While some may say that forced induction is forced induction we would argue that there are staggering differences among the options. The choice of either supercharging or turbocharging your engine is a journey riddled with pros, cons, questions, answers, options, impossibilities, and everything in between. The first and foremost question enthusiasts have to ask themselves is, What type of forced-induction kits are available for my car? What's the cost? Are there any associated costs (i.e. need to change other parts based upon going with a certain kit)? What are the purported horsepower gains? Will the "feel" of the kit fit my driving style (midrange or top-end power)? There are a multitude of other issues to consider in making the decision to either supercharge or turbocharge.
We attempted to answer some of these questions with a toe-to-toe comparison between the TRD supercharger and Turbonetics turbocharger kits for the Scion tC. The tC is the third model Scion rolled off the line to diversify their image of a car company mostly for hip youngsters. With a base price of just under $17,000 the tC comes loaded with features. From the cool glass roof/moonroof to the European-styled front end the tC is a great buy.
The suspension and braking systems are extremely close in design to what is found under the Toyota Celica GT-S so you know the car can carve the hairpins. The braking system is so close the two vehicles share the same aftermarket front brake upgrade kit. The only downfall of the tC is the powerplant. Toyota decided to use the 2AZ four-cylinder engine from the Camry/Solara instead of the 1ZZ or 2ZZ engines found in the Celica. Our theory for this is because the tC is targeted for a slightly older demographic the need for a high-revving four-cylinder engine was deemed unnecessary. However, the 2AZ does have one advantage over the 1ZZ and 2ZZ engines: displacement. The 2.4-liter engine is torque machine, pumping out 168 lb-ft of torque at the flywheel. The engine produces more torque than horsepower (168 lb-ft vs 162hp). This larger displacement makes it ideal for forced-induction applications.
Before strapping the vehicles to the Dynojet chassis dyno we took both Scions out for a test drive to assess their real-world capabilities. Out on the open road is where dyno numbers melt away and it is all about the feel of the car and the pure driving enjoyment. It is out here the power of the Turbonetics tC shines. The turboed tC takes the prize hands down for pure fun and excitement. The TRD tC only throws your head back into the headrest while doing some big freeway entrance ramp runs. On the other hand, the Turbonetics tC produces enough g-force to knock you back every time the go pedal is smashed. It is quite the fun ride for both in-town and freeway driving. Turbonetics' tC drove like an incredibly fast car, it was hard to believe we were in a Scion tC and not a WRX or some other car you expect to be fast.
We tested three tCs on the dyno: a bone-stock tC, TRD's supercharged tC, and Turbonetics' turboed tC. Scion rates the tC at 162 horsepower and 168 lb-ft of torque at the flywheel. The stock tC registered 140.9 horsepower and 149.1 lb-ft of torque to the wheels. Based on the road test, we were somewhat surprised to see the TRD supercharged tC generate 200.1 horsepower and 180.7 lb-ft to the wheels, a gain of 59.2 horsepower and 31.6 lb-ft of torque over stock. The Vortech-based supercharger kit produced a very linear dyno graph, generating peak horsepower at redline. If the redline was raised an additional 500 rpm we wouldn't be surprised to see another 20 or so horsepower. The largest horsepower gain over stock occurred at 6335 rpm with a gain of 68.4 horsepower. On the torque side, the largest gain was also realized at 6335 rpm with a gain of 66.7 lb-ft.
What is interesting is that the TRD-equipped tC did not drive like a 200 horsepower car. Turbo's Project Integra (an all-motor 200hp vehicle) and Project Celica (a Blitz supercharged 205hp vehicle) are near in horsepower output but seem like they are miles ahead in driving "feel."
The "kick" of the similarly-horsepowered Project Celica is no comparison to the TRD tC. Project Celica drives much more like the Turbonetics tC. Likewise, Project Integra throws you around like you are driving a race car and feels like you have more power than the TRD supercharged tC.
Up next on the dyno was the Turbonetics tC. Once strapped down the T4/T3 sung to a tune of 244.1 horsepower and a torque pounding 262.7 lb-ft. On the street the car feels like it has roughly 300 horsepower but the dyno told us otherwise. The power we were feeling was the torque pushing us deep into the seat. By 3920 rpm the Turbonetics tC reaches peak torque, explaining why the car has a hard time maintaining traction in first and second gear. Peak horsepower of the Turbonetics tC was also realized earlier in the powerband than the TRD tC, registering 244.1 horsepower at 5495 rpm. Unlike the TRD tC where the largest power gain was realized at redline, the Turbonetics tC generated 103.7 horsepower more than stock at 5495 rpm and 114.3 more lb-ft of torque at 3920 rpm.
While I am a huge TRD fan, I gotta say in this instance the supercharger kit is not the way to go if you want the biggest jump in power. The advantage of going the TRD route is that it is 50-state legal, warranty-compliant, and dealer installed. The downside is that it is a heck of a lot of money to spend for a forced-induction kit that feels almost stock afterward.
With the Turbonetics kit every dollar spent is felt in throttle response and sheer power. A potential con to the Turbonetics kit is that because you are producing so much power the question looms if all of the stock components can handle the power jump. Tyler Tanaka of Turbonetics, says they have had no problems running stock internals with their turbo kit. Aftermarket performance rods and pistons (and bigger injectors, etc.) are available to tC owners who want to be on the safe side or who experience problems in the future.
In this case of the Great Debate we have clearly announced a winner in generating power. There are distinct advantages to both the TRD supercharger and the Turbonetics turbo kits. It is up to you to decide which side of the line you want to petition upon.