Making More Horsepower
Like most dumb kids with few tools, little money, and even less sense, my first performance modification was cutting the muffler off of my Toyota 4x4 with a hacksaw. It may not have increased the power output of my truck’s engine, but at least it sounded faster.
Growing up in a state that has had smog laws for as long as I can remember really put a damper on the performance modifications available to me, especially in the early years. I could only dream of removing the pathetic factory carburetor and miles of cracked vacuum lines on my first 4x4 and replace them with a pair of four-cylinder-churning Weber side-draft carbs. Engine swaps in my state were like flying pig-unicorns. Fortunately (at the time), vehicles manufactured in 1965 or earlier were exempt from the bi-annual smog tests. Today things are much more promising. Hundreds of companies offer smog-legal bolt-on power-adders and even complete, 50-state-legal, high-performance crate engines are available, such as the 556hp GM Performance Parts E-Rod LSA engine.
I’ve had the chance to try out many different bolt-on performance parts over the years. Some of which worked amazingly well, such as the Avenger supercharger that made an additional 80hp at only 5 psi and lasted well over 100,000 miles on a Jeep 4.0L. However, I’ve also seen other fairly expensive mods fail miserably and actually make less power than the factory parts when put on a dyno.
From all of this I have learned a few things. If you’re starting with a gutless engine, the only way to make significantly more power is to add a supercharger or turbo. And despite the arguments you might hear online and around the campfire, the truth is that in most cases these forced-induction power-adders will adversely affect fuel economy and engine life. If you really want significantly more power, you should swap the engine or sell the slug 4x4 and buy something with more power from the start.
I think some vehicles are meant to be pigs and should remain that way, unless for some reason you enjoy throwing away money for minimal and often unnoticeable performance returns. Rather than modify the engines in these pigs, I’ve found ways to have an unbelievable amount of fun in the gutless 4x4s I have owned. All it takes is a little imagination, patience, and a bit of driving skill, all three of which will offer more entertainment than a $1,000 exhaust system that makes 0hp over stock. The key is staying away from buddies with fire-breathing big-blocks and other V-8s. Most trails can be conquered with minimal horsepower anyway.
I’ve been lucky enough to swap a few engines, too. Interestingly enough, the swaps are never as inexpensive as you think. Just because you have a cheap, or even free, engine does not mean it is a good swap candidate. I get lots of questions about engine swaps and most readers have no idea what they are getting themselves into. They often underestimate the cost of or completely forget about things like cooling, driveshaft modifications, exhaust, fuel system, wiring, and so on. It’s easy for an engine swap to cost more than triple the price of the engine alone.
When it comes to swapping, I’m probably a little bit old school. One of my favorite swaps ever was with a GM Performance Parts Ram Jet 350. It was amazingly easy to install, required zero tuning, and it was an aggressive and violent-fun engine to drive, even in a 4,500-pound 4x4. I don’t know if it’s just that I got the gearing spot-on or what, but I’ve yet to replicate that combo which included 38-inch tires, a TH350 auto transmission, a Dana 300 T-case with the factory 2.62:1 low range, and 5.13:1 axle gears. Someday I hope to match the performance of that rig.
I’ve also messed with the newer LS engines. They seem to have massive potential for power and I often dream about and drool over the GM Performance Parts 700hp LSX 454 small-block. But there are some little things about the LS engines that I just haven’t gotten over. The motor mounts and exhaust are totally different than the early small-block. I prefer to have a mechanical temperature gauge and there really isn’t a place to put the larger sending unit in the LS block or heads. You also have to mix and match flywheel parts and spacers to mate the LS block to the older bomb-proof, three-speed GM transmissions (TH350 and TH400).
Ultimately the amount of power you have is all about perception. If the truth were known, I probably lost horsepower by decreasing the backpressure when I hacked off my truck’s muffler so many years ago. But since it was louder and had a more aggressive tone, I thought it was more powerful and that’s all that really mattered. Today I’ve found a more reasonable and less obnoxious equivalent in the form of a 40-Series Flowmaster muffler. These things have made my most-pathetic V-8s rumble like race cars. I don’t know if the addition of a Flowmaster 40-Series muffler makes any more or less power when added to my low-compression, high-mileage engines, but it sure makes them sound cool.