Project Toyota SR-5: Part 1

giving new life to a tired friend

Don Weberg
Nov 8, 2002
There must be more than 100 reasons for getting rid of a 10-year-old truck with over 100,000 miles the clock. There are, however, strong arguments for keeping such a truck; namely, it's paid for and it still looks fine.
Our '92 Toyota SR-5 4x4 pickup appeared in excellent condition: the red paint just barely faded, the interior mint and stock right down to the stereo. The only obvious problems were a broken cupholder, an extremely worn driver floormat, and a chip on the hood. We contacted Downey Off-Road for an opinion.
Photo 2/7   |   Toyota rated the 3.0L V-6 at 150 hp. Awkward, lanky, and out of date, the stock airbox (lower left) didn't do wonders to help the truck breathe.
"The first thing I would do," Jim Sickles, president of Downey Off-Road, told us, "is have a compression check to ensure that it's a truck worth sinking some money into."
The advice was taken, and a stop at a local mechanic proved that compression was fine.
Our Toyota wasn't the quickest gun on the block; box stock, the truck struggled 0-60 mph in 13.3 sec. Basically, it was ready to race Yugos. With that information, we turned to K&N Engineering in Riverside, California, to find out what kind of power was being made at the wheels. K&N technician Kirk Swanson put it on the dynamometer and found that of the 150 ponies, only 117 made it to the pavement. That said, he replaced the massive (and dated) stock airbox with a K&N Fuel Injection Performance Kit.
Photo 3/7   |   The Downey Off-Road exhaust system sports a header that's larger, louder, and easier to look at than Toyota's original manifold. Toyotaphiles will recall the anemic exhaust notes from the stock SR-5. The Downey Off-Road system took care of that.
Computer-controlled vehicles are funny things. Although the Toyota was now louder underhood, in fact, the dyno showed it actually lost power and dipped to 112 hp.
"After some mileage," said Swanson, "the computer will learn that more air is being forced into the induction system. Once that happens, the timing will adjust, and the power should go up."
With that in mind, we put an additional 1000 miles on the Toyota and paid the dyno another visit. The numbers went up from stock by one, and 118 hp showed up at the wheels. Although the numbers were not impressive, the new 0-60 time was. The FIPK clipped a little off the clock, and the truck turned in a time of 13.0 sec. Not bad for a half-hour job.
Photo 4/7   |   At 100,000 miles, most catalytic converters have served their time, clogged with carbon debris- the Toyota cat was no different. The complete Downey Off-Road exhaust system provided a new one that alone improved the flow due to its cleanliness.
As with every upgrade, others inevitably follow. We turned to Downey Off-Road in Santa Fe Springs for a complete Downey exhaust system, which included headers, catalytic converter, Magnaflow mufflers, all the piping hardware, and the all-important CARB certification sticker to pass emissions. We went to Keith Pollastrini of K&K Auto Care in Torrance for the installation.
At one point, K&K master mechanic Robert Kawamoto had to remove the entire front transaxle to take off the stock manifolds. According to Pollastrini, the work was not as easy as the directions claimed.
Photo 5/7   |   RC Engineering completes injection balancing by putting each fuel injector in an ultrasonic dipping pan to ensure maximum cleanliness after a cleansing agent is sprayed through the jets. After balancing, the Denso fuel injectors passed 189.0 and 190.0 cc of fuel per minute.
"It's really not a job for someone in his backyard," he said.
Pollastrini also noted the installation required one of the tubes be cut into three pieces to make room for the catalytic converter. After a brief drive, it became obvious the tailpipe was being pinched between the leaf-spring and frame. Although Pollastrini said it didn't hurt the system, it made for some strange noises going over bumps and through dips. The problem was cured with a quick stop at a local muffler shop, where a new tube was bent.
Despite the work required to install the system, it was well worth it. Coupled with the K&N FIPK, the truck now sounded like a hungry predator.
Photo 6/7   |   While K&K Auto Care proved the exhaust swap no easy business, it also yanked the original Denso fuel injectors for balancing.
With mileage rapidly climbing on the truck (107,001 at this point), it wasn't a bad idea to have the fuel injectors checked. K&K pulled out the original Denso injectors and sent them to Russ Collins of RC Engineering in Torrance for balancing--a full working inspection of each individual injector by placing them in a clear cylinder one at a time, forcing fuel through them, and not only observing what they're doing, but monitoring them electronically to find out how much fuel is passed through each jet at a given moment.
"It helps in various ways, such as cold-starting behavior and passing the emissions," said Collins.
RC tech John Park was impressed with the condition of the SR-5's injectors because of the consistent 187.0 cc per minute that flowed through. This, he said, is good considering the high miles. Two of the six injectors were varied, though, passing 189.0. According to the technicians, detergent-added high-octane-fuel is a reason for the cleanliness of these injectors.
Photo 7/7   |   Installed in about 30 min, the 50-state-legal K&N FIPK unit not only brought more power to the Toyota, but the 360*-intake design added a modern, racy look underhood.
After the inspection, a cleaning agent was sprayed through, the injectors were placed in a dipping pan and cleaned ultrasonically. The dirty 187.0/189.0 readings were acceptable, but after the cleaning, three of the injectors read 190.0, while the others read 189.0.
With the Downey exhaust in place and corrected, fuel injectors balanced, and the FIPK bringing in cold air, it was back to the K&N dyno for testing. The new exhaust helped create a best dyno number of 121 hp. Although the numbers seem low and relatively unexciting, it's more about the seat-of-the-pants joy created by the underhood additions.
New 0-60-mph runs clicked at 12.8 sec, not bad, in view of the original run of 13.3. It was never meant to be a Ferrari fighter. If that were the case, V-8 power would better suit the job, not to mention a two-wheel-drive application. The point lies in the fun factor, turning an all-too-familiar friend into something more enjoyable without breaking the bank. Fuel economy also has improved.
In stock guise, the little 4x4 ran an average of 15 mpg. The K&N increased it to 15.9, and when the balanced injectors and Downey system joined the FIPK, it achieved a 16.3-mpg average.
A basic setup that could've been taken to the max with the addition of a TRD supercharger, performance chip, cams, heads, and so on, but in the interest of keeping the project basic, inexpensive, and maintaining the daily-driver reliability and friendliness meant this was all the work necessary. The next step will be addressing the appearance of the old Toyota, turning to Performance Products, KMC Wheels, Toyo Tires, and Explorer Pro Comp for interior and exterior goodies in Part 2.
K&N Fuel Injection
Performance Kit (FIPK)$314.02
Downey Off-Road Exhaust System
 cat and pipes$295.00
K&K Auto Care Service
 E.F.I. R&R$195.00
 exhaust swap$700.00
RC Engineering
 per injector cost$24



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