The Super Seven

Yellow Jacket

Fast street cars don't just happen. They are the result of careful planning and attention to parts that work together. Jackiee Henderson and her husband Chris are two diehard enthusiasts with a passion for Bow Tie power. Approximately four years ago, they decided that it would be fun to build Jackiee a car that she could race. The project started off with a few interior modifications, and soon their '69 Camaro received a rebuilt 350ci engine.

Chris and family friend Paul Alhouse put just enough power into the 350 to push the Camaro into the 12-second zone. Jackie spent several years refining her driving skills and getting comfortable with the car before the guys started on another small-block. This time they pumped the displacement to 383 inches and added a better set of AFR cylinder heads and a Crane Cams camshaft. Behind the 383ci is a transbrake-equipped TH400 transmission carrying a 4,200-stall converter that shocks a 4.88-geared 12-bolt with posi-traction.

With all this power and technology under Jackiee's right foot, her best quarter-mile pass to date is 10.98 at 124 mph. The Henderson's Camaro is a classic example of bolting on a few carefully selected parts and making them work in 10-second harmony. It doesn't get much better than that.

The key to any good performance machine is parts selection. Whether your engine is big or small, it's capable of producing big power so long as the correct parts are chosen. It's OK to let the import crowd believe giant wings, stickers, and 5-inch tailpipes are the way to a lower e.t. You're smarter than that and should demand to see some real-world testing. Because we're like you, the CHP staff has compiled seven low-cost ideas that have proven themselves on the dyno and at the dragstrip. Each part was tested in a real-world application in order to extract the most realistic results.

Whether your car is motivated by a big-inch thumper or small-cube motor, each of our test subjects is guaranteed to improve the performance of your ride. We performed our testing on several different vehicles in order to show how a variety of vehicles can benefit from numerous parts. If there's one thing to take away from this story, it's the theory and understanding of how each part works within its application rather than the individual test itself. Follow along as we take you on a seven-proof power tour.

Take It In

Starting Price: $125

The more air you can move through an engine, the more power that engine will make. While bolting on the go-fast goodies gets expensive, there is a way to work in steps and improve the horsepower and looks at the same time. Many low-performance factory V-8 engines came with two-barrel carburetors and cast-iron intake manifolds that are restrictive to say the least. Intake manifolds play a critical role in proper air/fuel distribution and must be sized according to the engine. The most important factors to take into consideration are runner length and size. Shorter runners provide improved top-end power. Long runners increase low-rpm torque. Runner size most directly determines the velocity of the air/fuel charge as it travels into the cylinder heads. A smaller runner tends to increase torque by increasing inlet air speed at lower engine speeds.

However, this creates a restriction at high rpm. Larger intake ports slow the inlet air down at lower engine speeds, reducing the potential torque the engine can make. A manifold with the properly chosen runner length and size will benefit the engine with the best overall power curve. Those high-rise dual-plane intakes like the Edelbrock Performer RPM work so well because they offer decent runner size and enough length to make power throughout the typical rpm range of most street engines.

To demonstrate this principle, we equipped a stock 350ci with a stock Q-jet aluminum intake manifold, Q-jet four-barrel carb, stock cam and iron cylinder heads, 15/8-inch headers, and a 21/4-inch exhaust system with 34 degrees of total timing. This motor managed 349 lb-ft of torque at 3,600 rpm and 255 hp at 4,400 rpm. Then, we installed a dual-plane Edelbrock Performer intake manifold and let the dyno handle fly. With no other changes, torque improved marginally by 1 lb-ft at the same rpm but we gained 10 hp at 4,300 rpm. An engine originally equipped with a two-barrel setup would have shown almost twice the power gain. We should also mention that the aftermarket intake manifold is capable of supporting more power with a larger camshaft and improved cylinder heads. Had we tested this same engine with a better cam and better heads, we would have seen even more power.

Power Pipes

Starting Price: $99

What is one of the few systems that is capable of adding torque and horsepower to an engine while also improving fuel mileage? If your answer was exhaust, you are correct. Headers perform the task of providing a more efficient path for the exhaust to leave the cylinder. Stock cast-iron exhaust manifolds are more restrictive and create pressure in the exhaust system. This backpressure is detrimental to making power, especially if not all the exhaust exits the cylinder after the exhaust valve closes. When this happens, the spent fumes contaminate the intake charge, which robs the engine of potential power.

Much like the intake manifold example, headers must also be correctly sized to maximize the scavenging effect of evacuating the cylinder of all residual exhaust gas. Too large of a header will slow exhaust velocity and hurt low-rpm torque, while a too-small header pipe will restrict top-end horsepower potential. Engines producing up to 450 hp most commonly benefit from a 15/8-inch header. Engines producing upwards of 600 hp can benefit from a larger 13/4- or 17/8-inch primary pipe. Of course, this is all relative to the particular type of engine, camshaft, and cylinder head.

To evaluate what a set of headers are worth on a small-block Chevy, we dug up two small-blocks and ran some tests. In the first test, we started with stock cast-iron exhaust manifolds on a 350 that made 321 lb-ft of torque at 3,800 rpm and 239 hp at 4,200 rpm. For test two, we installed a set of 15/8-inch Hooker long-tube headers to make 349 lb-ft of torque at 3,600 rpm and 255 hp at 4,400 rpm. What's amazing is that torque gained an average of 27 lb-ft from 3,200 rpm to 4,400 and saw a 53 lb-ft peak improvement at 3,400 rpm.

The swap averaged a 20hp increase between the same rpm range and showed a peaked gain of 34 hp at 3,400. As in the intake manifold test, a more powerful engine would show even more impressive gains so we decided to repeat the same header test with a more powerful 350. During our baseline pull, the stock exhaust manifolds managed 340 lb-ft of torque at 5,000 rpm and 382 hp at 6,200 rpm. Then we added the same 15/8-inch headers and saw 406 lb-ft of torque at 5,000 rpm and 438 hp at 6,600 rpm. Torque averaged almost 43 lb-ft from 3,200 rpm to 6,600 rpm with a peak of 68 lb-ft at 4,800 rpm. The horsepower numbers moved up the rpm curve and averaged almost 59 hp from 4,400 to 6,600 rpm with a peak of 70 hp at 6,200 rpm. The results kinda speak for themselves, don't they?

Deep Breathing

Starting Price: $300

Backpressure doesn't end with the headers. You also have to match a good set of headers with an equally good-flowing exhaust system. In our previous header test, we showed how important it is to properly match headers to an engine in order to provide the most amount of horsepower. Exhaust system efficiency is very similar to that of the headers with the exception that the primary function is to muffle sound.

It's difficult to equate gains on the dyno to actual numbers at the track, so instead of testing a complete exhaust system on the dyno we decided to upgrade the exhaust on a project Camaro and make a race day out of it. On a previous trip to the dragstrip, CHP's My Generation Camaro consistently ran 16.75s at 84.25 mph. Cast-iron exhaust manifolds and a small header Y-pipe flowing through one tiny catalytic converter and single muffler certainly hindered the Camaro's mild-mannered 305ci.

This led us to Edelbrock's 50-state smog-legal 15/8-inch headers and 3-inch Y-pipe leading into a 3-inch DynoMax converter and a single Flowmaster muffler with dual outlets. When the new exhaust system was installed, we were expecting to see a tenth or two at the dragstrip, but we were instead rewarded with a 0.46-second reduction in e.t. and a 2.34-mph gain through the traps. The 2.34-mph improvement in trap speed shows a definite increase in power that came from a bottled-up exhaust. On top of the increased power, we also came away with a Camaro that sounds more aggressive.

Torque Time

Starting Price: $100

Once you're making respectable power, it's up to the driveline to help determine how quick your car will run. Acceleration is a game of leverage using gears. For our purposes, an automatic trans and a torque converter will serve as an example. A torque converter resembles a large round case with a splined centersection to accommodate the transmission's input shaft. The torque converter is basically a fluid coupling that connects the engine to the transmission.

This fluid coupling intentionally creates a certain amount of slippage, which is referred to as stall speed. But the reason it's called a torque converter is that at low vehicle speeds, this device also multiplies torque. This additional power comes from the stator inside the converter that typically multiplies engine torque between 2 and 2.5 times. Shortly after initial acceleration, torque multiplication from the stator tapers off and the converter applies actual engine torque to the transmission. Depending on the angle of the converter's internal fins, converter stall speed can be varied. Additional stall speed allows the engine to "flash" to a higher rpm where the engine makes more torque.

This applies more power to accelerate the car from a dead stop. The negative side to a higher stall speed is increased slippage, which hurts top-end efficiency and highway fuel mileage. All this slippage also creates heat that can be detrimental to transmission life. As you can see, selecting the right torque converter can improve acceleration, but it usually comes at the cost of some street manners.

Dan Ledbetter's '66 Chevelle featured last month is a perfect example of maximum launch rpm and power output. The 3,860-pound Chevelle relies on a 498ci Rat to pull off wheel-lifting 10-second passes. Ledbetter's 60-foot times started out in the 1.70s with a tight 2,300-rpm torque converter that caused the car to leave soft. After consulting with Randy's Transmission in Anaheim, California, Ledbetter switched to a Big 10-inch torque converter that allowed the Rat to stall closer to its peak torque and launch the car more quickly.

With a looser 3,250-stall converter in place, Ledbetter's heavy Chevy pulls the front wheels and runs 0.10-second-quicker 60-foot times and 0.25-second-quicker eighth-mile times. While he's happy with the new converter, he's working with Randy's Transmission to design something that offers less high-gear slippage in hopes of improving the Chevelle's top-end mph.

Gears to Go

Starting Price: $175 Plus Labor

Mechanical advantage is a wonderful thing when it comes to multiplying torque and horsepower. Once the torque converter and transmission enhance the engine's power output, it's up to the rear gears to multiply and distribute that power.

The rearend ratio affects all aspects of vehicle operation including high-gear cruising. In drag racing applications, it's best to gear the vehicle to keep the engine within its power band as much as possible. For a street car, the ideal gear for best engine life and mileage is at the other end of the ratio spectrum. Therefore, street gearing has to be some kind of compromise. The formula: (mph x rear gear ratio x 336) / tire diameter = rpm will often help you determine the best overall gear. Depending on the engine's torque curve, a drag race vehicle making peak engine power at 6,000 rpm might run best with a 4.10 and run approximately 115 mph on a 26-inch-tall tire--(115 x 4.10 x 336) / 26 = 6,093 rpm.

On a recent test-and-tune day at LACR, we ran our 305ci third-generation Camaro with 2.73 freeway flyer gears. The best quarter-mile time we could manage was a 16.29 at 86.59 mph. Since the goal was to break out of the 16s, we knew the Camaro needed more gear. Since the Camaro was equipped with an overdrive-Fourth-gear TH700-R4, we decided to install a set of 3.73 rearend gears to help the acceleration. The gear change rewarded us with a 0.47-second reduction in e.t. and a 0.15-mph gain. By optimizing our combination with a set of 3.73 gears, we gained almost half a second and broke into the 15-second zone. Isn't science fun?

Ground Gripping

Starting Price: Variable

There's much more to high-performance fun than just going fast in a straight line. There are miles of road that offer plenty of curves, twists, and bends. It's roads like these that are the reason Pro Touring cars were created. A vehicle's suspension and tuning can be quite complex, but if you choose the correct combination of parts and install them properly, you can't go wrong. One of the easiest handling upgrades is to purchase a set of wide tires and wheels. The more rubber you put on the ground, the better your ride will grip the pavement.

Once you've installed the biggest meats you can fit under your ride, it's imperative to check out the existing suspension components. Worn steering boxes or loose tie-rod ends and ball joints can cost you a lot of corner-carving potential. Once you've rebuilt that front end and tightened everything up, a properly sized front and/or rear sway bar can help control body roll, as can stiffer bushings, tuned shocks, and stiffer springs. Lowering the center of gravity and controlling it with quality shocks will provide your ride with improved control around the corners.

Several years ago we got our hands on a '91 Camaro with a healthy dose of street power. The first time we looked under the car it became clear why the 88,000-mile Camaro wouldn't turn to save its life. Its suspension was worn beyond belief. Because we wanted to test the Camaro's untouched factory suspension performance, we ran it on a skid pad and through a slalom course. The loose suspension times managed a reasonable 0.88 g on the pad result and 61.7 mph through the slalom course. After the Camaro returned to the shop, we decided to give the suspension an entire Chevy High makeover. All the bushings were replaced with Moog performance pieces. A larger factory Z28 17/16-inch sway bar went on the front, and a Hotchkis 0.904-inch bar went on the rear. We also added a set of Hotchkis subframe connectors and lowering springs to lower and stiffen the chassis. An AGR steering box improved the steering ratio with a 12:1 setup. Before we hit the track, we bolted on a set of 5.5-inch back-spaced 17x9.5-inch Center Line wheels mounted with P275/40R17 BFG tires. Our new Camaro knocked out a killer 0.95-g skidpad result and 66.9 mph slalom speed. To put those numbers into perspective, Motor Trend tested a '99 Corvette on the skidpad pulling 0.91 g and running 61.0 mph on the slalom course. Needless to say, our F-body adventure was an unqualified success.

Diet Days

Starting Price: Free

They say you can't be too skinny or too rich. That's also true with performance cars. Weight plays a crucial role in all aspects of vehicle performance. Lighten your car and the suspension and engine don't have to work as hard to get the job done. The ultimate example of power-per-pound performance can be seen on a motorcycle. Many of today's production street bikes weigh roughly 600 pounds and sport nearly 150 hp, that's (600 pounds/150 hp = 4 pounds/hp).

A typical street car weighs approximately 3,500 pounds and is lucky to have 400 hp. As you can see (3,500 pounds/400 hp = 8.75 pounds/hp), the typical street machine is lucky to come up at over twice the weight per power. This drastically affects a vehicle's acceleration rate.

Since losing weight is the equivalent of free power, we decided to put our project car "Moby" on a diet and see just how much weight the whale could drop. For example, Unlimited Products supplied us with a fiberglass hood that shaved 38 pounds off the factory-steel piece. If you believe in the drag racer rule-of-thumb that every 100 pounds is worth a tenth in the quarter-mile, then it doesn't take much to see that if you can shave 200 pounds off the weight of a 3,600-pound Chevelle, you'll be making that quarter-mile trip much quicker and those passes won't be quite so tough on the drivetrain parts.