APS Tall-Boy Balanced Distribution Intake Plenum

At high engine horsepower levels the stock inlet plenum not only becomes restrictive, but more importantly the air distribution across cylinders becomes uneven and results in a variation in air/fuel mixtures from cylinder to cylinder.

To solve these issues, APS has developed what is arguably the ultimate inlet plenum for the 350Z in high horsepower naturally aspirated and forced induction applications.

In day to day driving conditions, the APS Tall Boy plenum delivers crisp throttle response and higher torque - resulting in an even more enjoyable drive. And the higher the horsepower, the wilder the ride!

Cast in light weight alloy and then NC precision machined, the APS plenum pumps-up the internal plenum volume and delivers the optimum distribution of air to each inlet trumpet.

For ultra high horsepower (over 600 flywheel horsepower) applications, the APS Tall Boy plenum has provision for an additional 6 auxiliary injectors - one for each intake runner.

An often asked question of APS is why two injectors per cylinder and not one very large injector in the stock location. Injectors have fidelity to operate within a well-defined range. When operating outside their “sweet spot” range, particularly at very low injector duty cycles (low fuel flow rate conditions), the fuel injection and combustion characteristics degrade. For example, to expect injectors for the 350Z that can support 900 horsepower to trickle fuel in an efficient manner at 35 mph cruise is a tall ask. As is any situation really where light throttle/low engine rpm operating conditions are called for.

Traditionally, it is easy to just slip in a set of large injectors to support the desired engine power level and tune accordingly. Yes the engine will start, run and make power, but fuel economy, throttle response, emissions etc will suffer accordingly. When fitted with an appropriate set of injectors for part throttle applications, the engine’s “laziness” improves markedly and you end up with a car that feels crisp and responsive at light throttle and returns the optimum fuel economy at highway cruise.

Because many APS 350 Z TT customers use their Zs as daily drivers, APS feels that it is important that APS delivers a fuel system (indeed the whole intercooled TT system) that results not only in big horsepower, but strong torque and crisp throttle response throughout the entire rpm range – as well as the best fuel economy possible.

The dual injector per cylinder approach that APS has taken with the 350 Z is one that utilizes the primary injectors for engine operating conditions that require modest fuel deliver, but then begin driving the secondary injectors as the fuel demands increase over and above those that the primary injectors are able to supply. The net effect is regardless of the engine’s operating conditions, the optimum fuel spray and combustion characteristics are realized in addition to the optimum amount of fuel for the power demand.

With the base APS 350 Z Intercooled TT, a larger set of injectors and bolt/plug-in fuel system is included to support up to 600 horsepower and this is about as large as one should go with the 350 Z before affecting the driving characteristics discussed above. The APS 900 horsepower upgrade fuel system to be released in the near future will utilize the stock injectors as secondary injectors and these will be mounted in the APS plenum.

Whilst the secondary injectors/plenum combination is a technically demanding approach (engineering wise), at the end of the day the cost to the consumer is kept to a reasonable level because the stock injectors are utilized to supply the additional fuel requirements. The benefits of improved throttle response and fuel economy over larger injectors are in my opinion worth the effort.

With dead true NC machined mating faces, the APS Tall-Boy is a direct bolt-on replacement of the stock plenum and utilizes the stock gasket. All ancillary hardware for easy installation (in under an hour) is included.

Power through precision is a frequently heard motto at APS - and the Tall-Boy plenum is a perfect example.

NOTE: High Rise strut brace required for clearance above APS Tall-Boy plenum.