By Jack Lanier
Friends Don't Let Friends Modify Cars

03-17-2005

Today, it's difficult to make cars better and extremely easy to make them worse. Or dangerous.

As a journalist driving modified cars, I've been sprayed with gasoline, boiling coolant, super-heated transmission fluid and nitrous oxide. (The latter was more entertaining than the former.) Several have burst into flames. Throttles have stuck wide open, brake calipers snapped clean off, suspensions ripped from their mounts and seatbelt mounting hardware has dropped into my lap. All this is on top of the expected thrown connecting rod, blown head gasket, exploded clutch, disintegrated turbocharger and broken timing belt.

The vast majority of these vehicles were built by professionals. Many were from big-name tuners. Most performed as if they were constructed in a shop class at a high school with a lax drug policy. Once, after a suspension component fell off a car from a big-name tuner, the car actually handled better.

For every modified and tuner car that performed better than stock, I've driven numerous examples that were slower. If they were quicker, it was often in an area that can't be used on the street. What's the use of gaining 0.2 second in the quarter-mile if the car is slower 0-60 mph? And costs $10,000 more?

Long ago — when your grandparents were kids and the president was Dwight Eisenhower — it was easy to improve cars. Back then, carmakers designed vehicles largely for production convenience. It's not difficult to improve the handling of a car that had one steering idler arm a little longer than a man's shoe and the other more than the length of his arm: Stiffen the suspension to the point that it doesn't move. Also, in the olden days, cars were so simple virtually anybody could work on them. Replacing the stock two-barrel carburetor (ask your grandfather) with a four-barrel reaped easy power: There were no sensors or computers to confuse, as often happens if you tinker with today's engines.

The Old Ones wonder why today's kids want to "improve" cars. This is partially because something like an '05 Mustang V6 — does the term "secretary's car" come to mind? — has more horsepower and is quicker than an '84 Corvette. Put both on the same tires and the '05 V6 would give the '84 Vette all it could handle on a road racing circuit.

I'm guilty of modifying cars. Mea culpa. In an effort to improve a very sweet handling sport sedan, I added the biggest antiroll bars and stiffest shocks I could find. The result sucked. One doesn't have to reinstall too many stock antiroll bars and redeal with a strut compressor to earn a bad attitude about modifying cars.

Recently, I autocrossed a pair of Subaru WRXs. One was a dead-stock WRX. The other, a tricked-out STi lowered with stiffer springs, shocks and bars and an exhaust kit and air filter. The STi is supposed to have an advantage of some 70 horsepower. Maybe the exhaust and filter moved the power up in the rev band where it couldn't be used. The lowered, stiffened STi regularly bottomed against its bump stops. When a car hits its bump stops, the spring rate goes to infinity and tire grip drops to near zero. This caused the STi to leap into the worst understeer I've experienced with inflated front tires. Meanwhile, in the unmodified WRX, I could be hard in the throttle at the same point. The result: The dead-stock WRX was at least as quick as the STi and far easier to drive. Easy to make worse, harder to make better.

Don't get me started on brake "upgrades." On one hand I can count the brake modifications that out-performed stock. Auto manufacturers spend millions of dollars on brake design, while aftermarket brake manufacturers often allow their customers to participate in the development process. Gulp.

Fitting larger-diameter wheels is another excellent opportunity to reduce performance. Wagon-wheel-sized wheels are all about bling and little about blast. Most larger-diameter wheels are notably heavier than what they're replacing: Aluminum is heavier than the air and rubber. This additional mass requires more horsepower to accelerate, more braking power to stop and more shock valving to control. Translation: Bigger equals slower. Also, lower-profile tires tend to be more difficult to drive at the limit. Most drivers will be quicker and in better control on 17s than on 19s.

On the street, it's almost impossible to accurately assess whether a modification has aided performance. People often judge handling by how the car rides and acceleration by noise: If it's rough and loud, it's got to handle better and be quicker, they think. This is the "Bactine Theory": If the medicine hurts, it must be working. The Placebo Effect also comes into play: If you've just spent a couple of grand to improve something, you will believe it's working.

The only modification that consistently produces positive results are tires. A change from original-equipment rubber to expensive gumballs will reap guaranteed thrills. If you like your car but want more from it, step up to the best ultrahigh-performance tire.

My best advice is this: If you don't like your car and want to make it better, buy something else.