Racing Tips - Vehicle Setup
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Vehicle Setup
BEFORE MAKING ANY CHANGES TO YOUR VEHICLE, MAKE SURE THE CHANGES ARE LEGAL, SAFE AND ALLOWED BY YOUR RACING CLUB. WE CANNOT BE HELD RESPONSIBLE FOR ANY CHANGES MADE BY YOU OR SOMEONE ELSE TO YOUR VEHICLE, REGARDLESS OF WHAT YOU HAVE READ HERE.
Most of this is fairly obvious stuff, but...
Make sure your suspension is in good condition, particularly your shock absorbers. Your front shocks are most important as these assist your steering and braking significantly. If you've just bought a second hand car, or you've never had the suspension checked, get it done. At any one time there are usually several companies offering free suspension checks. A simple test you can do yourself is to find a solid piece of body panel on each corner of the car, and then push down with both hands and let go quickly. The car should bob down, then up and stop. If it moves again after it has come up the first time, something isn't working properly, probably the shocks are worn. Not only will you not brake or steer as well, but on slippery surfaces like grass you may not be able get traction or you may find you almost can't turn at all (understeer).
For grass surfaces, lower your tire pressues and this should help you to gain traction - but its a good idea to get inner tubes put between the tires and rims to help prevent the tires from being torn off when you start slidnig the car around.
To get a reasonable increase in power fairly cheaply you should look at getting a modified exhaust and air intake. For the exhaust, you want a free-flow type exhaust (simply adding a tip that makes it louder won't help much if at all). Removing the catalytic converter or replacing it with a higher flow one can also help, but make sure its legal for where you are living/competing. Several companies, such as Pitstop can do this for you, and there are many companies specialising in performance exhausts so check your yellow pages. Also note that many countries/states have restrictions on volume of exhausts, as do many race venues. It is possible to be banned from racing (even at a track) if a vehicle is too noisy.
As for air intakes, you can simply fit a high-flow filter, such as a K & N air filter, or you can go for proper setup that ducts cold air in from a high pressure area. Note that a 'pod' air filter is likely to give you a better increase in power than a replacement for the stock filter, but pod filters are unlikely to fit in the stock air box. This will cause two problems, first of all the filter can get very dirty very easily, particular at grass/gravel events. Secondly, the filter will likely suck in hot air from the engine bay (due to there being no cold air box), which will decrease the overall power. It is recommended that if you do this that you create a custom cold air box, or have one built for you. This isn't a particularly difficult job, the most important part is deciding which point is best to duct air in from, searching for this information on the Internet will provide a number of cheap solutions to solve this problem, or if you're not worried about acheiving the absolute top gain simply choose a suitable spot at random. Try to keep it away from any hot engine parts however.
When making improvments to your vehicle its important to find out whether the changes are allowed within your 'class'. For example if you have a 1.6 litre engine, and add a supercharger you may find you end up in a special class with other supercharged/turbocharged cars, or you may be pushed into the 2 litre + class. If this happens, while you will be going faster so will the people you are now racing against, and so you may not actually improve your rankings 'in class' because all you've done is moved up the scale. The same rule applies to AWD/Four wheel drive systems and the like. Check with your club officials if you are unsure.
To improve handling you are usually best to change your shocks and springs to a stiffer set. You should be careful however not to go too stiff, as this can reduce wheel travel which results in the wheel spending less time in contact with the road and therefore less speed. The other thing to note is that while lowering a car will generally improve its handling this needs to be done properly. Improperly lowering a vehicle can actually hurt the handling as well as cause increased tire wear etc. Simply cutting springs is not usually the answer, instead buy a set of shorter springs. The other important thing to consider is where and what type of racing you'll be doing. If you plan on doing rallies or rally sprints then you may not want to lower the vehicle at all, in fact the most heavily modified MR2 I know of has been raised about an inch to give it the clearance it needs for this type of event. Lowered vehicles can also sometimes have problems at autocrosses/hillclimbs, and very ocassionally at motorkhanas too. If you don't want to lower your vehicle, or even if you want to raise it, you should still be able to purchase stiffer springs that are the same or longer than stock which will improve the handling while maintaining or increase road clearance.
A set of rally tyres for racing on unsealed surfaces and a set of good race
(track) tyres are also worth their weight in gold, but make sure whatever
tyres you are buy are allowed in the events you'll be driving in. Other methods for improving handling often involve adding or upgrading sways bars and strut braces.
For this kind of thing we suggest you search the Internet for details specific to your make and model of vehicle.