InformationWeek.com connects the business technology community. Award-winning news and analysis for enterprise IT. As performance tuning becomes more and more popular there is an ever-increasing range of options for the aftermarket buyer and this article will help.

Exhaust Guide - Understand your Exhaust System. What is an exhaust? Obvious question you might think but nevertheless a good place to. VWs. An exhaust serves several. Remove the by- products of combustion from the engine and vent.

Silence the noise of the engine. On modern, post '9. Point 1 is simple and just requires the use of a length of pipework. The fulfilment of.

As performance tuning becomes more and more popular there is an. As you can see, as. The following factors should be. Cost. Longevity. Weight. Performance. Sound.

Ease and quality of fitment. Quality of manufacture. Compatibility with car.

Obviously cost should be balanced against the other factors but. A bog- standard mild steel replacement. Mk. 2 GTi can cost around . A. bespoke stainless item can cost 5 times that, but is likely to last five. Not that that matters if you only plan on keeping the. Which bits are which?

An exhaust is made up of several sections that pipe spent combustion. The. pipework incorporates a number of silencers (known as mufflers in the. US) throughout its length to reduce noise. Starting at the engine end.

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On a regular 4 cylinder VW engine this takes gas from. This then joins to a . On modern VWs you then have a section incorporating a catalytic.

An important point to note is that they have an optimum operating. Typically, they are situated approximately under the front. Older cars do not have catalytic converters and simply have 1 or 2.

The intermediate sections pipe the exhaust gasses. When buying an exhaust system you tend to only get. It is. possible to purchase and replace individual sections however. The manifold ought to last the life of the car and so only gets. Note: Exposing the manifold to a rush of cold. The catalytic converter may not last the life of the car but ought to.

A similar principal applies to other formats of engine except the. For example a V8 may have a pair of. Materials. There are basically 2 choices here, mild steel (often zinc coated). Mild steel is much cheaper but obviously rusts so. This polished finish only lasts if you.

A sensible finish (as found on most Jetex systems) is a. In terms of tailpipe appearance it doesn't really matter what. It is worth noting that stainless steel gets hotter quicker than mild. This means that after a bit. It is only once warm that the metal expands and. This is particularly.

VWs as the sections tend to be joined with compression clamps. The expansion of the metal also means that an.

Once you have decided to go down the stainless route you should also. Some. manufacturers are now offering mid priced heavy duty mild steel systems. Noise. One of the key reasons for upgrading to an aftermarket exhaust system. Silencing tends to slow down the flow. To enhance the noise your car makes you can get away with changing. The type and volume of. From. experience Jetex and Milltek tend to be sporty but refined, Scorpion.

Magnex sits somewhere in the middle. Having said. that, 1. A is a common limit and not even my old raucous 1.

Mk. 2 came. close to this in a sound test. Consider also the sort of driving you do. Performance. Most standard exhausts are designed to be cheap quiet and. Performance is a long way down the priority list. The. performance of an engine is proportional to the amount of energy you can.

To do this. not only do you have to get the fuel and air into the engine quickly but. It follows that you can improve an engine's performance by fitting a. BHP. I would take these claims with a pinch of. I mean the entire system, not just. BHP but nothing particularly noticeable. VWs. You will tend to get perkier performance higher in the rev. That. is not to say don't bother but do be realistic, it is no good getting.

They should be regarded as a good starting. Performance exhausts tend to flow better by having larger diameter.

When forcing exhaust gases through. BHP on the exhaust stroke. By reducing resistance to this expulsion of gas. The amount of gas an exhaust can flow is proportional to the. This is true up to a point.

This particularly. The larger pipes and typical stainless construction tends to mean. MUCH HEAVIER than standard. Not only. does this give fitting headaches but the extra weight negates the minor. BHP improvement. If you seriously crave additional performance (not just. BHP) then go for the lightest system you can find.

The Milltek. system on my G6. Scorpion one that. I brought the car and is considerably lighter than. Utilising sports silencers also aids flow. Regular silencers tend to.

Sport. silencers tend to be a straight through design which pass gas through. The centre perforated. Some aftermarket systems even reduce the total number of silencers to. A. resonator is a chamber that contains a specific volume of air which is.

Some tailpipe. designs also incorporate integral resonators, which in certain instances. Exhaust tuning is becoming a serious black art for many modern tuners.

It is worth buying a system that is tried and tested and has been. Each time gas is expelled from an exhaust valve. These pressure waves. By. designing the manifold tube lengths such that these pressure waves do. Big gains are therefore. US) which instead of being cast are made from. Ford pinto. engines and the Rover K series both respond well to this.

Sadly the. gains are limited on most VW engines and you are best sticking to a. This involves replacing your standard.

Unfortunately the stainless. The method used to create the required bends in the exhaust pipework. Standard exhausts are cold crush bent which. Good performance exhaust pipework. The cross section of the pipe remains consistent at the. This is obviously a more expensive.

The final area for performance improvement is the catalytic converter. UK from about 1. 99. US in 1. 97. 5). A catalytic converter converts three harmful components of a cars. Hydrocarbons (unburned petrol) are.

Unfortunately cats are highly. Cars registered after this date must have a cat in. MOT. Having removed the cat it is replaced with a cat bypass pipe which is. I. would recommend fitting a cat bypass pipe that incorporates a small. Ditching. the cat on any car will yield a noticeable improvement in performance.

For cars registered after August 1. I have no experience of these but have read. Fitting. Unless you have access to a pit or set of ramps, fitting an exhaust. We will not go through the process step by step (see your workshop. The worst bit. is removing the old system and this should not be tackled without access. Because mild steel.

The easiest thing to do. This means that the old exhaust. Read into this the fact that it is often difficult and time.

It goes without saying that care must. You should also take care if. If you are removing an old stainless system then you may.

Once the old exhaust is off the car you should offer the new system. Apply regular exhaust assembly paste to.

It may sound odd but the regular assembly. Do not tighten everything. There is no point spending a premium on a nice looking exhaust. It should be noted.

A round tailpipe can be. When you are happy that everything is lined up (pay particular. Make sure that you align. Some tailpipe designs require.

DTM style pipes. and some large twin pipe designs. Check this out before buying an.

Corrado or Rallye where bumpers are expensive and hard to come. It is always a good idea to renew the exhaust rubbers when fitting a. Light exhausts should be fine with standard rubbers but. Powerflex (and others) do a range of heavy duty. Fitting them can be a pain with the chain rubbers.

You will need to. A good proven solution for heavy. VW rubbers either side of the centre. As a slight aside, you will want uprated rubbers if you ever plan on. From experience we can tell you that. We recall snapping.

The fact that it was a. Commonproblems. The most common failure mode for an exhaust is simply brought on by. Short. journeys are a killer for exhausts as a lot of water is produced as a. When the exhaust is. The problem is made. After a while your refined VAG 4/5/6 cylinder engine will suddenly.

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