Weight is one of the most important issues to consider when building a fast car for road or track. Putting a car on a serious diet is pretty much free horsepower, as any attempt to lighten a car improves the power to weight ratio, this seriously improves acceleration.
The gains on a lightening a car are huge and not just limited to gains in acceleration either. Once you have lightened a fast car you will find the car performs better in the corners and under braking, parts such as brakes and tires will last longer on the car also.
The potential gains are huge but it must be done correctly, you would not want to lighten a rear wheel drive car too much on the rear or you may find traction a problem particularly with a high power output.
The truth is your fast car could be made a great deal faster cheaply and easily just by shaving a few pounds off the body.
How do we remove weight from the fast car?
This bit is as easy as you want it to be, but as with most forms of car modification it depends on how far you want to go. I know a guy who races a BMW and he decided to go all out on weight saving, he even scraped every bit of under-seal from the floors of the car, extreme perhaps but he managed to remove nearly 2 stone of under-seal, not a bad effort.
The obvious place to start saving weight on your fast car is by removing the interior, and anything else that you do not need, the front seats can be replaced with light weight racing items, the unused wiring removed, carpets and sound deadening, pretty much all of the unnecessary parts, my car has just a driver seat and a cage with much of the unnecessary wiring removed. This makes for a car with very impressive performance.
Many other components can be replaced with lighter parts, gear box casings, axle covers etc. It is worth noting that a stainless steel exhaust is lighter than the same in mild steel, so this constitutes a worthwhile investment.
It is also important to reduce the unsprung weight on the car also, by this I mean wheels, brakes and anything else before the suspension mounts, this provides a very good increase in the handling of the car.