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Blueprint for Success

Making a Factory TBI System the Best It Can Be

John Nelson Nov 6, 2003
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What's the most basic performance modification of all? A new set of sticky tires and big wheels? A high-flow air filter and a cat-back? A bunch of stickers and a big wing? (Just kidding.) The first two are good places to start, but we'd like to suggest that the most basic performance mod of all is blueprinting--in other words, making sure that a vehicle's factory systems are in perfect working order. What's the point of installing that high-flow cat-back if our intake system isn't up to snuff? With this goal in mind, we yanked a factory TBI assembly off a '92 Camaro and took it to Jet Performance Products to see what could be done to put this oft-maligned injection system into something resembling fighting shape.

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This kit comes complete with replacement gaskets, O-rings, bushings, injector filters, and a new fuel-pressure regulator diaphragm, all of which will be installed during the blueprinting process.

Chevrolet instituted throttle-body injection systems in the '80s and continued to make use of them (most notably on trucks) into the '90s. This injector setup is usually not the first choice of performance enthusiasts, but many Chevys still run the TBI system they came equipped with. Some find it too costly to swap the stock injectors and manifold out, some don't want to modify their vehicle to that extent, and still others are stuck with their stock system through state mandate.

That's where blueprinting comes in. It's more than a tune-up or a rebuild. The point of blueprinting is to optimize a system's operation, to make it work as perfectly as possible--better than new, if you will. A fresh-off-the-assembly-line system is good, but it's still the result of mass production. That's why the couple hours of attention that Jet gives to each TBI unit it sees results in improved performance.

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The fuel-line fittings must be removed before the injector housing can be separated from the throttle body...

Not that Jet markets its TBI blueprinting service as a performance enhancer in the "more power" sense. The company doesn't enlarge the throttle-body bores or install bigger nozzles. The goal is to make the system the best it can be. Each unit is completely disassembled, and all components thoroughly cleaned. All gaskets, filters, and diaphragms are replaced, and the injectors themselves are ultrasonically cleaned. This in itself would improve the performance of a well-worn unit, but Jet also reinstalls the throttle shaft with bronze bushings to guard against air leaks, flow-matches the injectors, and can install an adjustable fuel-pressure regulator if desired (a must if further engine mods are to follow).

With our newly blueprinted TBI system replaced atop our subject Camaro's anemic 305, we found that we did indeed have improved performance. Maybe not in the power area; we didn't run before-and-after dyno tests. But the car's owner reports that, without fine-tuning the fuel pressure, he had a silky smooth, is-it-running-or-not idle, much better throttle response, and even improved gas mileage (23 versus 20 mpg). And with better throttle response, he now feels like he's getting the most out of what power the Camaro is making. We now have a much better performing vehicle--and one that will respond even better to future modifications.


JET Performance Products
Huntington Beach , CA

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