More Power & mileage?
Q I have big tires, low gears, lockers, and a towstrap in my (any make and model of 4x4 here), and now it is slow and gets bad mileage. What can I do to get all that power and economy back?
A Some things are just not possible. Big tires, big fuel economy, and big power are three things that do not like to live happily together, but there is hope.
Big tires are heavier tires and thus have a greater resistance to rolling. Their larger front face reduces aerodynamics too. The requirements to fit big tires often also reduce aerodynamics, in turn reducing mileage. Plus, it saps big power to start turning and continue turning big tires. With correct gearing you can usually get back to near-factory power feel, but it gets difficult as the tires grow. We have found that higher tire pressures can help in mileage numbers though.
The two simplest steps for power and mileage are “air in, air out”. The gasoline combustion engine likes to breathe. The easier it breathes, the better it works, the more efficient it is, and the more powerful it feels. Fresh, clean, cool air and easy-flowing exhaust will help with both steps. Superchargers and turbos can increase power also, but with additional costs to install and run higher-octane fuel.
Additionally, unlocking your front hubs, removing heavy tools and spare parts, and driving slower and less aggressively on-road can all improve mileage.
Reducing weight is also important for power. The less truck the engine needs to move, the more powerful it feels.
Engine swaps are a can of worms I’m not going to get into at this point, but here are some guidelines to consider before you start exploring engine swaps.
1. Just because you have the engine doesn’t mean it’s a good candidate for an engine swap.
2. The Rule of 2: Swapping in a new engine always costs twice as much, takes twice as long, and requires twice the radiator to cool it.
3. Just because a foreign engine runs well doesn’t mean it is right for an American-made 4x4. Yes, it has been done. Yes, they run great. But it’s just wrong.
4. A Jeep 4.0L is a great engine in whatever it came in, but not good enough to swap into something else (not even a four-cylinder Wrangler).
5. If the vehicle you are building is already available from a manufacturer, just sell your project and buy one. It’ll be cheaper. (This also goes for 2x4-to-4x4 swaps.) For example, see No. 4.
6. You will need custom exhaust to make it work and fit well under in the framerails.
7. Before you remove the old engine, take pictures and mark every wire and hose.
8. Don’t be scared of fuel injection if the engine you are swapping in has an aftermarket wiring harnesses available (for example, TBI GM, 5.0L Ford, LS series GM). But be afraid of trying to make a junkyard fuel-injected engine run with the original wiring harness.
9. Oil pans can cause problems with front axles. Driveshafts can cause problems with starters.
9. Swapping to a diesel engine will cost more than you will save by swapping to a diesel engine.
10. GM V-8 swaps are boring, but there is a reason everyone does it. The cool, unusual engine is also expensive to fix and keep running.
Vibration & Wobble?
Q I have been driving my lifted and locked (any make and model of 4x4 here) and wheeling it with my buddies. We’re having a great time. But now for some reason I am beginning to notice a weird vibration. Any idea what that is?
A Vibrations come in every shape and size when you start modifying a vehicle. The original equipment manufacturers (OEMs) spend millions of dollars to alleviate unwanted NVH (noise, vibration, and harmonics), and everything we do, from bigger tires to everything associated with getting them on and working, can add to unwanted NVH. Raising the vehicle can increase driveshaft angles, and this can cause driveshaft vibrations. Worn-out steering or gear-train components from adding larger tires can cause steering vibrations and possibly the notorious death-wobble. And larger tires themselves can cause issues if unbalanced or at low air pressure, or if they’re packed with mud in the wheels or lugs from your latest off-road excursion. There are fixes for almost everything, but the first step is diagnosis. Diagnosis is nearly impossible in the pages of a magazine, but here are some starting points.
Clean the truck well. This will remove mud and dirt, allowing for better investigation. Concentrate on the bottom side.
Air up the tires and look for missing wheel weights if the wheels were balanced. Also notice whether the tires seem to have spun on the rim, as can happen when they have been aired down for off-road use.
Check the driveshafts for loose connections, dents, or worn-out U-joints.
Have someone turn the steering back and forth while you watch the wheels. Is everything turning smoothly? Anything popping or not moving that should be?
Any leaks between gearboxes? That may be a sign that the bolts holding everything together are loose.
Any cracks around the steering box mounts, leaf spring mounts, shock mounts, body mounts, and link arm mounts along the frame?
Check steering knuckle joints and suspension joints for any slop.
The dreaded Duo of Questions: best & cheap
Q My buddy Freddy has a (any make and model of 4x4 here), and I really like it. I want to be able to keep up with him or, better yet, pass him on the trail and in the mud. I recently purchased a (any make and model of 4x4 here), and I want to lift it, lock it, put on big tires, and have more power. What is the best part for each? Also, how can I do this cheap because I am a (student, burger jockey, magazine writer) and have no money?
Freddy’s Friend Frank
A Though I test a lot of parts and see a lot of trucks and wheel (or hike while others wheel) a lot of trails, I still cannot tell you what the best parts are. I have not driven every vehicle, tested every lift kit, nor driven every tire over every terrain, though I’m working on doing just that. Hopefully, I won’t die first.
The best advice I can give you is to talk to guys with similar vehicles and ask them what they have used. Read reviews of parts and ask your local 4x4 shop owner. Discuss what you have learned and take everyone’s advice into consideration. Then go wheeling with your stock vehicle, learn to drive it the way Freddy did, and you’ll quickly find out what parts you need to upgrade from there.
As for how to do it cheaply, I’ll start by saying four-wheeling isn’t a cheap hobby. It can be done inexpensively and on a budget, but if you want a cheap hobby, try Frisbee. Watch classified ads for slightly used parts, build stuff yourself, and buy the best parts you can afford. Slowly but surely you’ll have a good truck. I always recommend buying American when possible, but that’s more a patriotic feeling than anything else, as I do number a Toyota amongst my other old battered 4x4s and it’s a pretty darn good truck.
Also stay in school, get a degree or three, study a little business, and work hard wherever you end up. If you become a doctor, spend your coin in the four-wheeling community instead of golf. If you’re a fabricator or 4x4 mechanic, build cool stuff. And don’t knock the new guy getting into the sport, as he may be a doctor with a lot of money who just wants to go four-wheeling.