Impala Breathing Exercise

Aerobics for Your Impala SS

Mike Petralia Jul 6, 1998 0 Comment(s)

Step By Step

Late-model computer-controlled cars are not untouchable and can be modified to make some real power with very easy modifications.

Airflow is the key to power, and K&N is the airflow expert. K&N bolted its Generation II fuel-injection kit (PN 57-3011) to our Impala SS and ran it on its Dynojet chassis dynamometer.

You can just make out the small K&N PCV filter hidden behind the big 360-degree open-element air filter mounted in K&N's cold-air chamber behind the driver-side headlamp assembly. This aluminum box is an easy bolt-in requiring only one extra hole to be drilled for a mounting bracket. Note how the driver-side header snakes up and around.

Engine dynos are great for finding out how much power the engine makes, but the real power is at the rear wheels. The chassis dyno measures actual power that gets to the ground.

This is a close-up of the passenger-side Edelbrock header. It's a tight fit, but all stock components re-main in place. Note how the No. 2 cylinder tube kicks up and over the Nos. 4 and 6 tubes.

This is the super-tuning tool of the 21st century. The Hypertech Power Programmer enables your car's computer to take advantage of the engine's newly discovered VE when bolt-ons are added to build maximum power.

An engine is just an air pump, so what would you think is the easiest way to get more power out of it? If you say pump more air into it, you'd only be half right. What if we told you that we knew of a way you could plug in a few new parts to your Impala SS and increase rear-wheel power by as much as 18 percent? You say you've tried the simple bolt-on thing, using parts guaranteed to increase the airflow into and out of your engine, and it didn't make your car feel any faster. And to make matters worse, you took your car to the track and it actually slowed down!

With today's computer-controlled engines, simply pumping more air in and out may not be the only answer. Bolting on better breathing components and increasing the engine's volumetric efficiency (VE) is one thing, but the computer now needs to be told that the new parts have been added. It needs to be told how to take advantage of these new parts and create more power with them. To make power, all that newly ingested air needs to be put to work burning more fuel. The computer needs to be told to inject more fuel into the engine. Often this also changes the ignition timing. The factory computer's programming doesn't understand the new signals it's receiving from the engine's sensors and cannot compensate correctly, so the engine runs the same or makes even less power than before, and you feel as if you've thrown money out the window.

When developing and testing new products, a manufacturer will use equipment such as a chassis dyno to test what effect the new product has on performance. Having the ability to bolt on a new part and then immediately test it can be a real sanity saver. That's what the folks at Edelbrock, K&N, and Hypertech do when they develop products for your car. They will also sometimes run the car down the quarter-mile and around town.

Chevrolet and GM have some of the most sophisticated testing equipment in the world, and it shows in the engines they are producing today. The Chevy LT1 engine was designed from the factory to breathe easily, and it is capable of making over 300 hp in stock trim. But the LT1 was sometimes dropped into vehicles that compromised its true performance. The late-model Impala SS is one of those vehicles. Both the inlet and exhaust systems on these factory hot rods leave much to be desired.

New Air

K&N has developed a new air-intake system for the Impala SS called the Generation II fuel-injection kit. It replaces the factory air resonator chamber with a large, straight through-design plastic tube and the factory filter box with a new cold-air chamber. The K&N open-element, 360-degree air and PCV filters are located within this cold-air chamber, directly behind the driver-side headlight where they ingest cool air. K&N designed this system as a bolt-on to increase power in stock vehicles with little or no aftermarket modifications.

We tested the K&N kit on a 1996 Impala SS on K&N’s Dynojet chassis dynamometer to see what kind of rear-wheel horsepower it would make. In stock form, the Impala churned out a corrected 211 hp at 4,500 rpm and 262 lb-ft of torque at 3,400 rpm at the rear wheels. With baseline power established, K&N bolted on its new kit and reran it on the chassis dyno. With its newfound breathing ability, power jumped to a corrected 232 hp at 4,700 rpm with and 290 lb-ft of torque at 3,300 rpm. Not only did overall torque output increase by 28 lb-ft, but the torque peak moved down 100 rpm, making more usable torque where it’s needed most. And best of all, there was no sacrifice in power over the entire rpm band.

New Exhaust

Now that we knew the Impala liked having its sinuses opened up, we felt the next logical modification would be a new exhaust system to get all that air out. Edelbrock stepped up with its Tubular Exhaust System Headers, mufflers, and after-cat exhaust. We liked the thought of the high-flow exhaust, and the sound of that deep V-8 rumble made our skin tingle. Edelbrock swapped in its new exhaust system, and the Impala was shuffled back to K&N for repeat testing. Although the Impala did end up making more power and torque in the upper rpm range than with just the K&N kit installed, it was not as much as expected. In fact, the torque peak was again up to 3,800 rpm making 284 lb-ft, horsepower only increased by 10 to 239, and the horsepower peak was up at 4,600 rpm. The engine actually lost power at 3,300 rpm (its previous torque peak). Something was not right.

Super Tuning

That's when Hypertech stepped in. Hypertech has developed its Power Programmer, a handheld computer reprogrammer that actually reads your vehicle's existing program and changes the parameters you specify after you've made modifications. You simply plug it into the vehicle's computer and it automatically downloads all the factory settings, saving them for future reference. The Power Programmer then prompts you to enter the modifications you've made to your vehicle, and it reprograms the vehicle's computer accordingly. Let's say you've done as we have and bolted on a new intake and exhaust system and then you plug in the Power Programmer and input your modifications. The programmer contains standard performance programming, which Hypertech has determined will work with the modifications you made and enhance the performance of the parts you've added on. The Power Programmer can be used to supertune the vehicle's spark timing, air/fuel ratio, transmission shift points, and shift firmness, and it can even change the cycling temperature of the electric engine cooling fan to offset a new low-temperature thermostat. It can also correct the speedo, odometer, ABS, and transmission shifting after you've installed a new rearend gearset or a different-size rear tire. The Power Programmer even allows you to change the engine rev limit set by the manufacturer and will allow you to reprogram the vehicle's built-in speed limiter should you put on a set of high speed-rated tires. Best of all, if needed, the programmer can switch all settings back to stock in minutes.

Hypertech dialed in a new fuel and spark curve and downloaded it into the Impala SS computer. The Impala went back on the dyno, and with Hypertech's Power Tuning it was able to crank out 306 lb-ft of torque at as low as 3,100 rpm. It also bumped horsepower up to 250 at 4,600 rpm. The Hypertech Power Programmer enabled the Edelbrock exhaust and K&N filter kit to perform to their full potential. All together it was worth a total increase of 39 hp and 44 lb-ft of torque over stock. That's roughly an 18 percent increase--all with simple bolt-ons. These are the kind of bolt-ons everyone can love since the Power Programmer, the Generation II fuel-injection kit, and the Edelbrock exhaust system are all CARB-exempt.

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