Gas Or Diesel? Ifs Or Solid Axle? Our Editors Tell You What Setups Works Best Or Not
As a rule, we try to avoid arguments. Hey, we're lovers, not fighters-it's our nature. Like Ferdinand the Bull of storybook lore, we'd rather spend our time outdoors smelling the roses than feuding-heck, isn't that why we go venturing into the backcountry in the first place?
But every now and then, while wheeling the trail, we overhear some smarty-pants remark about "inferior front suspension" or "that cruddy carb" that really gets our dander up, and Real Men that we are, we just gotta throw down the gauntlet (OK, the Mechanix gloves) and engage in a little playful 4x4 smacktalk. In the following pages we'll cover several points of contention-gas or diesel? carb or injection? leaf springs or coils?-that wheelers have debated 'round the campfire for years. We may not convince any true believers out there, but hopefully we'll provide you with some food for thought that'll help you out the next time you find yourself stuck in the middle of a good ol'-fashioned 4x4 Throwdown.
Gasoline: The Superior Fuel
Diesel has recently been touted as the great savior, especially now that its gritty reputation has been minimized and clean technologies such as low-sulfur fuels and exhaust after-treatments are coming on line, but is this enough to make diesel the better fuel to most wheelers? My argument is no, and that gasoline is still the superior fuel.
Why would I argue for gas? How about its greater availability, for one? The infrastructure for gasoline far exceeds that of diesel and if you've ever had the "low fuel" light on in a diesel truck as you anxiously look to refuel your oil-burner, you'll know how frustrating this can be. Gasoline engines also run smoother and quieter, and are much easier to start in cold weather. Gasoline also has the distinct advantage of engine braking and immediate throttle response, as opposed to the turbo lag and no engine braking afflicting most diesel engines. Speaking of turbos, aren't those expensive? You're damn right they are. Whatever happened to the advantage of a diesel being its simplicity? One look under the hood of a modern diesel truck and you will see this is no longer the case. Now saddled with specialized high-pressure fuel systems, turbos, intercoolers, particulate filters, and soon after-treatments of urea all bring the cost of the diesel option up even further, which means the cost benEFIt of a diesel over the lifetime of a vehicle now takes longer to see, especially when you consider diesel fuels higher price. As of this writing, regular 87 gas was $4.33 in our neighborhood, while diesel was a stunning $5.19-almost a full 20-percent more expensive.
This leads me in to my next point. Because diesel fuel holds more energy per gallon than gasoline, they typically get 20-percent better fuel economy than gas, but if the fuel itself is 20-percent more expensive, it appears to be a wash to me. Especially when you consider that clean diesels don't typically see the full 20-percent economy improvement that diesels enjoyed before the new emissions equipment was required. So now that we know diesels are more expensive to buy (don't be fooled by those who say diesels have a higher resale value, as they're more expensive than gas new, and this is reflected in the used market), more expensive to fuel, and did you know more expensive to service? That's right, a higher volume of pricey diesel-specific oil, fuel filters, and water separators all conspire to raise the price of service. Factor in 100,000-mile tune-ups and 7,500-mile-or-greater service intervals for gas engines and the deck appears to be stacked against diesel. Sure, diesels have superior durability, but if you aren't hauling at max load all the time and aren't planning on keeping your rig past the 200,000 miles that most modern gas engines are good for these days, do you really need to pay the premium for diesel?
The fact of the matter is, gasoline is still plentiful, relatively cheap, and can be found on any corner in America-not something you can say about diesel. Also, the historic simplicity and affordability that used to make diesel the attractive option is no longer the case. In conclusion, there is a reason why gas has been the fuel of choice for more than 100 years and if it's in my garage, I have got to go with gas.
-Sean P. Holman
Diesel: The Obvious Choice In terms of potential energy, diesel fuel contains approximately 30 percent more heat energy, measured in Btu, than gasoline. Diesel engines also produce more cylinder pressure than gasoline engines due to the length of the combustion process. See, diesels burn more like flame throwers, and gasoline engines burn more like bombs. More cylinder pressure = more torque, and more torque = more power from each gallon of fuel burned.
Also noteworthy is the actual process by which diesel fuel is rEFIned from crude oil. Not only is it less expensive, but it requires less time to develop batch quantities. Furthermore, diesel fuel is much safer to transport over the open road, thanks to its higher flash point.
The lubricity of diesel fuel offers added value by helping to protect moving parts like pumps and injectors. And nobody will argue the fact that diesel is the dominant transportation fuel used worldwide-subsequently, the distribution network is usually just minutes from any Interstate.
Yes, the cost of diesel is generally higher in today's turbulent economy. But let's face it-diesel engines are more robust while keeping electrical systems simpler, and they offer a longer life expectancy than gasoline engines. While I'll admit the modern diesel engine will cost you more up front-in many cases, a lot more-I also want to point out the fact that all the newly imposed "clean diesel" emissions regulations require new technologies, and the automotive industry is still in the technology learning curve at the present time, just like the late '70s when complex vacuum systems and smog pumps were being added to gasoline engines.
Injection is Perfection, Or Something Close to It
We'll grant the obvious: for your average home wrench, a carb is simpler to take apart and rebuild, and less costly to purchase and modify. But modern-day electronic fuel injection does the better job by far of providing the best balance of power, performance, and economy, and doing it predictably and efficiently. And contrary to popular belief, converting an older rig to EFI isn't all that daunting anymore; just about any Chevy V-8, for instance, can be converted to throttle-body or tuned-port injection using nothing more than off-the-shelf OE parts and an aftermarket wiring harness. If it's tunability you're looking for, EFI has that, too-there are plenty of programmable plug-in modules nowadays that can work in harmony with your EFI to recalibrate your torque curve to provide an extra boost. And if you really want to tailor your fuel delivery, there are companies out there that offer EFI controllers that use open-source software and which you can "build" to your own specs.
Another thing: because EFI systems use constant pressure instead of vacuum to deliver fuel to the cylinders, there are no worries about operating angles, or gravity affecting fuel flow. That's the one huge advantage EFI has for wheelers. Simply put, it'll run the same way, regardless of angle-whether your rig's on its side, or even upside down-as long as the engine's got oil pressure. No carbureted induction system can promise that. And more constant fuel delivery generally translates into better mileage for injected rigs, too.
And contrary to the old clich, you can indeed "fix" your EFI with very few tools other than a sim-ple screwdriver-just carry some spare injectors in your part's bin, and you can chuck all those myriad floats, springs, and jets out of the toolbox for good. Then enjoy your day on the trail, even if you make a mess of it and end up on your lid. Did we mention EFI runs just fine upside down?
Carbs: An Easy ChoiceIn every classic battle there are two passionate sides of the equation and sometimes one argument is seemingly the clear winner until you dig a little bit deeper. This is one of those times when a little information might be enough to sway your opinion.
Mechanical carburetors have been around for over a century and are tried and true, offering the ability for field repairs if necessary. Carbs are also cheaper to buy and repair and don't need to rely on an expensive computer to make decisions for it, and the aftermarket is filled with interesting options.
Carbs also give your rig a sense of character as it coughs and sputters in the cold mornings, on steep inclines, or at altitude. It's the smell of fuel in your garage and unburned hydrocarbons wafting through the air on a hot day that help to let you know you are alive.
Those intricacies aside, a carburetor is perfect for those who lack a knowledge of electronics, and are ideal for those who want to plumb in nitrous, but don't want to mess with tuning and ECU calibration. And for those of you who like to play in the mud, a carb isn't going to leave you stranded in the moisture and muck.
While you may want EFI on your daily driver, nothing is more rewarding than getting your carb working again out on the trail after it sputters to silence. Hey wasn't it just running 10 minutes ago? If you like challenges and character or are on a budget, a carburetor is for you.
-Sean P. Holman
Turbochargers are driven by exhaust gases as they exit the combustion chamber. As these gases are channeled away from the head, special ducting forces them through a turbine wheel, which is connected to a fan designed to compress intake air prior to the combustion chamber. So when you stop and think about it, turbochargers actually salvage energy that would otherwise go to waste.
The opposite is true for superchargers. A supercharger requires a mechanical connection to the engine crankshaft. Initially, this method creates drag on the engine-drag that must first be overcome to produce additional power. Once the drag is overcome, superchargers are limited by engine speed and drive pulley ratios. Turbochargers, on the other hand, are only limited by volumetric physics. In other words, the more exhaust gas you force through the hot side of a turbo, the faster it will spin, and the faster it spins, the more volume of compressed air it will produce.
Superchargers Blow Turbos Away
Superchargers and turbochargers are actually quite similar in that they are both forced-induction systems that compress air and force more air molecules into your engine's combustion chambers. The result is that by forcing the air into the cylinders, instead of relying on the air being sucked in naturally by the pumping action of the pistons, the engine can burn more fuel per power stroke. This means a significant increase in power. We're talking increases in the 30-percent-and-up range. Both the supercharger and turbocharger may both be forced-air-induction systems that generate the same result, but they accomplish that end in very different ways, and the supercharger rules.
A supercharger and turbocharger are similar in price, and depending on the amount of boost and the engine they're installed on, they are also comparable when it comes to the increase in power. The difference is in how that power is delivered. Superchargers typically deliver power smoothly because they are connected directly to the engine crankshaft via a pulley. Turbochargers are notorious for lag because they have to spool up before the boost is delivered to the engine. Bigger turbos have more lag than smaller turbos. The result can be a sudden hit of power, which may be big fun when you're showing off to your friends, but it can be hard on drivetrain components and a real pain in the neck when you're trying to carefully tow a trailer or power over an obstacle.
Another reason why the supercharger slaps down the turbo is reliability. The exhaust that drives the turbo is, as you can expect, very hot. This means the turbo itself gets very hot. This is why shutting off a turbocharged engine after hard use is a bad idea. The stored heat in the turbo can literally bake the oil around the bearings. This can cause extensive damage. Who wants to babysit a turbo and wait for it to cool down? Now, there are aftermarket companies that make electronic devices that monitor turbo temperature and keep the engine running until the turbo cools, but these add even more expense to the cost of the system.
Ultimately, the supercharger is the best. It has a broad powerband and because it has fewer components than a turbo, it is far easier to install.
Auto All The Way
If you break down the task of driving into the four specific categories, you get steering, accelerating and braking, selecting gears, and operating accessories like windshield wipers and blinker controls. If we subtract one of those jobs, we reduce driver effort by 25 percent. In other words, when you don't have to press a clutch pedal and choose a gear for a given scenario, you allow yourself more freedom to the remaining operations.
Sure, automatics are more complex on the inside, and they cost more than manuals, but when you stop and think about it, you get what you pay for. The added costs free up a foot and a hand, requiring less input and concentration. This saved effort can be spent sending text messages and applying make-up. Well, maybe not, but for hard-core trail rigs, this might allow freeing up hands and feet for engaging cutting brakes, selectable lockers, or rear steering on-the-fly.
Automatics aid drivers on difficult obstacles, too, thanks to torque-converter slippage, allowing the driver almost surgical precision of both forward and backward motion. Where lower gearing might have been necessary with a manual transmission, simply modulate the gas pedal and let the torque converter do the rest. Sure, you can't bump-start a vehicle equipped with an automatic if your starter fails, but how often does this issue actually arise? Another point where automatics are far superior is towing with a turbodiesel pickup. With a manual, each time you shift gears you lose the built-up turbo pressure and start out again at zero psi. This can cost you valuable speed when climbing steep hills. When it comes to performance, I'd take an automatic any day.
Man Up And Go Manual
Driving a manual transmission is a dying art, and as drivers get lazier, manufacturers offer us loyalists fewer manual choices. While it is true an automatic transmission can make wheeling easier, those who master the manual transmission are rewarded with superior vehicle control, more favorable low-range gearing compared to the same vehicle with an automatic, and a more satisfying driving experience.
Perhaps this certain satisfaction that comes from wheeling with a stick is from the increased skill required, the challenge, or maybe it is the feeling of being more in tune with the machinery. Have you ever tried to scale an obstacle in an automatic-equipped rig, only to be hard on the brakes on the downside to combat torque-converter surge? In a manual transmission, engine braking can take you over the top and return a smoother, more controlled descent. Other benEFIts of manual transmissions include better engine performance, less wear and tear on the braking system, and better fuel economy. A manual transmission can also get you unstuck by rocking between forward and reverse gears, something impossible or nearly so in an automatic-equipped rig. You also don't need to worry about remote transmission oil coolers with a manual, making for greater simplicity.
Lastly, and probably the best reason to run a manual: If you blow an automatic on the trail, your day is done, but chances are with a manual, you can find a gear that will get you off the trail-especially if water is often encountered. Ever try driving an automatic with water in it? It just doesn't work, although the same situation in a manual transmission won't leave you stranded. The point was never more clearly illustrated than at TTC 2006 when a vehicle on pace to set a Tank Trap record failed to complete the Tank Trap due to a water-logged transmission-if the vehicle was equipped with a stick it would have at least been able to finish.
-Sean P. Holman
Declaration Of Independents
We hold these truths to be self-evident, that all trucks are created equal...but some trucks are more equal than others. The kinds of trucks that can not only crawl through ruts and cycle over rocks, but also go fast in the desert and take us to the job site or school every day in comfort. A truck for all seasons, in other words, and for those of us who want the best combination of performance and manners in the dirt and on pavement, there's no beating independent suspension.
We'll grant you, lifting an IFS truck generally requires more time and expense than lifting an older solid-axle rig, and there are limits with an independent suspension on how high you can realistically go if you need any suspension movement. On the other hand, you don't really need to lift an IFS rig so much since one inherent virtue of its design is the way it relocates the front diff upward to increase ground clearance. To get the same benEFIt in a solid axle, you'd need to swap in Euro-style portals, which are not easy to find, and far from inexpensive. And IFS technology only continues to get better-witness the new generation of OE adjustable airbag and/or electrohydraulic setups such as those found on the newest Land Cruisers and Land Rovers, which can compensate for IFS's shortcomings in travel. And if you don't think these new technologies won't eventually trickle down to the average-guy aftermarket, just wait-20 years ago, they said the same thing about multilinks on monster trucks.
We'll also concede that some of the earliest "inferior" front suspension kits had reputations for poor reliability. But nowadays, quality aftermarket IFS setups feature aircraft-grade componentry machined out of CNC billet and other space-age goodies, so toughness is no longer an issue. That's why Baja racers have run independent setups for years, and there's no one else on the planet who's tougher on suspension parts than those guys.
Of course, if you need a vehicle with huuuuge flex (e.g., rock buggies), or you've simply got to have 49-inch tires with that 18-inch spring lift (old-school boggers on a budget), OK, a solid axle is really your only option. But for the other 90 percent of us who need our rigs to Do It All, and do it elegantly, an independent suspension is the way to go.
The future of new vehicles is all about IFS, which does have advantages over solid axles, such as lower unsprung weight, better ride, handling, and high-speed stability. However, when it comes to real wheeling, solid axles hold a superior position over IFS.
With a solid axle, you have the inherent benEFIt of constant traction in the design. As long as there is enough suspension travel to compensate for the terrain, a solid-axled vehicle is more likely to have all four wheels touching the ground because as one side is forced up by the terrain, the other is forced down in contact on the opposite side, unlike IFS which often hangs a wheel in the air, relying on traction control or a traction aid to keep the other wheel in contact with the ground moving.
Solid axles also keep more weight toward the bottom of a vehicle, for a lower center of gravity, helping keep the rig upright in extreme situations. They are stronger and more rugged, with cast-iron housings that can take trail abuse and handle lockers and shock loads better than the lightweight aluminum housings found in most IFS rigs. Solid axles also maintain the same ground clearance over obstacles, while IFS has variable ground clearance as the suspension goes through its cycle, raising and lowering the front subframe. And solid-axle setups often have stronger steering systems and aren't susceptible to extreme camber and toe changes under load and cycle as an IFS rig is.
Other advantages to a solid axle include a simpler design, with less moving parts that are easier to service without any subframes in the way. And when it comes to suspension modifications, such as lifts, it is far easier and more affordable to lift the solid-axled vehicle. Solid axles are also more cost effective and easier to beef up, whereas the IFS strength is built in to the design and is not easily upgradeable. The bottom line is that solid axles are affordable and plentiful, and there just isn't an affordable IFS system that will match the strength and reliability of a comparable solid axle.
While it is true that IFS has its place and can be designed to work quite well, you don't often hear of IFS swaps. I rest my case.
-Sean P. Holman
Sprung On Coils, And Proud Of It
Take a look around. The auto industry has already graduated from the high-friction horse-and-buggy technology of yesteryear. Abandoned for good reason, leaf-pack technology has almost completely disappeared in favor of the compact, precise, and better-riding coil spring of today. We dare you to find a new car that still has leaf springs under it from the factory. The pickings are slim if any. Sure, you will still find them in the back of trusty pickup trucks, but even those are a dying breed as demonstrated by the new configuration on the rear of the '09 Dodge Ram 1/2-ton pickup shown here.
The reason for this shift in technology is obvious. Coils weigh less. When it comes to new vehicle production, weight savings is a top priority. Coils are also now much simpler to manufacture than leaf springs, and they require less raw material to start with. The basic nature of a coil-sprung link-type suspension also eliminates that dreaded axlewrap. Just compare a Jeep YJ to the newer TJ or JK; coils have a lot to do with the Wrangler's improved performance.
The basic function of springs in a suspension system is to change mechanical motion into heat energy, and our centuries-old leaf-spring technology does that very well. However, when you consider the weight and the intense friction created by multiple layers of metal rubbing against each other as a leaf spring flexes, you have to wonder why this method is still in use today. Another place where coils have been proven over and over is in desert racing; when was the last time you noticed a set of leaf springs under a Trophy Truck? Bound for success, coils are the new gold standard.
Leaf Springs: Simple, Functional
The leaf spring has been the standard for suspension systems since the dawn of the automobile, and the mighty leaf isn't going anywhere anytime soon. Coil springs may be less expensive to produce when compared to a leaf spring, but that savings is offset by the fact that a coil-spring setup requires links to locate the axle. These links add cost and weight and require a fair amount of configuring and subsequent testing to work correctly. If they're not installed correctly, they can actually limit the steering radius because the tire will come in contact with links. The leaf spring, in all its glory, doesn't require any links because the spring locates the axle by itself. That's simplicity, and simplicity is good.
Another benefit to leaf springs is their strength and stability. If you drive a trail toy this probably is of no concern to you, but if you're a workin' Joe who uses his truck to tow and haul, it is of utmost importance. Look, there's a reason why 3/4- and 1-ton pickups don't have a coil-spring rear suspension. Leaf springs are stronger than a coil spring, they have more load-carrying capacity, and they also help reduce sway.
While we're on the subject of capacity, let's talk about ride quality because the misconception is that leaf springs can't offer a high capacity while providing a smooth ride. Hogwash. Clearly, the balance between the two is a tradeoff in any spring design, but a custom leaf-spring manufacturer can work with you to make springs for your rig that achieve an acceptable balance.
Let's talk wheel travel. Sure, we've all seen coil-sprung rigs that have incredible wheel travel. What did it take to get that? Well, it probably took gobs of time-consuming engineering, custom long-arm links that required relocation or custom fabbing of the link mounts, and expensive spherical rod ends or some kind of high-falutin' flexy joint. Sure, it probably impresses the heck out of their friends, and it's way prettier than a simple leaf-spring pack, but it takes lots more time and money. With the leaf spring, you don't have to deal with any of that. We've seen gut-wrenchingly simple leaf-spring setups that offer crazy axle flex. Bottom line: They're not perfect, but leaf springs offer a variety of benEFIts in a simple, cost-effective package.
Lift Kit: Mandatory Dirt Mod
Most of the suspension systems found under four-wheel-drive vehicles are designed to be a compromise between streetability and off-roadability with a slant toward on-road driving. Engineers know that keeping a vehicle low in the front can help increase fuel mileage by cutting down on aerodynamic drag. Keeping vehicles low also means a lower step-in height for passengers. Then there are the corporate lawyers who are paid to keep the manufacturers out of court and seem to be obsessed with analyzing ride height in respect to rollover potential. All these things work against us off-highway junkies to create SUVs and pickups that are good on-road but fall short in the dirt. Thank goodness for lift kits.
On a rig with solid axles, a suspension lift is generally quite simple to install. The beauty is that not only will you gain improvements in approach, departure, and rampover angles, you'll also be able to fit larger-diameter tires. The larger tires will improve the clearance between the axles and the ground, which will improve your minimum ground clearance numbers. The larger tires will also help create even better approach, departure, and rampover angles. The benEFIts of all these things will become crystal clear the first time you hit the trail and whiz by the unlifted rig that's stuck on an obstacle due to poor ground clearance. On IFS rigs, or rigs with IFS/IRS, the installation is a bit more complicated, but you'll get the same benEFIts.
Detractors of lift kits will argue that the increased driveshaft angles and/or CV axle angles will put stress on these components, which may cause them to fail prematurely. Not to worry. Lift kit manufacturers address these issues by including spacers and other components to correct issues like these. Heck, the last thing the suspension manufacturers want is a bunch of phone calls from angry truck owners with broken rigs. Detractors may also argue that the truck becomes too tall to easily enter and exit. Those people should get nerf bars, electric steps, or a Corolla. Some will argue that the cost of the lift and the installation isn't worth it. Those people must not wheel much. Anyone who has spent time on the trail knows that an unlifted rig has a far greater probability of suffering underbody damage than a lifted rig. Even a couple of inches of ground clearance can make the difference between making it down the trail or over the snowbank.
Low + Long-Travel = The Logical Lift That Isn't
Dude, what's a snowbank? OK, in the argument for "no lift," I give you Exhibits A and B: The Jeep Wrangler JK and the Hummer H3, both superb off-pavement performers that'll go just about anywhere a modifed rig will-and most likely, some places the non-stocker won't, depending on its height and girth. Heck, we've driven unlifted TJs and YJs over the Rubicon, needing nothing more than a tow strap, skidplates, and rock rails to keep going. It's a simple formula: Stock Jeep + skilled driver = case closed.
Unless, of course, it isn't. For the rest of us who aren't buying a new Hummer or JK, we'll cheat a bit here and substitute "mini-lift" for "none at all." By "mini," we mean the kind of setup that'll allow tires up to 35 inches in diameter-maybe even 37s-without messing up your OE steering and driveline geometry. The kind of "lift" that'll keep your center of gravity low-where it belongs-and your vehicle 100-percent street-legal and daily-driveable. Of course we're talking about those so-called "long-arm" link suspensions-once only available for pro racers-that are offered by a number of companies and which can allow for fitting fairly substantial rubber underneath your rig without lifting the vehicle much, if at all.
How do they work? Typically, by increasing track width, moving your (bigger) tires safely out of the inner fenderwells, and by using control arms and coilovers designed to provide up to 14 inches or more of suspension travel. Our own "Range Runner" and "Con Artist" projects both run these setups, and believe me, they offer all the flex you could want for slow-speed crawling, the softness to absorb high-speed desert whoops, and the ability to do it all with a level of stability you'd never experience with a conventional lift. And to top it off, since these vehicles' ride and handling characteristics are virtually unchanged from stock, you can drive them home-yeah, on the Interstate-at the end of your wheeling day. Yes, they're more expensive, and yes, you'll need to trim your fenders-or order up some replacement flares-to clear the tires and preserve uptravel, but for versatility on the trail and sensibility on the street, it's darn near impossible to beat long arms and low elevation.-Douglas McColloch
No Need To Regear, Just Power Up
So you just installed that new lift kit under your rig, which allowed you to fit bigger meats. Life is good. Instead of rollin' on those stock 29s you're livin' large on a set of 37s. But there's a problem. During your first testdrive, you notice that your rig seems sluggish on acceleration. Your engine, which in the past threw down enough power to smack down your buddies' rigs every time, seems to be laboring. As a matter of fact, things only get worse when you get out on the highway. You used to be able to cruise along at 65 mph and your rig would easily climb that long grade outside of town without downshifting from Overdrive. Now your transmission exhibits signs of Alzheimer's. It can't seem to remember what gear to be in, so it shifts in and out of Overdrive continuously, sometimes even dropping two gears. What the heck?
The deal is that with the increased diameter of the larger tires you've effectively changed your driveline gearing ratio. Your rig isn't rolling along at the same rpm as it used to because of the increase in tire diameter. Your rig now rolls at less rpm at a given speed. Not only that, the larger tires have added weight to your truck and the lift has changed the aerodynamics, and not for the better. What to do?
You could go in and regear the differentials in your axles to a lower (numerically higher) ratio. If done correctly, this would not only return your transmission to its happy place, but it would also help compensate for the added weight. Problem is, gears and install kits are expensive, and if you're not well-versed in installing gears you'll probably have to pay someone to install them. Matt Dinelli at Attitude Performance says that on average he charges $1,500 to regear both axles on a rig. A more cost-effective way to solve the problem is to upgrade your engine so its makes more power.
Obviously, the smartest move here is to increase power as inexpensively as possible, so start with an aftermarket performance computer chip. They're easy to install and provide an instant increase in horsepower and torque. A quality after-cat exhaust, combined with a free-flowing intake system, is another option. Both are relatively easy to install and provide an increase in power. Not only will you improve your engine's output, but depending on how your rig is geared, you might even improve your highway fuel mileage.
Power Down And Do It Right With Gears
I have to go with gearing on this one. I'd rather have the proper mechanical advantage working for me, rather than adding power to compensate for big tires and stock gears. I am as willing as the next guy to use an intake, chip, and exhaust-or even a blower-to get the most out of my engine, but not until I address what is more important: Gears.
How fast do you really need to go on the trail? With only 60 hp and 5.38:1 gears, our project Willys cuts the mustard on the trail just fine, thank you very much. Big power may be nice for those short bursts, but you have to understand that it starts a vicious cycle by shortening the life of components, which you can compensate for by beefing up components, only to find that you have added more weight, which in turn could mean you need more power. And don't forget to think of the fuel economy penalty for big power, especially if you have a small fuel tank and limited cargo space for extra fuel.
Gears give you the mechanical advantage and are the correct way to get the most power to the ground through torque. Think of it this way: You are trying to loosen a tight bolt in your garage, but just can't seem to make it budge with your short wrench. Would you rather have to offer your juiced neighbor a beer to come over with his giant bratwurst arms and risk humiliation, or would you rather just get a pipe on the end of the wrench and do it yourself?
When it comes to my trail rig, I'll choose gears over power any day of the week.
-Sean P. Holman
Better Be Bias
When it comes to trail-only machines, bias-ply tires are the way to go. By design, a bias-ply's tread flexes much easier than a radial design, allowing it to conform and grip uneven surfaces commonly found in the backcountry. Sure, they won't provide the same sure-footed high-speed stability as a radial tire, but neither will a radial tire flex and conform to the terrain where most wheelers actually use their purpose-built rigs. And bias-ply tires tend to be less expensive than radials, too, given identical sizes.
While you can expect increased rolling resistance on pavement from a bias-ply tire, it is important to remember that most of the trail-only rigs out there typically remain on a trailer until the start of a trail.
Real, Righteous Radials
This really is not a fair fight-the number of advantages a radial has over a bias-ply tire are too numerous to mention. Here's one that's especially timely, however: because a radial uses a dedicated set of steel belts across its tread-versus a bias-ply, where tread and sidewall share the same overlapping belt pattern-the tread and sidewall can act "independently" of each other, which allows a radial's sidewall to flex more readily than a bias-ply. More relevantly here, tread deformation is minimized with a radial as the sidewall flexes, allowing the tread to maintain a more constant contact pattern, which in turn equals more consistent traction and greater flotation. And greater flotation in dirt equals Treading (More) Lightly, with less tire-spinning, rooster-tailing, rock-flinging, and all those trail behaviors that certain eco-killjoys find objectionable. So among its other virtues, a radial tire is much more of a (dare we say?) "rock hugger" than a bias-ply ever could be.
That same spirit of "independence" also works well on the street, allowing the tread to maintain better contact with the road surface while the sidewall absorbs lateral forces, as in corners. This of course translates into superior directional stability, and with it, more predictable handling. And that additional "gription" comes in handy not only in corners, but on rain-slicked roads and other low-traction surfaces. Want more? Less slippage and less tread deformation equals less rolling resistance, hence better mileage and-you guessed it-a cooler-running tire that should outlive a bias-ply in any similar application.
Now it's true, for certain setups-pro rockcrawlers, for example-bias-plies come in handy when aired waaaaay down, due to their greater puncture resistance. And rigs that haul mega-heavy loads can certainly use that stiffer sidewall, too. But for just about everyone else, radials are golden. And now that companies like Michelin are making them in sizes up to 53s, there's really no excuse anymore for not making the swap to radial rubber.
Make Mine Inline
Why an inline? For starters, they're inherently smoother runners than V-motors due to their design. Granted, improvements in balance-shaft technology over the years have made the V-motors run much more smoothly than they used to, but the I-6 is still inherently smoother-running in design and, for all intents and purposes, does not require balancing as you're using only a one-piece casting with a single cylinder bank. And yes, this means you can build out a straight-six without much excessive vibration. Also, one-piece inline engines have been less costly for the OEs to produce in large numbers, which means no shortage of older I-6s in junkyards. Looking for a venerable 232/258 Jeep motor from the '70s to scavenge parts from? Not a problem. Want a lightweight Buick V-8 of the same vintage? Happy hunting.
The big reason why you want an I-6, though, is low-end power, aka, torque. Inline engines, by their longish design, pose a fitment problem in a lot of newer vehicles (though they run just fine mounted transversely), so the traditional solution has been to keep their lengths as short as possible via long strokes and tall block heights. This undersquare design results in increased crank throw and piston speed that inhibits the engine's ability to turn high revs but maximizes its ability to produce peak power at lower rpm levels. And that in turn translates into an engine that'll make its maximum power at the kinds of slow speeds we like to run on rocky, rutted trails.
Finally, think about all the most legendary 4x4s of yore-the CJs and Scouts and early Broncos, the FJ-40s and Series 1 Landys. What did they all have in common? They all came standard with inline engines, most of 'em for many years. Jeep offered inline engines in every bobtail they ever built for nearly 60 years! So, for smoothness, availability, torque-per-liter, and simplicity of design (and in most cases, mileage, too), an inline-six has a V-block beat hands-down every time. If they're good enough for Unimogs, bygawd, they're good enough for us Real Wheelers.
Gee, I Could Have Had A V-8
We hear it all the time. Wheelers verbally wishing they could have a V-8 between the framerails of their Wrangler instead of the 4.0L I-6. Sure, the I-6 is a legendary engine that produces a fair amount of power and decent torque, and it's adequate for a stock Wrangler. But when you start bolting in the heavy mandatory trail must-haves, it becomes crystal clear that the I-6 isn't so adequate anymore.
Can you build up an I-6? Sure, and it can be made to be a real screamer. But here's the thing: You can pour stacks of money and untold hours into the I-6, but at the end of the day all you have is an engine that merely matches the baseline performance of a modern fuel-injected small-block V-8. The reality is that for most wheeling disciplines, the V-8 is the perfect engine. Think only the I-6 can make decent torque? Whether a small-block or big-block, a V-8 can offer equal servings of horsepower and torque when built correctly. You'll end up with ample horsepower for those high-speed mud pits and fire-road romps and deep torque for those rocky hillclimbs. The V-8 may not make the torque at low rpm like the I-6, but gearing can solve that in short order. And the aftermarket support for the V-8 is extensive.
Realistically, the V-8 vs. I-6 debate can be expanded to include the V-6 that is found in the new Wrangler JK. Many of the same folks who lamented the I-6's power shortfalls have shifted their attention to the V-6, and they're one of the catalysts for the booming Hemi V-8 conversion business. It didn't take long for companies like Burnsville Off Road to see that vast numbers of wheelers wanted more power. Now Burnsville has a stand-alone Hemi-to-JK conversion shop. Clearly, the people have spoken.
If you're like most wheelers, you have to drive your rig every day and naturally you need to get the most miles per gallon. Some will argue that the six-bangers get far better mileage. Not so fast there, Skippy. Once again, when folks see the small real-world mpg difference between the six-cylinder and the small-block V-8 they end up wishing they had the eight-banger. The reality is that the V-8 is a versatile performer that can do everything the six-cylinder can, only better.