Having gobs of power on tap is cool. Getting it free is cool, too. And concealing it from the outside world while never having to worry about turning it on is even cooler, still. Only a turbocharger can give you the best of all worlds, and we wanted to know what makes them tick and why they have suddenly "appeared" on the market as the best power-adder available. We know that turbos are nothing new and have been making power on automobile engines for decades. Unfortunately, turbocharging has been overlooked in the past as a viable power enhancer due to its inherently high cost and troublesome installation. That is until now.
While it's true that turbos will always be a costly bolt-on, huge advances in computers and Electronic Fuel Injection (EFI) technology have given the average street enthusiast access to usable turbo systems for his everyday car. And it's these advances that have allowed regular-guy racers, who are not typically fond of installing computers with complicated EFI and the expensive exhaust systems needed to drive a turbo, to overlook these difficulties and take advantage of all the power a turbo can make. Today, records are being broken in just about every form of motorsports thanks to turbos, and there's relatively little chance of that trend slowing down any time soon.
What Makes A Turbo Better?
A turbocharger is a very efficient way to supercharge an engine by pumping more air into it than it could breath normally. Turbos are also as close to free horsepower as we might ever get. That's because, unlike a blower that's driven off the crankshaft, a turbo uses the engine's exhaust gasses to drive it. And unlike nitrous, a turbo is on all the time and requires little maintenance. But, as with blowers and nitrous oxide, turbos also need extra fuel to burn with all that extra air, so any turbo upgrade will probably require a fuel system revamp, as well. While turbos have been tried on carbureted engines with moderate success in the past, it's been the giant leaps in racing EFI that have given turbos a new resurgence of success. And with the cost of EFI systems reaching very affordable levels, bolting a turbo onto your '68 Camaro doesn't seem so daunting.
Factory-installed turbo systems of the past also gave the whole idea a bad rap. While automakers were trying everything in their bag of tricks to up the power and economy of their mid-'80's cars, the technology required to back them up just wasn't there. Many OEM turbo systems failed, and aftermarket turbocharging was, so to speak, shelved. Then, with the huge insurgence of "street-car"-type drag racing came a new whole new addiction to any kind of power adders. While nitrous still plays a dominant role in that type of racing, turbos are taking over fast.
The reasons for turbos moving ahead of nitrous on the racetrack are the same as on the street: advances in EFI technology. Using a turbo offers greater reliability, and it's a more easily controlled power enhancement. Sure, the costs can be 5-10 times greater to build a competitive turbocharged race car, but when you're standing in the winner's circle, nobody remembers how much it cost to get there.
The gearheads at Innovative Turbo have seen more than their share of turbo-related carnage and gave us the low-down on what causes turbo failures and how to avoid them. Most turbocharger damage can be traced back to just a few basic causes: lubrication problems, foreign object damage, temperature extremes, or poor materials and workmanship. While you have little control over the latter, the first three are within your grasp. Since turbos are lubricated and cooled by engine oil and, in some cases engine coolant as well, it's critical to maintain a strict oil/cooling system maintenance schedule when running a turbocharger.
If you're adding a turbo to your daily driver, then it's not a bad idea to make the switch to 100 percent pure synthetic motor oil, due to its high heat-handling capabilities. Installing dual, remote oil filters connected to an auxiliary oil cooler is also a good idea because after a hard run at full boost, the oil temp will rise, and it's important to get it cooled down to normal operating temperature quickly. The turbo's bearings are lubed with pressurized oil from the engine's oil pump, and since pressures are lowest at idle, a turbocharged car should not be idled after a hard run. Instead, slowly drive the car around in Low gear, maintaining high oil pressure, but opening the throttle as little as possible so there won't be much exhaust gas flowing to load the turbo.
Of course, the compressor side of the turbo is also subject to damage when its inlet is not properly maintained. The best defense against destroying a turbo on the intake side is a tightly sealed air intake using a high-quality filter.
As the OEMs and aftermarket continue to develop new and improved EFI systems and racers continue to push the envelope, better turbo systems will be the end result. We will all benefit from this new wave of turbo technology, so take advantage of it, and after you've read this story, consider yourself a graduate of: Turbogineering 101.
Anatomy Of A Turbo
The guys at Innovative Turbo explained turbos to us in full detail. We learned how a turbo is driven, where it gets its air from, where it sends it to, and some of the various control devices used with turbos. Here's the drive side of the turbo, called the Turbine Housing. It is usually made of cast iron due to the extremely high temperatures it must endure.
Hot exhaust gas enters the Turbine inlet here (1) and is routed directly into the housing's Volute. The Wastegate is typically mounted here, except in tight race car chassis. The gas then strikes the Turbine Diameter blades (2), which are connected to a common shaft driving the compressor's impeller. The gas then exits the housing (3) and goes straight out the tailpipe.
This photo shows the aluminum Compressor Housing with its impeller to the side. Normally the impeller would run inside the housing with its blades facing the radiused part of the housing.
Opposite this side of the housing is where filtered, outside air is introduced into the compressor (1). The air is then accelerated through the impeller wheel and across the radiused Contour (2). The Impeller discharges the air into the Diffuser (3), which slows the air down and increases its pressure, creating boost. The boosted air is recovered in the Volute (4) and is directed through the discharge nozzle (5) into the engine or intercooler. Turbos run "dry," boosting only inlet air. Fuel is mixed in downstream, usually just before the boosted air enters the cylinder head.
Compressor shaft speeds inside a turbo can exceed 100,000 rpm, so it must be precision-balanced to the extreme. This machine is made strictly for that purpose.
This photo shows the complicated exhaust routing involved with a typical race turbo. The Wastegate bypasses extra exhaust gasses from the header collector, allowing only the correct amount of exhaust into the turbo housing, which is wrapped in the heat blanket. The Compressor Housing outlet, welded to the intercooler tubing, can be seen to the right of the Wastegate with the pressurized oil line coming from the engine in the center. Try changing spark plugs in here!