Power Play

Learn how turbochargers and superchargers put extra power under your hood.

So, you’ve come to the conclusion that your vehicle is not fast enough. Join the club. Is any vehicle ever fast enough? If that’s how you feel about your vehicle, then come on, we’re going to have some fun today. Why, you may ask? Because today is the day we talk real horsepower — real gut-wrenching torque, tire smoking, and all. Yes, we’re talking about supercharging or turbocharging your vehicle. Let’s explore the fact and fiction of these two very neat additions.

Turbo
We’ll start with turbochargers (turbos for short). A turbo is a small turbine that’s mounted to the exhaust manifold on your engine. As your engine speed increases, so does exhaust gas. The gas spins the turbine, which creates boost, which, in effect, is ramming air into your engine. The more boost, the more air forced into your engine. The big advantage of a turbo is that it’s “free” horsepower, meaning it doesn’t use engine power to make boost like a supercharger. The downside is that the boosted air is very hot because the turbo is connected to the exhaust, which is, in turn, very hot.

A turbo system will use a device called an intercooler to cool the air. The intercooler is typically mounted on the front of the car under the bumper, and most use the air forced into it when driving to dissipate heat. Some use a combination of air and water to achieve the effect. There are even water spray systems that will actually spray water on the surface of the intercooler at specific times to make the intercooler more efficient.

The single most important part of the turbo system on a modern car is the engine management software. This is what separates the men from the boys. It’s very possible to take a turbocharged car that’s tuned o.k. and fine tune it and get another 10- to 20-percent more power. This is typically done with the car on a chassis dyno to simulate the load an engine is under when being driven. This isn’t inexpensive, but the benefits far outweigh the cost. Imagine getting a turbo kit installed on your Honda Prelude and getting 275 hp at the wheels with the software supplied by the kit manufacturer. Let’s say the kit was $5000 installed. Would it be worth $1000 more to get an additional 30–60 hp? I think you get the point.

Another advantage of turbo kits is that they’re more efficient at higher engine RPMs than superchargers. But there is a tradeoff — they don’t have as much low end and midrange power as a supercharger. And they have what’s called “lag,” which refers to the amount of time from when you push down on the gas to when the turbo can spool up and deliver boost. The smaller the turbo, the lower the lag time. The larger turbo will make more boost but will take longer to spool up which translates to longer lag time. You’ll have to decide how much lag time is acceptable to you. I personally hate lag time, so I’m more of a supercharger guy.

Superchargers
Let’s talk superchargers. They are air pumps that are driven typically by belts and either mount beside the engine and feed air into the intake manifold, or are directly attached to the engine and are integrated into the intake manifold. They have a few big advantages. Their boost is instantaneous once the engine speed is high enough. They do not heat the air as much as a turbo and therefore do not rely as heavily on intercoolers. Superchargers are available with intercoolers, and they do work, just not with as large a power gain as on a turbo system. Superchargers have no “lag” to speak of like a turbo, and they typically develop more horsepower at lower rpm’s than a turbo. But, like we said earlier, superchargers do lose efficiency at higher rpm’s and they do draw power from the engine to make power.

This is how I make suggestions on both types of systems. If you’re looking for more power across all RPM’s and want that power instantly, you’re a supercharger person. If all-out horsepower is your claim to fame, buy a turbo kit.

I’ll note that there are some exceptions to this. There are some supercharger manufacturers making kits that’ll make loads of top end horsepower. A good example would be the 32-valve Ford 4.6 that can make 800 to 900 horsepower very easily with a good supercharger. There are also small turbo kits for some vehicles, like a Honda Civic, that are designed for lower boost levels and will spool up very quickly.

Complete Turbo Kits
If you own a Honda or Acura, Greddy and Apex’I make systems for you. So do Drag and F-Max. One thing to note is that all of these systems are NOT emissions legal and you need to think that one through very carefully. Most turbo kits available today focus on the sport/compact market. Hahn Racecraft make systems for Dodge and Mitsubishi products. There are some reputable companies making turbo kits for muscle cars and trucks, but that market is dominated by superchargers. If you own a muscle car or truck, you need to look up Vortech or Paxton (which Vortech now owns), Powerdyne, ATI, or Magnacharger. Most all of their systems are emissions legal and most systems can be installed in a weekend by a good mechanic. Three companies that stand out for the import crowd are Jackson Racing, Vortech, and Powerdyne. They all make systems for Honda products, and Jackson Racing also makes kits for the Ford Focus and the Mazda Miata. Neuspeed has also just released a kit for the 2-liter VW that looks very nice as well.

The BMW market is seeing more and more kits available for its cars. Most systems focus on the 3 series cars, but there are other applications available. Active Autowerke has stood out for many years as a supplier of turbo kits for BMW owners. There are several companies making superchargers for BMW’s, yet two names stand out. Dinan has been making superchargers for a long time and has the largest assortment of fitments available. Race Marque Systems is unique in that they were the first to bring intercoolers to the BMW market. They make an intercooled supercharger system (they call it aftercooled) for the 96-99 BMW M3 that make 411 hp. That is incredible. They’ve also just released a new series of supercharger kits that retail for $3995, which is about $2000 less than most other kits out there. It makes you want to go out and buy a used 325i BMW, doesn’t it?

There are some other things that you need to consider when deciding whether or not to install a turbo or supercharger kit. If you own a manual transmission, will your clutch handle the increase in power? If you own an automatic, do you need a transmission cooler? Should you consider a limited slip differential if your vehicle doesn’t have one so you can get the power to both wheels, and not just one? Do you need to upgrade your exhaust system? How about brakes? If you’re adding a lot of new power, I would think that one would be a no-brainer.

Who’s going to install the kit? Is it worth paying a professional to do the job? I can tell you from experience that most of the labor times that kit manufacturers quote customers is for a professional that has done those kits before. We installed a kit on a Civic and were told eight to ten hours. It took us 14 hours. We will do the next kit in 12 hours and could probably slim it to 10, but eight is for an extremely fast installer — one thing to consider. If you mail order a kit and start the install yourself and get stuck, you could be in a jam. You will have a torn apart vehicle that many shops will not want to touch. So, consider the advantages of buying your kit from a local dealer and having them install it very carefully. It becomes their problem, and if you choose the dealer carefully, you should be guaranteed a good job.

So, in closing, if you’re looking for more power to pull that boat, want to make your Mustang faster, or just want your Civic to beat that Mustang, this just might be your ticket. As always, feel free to email me with any questions. And if you email any of these manufacturers, feel free to tell them that CAR SOUND & PERFORMANCE magazine sent you.