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Performance Pickup

Adding Affordable Power To Late-Model TBI Trucks

Bob Mehlhoff Apr 9, 2003
148_0307_tbi_lead_z 2/14


The stock TBI small-block Chevy is a great starting point for a performance buildup. The parts we selected from Edelbrock, K&N, March Performance, and Jet Performance Products installed in a weekend's time.

This is the Edelbrock RPM series Cat-Back system. The kit includes everything needed to install the system including the hangers and hardware.

The new Edelbrock system installed easily with common tools. All Edelbrock Cat-Back systems are stock replacement parts and street legal in all 50 states.

Edelbrock offers many versions of the Cat-Back kit for pickups depending on the exhaust exit and bed length. We opted for the rear-exit kit for a shortbed that positions two tailpipes neatly together on the right rear side. Because Patrick's truck has been outfitted with a custom roll pan that replaced the rear bumper, we removed a few inches of tail pipe to reduce the length. The exhaust kit took less than 90 minutes to install at Super Tuning Performance in Van Nuys, California, and the exhaust sounds aggressive.

The stock air cleaner...

...removed easily in just a few minutes.

The new K&N fuel-injection performance kit reduces intake restriction as it smoothes and straightens airflow. The larger amount of available air allows more usable power throughout the entire rpm range. These filters also meet California Air Resource Board (CARB) standards and are emissions legal, as are all the parts used on this truck.

To reduce accessory drag and dress up the engine compartment, we installed a full set of March Power and Amp series pulleys. The pulleys are CNC-machined to run perfectly true for precise alignment and long belt life and have a clearcoated polished finish to keep the show-quality shine.

Replacing the power-steering pulley required the use of a special puller to remove the existing stock pulley.

The Jet 6-Pak chip...

...carries CARB certification and installs easily into the factory computer.

The Jet Powertech 6-Pak chip comes with this locking control box that allows the system to be placed in one of several different performance settings. For the best performance gains, we selected setting No. 4. This position (Stage 2) requires a 180-degree thermostat and a minimum of 91-octane fuel. Other settings are Economy, Towing, Stage 1, a security mode, and Valet Parking.

Testing the pickup with all the upgrades installed, we added almost 20 additional horsepower to the rear wheels, but best of all, we increased the level of torque throughout most of the rpm range.

There's power hidden in your stock late-model Chevy pickup just waiting to be unlocked. Although that throttle-body injection (TBI) engine is disguised as just another pedestrian small-block Chevy, with a weekend's worth of wrenching and a few affordable parts, you can easily turn your truck from daily driver into a better performer.

Recently we decided to see just how easy it is to transform a stock '91 Chevy pickup into something with more performance. After all, just because it's your daily transportation doesn't mean it has to be boring. So with our buddy Patrick Peterson and his '91 Chevy shortbed pickup, we set out to see how many extra horses we could unleash with a weekend's work. We chose an after-cat exhaust system from Edelbrock, a K&N air-filter system, March pulleys, and some pieces from Jet Performance.

Before we laid a wrench on the truck we wanted to see just how much power the stock 350 produced. So we headed out to our friend Mark D'Anna's SuperFlow chassis dyno at Bottle Blown Racing in Camarillo, California. On the chassis dyno, Patrick's 350ci (5.7L) engine developed a respectable 164.5 hp at the rear wheels. Granted, this isn't bad for a stocker, but we felt we could find more power.

If you've been reading CHP for some time, you know that the key to more power is better breathing, so we decided to tackle the exhaust and air-cleaner systems first. We started with Edelbrock's RPM series Cat-Back system, which uses mandrel-bent stainless tubing for durability and increased flow, along with Edelbrock's muffler to make a little extra power. After removing the original exhaust system, the new Edelbrock kit easily bolted into place in about 90 minutes. We immediately felt the difference in power, and the truck now had a more authoritative sound.

Next we wanted to improve the flow of incoming air into the engine. The stock air-cleaner system on TBI pickup trucks sources the air intake from the passenger-side fenderwell and feeds it into the stock air-cleaner assembly.

To improve the airflow, we selected a K&N fuel-injection performance kit that uses a high-flow air-filter element and replaces the engine's stock air-cleaner intake tract with a low-restriction K&N filter assembly. The K&N element is also cleanable.

We decided to reduce accessory drag and dress up the engine compartment at the same time with a set of March Power and Amp series billet pulleys. The kit installed easily and the only problem we encountered was removing the factory pressed-on power-steering-pump pulley. To remove the pulley, we purchased a power-steering-pulley remover for about $60. They are also available from most rental yards. Don't try removing the stock pulley with a hammer, since that will typically damage the power-steering pump.

To enhance the performance of our bolt-on improvements and provide the best on-board tuning possible, we contacted the folks at Jet Performance Products. In stock trim, the original computer chip manages the proper fuel and spark delivery, but with a high-flow exhaust system, better air intake, and low-drag pulleys, we wanted to optimize the engine tune. We installed one of Jet's Powertech 6-Pak chips, which allows one of six different settings that range from Economy to Stage 2 (the maximum performance selection requires 91-octane fuel). Finally, we installed a Jet Low-Temp thermostat and an adjustable fuel-pressure regulator.

We eagerly wanted to see how much more power the truck produced with all the new performance parts installed. The seat-of-the-pants performance definitely increased, but we wanted hard data. So we traveled back out to the dyno at Bottle Blown Racing. With the truck on the SuperFlow dyno, we watched as the numbers came in. At the peak, we added almost 20 hp to the rear wheels, but better than that, we had increased the overall torque curve throughout most of the rpm range by 5 to 15 lb-ft. So with a weekend's worth of work and some affordable parts, Patrick's truck now runs better, sounds stronger, and has improved its underhood image. This daily driver is now exciting and fun to drive.


K&N Engineering
Riverside, CA 92507
March Performance
Naples, FL 34110
JET Performance Products
Huntington Beach , CA
Bottle Blown Racing
Camarillo, CA 93010
Super Tuning Performance (STP)
Van Nuys, CA 91411

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