The Dyno

As we saw in the first installment, tuning can greatly impact the performance gains realized by every individual component. Again we called on Koji to tune the A’PEXi Power FC engine-management system. Dyno figures would again be measured on both the DTS AWD dynamometer at XS Engineering in Garden Grove, California as well as the Dynojet dynamometer at MD Automotive in Westminster, California. The Silvia finished at 232.6 horsepower at the wheels the last time it was strapped to the DTS dyno.

232.6 WHP
215.7 LB-FT TQ

Test 1: BLITZ LM Intercooler

In comparison to the factory intercooler, we noticed a drop of nearly 20-degrees Fahrenheit at the intake manifold, clearly illustrating the benefit of the larger surface area for heat exchange. The added cooling capacity with the increased boost pressure resulted in an increase of 29.1 peak horsepower and 33 lb-ft of peak torque. Linear gains were recorded throughout the RPM range from 2,700 RPM through redline.

261.7 WHP
248.7 LB-FT TQ

Blitz aluminum “Tube and Fin” intercooler cores exhibit low pressure drop while effectively lowering intake air temperatures. In comparison to the factory intercooler, we noticed a drop of nearly 20-degrees Fahrenheit. Once the intercooler was in place, the boost was safely increased to 18psi (1.25bar). The added cooling capacity and increased boost pressure resulted in an increase of 29.1 peak horsepower and 33 lb-ft of peak torque.

Test 2: A’PEXI Super Suction Intake Kit

With the A’PEXi Super Suction intake kit (p/n 538-N021) installed, we were back on the dyno with the boost set to 18psi. The fuel and ignition maps were adjusted for the additional airflow the turbo could now generate. The S15 generated gains on the order of 6.6 peak horsepower. Five-to-ten horsepower gains were noticed from 2,500 RPM to 3,500 RPM as well as from 6,000 RPM to redline.

268.3 WHP
250.1 LB-FT TQ

The Super Suction kit intake pipe is a polished, cast piece that is not susceptible to collapsing like the factory rubber hose. This intake installed without incident, allowing us to remove the restrictive stock MAF sensor and sensor housing. This allowed for gains on the order of 6.6 peak horsepower.

Test 3: Tanabe Cat-Delete Pipe

We installed the cat-delete pipe that was included with the Tanabe Medalion Concept G Blue exhaust system. With practically no restriction or bottlenecks left before or after the turbo, the free-breathing GT28R helped to generate 268.9 peak horsepower and 261.5 lb-ft of torque. Although peak power only gained slightly, there were incremental gains of five-to-ten horsepower from 4,000 through 6,500 RPM. The torque curve was also smoothed out significantly, showing torque gains of five-to-15 lb-ft also between 4,000 and 6,500 RPM.

268.9 WHP
261.5 LB-FT TQ

Constructed from 80mm piping, theTanabe Concept G Blue cat-delete pipe installed without a hitch. The Concept G Blue turbo-back exhaust was intended as an off-road, race-only system. With practically no restriction or bottlenecks left before or after the turbo, the free-breathing GT28R helped to generate 268.9 peak horsepower and 261.5 lb-ft of torque.