If any component can be truly described as the “heart” of a turbo system, then the APS Intercooled Twin Turbo system for the 4th generation Fbody truly has the biggest heart of all!! Or, to be precise, TWO hearts!!
With the V configuration of the LS1 engine (two banks of 4 cylinders each), each bank drives its own turbocharger for truly balanced engine operation. The APS twin turbocharger approach completely solves the problems associated with single turbocharger system configurations that route exhaust gasses from one bank of cylinders, all the way across the engine bay to finally join up and drive the single turbocharger.
Twin, state of the art and liquid cooled turbochargers deliver 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 dynamics of the vehicle.
The highly specialized turbochargers are based upon custom Mitsubishi gasoline spec turbochargers with an Inconel 713C turbine wheel, liquid cooled bearing housing (50 lbs per minute mass air flow @ 18 PSI), APS single entry .84 A/R turbine housings with external waste gate port/provision and APS designed and manufactured .65 A/R compressor housing.
But engineering excellence doesn't just stop with the turbochargers alone.
High engine bay temperatures have always been the Achilles heel of forced induction engine performance. With each turbocharger tucked up under the chassis, heat is channelled away from the engine compartment for high engine durability and consistently high engine performance. With the APS stealth Twin Turbo configuration, under bonnet air temperatures are a fraction of traditional turbocharger designs. Let's face it, nobody likes to wait for extended cool down periods, when you can simply turn around and line up for another screaming pass down the quarter mile track.
The turbochargers are positioned low and mean (right where the stock air flow is designed to carry and discharge hot under-hood air) with the turbine side facing rearwards. This ensures normal operation of the steering rack components and provides the best protection to the many ancillary components both inside and under the engine bay.
Each liquid cooled turbocharger is directly coupled to the custom APS High Energy exhaust manifolds, cast in super tough high silicon/moly Iron for maximum durability and precision NC machined for leak free exhaust operation. In addition, this superior exhaust manifolding design transfers the greatest amount of total energy to drive each turbocharger and delivers instant engine response (even in part throttle openings) - for the most awesome ride of your life!
Custom trimmed OEM quality heat shields are also included with the APS Intercooled Twin Turbo system for low under hood temperatures and the maximum exhaust gas heat retention - to deliver the highest energy to each turbocharger.
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 liquid 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.