The original and subsequent Hondata systems involve the ability to add multiple capabilities to the original Honda ECU. These include datalogging, boost control, launch controls and, most importantly, full fuel and timing control. These changes are implemented with some add on hardware, an emulator and a rom burner (so the owner can reprogram the ECU himself). When Hondata began to look at the RSX ECU, they realized that things would be a bit different because the ECU is reprogrammable from the factory! That's right, the RSX, Civic, CRV and probably the new Accord all use a flash based ECU which allows dealers to reflash the ECU with new maps should Honda deem it necessary. This meant that Hondata needed to take a different approach. After much work, they've developed several new engine control maps for the RSX-S. However, the ECU is not user reprogrammable, so you need to take your ECU to a Hondata reseller to have the new program uploaded.

Before we go any further, I must provide a disclaimer. Hondata spent many hours on my Dynapack dyno developing the ECU maps for the RSX. I watched in awe as power figures continued to go up and up. But since I was involved in the development process (even though I didn't have anything to do with the ECU), fair reporting dictates that I make that clear to you, the reader.

Now, for the juicy stuff. I've now tested several cars with the Hondata ECU on the dyno, and the performance gains are simply incredible. Below you can see the Hondata provided graph and I can tell you that the gains are representative of all the cars I tested. The car in the graph was completely stock with the exception of the Hondata ECU and a Hondata intake gasket (the gasket was in place for both the baselines and the ECU test).

Even better, in my opinion, are the results on modified cars. On my Dynapack, a stock RSX-S produces approximately 170-171 axle hp (vs. 160 or so on a Dynojet). With a simple cold air intake, those numbers jump into the mid-high 180's (188 in the case of the test car I worked with). Based on past history with Honda engines, you wouldn't expect to be able to get much more without internal changes, and certainly not with ECU maps. But you'd be very, very wrong. The owner of the 188 hp car purchased one of the first Hondata ECUs and came back to my dyno. The results? 202 axle hp and a torque curve that made over 90% of peak torque from 2000 to 7000 rpm. Just for reference, a stock S2000 produces 210-214 hp on my dyno, so that would mean that the RSX-S, with just a CAI and Hondata ECU, is producing just 10 hp less than the 240 hp S2000! That is very, very impressive.

I also was given a chance to perform some instrumented testing on the stock RSX featured in the published graph from Hondata. I spent about 45 minutes driving the car with both the stock and Hondata ECU programs and doing some simple acceleration tests with TOV's Vericom VC2000 acceleration performance computer. The first thing one notices when switching from the stock maps to the Hondata maps is the low end performance. Off the line and at very low rpms, the engine pulls with much more authority. On the freeway, 6th gear would pull comfortably from as low as 2000 rpm, and with authority from 2500-3000 rpm or so. The second thing you notice is the improved high end power. With the 8600+ rpm rev limiter (there are a couple of options available, but we shifted at 8600 rpm), each gear pulls much longer and shifting puts you in a meatier part of the power band than with the stock limit. All told, the engine feels a lot more impressive, with a more linear torque curve, more low end, more top end, etc. The previous 5k-6k torque dip is virtually gone (and is completely gone when you add an intake) and the car is just more fun to drive. And the objective results reflect this as the table below will show.