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AU Modification Guide



Useless Mods

This first part is very important to read as it contains information on cheap useless modifications and other useless inventions that you should avoid. There are a few basic things to remember with adding modifications to your car. First is that there is no such thing as a good cheap engine modification. Second is that if there is some sort of modification being advertised for a very cheap price, it’s probably too good to be true, and you should steer clear of this.
1. $20 eBay intake mod – These sorts of modifications suck you in for an increase of up to 20 horse power for about $15 to $20. All this modification actually is, is a resistor connected to your intake temperature sensor, and causes the ECU to lean out. However, this is useless because your ECU will learn the effects of what happening here, and you will loose efficiency of this modification within 100Km.
2. Homemade Electric Supercharger – This modification is utterly useless. The concept of this defies physics and fluid dynamics. This modification usually consists of adding a PC case fan (or similar) somewhere along your intake, either before or after the filter. In theory, this will reduce intake temperature and push more air in the engine, but your engine will suck more air then this baby can blow. Also, a fan will not cool air, nor can a small fan like this create pressure… a fan is just that… it moves air.
3. Hi-clone – This is another one of those modifications where the technical advantage can only be explained by a rocket scientist and it’s advantages gives you about the same advantage of a weight reduction by throwing away a cassette tape. This works by getting a specially designed twisted bit a metal and putting it along your intake. As the air flows through this twist, it creates a vortex, and therefore, somehow is meant to do something. The stupid thing about this, is that positioned after the hi-clone, the twists of the intake pipe, throttle body, intake manifold and valves, you will loose all the vortex effect generated, and therefore, it just ends up as drag along your intake pipe.
4. Magnets – Here is something that Peter Brock would like never to be mentioned again. This modification involves placing magnets, or some special designed magnet that wraps around you fuel lines, and ionizes the fuel atoms, which in turn give a better bang… some crap like that. Point is, it doesn’t work!

Number #1: 2.5” Cat back exhaust system

This is the first modification that should be done to most cars. This modification will give you a slight increase in performance an also give you that sweet tone you’ve been searching for in this car…
For this setup, most exhaust shops should be able to do this starting from around the $400 mark, but some shops may give you a better rate if you get modification #2 at the same time.
The extra detail for this modification is a nice looking exhaust tip. Most people prefer a bold chrome tip to enhance the appearance of your aftermarket exhaust, but bare in mind that a tip may not be necessary if you are looking at getting an aftermarket body kit, as some kits don’t have an exhaust exit, and need the exhaust to be dumped before the rear bumper. Side exit exhausts are always an option here to, but be sure to look into the legalities of this. It seems that the catalytic converter already on the AU’s will be up to the job for a 2.5” exhaust, though any bigger, or if you have a V8, you may want to consider getting a hi-flow cat installed too. This is about $200.

Number #2: Extractors

Extractors is one of those modifications that people usually like to whack on their car and not do any more, but we know that’s not you! Extractors work by giving each piston chamber an exhaust pipe of equal length that all eventually come into one pipe that is then in turn, connected to the exhaust system. By doing this, exhaust gases flow more easily and therefore, the engine works more efficiently. Be aware, that doing this modification, increases the exhaust noise, and in some circumstances, may put your car over the legal noise limit. Extractors for the I6 engine will come in two types: 6-2-1 and 6-1. This means that it goes from 6 pipes, to 2 pipes to 1 pipe, or 6 pipes to one pipe. Depending on which type you get, will depend on where the majority of your power will come into effect in the rev range. You are best to talk this over with your mechanic when getting your extractors fitted, as everyone’s circumstances, wants and needs vary. You can also look at the option of painting your extractors different colours. Pacemaker extractors can be ordered chromed from the factory. This is about a $200 option though.

Number #3: High Flow Air Filters and Pod Filters

After market air filters is an area where not everyone agrees on. Some people suggest that the factory filter will do the best job of filtering air, while allowing the most airflow… but we know better! The recommended here would be to pull out the standard filter and replace it with a K&N High Flow panel filter (or similar). These can be purchased from most auto parts stores such as Super Cheap and AutoBahn. A K&N panel will set you back around $140 and you can wash them when they get dirty, unlike normal paper air filters. This setup is recommended over a pod filter because of legalities and simplicity. There is a bit of a grey spot in the law with the fitting of pod filters, although it is cheaper.

Number #4: Breathe Easy!

The next modification is to allow the engine to breathe easier. This will involve modifying your intake piping. The first thing to do here would be to pop down to your local Ford Spares Shop and pick up a Tickford Air Intake Snorkel. This snorkel is about twice the volume of the stock one. This snorkel is also known as a “Cold Air Intake” or CAI for short. The second part to this modification is to replace the existing intake piping from the air box to the throttle body. This is more of a part that you can make, and install yourself. You can either get some stainless steel metal made up for this modification, or on the cheaper end, you can buy and fit your own materials. SuperCheap do have their own plastic 90mm intake pipe that you can buy, but it does look a little tacky. Your best bet is to either get PVC piping from Bunnings, or source some flexipipe. PVC piping is the preferred method. Pretty straight forward really, just attach your pipe to the throttle body with some pipe clamps (same as the ones found on radiator hoses, just bigger) and then attach it to your air box. This can be done two ways. You could go out to the wreckers and get an air box lid from an EF/EL Falcon (as this has the 80-90mm opening), or just give your air box a bigger hole. Then attach the other end of the piping in here, being careful to seal all holes, and you’re done!

Number #5: High Stall Converter

This modification becomes quite useful for great take offs. Unfortunately the AU has a terrible takeoff from the line, and really needs to be pointing downhill to get a good start, but a high stall converter will fix this. Put simply, a stall converter acts like a clutch. When taking off from a standing start, the stock converter feels like a clutch very slowly being released. With a hi-stall, in effect, it will simply dump the clutch. Without getting massively technical about stall converters, this is the best, short description that can be given. Stall converters can come at different stall rates, but the best rate for the AU would be 2800rpm. But be warned, to do this properly, you need to get a transmission cooler fitted as well. The approximate cost for a full hi-stall setup is around the $1000 mark. By fitting this modification, you may notice a decrease of about 10Kw of so on the dyno, but on the track, the hi-stall will give you a reduced ¼ mile time, because of a better launch.

Number #6: Cams

Now’s the part where we crack open the engine and actually give it a real upgrade! A cam is a long shaft with knobs machined in very accurate parts of this shaft (see picture below). The cam rotates around and pushes down on a valve stem which opens it up. The valves are closed via springs always holding it shut. The camshaft will open both intake and exhaust valves. By upgrading your cam, you would upgrade to a more “lumpy” cam which means it will open your intake and exhaust valves more, therefore, allowing your engine to breathe A LOT easier. Talk to your mechanic about which grade of cam you should get. Some cams will require a tune, or a full ECU change/flash. At the same time of fitting new cam, you should look at fitting a new Cam Gear, aka, Vernier Gear. A chain attached to your main crank at the bottom of the engine (timing chain) connects to this, and spins the gear, and cam, in sync with the rest of the engine, allowing the valve to open at the right times. Installing a Vernier Gear allows the timing of the cam to be changed. By how much depends on the gear. Again, this should be discussed with your mechanic, and depending on your circumstance, you may not need it. A new cam shaft, Vernier gear, and installation should start from $1000.

Number #7: ECU Flash Tune

This is the major step up in gaining the most out of your engine, without adding on anything that wasn’t their before. The old theory with EFI cars used to be that if you wanted to do anything big to your engine, then you would need to replace your ECU with an aftermarket one, but now, aftermarket ECU’s are old news. The best and most easy way to upgrade your carputer, is to flash it. This means to keep the actual ECU itself, but upload all new data to it. Tuners around Australia have modified and tuned falcons for years and have now got the best ECU map ready to upload to your cars ECU. Recommended would be CAPA or G&D Performance Tuning. Along with a flash, you will need a dyno tune to make car specific tuning changes, and to accommodate all your previous modifications. This can be done at the same time by your tuning specialist. For a flash upgrade and dyno tune, expect to pay $1000 upwards. If you have some serious gear fitted to your car, you may want to consider a custom tune… but by now, you should already know this.

Number #8: Brakes

Now that you have filled up your car with go fast bits, it’s time to make it go slow, quick. By that, I mean upgrading your brakes. Now the AU1 brakes are pretty pathetic, so a rotor and pad upgrade would be recommended here. I would recommend DBA slotted rotors, and Bendix pads. The AU2/3 had MUCH better brakes put on, and really only needs a rotor upgrade, though if your pads need changing, chuck in some Bendix pads. The slotted rotor will do two things: Firstly, eliminate warping of the discs, and secondly, eliminate brake shudder at high speeds. But mainly, with a good disc and pad combination, pull you up quickly without locking up the wheel… Plus they look good. You may also want to take this opportunity to paint your brake calipers. Bendix pads should start from about $100 a pair, and the DBA slotted rotors will start from about $140 each.

Number #8: Differential and LSD

Now here comes a very interesting modification that has a number of different effects. This involves changing your differential gears and (if you don’t have one already) adding an LSD (Limited Slip Differential). The differential will act as a final drive from your gearbox, and depending on what ratio of gears you have in your diff, it will spin your rear wheels at a slightly different speed compared to the driveshaft. Most standard 6 cylinder AU’s have a diff ratio of 3.23 and the V8’s had 3.45’s, which means the driveshaft will spin 3.23 times faster then the diff. So if you put a 3.9 or 4.11 diff in, you will take off faster, but don’t race out yet; The higher the diff ratio, the higher you car will be revving at 100Kmh. So you need to find a happy medium between your cruising speed revs, and a good takeoff. The following are some figures to help you decide what diff ratio best suits you:
3.45 @ 5500rpm = 179kph
3.73 @ 5500rpm = 166kph
3.90 @ 5500rpm = 158kph
4.11 @ 5500rpm = 150kph
Now comes the tricky part – LSD. An LSD not only makes your car handle better around corners but also helps put power down to the struggling wheel. All up, and diff upgrade with LSD should start of from around $1500, give or take $200. The price will vary on the quality of the diff gears, labour, if an LSD is to be fitted, and the new diff gear ratios. Remember to check your diff oil every 20,000Km!

Number #9: Wheels and Tyres

Wheels and tyre upgrades are a very important part of handling. If you already have 17” or larger wheels, you need not worry, however if you are running 15 or 16 inch rims, you may want to consider upgrading. Going to a 17” or larger rim will be you will get less tyre roll around corners which will greatly improve handling, especially when driving around suburbia. When you do go to an 18” rim or higher, tyre cost becomes a large factor, as tyres start to approach the $300 EACH! Some claim that the notable difference from a 17” to an 18” is very minimal, and not worth the expense, but some also prefer the look of lower profile tyres.
With tyre choice, if you decide to choose a more sticky, gripy tyre, bare in mind that this will wear a lot faster then a harder compound will, but which every tyre you end up choosing, it is VERY easy to get the falcon sideways in the wet, regardless how much money you throw at it. Also note, that if you intend on taking you car to the track, double check to what speed your tyre is rated to. You’ll be surprised that a lot of tyres are not rated past 140Kmh.
DO NOT HAVE RE-TREADS FITTED TO YOUR CAR!
Re-treads are dangerous as they are bits of rubber glued onto an old tyre. Some insurance policies do not cover the use of re-tread tyres. Re-treads are not rated for speeds above 80Kmh. You may also find that if you are always taking off fast from the traffic lights, you will soon peel the tread away from the tyre and do massive body damage to your car.

By au3 chaser
Document last updated 22:08 Fri Oct 27, 2006
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