850+ WHP RSX and pure corn juice street car madness!!

This past weekend, I had the chance to tune a car that if you looked at it quickly aside from the large amount of meat on the front tires you probably would immediately notice that it could be packing near 900 hp at the wheels.

Sure it has a hood exit exit exhaust, but otherwise it’s a blue Acura RSX that has some wider wheels up front with some sticky Nitto NT01 tires, a simple cage and two matching blue Recaro seats on the inside.  On the outside it’s all just stock bodywork and glass, no extra lips or spoilers, no stickers, no extra anything.

Under the hood though, it’s all business… a fully built 2L K-Series motor, tubular exhaust manifold, twin Turbosmart gates and a Massive BorgWarner S400 turbo with a 67mm compressor wheel feeding this motor.


The fuel system consists of the standard array of upgraded lines, fuel rail + pressure regulator, feeding all that is a set of twin Bosch Motorsports “044” pumps, and atomizing the E98 corn juice is a set of FIC 2150cc injectors.

Electronics wise, the car was equipped with the latest ECU from AEM in plug in play fashion of the Infinity ECU line, an AIM dash and an ARC 8000 flat dash mounted switch panel.  All nice, clean and simple.


So, tuning this car with it’s AEM Infinity ECU did provide a few challenges… the provided layout files in the Infinity Tuner software didn’t work, lots of missing channels, etc.  The file in the ECU from the previous tuner wasn’t up to my standards either, so after running the car as is on the dyno with the current tune as per the owners request it made 607whp.  Unfortunately most of the tables in the ECU weren’t correctly setup from the get go and since this ECU is now calculating fuel delivery via a VE based model that means changes need to be done with forethought as there are many tables that play a role in the calculations and changing one effects another.

For me that meant starting from scratch, redefining all the table axis because they were not high enough to reach our final boost targets, and of course manually remapping the ignition, lambda, VE tables which were already somewhat of a mess so no big deal there.

2nd area of interest to the owner was boost control (specifically boost by gear), and launch control (2-step limiter).  Both of which he told me the previous tuner was unable to get working correctly or at all.  He had also mentioned that they were unable to make more boost, which I felt was odd since the boost solenoid was already a 4-port variant.

Truth be told, the issue was not with the hardware but rather again with the setup of the ECU, which means getting baselines for duty of the boost tables, and defining the PID controller for closed loop feed back.  If course to get the boost by gear working the ECU also needed to be told where each gear starts and ends so it knows what boost to target depending on the gear the drivers is in. This was also done once the mapping was complete.


The end result?  The car made an easy 850+ whp and an impressive 535wtq over a very broad power band for a 2L 4 cylinder.  This around 33-34 psi from the S400 turbo.  After which we started to run out of fueling in the top end.  We ended up turning it down just a bit to ensure that we’re safe.  Obviously 900+ was in the cards if there was fuel left on the table.


Even more impressive was the consistency of the setup, below you will see multiple back to back runs showing how consistent the power output of the motor is at just a hair under 30 psi (this was done during mapping of the boost duty tables) although we did encounter some wheel spin here and there as you can see on the red run



We are still working with the customer now dialing in the boost response on the street using the closed loop control of the AEM to make sure the car is always pulling as hard as it possibly can in each gear. To that end, I’ll leave you with a video of one of the dyno runs which I believe was in the mid-high 700whp ranges: