If the turbocharger can be described as the heart of the system, then the intercooler must surely be the “lungs”!!
APS has designed and manufactured a custom configured, vertical flow high efficiency intercooler utilizing custom designed light weight cast aluminum end tanks. Extremely high flow rates and massive temperature reduction - a level of performance that other manufacturers can only aspire to achieve.
With a huge 25” x 9” x 3.5” core, at 650 hp flywheel, the pressure drop is less than 1.0 psi. At the same turbocharger flow conditions, the intercooler outlet temperature is less than 15°F higher than ambient, at any vehicle speed over 50mph. Truly outstanding results at such a huge horsepower level. So just like the APS turbochargers, the APS intercooler has massive additional headroom available.
Vertical flow inside the APS intercooler is by far the optimum configuration given the space considerations that must be accounted for in the front of the vehicle. This solves the huge air flow restriction problems that horizontal flow cores experience particularly at high power levels.
The horizontal flow configuration shown above forces the charge air to flow through very few internal intercooler passages. In addition, each internal passage is very long, causing further restriction to charge air flow - resulting in a high pressure drop.
The vertical flow configuration as specified by APS spreads the charge air flow evenly over a far greater number of internal passages and results in significantly less restriction. The path length of each internal passage is also shorter, with a smaller fraction of total charge air through each passage, thus further improving air flow over a horizontal design. The net effect is massive charge air reduction but with improved air flow and less restriction over a cheap horizontal core configuration intercooler.
Another important aspect of intercooler design for the 350Z is the number of times the charge air must change direction in order to enter and exit the intercooler. Since air flow is momentum based, each time the charge air must change direction, it consumes energy - which results in high pressure drop and reduced engine power.
With a horizontal flow core, the velocity vector turns 90 degrees twice on entry and again twice on exit. In addition, both turns must take place inside the hight of the end tank.
With the APS vertical flow intercooler, the velocity vectors turn only once over a very wide distance on entry (up to half the width of the core = 25/2 = 12.5 inches) on entry. This allows the air to turn very gradually a good thing. Air flow is momentum based and the end tanks on the APS intercooler are designed so that an equal mass of air reaches each internal passage. On exit, a similar situation exists however this time, the air velocity vector turns 90 degrees over a smaller distance (essentially the height of the exit end tank. This is one reason why the exit end tank is taller than the entry tanks.
Importantly, the APS intercooler uses the latest in Bar and Plate core technology, not low cost off the shelf tube and fin. Other than the fact that the APS intercooler core boasts the highest flow and greatest temperature reduction, the bar and plate construction results in an inherently strong intercooler core of high thermal inertia. The advantage here for the performance street car and drag race enthusiast is that with the core's high thermal inertia, massive reserves of cooling capacity are available in situations where ambient air flow over the core is low. So, after a power run to heat tyres prior to staging for a quarter mile pass, there is plenty of intercooler capacity to launch with full power at your disposal - rather than forsaking power with a tube and fin construction core that becomes heat soaked during the initial burst.
Another aspect worthy of consideration is the internal air passage cross sectional area and fin arrangement of the APS Bar and Plate construction in relation to tube and fin. The tube and fin core has a 5mm edge boundary so for say a 3.5" thick core, you lose half an inch in internal thickness which impacts on passage cross sectional area. In addition, the fins are extruded so they are essential in a straight line and parallel to flow. This means that the internal surface area presented to the charge air is nowhere near as great as that on a traditional bar and plate which has an alternating offset internal fin arrangement. The result is the bar and plate core used in the APS intercooler flows better and removes far more temperature than the traditional horizontal flow tube and fin. These are just some of the reasons for APS specifying this vertical flow bar and plate core on the 350Z TT.
That said, for other vehicles, other configurations may be applicable, which is why taking a general purpose core from one vehicle and using it in another different type of vehicle is often fraught with problems even though the cores may be of similar size.
Unlike other systems that require cutting or removal of structural components at the front of the vehicle, APS has designed the 350Z FMIC as a truly bolt-on unit that not only maintains the structural integrity of the vehicle, but also delivers outstanding intercooler performance.
In addition, the dual entry design of the APS intercooler allows for the ultimate in true equal length balanced ducting from each turbocharger to the intercooler.
Ducting length is critical on the 350 Z in order to achieve balanced induction and excellent driveability. By designing the turbocharger to intercooler ducting specifically to be of equal length, each turbocharger experiences exactly the same effective air path to the intercooler which results in totally balanced turbocharger performance. Other systems that are designed with unequal length, experience boost pressure and air movement issues where under certain conditions, one turbocharger pushes air back through the intercooler and into the other turbocharger ducting. As air movement is momentum based, this is simply wasted energy that should be better put towards producing horsepower, not restriction. In addition, these systems of unequal length take the charge air from one turbocharger all the way across the engine bay to the other side in order to enter the single air entry point to the intercooler. This creates a massive restriction compounded even further by having to turn almost 180 degrees in order to enter the intercooler.
The advanced APS dual entry intercooler not only solves this problem but allows APS to utilize true equal length ducting - the most efficient routing for the twin turbo Z!
The APS intercooler core is of internally finned construction and offers significantly enhanced flow and heat exchange performance, particularly at high charge air mass flow rates. Also, unlike other manufacturers of intercoolers who reduce cost by using low cost off the shelf cores, the APS intercooler is designed with the optimum ratio of intercooler core surface area (over 225 square inches!) to intercooler volume (787 cubic inches). The result is an intercooler system with outstanding flow and cooling performance, particularly at high engine horsepower levels of 500 - 700hp.
However, there is more to intercooling than size alone. Fully engineered light weight, cast aluminum end tanks ensure optimum charge air distribution throughout the entire cooling core for maximum charge air cooling and minimum pressure drop.
The reality of intercooler excellence in terms of performance equals:
- Largest intercooler surface area possible
- Optimal intercooler internal passage volume
- Lowest possible pressure drop
- Highest possible intercooler core efficiency
- Matched to the turbocharger air delivery in lb/min
In other words the greatest possible charge air temperature reduction with the lowest possible pressure loss at the rated flow of the turbocharger - Whilst maintaining good throttle response.
An intercooler drops the charge air temperature, which enhances the combustion of the air/fuel mixtures. This more complete combustion of air fuel mixtures produces higher engine power.
Intercooler performance is measured by the amount of energy (temperature) the intercooler can remove from the inlet charge air as well as the pressure drop across the entire system. It is important to consider the entire intercooler system and not simply the intercooler core itself.