Originally Published in the Summer 2005 issue of Sport Z Magazine (now Nissan Sport)
By Jeff Wisener, with Dave Ochenreider and Connor Wisener
There is an old saying that it's unwise to head into a gunfight with a knife. We chambered six turbocharger systems for the VQ35DE engine into our Summer 2005 shootout: Turbonetics, Jim Wolf Technology, Air Power Systems, GReddy, Power Enterprise, and Speed Force Racing. Nissan Sport's associate editor Jeff Wisener-along with editor-in-chief Dave Ochenreider and former Nissan Master Technician Connor Wisener-took all six turbochargers out to the shooting range for a detailed analysis, from dyno testing to daily driving impressions.
Arguably the crown jewel of engine performance modifications is the turbocharger. Depending on the boost level (and other factors), a turbocharger alone can increase a motor's torque and horsepower by 30 percent to over 100 percent. Turbocharging can transform the well-balanced stock 350Z-already capable of matching a Porsche Boxster's performance-into a sports car rivaling the awesome performance levels of a C6 Corvette and even a Porsche twin turbo. Knowing the modification potential of the 350Z and G35, aftermarket manufacturers from around the world have introduced a flood of turbocharger kits.
Sport Z (now Nissan Sport) assembled the leading turbocharger systems for an April showdown in Southern California. We analyzed their design, measured their ease of installation and service, evaluated their performance in street driving, and-of course-tested their dyno delivery capabilities. California is the epicenter of the performance modification world and, not surprisingly, four turbocharger kits originated from there: Jim Wolf Technology (JWT), Turbonetics, GReddy, and Speed Force Racing (SFR). We also included Power Enterprise (PE) from Japan and Air Power Systems (APS) from Australia.
Testing Basics
Prior to testing, all participants were afforded an opportunity to review and comment on the proposed dyno testing procedure. Their input was included wherever possible. Each participant completed a form listing the tuning specifications and car's modifications included within this article. No objections were made by any of the participants prior to or during the testing.
The cars were inspected and analyzed by our staff for accessibility to perform routine maintenance and overall design of each kit. We used three drivers, testing each car in stop-and-go traffic as well as freeway driving conditions. A Dynapack 2000 dynamometer was used for this shootout (see sidebar).
All builders of these kits participated with us or had a chosen representative present during testing with one exception. Unfortunately, Peter Luxon of APS informed us that it would be months before they could furnish an official APS test car. Since no turbo shootout would be complete without APS, we opted to use a car from an authorized APS dealer/installer. We welcome the opportunity to evaluate an APS-approved car when available.
As for modifications, in a perfect world we would only test stock cars with zero modifications except for the turbocharger system. Easier said than done. Readers should take into account any additional modifications and how those mods might alter a car's performance.
A final note before we take paces. Some readers (and you know who you are) will focus on dyno results and peak power numbers. These dyno results represent how each car performed on this one particular day. Changes in tuning could easily change each car's dyno performance. The test team placed higher priorities on real-world driving characteristics, engine and component accessibility, and serviceability. Finally, we want to express our gratitude to all shootout participants for allowing us to evaluate and test their cars. Now let's head over to the OK Corral and get it on.
Boost level of standard kit: 8 psi
Boost level during test: 8 psi
Modifications to standard kit: A'PEXi exhaust Kudos:
* Easy to install and service
* Priced significantly lower than the competition
* A one-year, no-hassle warranty on all components Bottom line: The user-friendly, affordable turbo system has arrived
In the Garage
The Turbonetics kit is the only single turbo in this test. With just an 8-hour install time (according to Turbonetics VP Brad Lewis) this kit should be the easiest to install and among the easiest to service. With the typical twin turbo setup taking 20+ hours, this can add up to a significant cost savings. The turbo and blow-off valve are located basically right where the stock air filter enclosure was located, letting everyone know this is not your stock VQ motor. The mandrel-bent exhaust tubing is stainless steel and a Spearco intercooler is included with the price of admission. Direct drop-in 380cc Nippondenso injectors are provided, which can simply be plugged into the stock wiring harness, thus avoiding the task of cutting wires. "The kit is available with a catalytic converter option," explains Brad. "It is also available in a tuner version with no fuel injectors, no flash, and no fuel pump for the real do-it-yourself type guys." The Turbonetics system is designed to be "plug-and-play," using a reprogrammed stock ECU. The owner simply packs his ECU in the supplied pre-addressed, prepaid, static-free box and ships it via FedEx to Turbonetics. They'll reflash the ECU and return it the same day it's received. Brad emphasized that all kits include a one-year, no-fault, no-hassle warranty, which covers any part of the kit for any reason, be it street or track use.
On the Street
Turbonetics planned to use their own car for this article, but unfortunately it was not available the day of our test. Customer Robert Suarez volunteered his 350Z (less than 24 hours removed from the body shop after extensive repairs due to a collision, no less), driving in record time from Escondido to our testing hub: Church's Automotive in Torrance. During our 18-mile test loop, the car reached boost threshold at about 4,100 rpm and continued to pull hard to redline. The sweet spot of the power band for this car was found in the higher end of the tachometer. We did experience an unidentified vibration on the vehicle while driving, which Brad said was not normal. It turned out his concerns were justified. After a Turbonetics re-evaluation the week following the test, Brad reported that Robert's car had a boost pressure leak in the silicone hose leading to the intercooler. He thinks the damage most likely occurred during the Z's earlier collision. We're happy to report the Z is now performing up to Turbonetics' expectations (and the advertised 365 rwhp) and Robert got to take advantage of the hassle-free warranty.
Boost level of standard kit: 4.35 psi
Boost level during test: 4.5 psi
Modifications to standard kit: HKS V-Pro stand-alone ECU, Blitz SBC-111 electronic boost controller, Blitz DTT DC11 turbo timer, Koyo radiator, XS engineering transmission cooler, XS Transmission cooler, Stillen exhaust
Kudos: * Base kit capable of higher boost and power
* New cast manifolds provide more reliable operation
* High-capacity aluminum oil pan design Bottom line: Most expensive kit tested in a competitive market filled with high performers
In the Garage
The PE kit is a true bolt-on kit, requiring no cutting or modification to the chassis. PE selected PE1420 ball-bearing turbochargers, which have separate boost actuators. Owners can replace the stock #3 actuator springs, which produce 4.5 psi boost, with stiffer #4 springs, raising the boost level to 7.25 psi (or replace the # 5 or # 6 springs for even greater boost levels). "The advantage of the separate actuators is the spring's cost ($20 each to change), which is a much less expensive way of controlling boost compared to purchasing a boost and gauge controller," explains Patrick Egawa of Power Enterprise. The kit requires that the power steering cooler and reservoir be moved; PE provides brackets and hoses needed for the task. A new fuel pump, fuel regulator, and six PE 380cc injectors replace the stock components. The cast aluminum oil pan increases capacity by 1 liter and is finned to assist in cooling. SZM noticed the intake piping was comprised of many welded sections instead of mandrel bent tubing. We feel this is an area of the design we would like to see them address, much like they did with offering cast manifolds this year. Like all cars in this test, the PE kit had adequate heat insulation and maintained acceptable engine coolant temperatures throughout the day.
On the Street
The good news is this test car included the new cast exhaust manifolds just released from PE, which replaced the 304 stainless steel units that were included in the original kits. The downside? Jay Lopez, owner and installer of the kit, had his car tuned with the older manifolds to run at 8 psi and he did not have time to retune the car as needed for our test after installing the new manifolds. Pressed for time, Jay lowered his car's boost to 4.5 psi to get it to run safely for the shootout. We believe the low boost level and lack of retuning may account for reduced performance in this test. The test car did exhibit quiet and smooth operation regardless of the rpm level, although there was a slight hesitation at about 3,800 rpm when at WOT. SZM attributes this again to probably a lack of tuning and not a reflection on the kit itself. We were impressed with Jay's clean self-install, which was done on jack stands with occasional help from a friend.
Boost level of standard kit: 6.8 psi
Boost level during test: 7.8 psi
Modifications to standard kit: Flywheel, clutch, NISMO Differential, NISMO exhaust
Kudos:
* Water-cooled, full ball bearing turbochargers
* Has everything you'd expect from a factory turbocharger
* Benchmark drivability characteristics, with across-the-board horsepower and torque delivery Bottom line: A Wolf in sheep's clothing-this twin turbo is so well executed it could pass for stock
In the Garage
JWT is the last of the kits tested to enter the market. A G35 coupe version as well as a 350Z version of the kit is slated for release as soon as CARB-approval is granted. Attention to detail is evident throughout every component of this kit. Twin JWT/Garrett water-cooled full ball bearing turbochargers promise to provide long-term high-performance use. To take advantage of the air inlets on the G35, the JWT/Garrett dual intercoolers are located farther apart than on the 350Z, which has a narrower version for the larger single opening of the 350Z bumper fascia. The mandrel-bent aluminum intake piping design is well thought out and incorporates design components that assure balanced airflow. An oil pan spacer and pick-up spacer increase the engine's oil capacity and places the oil pick-up an inch deeper into the sump. This system uses a JWT ignition retard module to pull the timing as boost increases. No ECU reflash is required. Getting CARB certified was paramount for developer Jim Wolf. "We opted to use a recirculation valve instead of a BOV (blow-off valve) because this insures a more constant A/F ratio at all times." The Walbro 190 high-pressure/flow fuel pump and FMU are located in the fuel tank, eliminating additional external fuel lines and regulators. The result: a safe, clean design that is CARB friendly.
On the Street
Many Z enthusiasts were disappointed when the 350Z was introduced without a turbocharged model. All three SZM test drivers agreed that if Nissan produced a stock twin turbo 350Z, it would feel just like JWT's tight setup. The smaller, well-suited ball bearing turbochargers enable the power band of the JWT system to reach boost threshold early, at 3,100 rpm, and it keeps pulling up to redline. The power is linear, smooth, and deceptively powerful. If not for the aid of the 350Z's speedometer and later dyno results, we could have easily underestimated the performance capability of this system. Our dyno tests indicated impressive horsepower and torque numbers while being quiet in operation, vibration free, and mimicking the characteristics of the stock VQ motor, only with a lot more power.
Boost level of standard kit: Information not provided by manufacturer.
Boost level during test: 8 psi
Modifications to standard kit: Colder range NGK spark plugs, Kinetix high-flow cats, and Stillen exhaust Kudos: * Water-cooled, full ball bearing turbochargers
* This kit's strengths are found in the details
* APS does everything you'd expect it to do Š and more Bottom line: The boys from Down Under certainly did their homework to produce an impressive system
In the Garage
The more we looked at this system, the more we liked this Aussie offering. The water-cooled Garrett twin ball bearing turbochargers should provide years of trouble-free service, are fast spooling, and efficient Š yet have the combined capacity to produce up to 800 hp air-flow capacity at 16 psi boost. The high-capacity finned and baffled, cast aluminum oil pan is designed to add an additional 1.35 quarts of oil. This type of attention to detail may not affect the drivability characteristics of a kit during typical street driving (or, for that matter, a dyno pull) but pays off when pushing your engine in extreme conditions like those found when tracking your car. Roshan Harileta of Brainstorm Performance, who installed and tuned our APS test car, explained it like this: "I have installed numerous brands of supercharger and turbocharger kits on 350Zs, and what impresses me is the extent to which APS went to engineer every aspect of their kit." For example? "APS felt it would be best to replace the existing exhaust manifold studs with their kit, which are details most kits don't include." APS's engine management includes a plug-and-play wiring harness that requires no cutting of wires with tuneability using the Unichip. New injectors, fuel pump, and fuel-pressure regulator are included as well.
On the Street
The water-cooled full ball bearing turbochargers aided in delivering constant power at lower rpms until redline on our road test. The broad horsepower and torque numbers are also strong, making this a well-balanced kit. Roshan indicated the test car had Kinetix high-flow cats and a Stillen exhaust system, which are excellent products in their own right. However, he expressed the opinion that the optional APS exhaust system would produce even more impressive power gains. Regardless, our opinion of the kit would be the sameŠ a refined and well-balanced offering of high performance with excellent drivability characteristics.
Boost level of standard kit: 5.5 psi
Boost level during test: 8 psi
Modifications to standard kit: Walbro 255 high-pressure fuel pump, GReddy exhaust, GReddy custom test pipes Kudos: * Base kit provides all the essentials
* Bigger-is-better design sure to please tuner crowd Bottom line: As tested, it is loud and wild, reminiscent of a fast muscle car
In the Garage
GReddy was the first kit of this group released to the 350Z/G35 market. Like all the other twin turbo kits in this comparison, the turbochargers are housed underneath and basically out of sight when the hood is first opened. The GReddy and other TT kits all have reasonable access for service; changing plugs or other routine tasks will not be a nightmare for owners. The large front-mounted GReddy type 23R optional intercooler capable of high-boost applications requires the horns and air bag sensor be relocated and the bumper reinforcement removed. Massive Mitsubishi TD05H-18 turbochargers with GReddy TIAL external wastegates feed this system, leaving ample room for owners to tune and enhance the performance of the standard kit. Fuel management is provided by GReddy's E-manage, allowing flexibility for tuning.
On the Street
Nothing about this kit is subtle. The GReddy test car's enhanced modifications clearly demonstrate the ability of this kit (and others) to be converted into a brute, rivaling almost any car you might encounter on the street. From the first nudge of the gas pedal, one realizes this kit transforms the VQ into a car begging to be driven hard, preferably WOT. Power from the GReddy slaps you in the face at around 3,700 rpm and by 5,000 rpm the beastly sound created with the optional test pipes and exhaust-combined with the spooling of its large turbos-provide a rush similar to that found in a race car. Our test drive revealed what the dyno later confirmed: the GReddy test car provides ample power in midrange, building to an abundance of power as you near redline. Yes, the optional fuel pump included in the test car is a little noisy, but it matches the kit's nature, which is raw and in your face. With the GReddy you just need to add modified engine internals, boost, and tuning to challenge heavily modified Supras for dyno bragging rights.
Boost level of standard kit: 6.7 to 7.0 shipped
Boost level during test: 8 psi
Modifications to standard kit: SFR custom intake manifold, high-stall torque converter, SFR test/Y-pipe, Fujitsubo exhaust Kudos:
* Stainless steel tubular exhaust manifolds (headers) and optional intake manifold sure look sweet
* 800+ hp potential for those willing to build the motor and boost
* This may not be Burger King, but SFR wants you to have it your way Bottom line: Custom turbo kit philosophy comes to the masses
In the Garage
Tim Richards of Speed Force Racing had a primary goal for their kit: "good performance out of the box, yet have the ability to ultimately produce 800 to 1,000 horsepower." They opted for Turbonetics's T3 turbochargers over the smaller Garrett T-28 hybrids because, says Tim, of the T3's greater horsepower potential. SFR uses an uncommon design for their 321 stainless steel exhaust manifolds (headers). According to SFR, their exhaust produces a broader horsepower and torque power band through its equal-length runners, which provide higher exhaust flow and velocity with less back pressure. They also mounted their turbos low to eliminate problems associated with heat generated by the turbos. High-output SFR 440cc injectors are included as well as a Split Second P1SC digital fuel controller for engine management. Installation requires that two wires be cut and soldered to add the piggyback unit.
On the Street
SFR specializes in tailoring its kit to meet whatever the customer might need. Their test car certainly reflects this philosophy. A custom intake was added as well as twin wastegates. "The custom intake on the test car produces slightly less low-end torque than the stock plenum at this boost level but really is advantageous for higher boost applications," explains Tim. The T3 turbochargers appeared to reach boost threshold just after 3,700 rpm and kept pulling to redline on our test drive. The power was smooth and strong, especially in the higher ends of the rpm range. Readers should remember that both the SFR and PE test cars had automatic transmissions. The Dynapack we tested these cars with was better suited for testing manual transmission vehicles at these power levels. Due to high levels of "flash" torque, dyno pulls for both of the AT cars started around 3,500 rpm. (See Church Automotive sidebar for more information.)
Each of these kits has distinct characteristics--you, the consumer, has to decide which of those qualities match your personal performance goals. Looking to jump into the turbo market but tight on cash? Turbonetics allows consumers to own a turbocharged 350Z or G35 for less money than the others, is relatively easy to install, and performs well. Want to ramp up your Z or G to crazy power levels? The GReddy kit is the least expensive of the twin turbo kits and offers tons of potential for those seeking to build their motors beyond entry level. Prefer stock-like build and performance? JWT produces a well-balanced system that performs smoothly and delivers impressive power at any rpm (and may be the first turbo system to offer CARB approval). Want something no one else has … and plan to turn it into something ever better? The SFR kit has large turbos begging to be boosted higher and their unique exhaust manifold configuration helps set it apart. Need flexibly to increase a kit’s boost and performance inexpensively? The Power Enterprise kit is quiet and smooth with sound components and power that can be increased simply by changing the actuator springs. Seeking rock-solid design backed up with performance? APS impresses us with its thorough design and refinement plus the potential to be upgraded with the optional APS “Tall Boy” plenum and APS dual 2.5” cat back exhaust system.
In most comparisons, readers tend to want to know who the “winner” is. Truth told, those seeking significantly greater performance from their Z or G can achieve it in any one of these turbocharger systems. So like our earlier supercharger (Spring 2004) and exhaust (Fall 2003) shootouts, we'll let you, the reader, decide what turbocharger setup works best for your needs
Sharp-eyed readers have noticed Church Automotive Testing mentioned in more than one issue of Sport Z Magazine. With all the dyno facilities in the Los Angeles area, why use this one shop? Simple-we like the way Shawn Church does business. Few meet his attention to detail, consistency of dyno operation, tuning ability, and overall professionalism.
Shawn, tired of paying big bucks to Honda S2000 tuners for limited results, started Church Automotive Testing in 2002. In only three years, his shop has gained regional and national acclaim, with frequent writeups in popular tuner magazines and the New York Times.
A new Model 4000 Dynapack will soon join the Model 2000 at Church's new 8,400 sq ft facility in Wilmington, California. According to Shawn the 1,300 hp / 3000 lb-ft dyno can be used for 2-wheel drive cars or it can be teamed up with his 500 hp / 400 lb-ft Model 2000 for AWD capability.
Like many things in this world, the relative advantages and disadvantages of each type of dynamometer are open to debate. Sport Z covered some dyno basics in the G35 Dyno Marathon Article (Winter 2005). For the few that missed it, the Dynapack power absorbers attach directly to the wheel hubs. According to their website, this eliminates the disadvantages related to tire/roller interface, enabling their dyno to make very sensitive readings over a wide range of engine speeds. And, unlike most dynamometers that incorporate a spark lead pick-up, the Dynapack uses hub speed to reference engine rpm. This works well and provides very repeatable (within 0.3 percent) dyno pulls-when used with a manual transmission and known rear-end gear ratio.
What works very well on an MT, isn't as good with an AT. Dynapacks depend on a constant engine-speed-to-hub-speed relationship for rpm data, and unless the torque converter can be "locked up," there's a chance of skewed dyno results. Even with a lock-up converter, dyno runs must be started above the converter's stall speed, around 3,500 rpm for 350Zs and G35s, to avoid "flash torque" readings and errors. Dynapack is considering a spark-lead pick-up option and Church Automotive Testing will be first in line if they do.
