Tech Letter Of The Month
Four-Cylinder Fun
Question: I just bought an '00 Jeep TJ. I have the lift and everything else planned but I have the bottom-base stock model with the 2.5L 150ci engine. It runs great in First gear going mild off road, but out on the highway or uphill I start to lose power. I'm a Marine stationed at Camp Pendleton and there are hills I have to take to get anywhere. What can I do to get more power out of my Jeep without having to get a whole new engine?
Semper Fi.
Jack W., via 4wheeloffroad.comv
Answer: I think the Jeep four-cylinder is a great engine. I've ridden across the country in a YJ and an XJ with that engine, and have wheeled with it and think it's a tough little bugger. It gets respectable fuel mileage, which is important these days, and I personally like wheeling with an underdog engine. However, the Jeep 2.5 needs any help it can get with breathing in and out. Look into an intake like the Brute Force from AEM (310.484.2322, www.aempower.com), a header like those from Pace Setter (602.266.1964, www.pacesetterexhaust.com), and a free-flowing catalytic converter such as the Super High Flow from Random Technology (770.554.4242, www.randomtechnology.com). Unfortunately there aren't any high-flow cats that are California-legal for use due to their not being able to pass the visual inspection, though they will still pass the sniff test.
Now if the cat was positioned above a skidplate, we're not sure it would be visible anyways, but we wouldn't condone such behavior. Hopefully your Jeep is registered in your home state even though you're stationed in California and that isn't a problem where you're from. Adding an aftermarket after-cat exhaust will also help in the flow area, such as one from Doug Thorley (800.347.8664, www.dougthorleyheaders.com).
Another upgrade is bumping the axle gearing a bit lower. Your Jeep came with 4.10 gears, and tires any larger than stock require lower gears. We built a TJ a while back with 32-inch tires and 4.88 gears. Lower gearing helps your engine accelerate and pull hills, though going too low can cause the engine to rev too high when at high speeds.
With the current fuel issues going on, I think building performance four-cylinder vehicles are important to consider. Though they don't compare to big V-8 power, they do offer a great way to combine daily driving and weekend wheeling. To help in your buildup I'd like to send you a new front hard-core bumper from Fab Fours (866.469.9056 www.fabfours.com). These TJ bumpers will give your little Jeep a rugged look as well as help to protect it when off road. Designed to support a winch if you wish, this front bumper offers clearance for bigger tires as well as improved approach angles when off road. Plus there are two shackle mounts for recovery points should your little four-cylinder get you too deep. Good luck with your buildup, and thanks for your service to our country.
Lost In The Dark
Question: I have an '07 F-350 and I just recently bought a rack for it with sport light mounting brackets. I was thinking I could have some nice lights to see better when backing up or to work behind the truck at night. However, I have looked all over for some kind of flood lights or work lights. Would you know of anything besides foglights? I just want some squared lights that really flood the back area of the truck and are not huge.
Jack
via 4wheeloffroad.com
Answer: I have used some great lights from Warn (800.910.1122, www.warn.com), as well as IPF lights from ARB (800.910.1122, www.arbusa.com), and both offer square off-road driving lights that should work for you, plus IPF has a light and wiring kit to tie into the factory reverse lights. Also check out the new line of lights from Daystar (800.595.7659, www.daystarweb.com). The Daystar lights are all round, but there are smallish 5-inch versions. An unknown lighting company I really like is Hamsar Diversco (800.567.5483, www.hamsar.com), which offers a ton of automotive and heavy equipment lights, and should also have what you need.
Lost Between Limited and Locked
Question: I'm trying to decide between a Detroit Locker and a limited-slip diff for my '85 4Runner rear. Which one will work best off-road and still be safe on the road, in bad weather, on the freeway, and so on?
Do I have to trade on-road manners for off-roadability, or is there a happy medium? I don't want all the extra parts and problems of an ARB Air Locker, just a simple, strong, carefree unit that works well on and off the pavement.
Jim
via 4wheeloffroad.com
Answer: I have found that for better performance you need to spend a little extra time with preventive maintenance. For example, you don't want all the parts and problems of the ARB, but I have found that with careful installation, proper routing of the air lines, and correct wiring of the air compressor and solenoids, the ARBs are practically trouble-free. The same goes for a Detroit. While some folks claim the Detroit has odd street driving characteristics with it constantly locking and unlocking as it goes down the street, I have found that if you keep your tires close to the same air pressure all around then these tribulations nearly disappear. Even a limited slip requires a bit of maintenance such that many with clutches need special oil additives and eventually the clutch material wears out. One unusual limted slip is the Truetrac, which uses helical gears instead of clutches to perform and really offers more streetable, long-lasting qualities. If it were me, I would choose the Detroit or ARB over a limited slip any day, because with a little maintenance and careful installation you will have a better-performing off-road traction device with very livable on-road characteristics.