Can blueprinting old fuel injectors really increase performance?

[Editor's Note: This article originally appeared in the December 2017 issue of Grassroots Motorsports.]

The first thing we do whenever we pick up an older car is go through the fuel system. So when we dove into a 1985 Toyota MR2 that recently fell into our laps, we started by shipping the fuel injectors out to noted EFI specialist RC Fuel Injection, Inc. in Torrance, California. 

Photography Credit: Tom Suddard

The work on our injectors was done by brothers Wayne and Keoki San Miguel, who were trained by RC’s founder, fuel injection whiz Russ Collins. They have been with the company for 25 and 19 years, respectively. 

The first step in the process is to visually inspect the injectors and check the electrical side of the equation for resistance. Depending on the injector type, the proper ranges are 2-4 Ohms (for our peak-and-hold injectors) or 12-16 Ohms (for high impedance “saturated” injectors). 

Next, the injectors are disassembled and subjected to pressure and flow analysis. As it turned out, one of our MR2’s four injectors was a “dribbler” that leaked fuel under pressure. This condition causes poor running since raw fuel enters the intake system before its time. The subsequent flow test revealed that three of our injectors flowed in the normal low-200cc range, while the dribbler put 468cc into the chamber due to a broken needle valve. Luckily, a replacement spare was available.

The road to recovery started with an external cleaning, which included both wire brushing and media blasting. Then came the important part: internal cleaning. RC relies on both pressure flushing and ultrasound to do this. The injectors are placed into a special cleaning solution that’s heated and repeatedly pulsed. This phase can take up to five hours, depending on how grungy the injectors were to start.

Next was a retest of the clean injectors. This time around all four flowed 205cc at 43.5 psi, which was within specs. (The acceptable minimum is plus or minus 2 percent.) 

Final touches include clear-coating the injector body or painting it black, then adding the familiar RC sticker. Budget about $25 per injector for this kind of spa treatment. 

According to RC’s Keith Pollastrini, who has handled the fuel system machining for more than 30 years, even moderately modified engines can work well with a balanced set of stock-flow injectors, since the pulse length can be increased to some degree to compensate for any new fuel requirements. For serious modifications and power-adders, the company offers a vast assortment of high-flow injectors providing outputs all the way up to 2400cc.

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