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Engine Tuning Comparison - Power Up Smack Down

A Four-way Battle Royale for the Ultimate Power Champion

Drew Hardin
Aug 16, 2007
Photographers: Carter Jung, Brian Gillespie

A word of warning - this could get ugly, people. This story started out as a typical Super Street tech assignment, with Nads asking me to find a couple of pros to summarize the four most popular power adders in the sport compact market. But then, he added a twist: We'll let these guys talk up their power maker of choice, as long as they talk trash about their competition. Tell us why the other guy's junk isn't fly. That should be far more entertaining than the usual press release fodder, and it just might make it easier for the readers to figure out who's being straight with us and who's full of it.

Honestly, not all the company reps we talked to took the bait. It's a small industry really, and some weren't comfortable dissing the competition on the record. Those who were though, seemed to enjoy getting some of their feelings out in the open.

There's more to this than just a bunch of trash talk. We've provided a short description of each power adder and the driving conditions it's best suited for. You'll find a "Bang for the Buck" rating, with 1 being ludicrously-expensive for the result and 10 being a value slam-dunk. Each section ends with arguments for (dope) and against (nope) each adder, which is where the fun really begins.

Ready to rumble? Let's do it.


How it works: Turbocharging and supercharging are forms of forced induction. Both components act as pumps that push compressed air into the combustion chambers. This compressed air charge is far denser than the air flow into the cylinders under normal atmospheric conditions. When the denser air charge is combined with an increased amount of fuel, the combination creates a more powerful burn, which exerts greater pressure on the pistons and therefore increases the engine's power output.

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One of the key differences between a turbocharger and a supercharger is the way they function. Inside a turbo's snail-shaped compartments are two finned wheels, joined by a common shaft. One wheel is the turbine, spun by exhaust gases leaving the engine. As the turbine spins, so does the compressor wheel at the other end of the shaft. The compressor takes fresh, incoming air and pressurizes it into the dense intake charge headed to the combustion chambers.

The turbo's reliance on exhaust gases to operate is a good-news/bad-news situation. The good: turbo advocates call it "free power" meaning that it places no mechanical drag on the engine, so doesn't use horsepower to make horsepower. The bad: big turbos - those with the potential to make huge power - require a fair amount of exhaust pressure to spool up. The time it takes for that to occur is known as turbo lag. A drag racer can use lag to maintain traction during initial launch, but it's no fun on the streets or a road course, where instantaneous throttle response is of more value.

Turbomakers say lag is a thing of the past, since a properly optimized turbo can make power nearly instantaneously. Those in competing camps disagree, as you'll see below.

Gauging the size of the turbo and the amount of boost that's right for your car is based on a number of factors ranging from how you'll use the car, to whether or not you want to reinforce the bottom end to withstand the greater stresses forced induction will put on them. The driven end of the car makes a difference, too. Enough boost to blow off the tires in three gears can be fun in a RWD car, but scary in a front-driver.

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Where it works best:
The streets, to drag race.

Bang for the Buck rating:
"If you want to get a certain amount of power for a given amount of dollar, turbocharging is the easiest way to do that."
- Doug Macmillin, Hondata

"Power is addicting. Once you get a taste, you want more and more and more. With a turbocharger, you can run 8 psi on pumped gas on the street, go to the track, fill up with 100-octane race fuel, and then turn up the boost with the boost controller. You can't do that with any other power adder."
- Tyler Tanaka, Turbonetics

"If someone wants to spend very little money and make good power, a simple bolt-in kit is the best way. The best bang for your buck is a turbo kit. If they want push in the seat, with a really hard hit, then turbo is the way to go."
- Charles Madrid, Skunk2 Racing

"Turbos can work extremely well on a car with rear-wheel-drive. You can put a manual boost controller on it and a "press to pass" button like the Indy cars do, so you'll have an extra amount of horsepower when you need it. But it's like an off-on switch. You want something more progressive on a front-wheel-drive, because you're steering with the same wheels that you're powering with."
- Brian Gillespie, Hasport

"There's a satisfaction that comes with building power naturally-aspirated. Anybody can slap a turbo on a motor, even a crappy one, to make power."
- Tony Shagday, Skunk2 Racing

"It's harder to kill a naturally-aspirated engine from poor tuning than with a turbo. Poor tuning will kill it very quickly."
- Doug Macmillin, Hondata

"With a turbo you supply gas, which adds exhaust, in turn creating boost, which causes more exhaust, leading to more boost and forming even more exhaust. You can keep a constant foot on the gas and the power still goes up. In the end, you wind up with too much acceleration."
- Brian Gillespie, Hasport


How it works:
Like turbocharging, supercharging is a means of forced induction that pumps greater amounts of air into the combustion chambers than atmospheric pressure would normally allow. When mixed with the right amount of fuel, the denser air creates a more powerful burn at combustion, which pushes harder on the pistons, therefore increasing power.

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A supercharger is different from a turbocharger in that it's driven by a direct mechanical link to the engine, often a belt that's turned by the crankshaft. This is also a good-news/ bad-news scenario. The good: There's no wait for exhaust gas pressure to build in order to deliver boost; the surge starts right off idle and power delivery is linear, rising with the engine's speed. The bad: A certain amount of the engine's power is required to turn the supercharger, in a state called parasitic loss.

Superchargers fall into two main types: Roots-style (known as screw or positive displacement) and centrifugal (known as dynamic). The Roots-style blower typically consists of a case, located between the intake and the cylinder heads, that houses two large screws, or rotors. These screws are driven by the belt off the crankshaft, and their spinning action compresses intake air, sending the dense charge to the cylinder heads.

A centrifugal supercharger looks and acts more like the compressor side of a turbocharger. It's also driven by the crankshaft, either via a pulley or gear set. But centrifugal blowers also contain a gear-drive system inside the case that can be set to drive the compressor wheel faster than the engine's speed. Some centrifugal superchargers can be equipped with a compressor bypass valve that bleeds off air pressure during deceleration (much like a turbo's blowoff valve) to reduce heat build-up and eliminate compressor surge. Centrifugal superchargers are smaller than Roots-style blowers, making it easier to find room for one in an otherwise crowded engine compartment.

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Where it works best:
Street, drag racing, road course

Bang for the Buck rating:
"Superchargers aren't cheap. However, the power made by bolting on a Stillen supercharger package is reliable, repeatable and FUN!"
- Michael Ullrich, Stillen

"There is an old saying that when it comes to cars, with the choice of power, reliability and affordability - you can only pick two. This is true for turbochargers, nitrous and all-motor vehicles. But a well-engineered supercharger can give you all three."
- Michael Ullrich, Stillen

"The basic difference [between a Roots-style and centrifugal supercharger] is with the power curve. The Roots-type is rather steep under 3,500 rpm, then crosses over the centrifugal curve and flattens out. On the other hand, the centrifugal curve is linear in nature and delivers power much like a rheostat does. The power continues building to and beyond the engine's redline. With high-revving sport-compact applications, power delivery of the centrifugal is preferred over the Roots-type."
- Vortech spokesman

"The Roots-style supercharger has instantaneous power delivery and will build a broad, flat torque curve. The focus is on useable power, not peak numbers."
- Michael Ullrich, Stillen

"There is no bottle to fill, no exhaust manifolds to install, no seeking out that neighborhood garage for a 'funny' smog certificate every two years. We've had owners report up to 150,000 miles on their original compressor!"
- Vortech spokesman

"Oscar Jackson is getting back into the game with a new supercharger setup. He's using the Rotrex supercharger, which spins a lot faster than the traditional Paxton or Roots-style that they had, to match the higher engine speeds people are turning now. I think that's going to put it back on the map."
- Tony Shagday, Skunk2 Racing

"Because superchargers deliver boost via rpm, the shock on an engine's internals is dramatic. You're slamming forced air directly on those components, and they're getting pounded."
- Tyler Tanaka, Turbonetics

"With a centrifugal supercharger, you get a lot of the negative aspects of a turbo and fewer of the positive aspects of a supercharger. A centrifugal supercharger is like half a turbo (on the cold side) with a belt strapped to it. These generally produce peak-type power - generally limited to upper-mid range and top end. Plus, installation can be a nightmare with complicated tubing routed from the intake to the unit, from the unit to the intercooler (if one is available) and finally to the intake. There is also the constant restriction of the unit itself at low rpm as well as the constant drain on the engine, due to the crank-driven belt."
- Michael Ullrich, Stillen

Nitrous Oxide injection

How it works: The key is in the oxide part of this power adder's name. Nitrous oxide, when sprayed into an engine's intake tract, introduces more oxygen into the combustion process than is found in the atmosphere. Because there's more oxygen in the chamber, more fuel can be added, since burning more air and fuel equals more power. Nitrous has an added benefit: When it vaporizes, it's extremely cold.

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That temperature change acts on the air around it, makes it denser, so more air can pack into the combustion chamber per cycle.

Nitrous oxide systems are typically sold per horsepower as a "shot." For example, a "50-shot" system will deliver 50 units of additional horsepower. Nitrous systems are also either "wet" or "dry," depending on whether the nitrous is mixed with fuel prior to entering the combustion chamber (wet) or not (dry).

Nitrous systems can be set to activate in several different ways. The simplest method is with a switch that introduces the nitrous only during WOT conditions. Or you can inject nitrous via the "happy button" that's gotten so much attention in movies. The most complex systems introduce nitrous to the engine in several stages, or with a progressive controller. Drag racers use this method to deliver a modulated amount of nitrous at launch (so the power delivery doesn't induce tire spin) and then increase the nitrous as speed builds. Activating each stage with a gear change, for example, will deliver maximum nitrous flow - and therefore horsepower - at the top end.

Nitrous is the only part-time power adder in this bunch. It only works when it's activated. When the system's off, the engine operates normally.

A nitrous system's packaging is different than that of either a turbo or supercharger. The nozzles, solenoids, lines and additional underhood parts can be routed in the engine compartment, but you'll have to make room for the bottle which stores the nitrous oxide.

Nitrous' inherent limitation: boost for only as long as the bottle is full. Nitrous Express' formula to calculate nitrous use is: 0.8 pounds of nitrous oxide times 10 seconds, equals 100 horsepower. So if your system is jetted to produce 100 horsepower, you'll use just under a pound of nitrous every 10 seconds and drain that 10-pound bottle in less than two minutes.

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Where it works best:
Drag racing.

Bang for the Buck rating:
"Nitrous Express has a nitrous system that retails for $399 that will provide up to 250 wheel horsepower. Name another power adder that can provide a $1.60 per horsepower ratio!"
- Mike Wood, Nitrous Express

"Nitrous provides instant torque at any rpm. This tremendous torque boost carries on unabated throughout the rpm range of the engine. No waiting; it's right now!"
- Mike Wood, Nitrous Express

"It's the most cost-effective way to add horsepower to any engine, from stock to highly modified. It's easy to install. There's less heat under the hood and less heat in the engine. It's only on when you need it to be. And in most cases, it requires little to zero upgrades to the fuel system or engine to use. Nitrous works great on turbo cars because it will also help cool the intake charge and the turbo."
- Matt Held, Nitrous Oxide Systems

"They're flying in those [naturally aspirated K-series Hondas] right now, absolutely flying. It works exceptionally well for road racing. The only problem is, if you have exceptionally long straights, a little squeeze will make you that much faster."
- Brian Gillespie, Hasport

"You might as well start tossing sticks of dynamite onto your cylinders and lighting them."
- Tyler Tanaka, Turbonetics

"No one really runs nitrous that much anymore in this industry. If you visit the message boards , or go to the races, you don't see that many people doing full-blown nitrous builds anymore. It's either a turbo setup or an all-motor setup. "
- Tony Shagday, Skunk2 Racing

"Nitrous cars may have cost covered at the front end, but after the sting of each bottle refill, those savings up front seem to dwindle. Not to mention the need to keep a watchful eye on bottle temperature, pressure and fuel for optimal performance and safety. Once the bottle is empty, you are forced to deal with a lower power level until the next refill."
- Michael Ullrich, Stillen


How it works: No forced induction, no spray. The all-motor (also known as naturally-aspirated) method of engine tuning means optimizing all the components already found in the engine. Using the engine-as-air-pump analogy, all-motor tuners concentrate on improving volumetric efficiency - helping the engine to breathe - at normal atmospheric pressures through intake, cylinder head, camshaft, valvetrain and exhaust modifications. Camshafts are typically the biggest contributors to power gains, followed by valvetrain and head work.

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All-motor tuners also earn power by increasing engine displacement with stroker kits, cylinder overboring or assembling hybrid "Frankenstein" engines, which is created by pairing a larger-displacement engine block with a cylinder head not offered from the factory. One of the hottest hybrids in the all-motor community right now is the Honda K24/K20, which combines a 2.4L block from a K24 engine found in Accords or CR-Vs with the K20A2 head, the RSX Type S head with VTEC on both the intake and exhaust cams. Combining the 2.4L's torque with the flow characteristics of a Type S head is a potent mix. When we visited Skunk2 Racing, there was a K24/K20-powered street-driven '88 Civic being prepped for a dyno pull that everyone expected would be near, or exceed, the 300-hp level.

One of the biggest knocks against the all-motor tuning route is its cost. The parts themselves are expensive, plus you have to factor in the labor costs for installation as well as any custom work, like head porting. Even the all-motor tuners admit theirs is far from a bang-for-the-buck solution to add power. However, if you're looking for moderate gains - in the neighborhood of 100 hp or so - the same $4,000 to $5,000 you'd spend on a turbo kit will get you there (or close) the all-motor way with a new cam and valvetrain, intake, throttle body, ECU programming, headers and exhaust.

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Where it works best:
Street, drag racing, road course

Bang for the Buck rating:
"Maybe a 4. The money becomes more of an issue as you step up."
- Charles Madrid, Skunk2 Racing (see above)

"With an all-motor car, the power curve is real broad and flat. Plus, the throttle response is really sharp, and really crisp. The power band has a different feel than a turbo car or a nitrous car. It's just a different beast, and the guys who go all-motor tend to like that beast."
- Tony Shagday, Skunk2 Racing

"I like the way it drives, the way it sounds. The throttle response is razor sharp. In a race, if you have two cars, one turbocharged and the other naturally-aspirated, the latter car could go just as fast, if not faster, with 20 percent less power. Once you come around the corner and put your foot down, the power's ready."
- Doug Macmillin, Hondata

"With the B-series engines, a GSR motor or a Type R motor, we know where our limit's at - how much power this motor can make. Now, the K keeps making power. That motor has so much potential. When we thought we were near the limit, boom, someone jumps it up. It just keeps going faster and faster."
- Charles Madrid, Skunk2 Racing

"The K motor, now that's insane. There's almost a cookie-cutter combo where people are slapping together the K24 bottom end with a K20 head, a 12.5:1 piston and a rod, and they'll put in some company's Stage 3 cam, and you can make 300 to the wheels, daily-driven and all-motor, that's completely reliable. Take those cars to the track and they can run low 11s on slicks."
- Tony Shagday, Skunk2 Racing

"I love an all-motor engine that makes big power, but I can tell you from experience that an all-motor engine that makes as much power as a nitrous engine will cost twice as much as a nitrous engine."
- Matt Held, Nitrous Oxide Systems

"If I had a 200hp Honda and I wanted 280, to 290 hp, I might spend, if I wanted to go all-out with a naturally- aspirated engine, $12,000 to $15,000 to build the engine - by sleeving the block, boring and stroking, with bigger valves, that's everything you can do. And I may get 80 to 100 hp out of it. Yet you could do that for $5,000 with a turbo or supercharger kit."
- Doug Macmillin, Hondata

"The naturally-aspirated guys are gluttons for punishment. No offense. I love Pro Stock - for the racing aspect. But to spend $100,000 to get 2 more horsepower baffles me. I don't like hitting myself on the head with a hammer and hoping for a different result. With $4,000 to $5,000, plus a couple of six-packs and wrenches over a weekend, you can double your horsepower with a turbo."
- Tyler Tanaka, Turbonetics

"Stroker assembly and cam setup may sing between 7,000 and 9,000 rpm, but from stoplight to stoplight you are left with a car that refuses to idle south of 1,000. In addition, pulling the motor and installing all of these internals is no cheap proposition. Plus, there's down time for the building, installation and tuning can run into months and even years, all at $95 per hour, plus the cost of your Ford Focus rental to travel to and from work. "When my car comes out of the shop it's gonna scream" is the battle cry of those brave enough to venture down this path."
- Michael Ullrich, Stillen

Turbo vs. NA: Dollar for Dollar

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Is the all-motor tuning route really that much more expensive than other power adders? That question prompted Charles Madrid and Tony Shagday of Skunk2 to do a cost analysis, comparing what it would take to add 75-100 horsepower to an otherwise stock '04 RSX-S using a turbo-charger versus leaving it naturally aspirated. Their results are in listed the chart below.

Note that the costs for the turbo pieces come from, but the Skunk2 prices are MSRP, meaning the "street" price of the Skunk2 components could be lower.

HKS 5,685.00
with 60mm exhaust and K-pro ECU
Full Race 6,294.00
Rev Hard 4,000.00
Greddy 3,644.00
Skunk2 Exhaust 70mm 631.75
K-pro ECU {{{900}}}.00
TOTAL $5,469
+Labor $800-$1000
+HP 75-100
Skunk2 Stage 3 Cams 836.{{{57}}}
Skunk2 High Comp. Valves 345.{{{80}}}
Skunk2 Tuner Series Springs 285.95
Skunk2 Retainers 226.10
Skunk2 Cam Gear (exhaust) 239.40
Port and polish head 700.00
Gaskets and seals 150.00
11.5 1 pistons 450.00
Oil pump 150.00
Rod Bearing 100.00
06 {{{Civic}}} Intake Manifold 303.24
Skunk2 Custom Adaptor plate 95.00
Skunk2 Throttle Body 345.80
Skunk2 Custom intake pipe 100.00
Headers 650.00
Skunk2 Exhaust 70mm 631.75
K-pro ECU 900.00
TOTAL $6,509.61
+Labor $1000-$1800
+HP 80-100


Skunk2 Racing
Norco, CA 92860
Costa Mesa, CA 92626
Nitrous Oxide Systems
Bowling Green, KY 42101
HASport Performance
Phoenix, AZ 85040
Torrance, CA 90503
Vortech Engineering
Oxnard, CA 93033
Simi Valley, CA 93065
Nitrous Express
Wichita Falls, TX 76310
Jackson Racing
Yorba Linda, CA 92887
By Drew Hardin
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