Building Horsepower for Right-Pedal Wheeling
Who among us doesn't wish he had enough horsepower under the hood to light a set of 44-inch Boggers on fire when he mats the throttle? Ask around the office here at 4-Wheel & Off-Road and even the secretaries will get giddy at the mere thought of having 600 hp. How often will you get to use all of that power? Who cares! We want it, we need it, and here's how to get it.
Sneaky Horsepower: Got Nitrous?
It is said that there is no better horsepower-to-dollar value than nitrous oxide. See, nitrous oxide (N2O) works to build mild-to-absolutely ridiculous horsepower by bringing liquid oxygen to the combustion chamber. You can think of nitrous as an on-demand liquid supercharger that is typically triggered to deliver liquid nitrous oxide (nitrogen and oxygen) into the engine when you hit wide-open throttle. With all this extra oxygen now present in the cylinder more gasoline can be introduced as well. The increase in horsepower actually comes from the increase in how much gas you can burn when the nitrous is on. As always, more gas burned equals more power.
Yes, nitrous can lead to a shorter lifespan for your engine, as extremely lean air/fuel ratios are possible if your kit is not dialed in properly. But current kits offer a safe and reliable fuel supply that can boost horsepower, without adding any complex mechanical systems, and with no additional drag to the rotating assembly.
The basis of a nitrous kit is a pressurized, refillable nitrous tank that works with electric solenoids to deliver the juice when the system is "armed" and you hit full throttle. A supplemental fuel supply, which is tuned to enrich the normal fuel/air mixture when the nitrous comes on, keeps the engine from running too lean and gives you the added horsepower. Spikes of 50-350 hp are available to make getting over or through any obstacle possible. The dentist's office isn't the only place where nitrous can make you smile.
Roller Rockin' Your Way to More Ponies
You can score all the added horsepower of a mild cam swap, plus reduced engine friction and lower oil temperatures, and get more accurate valve timing by removing the valve covers and adding a set of increased ratio rocker arms like these from Crane Cams (386/252-1151 www.cranecams.com). These 1.8-to-1 ratio Gold Race aluminum roller rockers for Chevy Gen III Vortec engines will make the stock 0.457-inch lift camshaft act like a bigger cam with 0.483-inch lift and even increase cam duration slightly. This increased lift means your valves will open further and let the engine breath better. Verdict: more power! Crane offers a full line of standard and increased ratio roller rockers that can add horsepower to virtually any Chevy, Ford, or Dodge engine with a stock or performance camshaft. Adding a set of these is a whole lot easier than swapping in a new cam.
The Rat Is Back
Put away those small-blocks because the secret to making big Super Swamper-burning horsepower is to start with a 500-plus cubic inch gargantuan engine. It's time to swap your 351ci for that 460ci, and, unless you want to be the last one off the trail, ditch that 350 for a 454. This new Ram Jet 502 from GM Performance Parts (www.gmgoodwrench.com) brings back all the canted-valve big-block glory that made you fall in love with the 454 in the '70s, and then goes even further by giving you fuel injection. Based on the 502ci ZZ502 long-block, this new Fuelie crate engine turns fuel and air into horsepower with a stand-alone speed density injection system that will work in any truck. You get aluminum heads, a forged steel crank, four-bolt main block, a roller cam, and a preprogrammed MEFI 3 ECM. Oh, and did we mention 502 hp and 565 lb-ft of torque?
Low Buck Power
During our "Ignition Shootout" story (Oct. '01) we test-fit one of K&N's (800/858-3333, www.knfilters.com) traditional open element filters on our Jimmy. We wanted to make a few dyno pulls to see how much better it would do than the stock snorkel air cleaner. Man, were we impressed! It never ceases to amaze us how one of these things can easily bring out 15 more horsepower on even a stock engine when you compare it to the restrictive factory setup. Hey, you have to run an air filter to keep the engine alive, and making horsepower doesn't get any easier (or cheaper) than this!
Let It Breathe
Simple law of physics: Your engine sucks air and fuel in and converts it into mechanical energy. Anything left unburned in the engine must get pushed out the exhaust system to make way for the next air/fuel charge. And the easier it is for the exhaust to get out of the engine, the less power will be lost. A free-flowing exhaust will not only unleash horsepower that would otherwise get plugged up in the stock asthma-inducing mufflers and tailpipes, but will also make the engine sound like the monster it truly is. The best (and unfortunately most expensive) exhaust systems will use large-diameter, stainless steel (for long life), mandrel-bent tubing, and free-flowing mufflers.
If you want a single exhaust pipe we'd use a 3-inch-diameter exhaust for small-block V-8s, and use a Y-pipe with a smooth transition to connect the driver and passenger side into one pipe. If you've got a big-block or turbodiesel then use 4- or 5-inch-diameter sewer pipe like this mandrel-bent, stainless, Power Stroke diesel system from Magnaflow Performance (800/990-0905, www.magnaflow.com). Power gains are up 18 hp and 51 lb-ft of torque with a system like this installed on your Super Duty.
A classic true dual exhaust system will work best with twin 211/44- or 211/42-inch pipes joined by a crossover (H-pipe) to equalize exhaust pulses on small and mild big-blocks. Really nasty 600-plus-horsepower big-block engines will want to run dual 3-inch systems. Again, even if you are having a system custom made at a shop, look for smooth bends and free-flowing mufflers that don't use cheesy adapters to radically neck up the pipe diameter.
The roller cam is especially suited for use in 4x4s because it allows for more lift with less duration than a flat-tappet cam ever could. This means you get all the horsepower you want (thanks to large valve lift heights) while maintaining a smooth idle because of the relatively low duration. A roller cam lobe can have an almost square shape because the roller lifter actually "rolls" up the side of the lobe that a conventional flat-tappet cam would just smash into. Think of the camshaft as the main component that determines the character of an engine. Choose the wrong cam and you can neuter all the power out of the meanest big-block because the valves will not open far (or long) enough to feed the air and fuel to the combustion chamber. Get too radical and you can produce a stock small-block that won't idle for spit and that fouls spark plugs like crazy. When shopping for the right cam for your application, put your faith in the cam manufacturers. They can help you pick exactly what you need to optimize your combination.
Heads, You Win
Money spent on your cylinder heads is money well spent. The heads are where the magic of internal combustion happens, so if you can optimize this part of the engine, then everything else you do to make power will work that much better. Yes, you can spend hundreds (even thousands) of dollars having your current heads ported, and the actual shape of the chamber can even be tailored to create a higher compression ratio for more power.
But being the bolt-on type of guys we are, we like performance parts we can buy right off the shelf, or over the phone, and knowing what kind of performance we can expect. In general, aluminum heads can offer greater performance than iron heads because their thermal properties tolerate higher compression ratios while still running on pump gas. Aftermarket heads often use larger valves, better combustion chamber designs, and optimized spark plug location for peak power. We're looking forward to playing in an upcoming issue with the set of big-block Mopar heads from Edelbrock (310/781-2222, www.edelbrock.com) shown here.
When you are stuck with a small (you know, like a 427ci) engine you can always make it produce more power with a blower. Turbochargers, centrifugal, roots, and screw-type superchargers all increase power by cramming in more air than the engine could otherwise suck. A supercharger basically makes an engine act like it has more cubic inches, because the more available air an engine has, the more fuel it can burn. The Toyota Race Development (800/688-5912, www.trdusa.com) supercharger shown here adds 75 hp and 77 lb-ft of torque to turn a 3.4L V-6 Tacoma into a V-8 killer with very little added weight. Superchargers can work great on any powerplant as long as you supply enough additional fuel to keep the engine from running too lean. Power increases in the 50-150 hp range are quite common, and even twin-turbo and twin-superchargers engine packages are available.