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1989 Toyota 4Runner - Tundra Power!

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Kevin Blumer | Writer
Posted July 1, 2010

Steroids Under The Hood, Long Legs On The Ground

Most first-generation ('84-to-'89) Toyota 4Runners are easy to catch. Not this one. In place of the 3.0 (AKA 3-point-slow) V-6, you'll find a thoroughly modern 4.7L i-Force V-8 plucked from a donor Tundra.

Will Browne of Redondo Beach, California, has owned this 'Runner for a long time, having purchased it with only 40,000 miles on the clock. Browne is a Baja fan and infused his ride with a Total Chaos Caddy Kit to handle the rough roads and trails south of the border. After several years and multiple trips, some of the 4Runner's stock parts began to call it quits. "I was a few miles into a trail in Baja when I heard a big clunk," recalls Will. "It turned out that the stock torsion bar mount had torn off of the frame on one side. I had to drive out lopsided. I found out that's a common problem on these trucks if they're used hard."

Around the time the torsion bar mount ripped free of the frame, the 3.0 V-6 was showing ominous signs of things to come. "It needed a rebuild," Browne told us. "It was gonna cost around $3,000 for the rebuild, and I found a used Tundra V-8 for the same price. The stock engine was slow and the fuel economy wasn't all that great. The Tundra engine is way faster and gets about 15 mpg."

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Swapping an i-Force V-8 in place of a 3.0 isn't for everyone. Browne is a salesman, but has the hands of a professional mechanic and the mind of an engineer-attributes he called on again and again during the engine swap and the rest of the build in general.

What was tricky about the engine swap? First was fitment. The 4.7L is a big pill for the first-generation 'Runner's engine bay to swallow. Custom engine mounts had to be fabricated, and a custom radiator was also required. The firewall was given some love with a sledge. Underneath, the oil pan had to be cut and re-configured to clear the front differential.

Another tricky aspect of the engine swap is that the Tundra motor was originally connected to a computer-controlled automatic, and Will wanted to use his Marlin Crawler-built five-speed manual tranny. To mate the i-Force to the five-speed, Browne cut an inch off of the front of the stock bellhousing. He then contacted a machine shop to have an adapter plate made. The resulting adapter plate is an inch thick and bolts to the back of the V-8. Browne TIG welded the adapter plate to the stock bellhousing. The next task was fitting the stock flywheel to the back of the Tundra crankshaft. This was successfully accomplished by having the Tundra bolt pattern bored into the flywheel. Finally, the engine computer had to be dealt with. Remember, the Tundra ECU is still looking for signals from an electronically-controlled automatic. "There are four solenoids that control the automatic transmission," Will informed us. "My first plan was to get the solenoids by themselves and hook them up to the wiring harness. My dad, who is an electronics engineer, told me that I'd just need to get some resistors of the proper size instead." As soon as the resistors were soldered in place, the Tundra ECU couldn't tell the difference between the resistors and the stock automatic transmission. The engine runs cleanly, and the Check Engine light stays dark. The ultra-picky CARB gave its seal of approval to the engine swap. There's an official California Air Resources Board decal in the passenger's side door jam.

The drivetrain was good to go, but the suspension still needed to be addressed. Instead of living with the shortcomings of the torsion bars, Browne decided to eliminate them in favor of coilover shocks. Up front in place of the original Total Chaos Caddy Kit you'll now find a Total Chaos Gen II Caddy Kit, which uses coilover shocks. The 4Runner's tail section is suspended by a pair of Deaver leaf packs which run under a swapped-in Tacoma axle. To eliminate axle wrap, Browne designed and built a four-link system. Stomp on the skinny pedal as hard as you can. The axle won't wrap one bit.

There's more to tell, but we'll leave that for the photo captions. We'll just say that with Tundra power under the hood and long legs on the ground, this is one 4Runner that's hard to catch.

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