. Thankfully the A4 uses the VW B5 platform and came with some great engines, so power modifications and tuning upgrades are readily available, we shall review the best upgrades for your A4 and highlight some of the pitfalls and problem areas when it comes to tuning and building a modified A4 B5.

The A4 B5 was the car of the year and loved by motoring journalists. It went to show that you could have a family size car which provided a good driver experience. Interior space is very similar to an A3. In a side by side comparison internally the Passat seems much bigger than the A4.

Since 1994, the Volkswagen Group "B" platform has been used to build the vehicle. Transaxle gearboxes were situated at the back of the engines, which were longitudinally mounted. The Audi 80 was replaced by the A4 B5 8D, which represented a significant advancement. It received a major revamp for the 1998 and 1999 model years (referred to as the 1999.5 version).

As far as tuning the A4 B5 goes we would shy away from the modest engine sizes. To get the most from the chassis you really need to get an engine with 130bhp or more. Thankfully the diesels and turbo diesels fit the bill nicely with some suitable modifications.

 

Tuning tips and articles

Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

See our video which covers all the principles of Audi A4 Tuning, it contains some tips on turbo swaps and covers performance and handling.

We would go for the 1.8T, the 2.0Tfsi the 2.5 and 2.8 V6 engines and the 1.9 TDi 130 and 2.0 TDi (avoid the 100ps version unless you are desperate for economy.

1.6 I4 8v SOHC 1994–2001 101 PS (74 kW; 100 bhp) 140 Nm (103 lbft)
1.6 I4 8v SOHC 2000–2001 102 PS (75 kW; 101 bhp) 148 Nm (109 lbft)
1.8 I4 20v DOHC 1994–2001 125 PS (92 kW; 123 bhp) 173 Nm (128 lbft)
1.8T I4 20v DOHC Turbo 1994–2001 150 PS (110 kW; 148 bhp) 210 Nm (155 lbft)
1.8T I4 20v DOHC Turbo 1997–2001 180 PS (132 kW; 178 bhp) 235 Nm (173 lbft)
2.4 V6 30v DOHC
BDV Engine
1997–2001 165 PS (121 kW; 163 bhp) 230 Nm (170 lbft)
2.6 V6 12v SOHC 1994–1997 150 PS (110 kW; 148 bhp) 225 Nm (166 lbft)
S4 2.7 V6 30v Biturbo 1997–2001 265 PS (195 kW; 261 bhp) 400 Nm (295 lbft)
RS4 2.7 V6 30v Biturbo 1999–2001 381 PS (280 kW; 376 bhp) 440 Nm (325 lbft)
2.8 V6 12v SOHC 1994–1997 174 PS (128 kW; 172 bhp) 245 Nm (181 lbft)
2.8 V6 30v DOHC 1997–2001 193 PS (142 kW; 190 bhp) 280 Nm (207 lbft)
diesel engines all Direct Injection
1.9 DI I4 8v SOHC 1996–2001 75 PS (55 kW; 74 bhp) 150 Nm (111 lbft)
1.9 TDI I4 8v SOHC 1994–1997 90 PS (66 kW; 89 bhp) 202 Nm (149 lbft)
1.9 TDI I4 8v SOHC 1997–2001 90 PS (66 kW; 89 bhp) 210 Nm (155 lbft)
1.9 TDI I4 8v SOHC 1994–1997 110 PS (81 kW; 108 bhp) 225 Nm (166 lbft)
1.9 TDI I4 8v SOHC 1997–2000 110 PS (81 kW; 108 bhp) 235 Nm (173 lbft)
1.9 TDI I4 8v SOHC PD 2000–2001 115 PS (85 kW; 113 bhp) 285 Nm (210 lbft)
2.5 V6 TDI 24v DOHC 1997–2001 150 PS (110 kW; 148 bhp) 310 Nm (229 lbft)

See our video which covers all the principles of tuning your Audi, it contains some tips on engine swaps and how to find cheaper performance components.

It's hard to live with the 170TDi's performance if you just make short trips since anything less than 130 horsepower would seem sluggish on such a wide platform. The later TFSi engines are good options, as are the 170TDi's.

Let's take a look at your A4 B5 tuning project's customization capabilities.

For families, the A4 B5 is a practical option that provides an enjoyable ride.

Handling adjustments are normally the first thing you look at for the A4 B5. Drop the automobile up to 35 millimetres and stiffen the dampers; larger dips usually need further modifications.

At the upper end of the rev range, our goal should be to improve peak horsepower and torque.

Larger engines provide the most power. Since the return on investment is greater for larger engines, engine swaps are an useful fix for small engines.

A4 B5 Tuning modifications.

These mods sports parts are usually installed by our members, decide how far you wish to go in your tuning project before you get started.

Getting the right modified parts for your planned usage of the car is a time and money saver. Stage 3 motor sport parts just don't work well on the road making the car difficult to drive.

Please watch our video which covers the top Audi A4 Tuning Mods. Be sure to keep up with our latest YouTube content and subscribe.

Best mods for your A4 B5

  1. Forced induction upgrades - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. Typically one of the most costly upgrades it offers big gains.
  2. Fast road Camshafts are one of the most significant mechanical changes, but they must be installed by someone who knows what they are doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  3. Engine Tunes - A Remapped A4 B5 ECU provides the most advantage for the money, aftermarket ECUs, and inline Tuning boxes are all alternatives.
  4. Intake and Exhaust - NB: on their own these mods won't ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.
  6. A4 B5 Suspension Upgrades - Fitting a more sporty Suspension kit dramatically improves A4 B5 handling Adjustable coilovers and better bushings are what is needed here.
  7. Brake Upgrades - Enhancing your stopping power should be high on your agenda.
  8. Lighter flyweel - on most models you'll appreciate the faster rev speed changes. But keep the DMF on the diesel engines.

A4 B5 Tuning Stages

Typical stage 1 mods often include: Alloy wheels, Lighter flywheel, Panel air filter, Engine Tunes/Remapping, Sports exhaust, Suspension upgrade (drop ).

Typical stage 2 mods often include: fuel pump upgrades, Fast road cam, high flow fuel injector, Power/Sport clutch, Ported and polished head.

Typical stage 3 mods often include: Sports gearbox, Adding or upgrading forced induction (turbo/supercharger), Internal engine upgrades (pistons/head/valves), Competition cam, Engine balancing.

Peak power is all well and good but for a daily driven car you need a wide power band and perhaps extending the rev range.

Let's look at these in more detail, in the meantime please watch our video on the best car mods, so you can maximize your return on your tuning investment.

A4 B5 B5 Suspension Mods.

Fast cornering is important on the track, and suspension plays a role. The track is forgiving, so you can use harsh suspension and lower the car for better aerodynamics and a lower center of gravity.

Upgrading your A4 Bushings

Enhancements to the bushings: Things you need to know

It is possible to connect the A4 B5's suspension components around the chassis of the A4 B5 using poly bushes, which are replacements for the rubber mounts. The rubber ones will degrade with time and need replacing anyway so why not upgrade.

That said, just installing new OEM rubber bushings may dramatically improve the performance of your car, but often you need a little more control and a little less flex.

Downsides to poly bushes

Because polyurethane bushes are stiffer, the ride may be firmer, but the bushes will last longer and maintain the car's handling for longer.

They may also hasten the depreciation of other suspension components due to the increased vibration and play.

Benefits of poly bushes

A new set of poly bushes may be able to eliminate the excessive play that comes with rubber bushes.

Unlike current model cars, which often come with a complete set of suspension bushes, rare and older models may only have polyurethane main bushes available via aftermarket bushing kits.

Often, custom A4 B5 bushes may be manufactured to your requirements allowing you to choose the firmness and qualities to suit your requirements.

Choose your suspension upgrades wisely

A common misconception is that a non-adjustable suspension system that lowers the vehicle by 60mm from a local car part shop is the best option. There is far more to setting up your suspension than this.

For a vast variety of vehicles, a 'compromized' approach is obviously incorrect so look at how your A4 is used, will it be track focussed or do you want to build a fast road daily driver?

How low should you go on the A4 B5?

When it comes to road cars, the optimal amount of suspension drop that can be achieved is between 24 and 42 millimetres, according to TorqueCars research and testing.

Changing the diameter of the wheels may drastically reduce the tolerances. Even with 17-inch wheels and standard suspension, lowering a car may cause a number of problems.

While the A4 B5's reduced height allows for less air to move underneath it, the main objective should always be to improve handling, and to increase stability.

Using the correct shock absorbers while lowering the springs is essential to provide a smooth ride. They need to be fitted as matched sets.

For the A4 B5, a few degrees of negative camber and 1-1.5 degrees of toe (to increase cornering or stability) on the front wheels are effective suspension modifications.

In time, the rubber suspension bushings of the A4 B5 may deteriorate and the suspension will not perform as well as it should.

If you cut your springs they will be prone to shatter or break without warning - SO NEVER EVER CUT YOUR SPRINGS!

Ideally, you should acquire a suspension package that can be quickly modified on the automobile to fit your driving style such as with adjustable coilover kits.

A good set of coilovers will help allowing you to adjust them to suit your driving style. Koni, Bilstein Eibach and KW make decent sets that work well on the A4 B5.

A4 B5 Brake upgrade mods

In addition to larger brake discs, don't forget to replace your A4 B5's brake pads, since they are just as crucial, if not more so, than the discs themselves.

Brakes are essential because if you're going fast, you'll need to be able to stop quickly! The friction pad presses against the disc to convert kinetic energy into heat, which is how a brake works and the better the car can dissipate this heat, the sharper the stopping ability.

In night-time racing, the brakes can literally glow red hot after intensive usage because of the accumulation of heat from extensive braking.

Your foot pressure is amplified by a servo, which is a magic box that utilises engine power to multiply your foot pressure when you press the brake pedal.

A brake fluid-filled tube delivers the additional pressure to the friction pads (liquids do not compress like air).

Additional pressure is placed on the brake fluid by the hot brake pad end, which may cause the braking fluid to become hotter than it should be.

If there are air bubbles or water in the brake fluid, it causes it to feel spongy at best and may prevent the brake from functioning totally at worst, which is why it is important to replace the fluid periodically and use a good quality brake fluid. (See the article on Brake Fade for additional information on this issue.)

The middle channel of the vented disc increases the surface-to-air ratio of the disc, resulting in quicker cooling.

Preventing buildup of gas vapors between a disc-pad interface is made easier with drilled discs, which increase air ratio and prevent gas from condensing in this area. Better cooling is a benefit of larger discs, however a new alloy wheel may be required.

Drawbacks From Race Brakes

Materials used to make your brake pads are an important consideration.

High-friction compounds are used in the production of racing pads because they perform better at higher temperatures.

Putting meatier brake discs and better high friction brake pads should make for radically enhanced braking.

We should point out that race pads will be noisy and will need to be hot before they bite.

On a road car the brakes are occasionally used so will not stop you as well so source pads which don't need to be really hot.

For road usage, race-grade brake pads are inappropriate due to their inability to function when cold or while braking for short periods of time.

According to TorqueCars, Pagid and Black Diamond fast road brake pads provide a decent balance of stopping power and wear.

Even though driving style affects pad and disc wear, certain high-performance brake pads emit practically no brake dust and last longer than the standard pads I was using before they broke down.

If you do not consider yourself to be a mechanic It's best to leave the brakes to the experts to prevent accidents, says Torquecars. Improve the stopping power of your vehicle by installing better brakes.

It is possible to enhance a car's braking ability. In most cases, discs and pads are both upgraded. Generally as a rule of thumb, the bigger the disc, the greater the friction and the greater the heat dissipation, but there are practical upper limits, and grip is certainly one of the limitations to this.

When you install a big brake disc conversion kit, you'll have better braking feel and be able to tell when your brakes are locking up on your A4.

Cheap Brake Upgrades for your A4

You may quickly and inexpensively acquire brake discs and servos from a performance model in the same family if you have a basic family A4 with smaller discs.

See our video on choosing brake upgrades for your A4.

The performance brakes (if they fit into the alloy wheels or you need to obtain bigger rims) are usually included in a compact family automobile.

Getting to know the other members of our community and their experiences with their own cars might be useful. This means that braking systems from different manufacturers may be used together since most hubs are interchangeable.

Calipers (which provide clamping force) and pistons are the next components to be discussed (which push the calipers).

Greater pistons means more clamping power, which means you can use bigger pads..

Making a dog bone adapter to mount them on the factory (or bigger) discs to replace the single piston sliding callipers isn't a straightforward solution.

The quantity of braking fluid used must be the same as what was in the donor car's master cylinder when the system was donated. As a result, the pedal will have to be pressed closer to the floor before the brakes engage, changing the feel and stroke of the pedal.

You may have to overbore or replace the stock master cylinder in order to match the capacity of the source vehicle's.

Increase the pad, calliper, and piston count to get the most out of your new discs.

A lighter flywheel

Rotational force is generated by the large wheel located between the engine and gearbox effectively storing engine power kinetically.

When cruising, this helps the car withstand fluctuations in engine speed, which is great, but may be harmful when you need a rapid engine response. Disadvantages - takes more effort to move the wheel and reduces engine speed

By reducing the load on the engine, a lighter wheel is able to provide more power and respond more quickly to changes in RPM.

On the other hand, if you have a lighter flywheel, you will lose more speed on a hill and incline.

For optimal torque and unhindered revving, a variety of flywheel weights are available. Your tick over may suffer if your A4 Flywheel is too light for the street. Discuss your application with other TorqueCars users in the car forums.

It's a good idea to replace the flywheel as well if you're changing the clutch.

A4 DMF Flywheels

A spring connects the two separate surfaces in a DMF Dual mass flywheel. The rotational acceleration and deceleration are both slowed down by the spring and engine vibrations are smoothed out.

This is particularly useful in diesel engines and lessens the risk of reversal in four-cylinder engines. Some of our members are switching to solid flywheels in place of DMFs, however we strongly advise you to read our lesson on DMF to SMF conversions first.

Remapping the A4 B5.

Remapping Issues and Drawbacks What are the hidden costs?

Prepare to get your motor serviced more regularly, and in certain cases, to have the interval cut by half. If the map was tuned for high octane gasoline,  you'll be restricted to using that, as normal octane fuel will now be prone to pinking or pinging and a loss of power.

Also you must be prepared to replace components that fail as a result of the additional work they are doing. Components such as air flow sensors are placed under increased stress when an engine is modified to produce more power.

The presence of weak areas in an engine even months after the tune/remap is common, these are pre-existing but manifest themselves after they are asked to work harder. You may get further information on how to troubleshoot a tune/remap in this article.

Generally, any turbocharger and clutch deficiencies will show up following a remap.

Also, turbos can wear out, essential components like pistons and bearings require care, and the clutch is less durable. What about NASP remaps? A tune/remap alone will only gain a few BHP if you don't have a turbo (10 percent is typical).

TorqueCars advises non-turbo automobiles to modify everything else first (cams, pistons, increase compression, engine balance, air intake, exhaust, head work, bigger valves etc...)

After this, you can consider a tune/remap to assist you get the most out of them.

So Why Remap Your A4?

What's the problem with OEM maps? To accommodate for temperature changes, minor faults, and poor weather, manufacturers create timing maps with a considerable error margin. Furthermore, to maintain all automobiles running properly on a worldwide scale, various nations use different fuel grades and experience varied levels of unfavourable weather.

Mechanical breakdowns and low fuel efficiency aren't something that manufacturers want their consumers to have to deal with, so they provide room for error.
The output of an A4 might vary optimally somewhere in the region of 20 horsepower depending on how well the components are machined and installed. They don't do a one-size-fits-all analysis of each vehicle, but rather employ a generic timing map.

To cut insurance costs and improve fuel efficiency, manufacturers use tunes or remaps to generate various power versions of the same engine.

In addition, consider the fact that most readers of TorqueCars are likely to be upgrading their vehicles.

Users' carelessness, such as infrequent service, dirty plugs and connections, clogged air filters, and partly blocked injectors, are also taken into account by the manufacturer. And so on and on. Remap who? Anyone who has improved their engine should think about having it remapped.

In addition, remaps, which increase power by 20-30 percent, are recommended for all current turbocharged engines. For turbocharged automobiles with electronically controlled fuel injection, TorqueCars highly advises a remap.

Turbocharged Engine Care Tips

The turbo is also likely to run hotter and quicker especially if a tune/remap adds boost at lower rpms.

Allowing the turbo to cool before shutting off would prevent oil degradation, which would need a costly turbo replacement. Turbo timers help to ensure that the engine runs until it cools down.

Don't believe everything you read about peak power Because some tuners have been known to fabricate a power blip or spike in order to obtain headline power statistics, please disregard peak power when comparing maps.

See the graph below for an example of what we're talking about.

As an alternative, pay attention to the whole torque curve. Increased torque at the bottom stresses the turbo and its components, whereas increased torque at the top strengthens it.

However, power is decreasing across the RPM range in the red plot whereas power is increasing evenly in the green one.

Peak power is shown at 4000rpm, which is excellent for an engine that redlines at 7000rpm, giving you plenty of additional power in the areas where you need it most.

When plotting a torque curve, we want to observe a continuous increase in torque over the whole rpm range, with no dips or troughs.

Quarter Mile times        
Base Power Quarter Mile Weight Tuned Power Quarter Mile
90hp 20.24 1500kg 110hp 18.96
100hp 19.56 1500kg 120hp 18.43
150hp 17.15 1500kg 175hp 16.31
163hp 16.69 1500kg 180hp 16.16
172hp 16.4 1500kg 195hp 15.75
180hp 16.6 1500kg 220hp 15.15
190hp 15.89 1500kg 250hp 14.54

Turbo modifications and upgrades for your A4 B5

A Guide to Volkswagen and Audi Group Turbochargers by VAG

Here, we'll take a look at some of the most popular turbocharged engines from the Volkswagen Group, as well as their differences and the finest upgrade options.

It's also worth noting that the turbo's power limits may be surpassed, resulting in a reduced turbo's life span.

In most cases, you'll hear a whining or alarm before you see any smoke coming from your turbo.

You should begin searching for a new job at this point. It's possible that a faulty turbo might do a lot of damage if the compressor breaks.

Differences between K03, K03s, and K04:

Making a direct comparison The K03 turbo was in production from 1996 until 2000, when it was superseded by the K03s turbo as the standard model.

The K03 turbos are used in the 1.8T AGU engines. MAF sensors, a cable-operated throttle, and smaller injectors are all standard on these engines.

K03s turbos are used in AUM engines that have MAF and MAP sensors. The improved drive-by-wire throttle on these engines improves both fuel economy and performance. In terms of turbos, Stigan and BorgWarner are the two most notable manufacturers.

KO3 and the KO3s Differences

The primary difference between turbos is the number of blades. Unlike the K03, the K03s has just 8 blades.

The actuator that opens the turbine bypass valve changes greatly from turbo to turbo, ranging from 65 N to 85 N, but some models contained a two-port actuator.

180-horsepower engines often employ actuators with improved quality and more opening force due to the higher boost pressure.

Increasing the compressor on the intake side of a hybrid turbo usually enhances power and is a standard strategy utilised by many manufacturers.

The original K03's power is the smallest amount you'll receive, thus it can only safely exceed 190 horsepower with the correct tweaks and upgrades.

However, the turbo's lifetime will be shortened if you push it beyond its safe limits.

The K03s is more powerful than its sibling, the K03. Any more than 215 horsepower is considered unsafe for K03s; any less and the turbos will fail.

You can get up to 250 horsepower out of this turbo, but anticipate it to have a shorter life expectancy.

More than a 25-bhp boost over K03s is possible if you're ready to sacrifice turbo life or are prepared to do more maintenance on the engine.

K04 has a more significant advantage than K01. When compared to the K03 and the K03s, the K04 is much larger and produces considerably better performance.

Even though the KO4's power output may be safely boosted to 220 hp with the necessary hardware aid, the K04's power output statistics can reach 350 hp.

The K03 and K03s turbos were both smaller than the K04. While the K04's power output was somewhat lower, the amount of space required for its installation was far less than that of the K04.

Turbo limits - safe should retain factory reliability and longevity, the Max however is pushing to the limits and will certainly shorten the lifespan of the turbo.

Turbo Safe Max Maximum
K03 190hp 220hp
K03s 215hp 250hp
K04 220hp 350hp

With a few minor adjustments with a Stage 1 remap, you should expect your A3's K03s turbo to produce between 210 and 220 horsepower (Air filter, exhaust, bolt-on modifications).

Is There a Reason to Upgrade Your Turbo?

For the following reasons, many drivers choose to replace or upgrade their turbochargers: A turbocharger upgrade is one of the most effective ways to improve a vehicle's performance.

Turbos degrade with time, necessitating re-purchasing. The most current turbos use newer technology advancements and provide additional options for car owners.

A4 Turbo Upgrades: How To Pick The Best

There is a trade-off between increased power and increased wear on the engine. A turbocharger on a petrol engine may run between 100,000 and 150,000 revolutions per minute (rpm) at temperatures as high as 1100 degrees Celsius.

These speeds can be doubled by certain turbo combinations and future models. Because of these speeds, proper lubrication, cooling, and balancing are all necessary. Severe wear on the bearings and oil seals are the most frequent issues.

There are two methods to increase the power of your turbocharger. A hybrid turbocharger (based on your OEM casing but with internals from another turbo or with a different design)

Install a bigger turbo, which necessitates the use of additional pipes and labour. Although most hybrid turbos will work perfectly on standard maps with lower boost levels, the first choice just replaces the original and necessitates remapping.

Compressor wheel and turbine profile are analysed as well as air intake hole shape. At high RPMs or low RPMs you may use them to spin faster and compress more air.

A smaller turbo produces a more linear torque curve with reduced latency for road vehicles.

It will also feature stronger bearings, better balance, and stronger seals in a hybrid turbo. RPM reduction improves reliability and boost.

Upgrading the vehicle's ECU MAP is usually required when installing a more powerful aftermarket turbo. Error codes will be issued if this step is skipped, and the engine will run lean or enter limp home mode as a consequence. Using a stock ECU will not allow you to enjoy the full advantages of your upgrade, thus you must utilise a new aftermarket ECU in some cases, but the A4 Bosch ECU's are quite effective when mapped on most upgrades.

Swapping out a turbo isn't always that easy. You'll normally need to follow these steps:

  1. Changing out the old fuel injectors
  2. Replacing exhaust mufflers
  3. Changing out the boost control circuit board
  4. Changing the exhaust pipe's diameter
  5. A new fuel pump may be installed easily.
  6. Adding cooling systems like intercoolers
  7. The waste gate needs to be replaced
  8. Using catalytic converters with less restrictions

There may seem to be a lot of work to be done, but it all depends on the kind of vehicle. The architecture of the engine compartment also plays an important role in deciding how difficult it will be to transfer an Audi turbo into a different model.

The exhaust and intake pipes may have to be rerouted, the intercooler may need to be increased in size, and there may be space limits. Turbochargers that run on a hybrid system.

Re-mapping of the K04

However, we've observed a number of high-quality gasoline (98+ Ron) and an enhanced FMIC (Front Mount Intercooler) among the numerous adjustments necessary to attain this high of a performance level with the K04 Turbo (your OEM clutch will slip).

Uprated injectors will enable you to supply sufficient fuel to the engine.

Uprate the fuel pump to cope with the extra fuel requirements of your tuned A4 B5's uprated injectors.

A4 B5 Intake and Exhaust Mods.

Now we move on to the intake and exhaust and ensure proper flow through the engine. Maximum power gains come from a full induction kit. On the lower powered engines you will actually lose low down power so we suggest you use a panel air filter instead made from a cotton gauze material.

Increasing the A4 B5 engine heads valve size, carrying out port work and head flowing will also lift torque, & importantly will afford you an opportunity to raise the torque increase on other tuning parts.

Unless there is a step that obstructs airflow into the engine, opening up the air intake port to match the intake manifold would not benefit much. As a result, most DIY port matching work is best done on the exhaust ports.

It should be noted that extending the port size is not always advantageous and is only required in highly tuned engines when the port size has become a bottleneck.

Slightly narrower channels with fewer bends or angles often enhance flow rates.

Because of the reduced weight and greater precision that moulded plastics provide, many contemporary intakes are now constructed from moulded plastic to achieve this aim of minimising turbulence on the downflow side.

The purpose of a highly tuned rally car engine, represented in this figure, is to achieve a seamless connection between the intake manifold (x) and the engine port (y).

Unlike direct injection engines, fuel injectors (f) spray fuel into the intake manifold and benefit from a direct route to the valves.

For smoother air flow, the intake angle has been made more shallow. This may not always be achievable for all engines, but the goal is to reduce air bends.

Exhausts with a diameter of 1.5 to 2.5 inches are generally the most effective for increasing horsepower, not the largest one you can find.

A good fast road power clutch will help to keep that power going where it should. Never skimp or expect a standard clutch to cope. Remaps offer significant power gains on all turbo charged cars. On NA (naturally aspirated) engines the benefits are doubtful, but will help unleash the potential if you have done a lot of mods.

A4 B5 Wheel Modifications.

Aside from the fact that alloy wheels are lighter than steel ones, they also aid in the cooling of the brakes. A4 B5 Big alloy wheels appear attractive, but their performance will be harmed by this accessory.

The higher you go, the lower your peak speed will be because of the shift in your effective final drive ratio. Try to maintain the factory-supplied wheel's total rolling diameter.

We don't advocate going larger than 18 inches in any situation. To suit Porsche brake conversions, several of our members have used larger 19 and 20-inch wheels, however they all suffered tram lining and other difficulties with the bigger rim size.

A4 B7 Common Problems and Issues

There are a few problems and issues to look out for on these, but I've split these off into other articles.

  1. 2.0 TFSi carbon buildup issues - direct injection engines require an intake clean.
  2. 2.0 TFSi problems - N75 and N249, high oil consumption,  Cam Follower wear, Water Pump failure, and Turbo issues
  3. 2.0 TDi problems - Flywheel, Oil pump,  Lumpy Idling
  4. 1.8T Problems - Diagnosing the common faults and issues

Please join us in our forum to discuss the A4 B5 options in more detail with our A4 B5 owners. It would also be worth reading our A4 B5 tuning articles to get a full grasp of the pros and cons of each type of modification.

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