Several folks have asked me what modifications I have done to my cars and why.
It has been an iterative process. As I learned more about cars I integrated my performance goals with an approach that fit my budget and available resources. If I could give any advice It would be to have fun, do your research, and take your best shot.
My approach to modifying a car is one where I strive to keep all parts of this complex system in balance. Now there is a concept for you to ponder. Think of the car as a system of many components that, to get the most out of any of them, must work in harmony with each other. Sounds kind of Zen like doesn’t it? But think about it. Before your car hit the dealer’s lot millions of dollars were invested to get it to that level of performance, comfort, handling, etc. It starts out with everything working together in relative harmony. Why? Because that is what must be done in order to produce a car that works as reliable transportation that can also be manufactured as cheaply as the car company can (they have got to make a profit, after all). In particular, with the warranties that exist today, the car companies will make sure that, as a system, you car is as balanced as it can be.
If you were to concentrate on only one aspect of the car, say getting power out of the engine, you would be asking all the other components to do much more than they were designed for. That means everything. The brakes, the engine mounts, the transmission, the wheels, the tires, everything; even the driver
Do I always hit perfection in terms of balance? I’d certainly like to think so, but reality is that I just get as close as I can. It can even be argued that the handling bias of a typical factory automobile is toward understeer and therefore is not balanced in the first place. The point is that you will find the results of your modifications much more rewarding and free of unwanted problems if you always keep in mind the need to coordinate changes in one area of the system with the system as a whole.
With all that stated I will go over the modifications that I’m familiar with, and how I’ve tried to maximize a vehicle’s potential without throwing the whole thing out of balance.
People love to start with the engine and why not. Who wouldn’t like to be pressed into the seat with acceleration? The only problem will be that at some point you will need to slow down or stop.
I’ve found that the best place to start is with the tires. The tires affect everything. It is where the car contacts the road. In fact many race cars are designed around the tires. You can make a substantial difference in how your car responds by upgrading the tires in terms of size and design. I my earlier posts I have gone over the impossible “ideal” tire that would have maximum performance in all conditions. In real life we have to make decisions based on the kind of handling we would like to achieve in the context of the road conditions we expect to encounter.
Tire Rack (www.tirerack.com) has an excellent site that you can use to help you with your decision. Then you can always explore other sources for your tires, if you choose. What Tire Rack (and other like companies) may not be so helpful with is what larger tire sizes you can entertain. Today this takes a lot of research of the forums that exist for your specific car. These forums can help you with the how much space is available within the stock wheel wells and the amount of offset that fits the best. Certain tire sizes offer you many more options in terms of performance choices than other sizes.
As you look for the “right” tire you also will need to find the “right” wheel. The rim width affects the set of the the tire and should be optimized for the particular size you wish to go with. The wheel also needs to have the offset that allows you to upgrade the size while allowing you to stay within the confines of the wheel wells, whether you are making a hard turn or have a lot of body roll.
You also need to keep in mind that the lighter the wheel, the more you will achieve in terms of handling. The wheels are part of the “unsprung” weight that you want to minimize. You will also want to keep in mind that you will want to clean your wheels from time to time as well. Some of the basket weave wheel designs look fantastic until you are squatting in front of them with a wash mitt and bucket and have to clean all the detailed parts to get out the brake dust. You can always pick a color wheel that camouflages the brake dust, but some day you will still have to clean that wheel.
Keep your wheel as light as possible, the correct width and diameter for the tire choice, and the right diameter to fit the brakes you are going to be using. Currently large diameter wheels are very much in fashion, but going large also means going heavy. Heavy is bad.
If your fenders are metal you can often accommodate larger tires by “rolling” the fenders. There are some pretty fancy tools for doing this. They bend over the lip on the inside of most fenders as well as form the edge of the fender so that it flairs out some. Often you will need to warm the paint as you roll the fender to keep from cracking the paint. This can be done by using a heat gun sometimes even a good hair blower. If you don’t have access to a fender roller you can use a wooden baseball bat too. Just place it between the tire and fender (heating the paint) and roll it under the arc of the fender.
With the tires and wheels sorted out you really should work on the brakes. This can be done in steps. Starting with better rotors and pads as well as swapping out the stock flexible brake lines for braided stainless steel hoses. Of course you should upgrade the brake fluid itself. It should be changed each year in any case, but there is a vast difference between the capabilities of brake fluid. Standard off the shelf fluid may have a dry boiling point in the 300 degree range where a high performance fluid will be over 500 degrees. Unless technology changes drastically I would not recommend synthetic brake fluids. To do so will require getting rid of any residual fluid so it usually means replacing all the components and brake lines.
There are many brake pads to choose from and the technology and compounds change frequently. The semi-metalics are temperature sensitive, are noisy, and tend to dust a lot. My current favorite for the street is Porterfield R4-S (http://www.porterfield-brakes.com/) and Performance Friction (http://www.performancefriction.com/) for the track.
Bedding the pads in post install is as important as the components you choose. It is also important to bleed the brakes correctly and then again after the pads have been bedded in.
I’ll write more on the subject of a balanced approach. You’ve done well if you’ve read through all this.