Project "Steal-J" - 1997 Jeep Wrangler TJ - Part 3Posted in Project Vehicles on July 21, 2006
In the last Steal-J installment we upgraded the interior and made it much more livable for longer drives. Now we'll turn our attention to what needs doing under the hood.
For the most part, we were happy with the power of the stock 4.0L. While a header and exhaust are popular upgrades -- unless your manifold is already cracked and you're looking for a more aggressive sound -- the stock exhaust system isn't all that restrictive and delivers a nice, quiet ride.
We had been eyeballing Edge Product's Trail Jammer performance kit for the 4.0L Jeep engine since it was introduced. We liked the fact that it uncorks the restrictive stock air intake and throttle body and includes a completely plug-in electronic control module that increases fuel delivery to better support the increased air supply.
The Trail Jammer is modular, in that you can do just the intake, intake and throttle body, or the whole deal with the electronics. We installed the whole package, including the cold-air intake, 62mm throttle body, and electronic module. While we didn't have a chance to dyno the system, based on our seat-of-the-pants estimates we have no reason to doubt Edge's power gain claims of 20 hp and 26 lb-ft.
Our mileage also went from 15.5 mpg stock to 16.8 mpg with the full Edgepackage. Disconnecting the electronic module resulted in an average of 17.4 mpg, but we did notice a slight drop in power, so we run with the electronics hooked up.
Nearly all '87-up Wrangler radiators develop a slight coolant leak where the upper plastic tank is clamped to the brass radiator core. Ours had begun seeping enough to kill any dog or cat that wandered by looking for a sweet drink of antifreeze. As a permanent cure, we went with a Novak Conversions high-performance aluminum replacement radiator (PN CR5087). The unit is pretty close to a bolt-in deal and its high-efficiency 1.5-inch core should cool our 4.0L easily no matter what. Novak also offers a dual 1-inch core version, as well as conversion radiators for Chevy and AMC engines.
To ensure we'll never have a radiator-hose issue for the rest of this Jeep's life, we upgraded to BRX's high-quality silicone radiator hoses. We ordered PN TJ27-KIT, which got us an upper and lower radiator hose. BRX even has silicone heater hoses. The silicone hose is resistant to all underhood chemicals, has a much longer life, and can handle four times the pressure of a stock hose. The hose also comes with a lifetime guarantee.
Tune in next month when we'll be turning our attention to the exterior for better looks, protection, and recovery capabilities.