If any component can be truly described as the “heart” of a turbo system, then the APS 350Z system truly has the biggest and quickest heart of all!!
A state of the art and water cooled Garrett twin ball bearing turbocharger delivers ballistic power with bullet proof turbocharger reliability - and with a custom APS aerodynamic configuration, that ballistic power is delivered in an extreme efficiency and super compact package that is ideally suited to the 350Z vehicle dynamics. In fact, with a built engine, how about 650 hp air flow capacity at just 16 psi of turbocharger boost pressure!
With the turbocharger mounted low and mean in the 350Z, APS ensures that the greatest amount of exhaust gas energy is available to the turbocharger for crisp turbocharger response and high power and torque. This solves the turbocharger lag problems associated with systems that situate the turbocharger inside the Z's engine bay. In addition, high engine bay temperatures (which is of great concern in high performance vehicles) are alleviated by the APS turbo system design. In fact, with positive manifold pressure just above idle and full steady state boost pressure at 2,500 RPM, the APS turbocharger delivers outstanding torque that others can only hope to achieve. After all, nobody likes to wait.
High energy exhaust gasses are routed from each cylinder bank in the shortest distance possible directly into the APS turbocharger. Shaving every inch of exhaust tube from the total length to the turbocharger counts when it comes to delivering all the available gas energy to the turbocharger for optimum turbocharger response.
Exhaust gases from the RHS cylinder bank are routed over the bell housing via cleverly designed 321 grade stainless steel tubing that is surrounded by highly effective heat shielding - to ensure no additional heat load to the bell housing assembly. In addition, a custom 321 grade stainless steel expansion/vibration joint is utilized at the highest point of the cross-over tubing to completely eliminate any exhaust leaks through expansion/contraction of the tubing when heat cycled. This also serves a very impotant role to minimize structural loads upon the exhaust manifolds.
Exhaust gasses from the RHS and LHS exhaust manifolds are combined via the innovative APS High Energy turbocharger entry pipe to direct the maximum amount of high speed/high energy exhaust gas into the turbine. Like the rest of the pre-turbo exhaust components utilized in the APS turbo system, 321 grade stainless steel is used for tubing and flanges (which are precision TIG welded to the tubing both inside and out for maximum durability).
And to top it off, a sturdy and robust impact shield is included for those situations where the driver may feel road obstacles or stones may present a hazard.
In reality, the location of the turbocharger in the APS intercooled single turbo system provides better protection than those that utilize the area in the front left hand side of the engine bay. This is due to the fact that a more likely scenario is a frontal collision that may damage the turbocharger assembly as opposed to a severe impact from underneath the vehicle that would need to destroy the front cross member and impact shield in order to damage the APS turbocharger. In any event, APS has the bases covered.
Note: Impact Shield above shown in raw state prior to applying protective coating.
|In a nutshell, through innovative turbocharger and tubing design, the APS intercooled single turbo system delivers crisp turbocharger and throttle response, strong low to mid RPM torque and outrageous high end horsepower to take the 350Z directly into the supercar club.
Why Twin Ball Bearing?
Demands for improving acceleration response and for the reduction of so-called turbo lag are popular amongst performance enthusiasts who wish to take advantage of the enormous gains in power and torque delivered by turbochargers. In addition, bullet-proof reliability is required particularly at high turbocharger boost pressure levels as well as at extreme exhaust gas temperatures commonly found in high performance turbocharged engines.
In order to achieve crisp turbocharger response, a number of advances in turbocharger design have been utilized over the past decade. Primarily through the use of modern metals/ceramics in order to reduce the mass of the rotating assembly. However, significant gains have been made by reducing the friction of the rotating assembly - and this has meant a departure from traditional turbocharger designs.
Traditional turbocharger design employs a conventional plain bearing that runs on a film of oil. This is known as a floating metal bush.
The diagram above shows the turbocharger main shaft supported by floating metal bushes. Oil is fed through the bushes and forms a cushioning layer between the turbocharger shaft and the supporting bush. The shaft relies on a constant supply of fresh, clean oil over a very wide contact area in order to maintain sufficient clearance from the bush itself. A similar approach is used to support the turbocharger main shaft from thrust loads as well.
Whilst floating metal designs have served us well in the past, the frictional forces are relatively high. This results in sluggish turbocharger response and can be somewhat fragile in nature under extreme operating conditions.
Nissan attacked this very issue some 15 years ago on the GTR Skyline by developing a turbocharger bearing system that forms the basis of the true high performance modern turbocharger.
By utilizing robust ball bearings at either side of the turbocharger main shaft, this did away with the floating metal and thrust bushes.
|APS turbocharger rotating group above is a true twin ball bearing unit that not only delivers huge power and torque, but is also extremely robust and incredibly compact in size.
As seen in the diagram above, the turbocharger shaft is supported by two ball bearing assemblies. These again are fed with engine oil, but no longer rely on a thin film of oil over a wide area to support the turbocharger shaft.
The result is an outstanding reduction of frictional torque on the rotating turbocharger assembly in contrast to the old fashioned floating metal bushes. The improvement in turbocharger response, particularly in the lower to mid turbocharger speed range is phenomenal.
The graph above shows frictional torque versus turbocharger speed of both old fashioned designs and modern ball bearing turbochargers. Clearly evident are the improvements with ball bearing turbochargers - especially at the low speed range of under 60,000 RPM where friction losses are reduced by 40% to 50%. This translates directly into a quantum leap in turbocharger response.
To show this in another way, the above chart demonstrates the mechanical efficiency advantage of the dual ball bearing design compared to journal (floating metal) and hybrid ball bearing turbochargers. The improved mechanical efficiency of the dual ball bearing design results in exceptionally crisp and strong throttle response over that of lesser turbocharger designs. This produces an improved response that can be converted to quicker 0-60 mph times.
Reduced Oil Flow
The dual ball bearing design reduces the required amount of oil to provide excellent lubrication. This lower volume reduces the lubrication load upon the entire engine lubrication system and allows more oil flow to vital engine components - resulting in improved engine durability.
The oil flow through the turbocharger is contolled precisely through an innovative oil flow control module that also acts as a highly effective debris separator in order to keep potentially harmful foreign particles from entering the turbocharger bearing assembly.
Improved Rotordynamics and Durability
The ball bearing cartridge delivers exceptional damping and control over shaft motion, allowing enhanced reliability for both everyday and extreme driving conditions. In addition, the opposed angular contact bearing cartridge eliminates the need for the thrust bearing, commonly a weak link in the turbo bearing system.
And best of all for those who wish to push the limits, ball bearing design turbochargers provide significantly higher robustness by better supporting the rotating turbocharger assembly, as well as better spreading thrust loads over old fashioned methods.
Whilst turbochargers began to be applied to passenger cars in the late 1970's in response to the energy crisis, the first generation passenger car turbochargers were derived directly from commercial diesel engines. Engine oil was used to provide both lubrication and cooling and whilst this was an effective compromise between cost, durability and performance, in high engine performance applications durability suffered through fouling of the turbocharger bearings through high turbine and bearing temperatures.
By encasing the turbocharger bearings in intricate water passages, engine coolant is used to significantly reduce turbocharger bearing temperatures in order to eliminate the coking and lacquering issues that fouled old fashioned turbocharger bearings. Non water cooled turbochargers have no place in a high performance gasoline engine application and should be avoided at all costs.
The graph above shows the turbocharger bearing temperature leading up to engine shutdown and for 20 minutes following shutdown. The temperature is displayed relative to the coking threshold of high quality mineral based oil.
As is clearly evident, the old fashioned non water cooled turbocharger operates above the coking threshold when under high load and experiences a very high temperature increase through heat soak immediately after engine shutdown. The APS water cooled turbocharger on the other hand remains cooler than the coking threshold at all times and the bearing temperature increase through heat soak immediately after shutdown is reduced drastically.
|By specifying the latest in turbocharger designs that incorporate both water cooling and true twin ball bearing designs, the APS turbochargers deliver bullet-proof reliability and durability along with exceptional power levels and unprecedented no-lag turbocharger response.
|Click Here for a discussion on how one turbocharger can deliver greater engine horsepower than another turbocharger at the same boost pressure.
|Click here for a discussion on turbocharger boost control and the affect a restrictive exhaust has on turbocharger boost pressure.