This reflash is specifically tuned for a K20A2 engine using Type R camshafts.

Applications

• K20A engine or K-Series engine built to K20A specifications (ECU part number PRB A01 through PRB A08 or PRC)

We do not recommend the use of nitrous or forced induction for this reflash. For these applications use the K-Pro.

Pricing

• K20A ECU flash program 5200 VTEC and 8800 rpm REV limit - $595
• K20A Flash upgrade - $200

The upgrade price applies to any K20A2 (RSX type S) owner that already has a Hondata flash program.

Hondata does not sell direct - all sales and payment must be conducted through Hondata dealers. The upgrade information form must be sent with your ECU.

Details

The engine tested here is a JDM K20A engine with Hondata intake gasket, CAI (cold air intake) and cat back. Headers and cat were stock RSX. Also tested was a bored and tapered 64mm throttle body. The major variations this engine has compared to the US K20A2 are:

• Cams (same lift and more duration)
• Compression (up from 11 to 11.5)
• Intake manifold (wider runners)

Three programs were tested.

• The stock ITR ECU
• The K20A2-4 flash program
• An optimized K20A2 program

Results at a glance

The RSX K20A2-4 program performs substantially better than the stock ITR ECU adding significant torque from 5500-7000 rpm.

The K20A program optimizes the fuel and cam timing, adding about 5 ft lb more torque for the high cam.

* Nitrous and boosted applications are not compatible with the Hondata ECU reflash.  Use them at your own risk.

ECU re-tuning – Comparisons to the ITR ECU

• 216 peak HP at 8300 rpm depending on the dyno and modifications
• 8 peak wheel hp increase from the ITR ECU.
• Power peak raised 200 rpm (8100-8300)
• Significant midrange torque increases form 5500-7000 rpm
• 15 ft/lb torque increase between 2500-3500 rpm.
• 20 ft/lb torque increase at 6300 rpm.
• Peak torque now at 6300 rpm, down from 7600.
• Rev limiter raised to 8800 rpm. (ITR ECU uses 8500 rpm rev limiter)
• VTEC point lowered from 6100 (ITR ECU) to 5200 rpm.
• Fully dealer compatible - works with all Honda scan tools and equipment.
  

This is a magnified view of the torque curves seen above.

What if you have modifications?

This program was tuned specifically for a CAI (cold air intake) as they give the best power gains. All future tuning will be done with either the stock or CAI intake.

Headers will be tested at a later date. This program should work OK with headers.

Test pipe. This will eventually give you an engine check light telling you have a faulty catalytic converter. We have not seen this error cause any power loss.

If you have nitrous this program will probably not be suitable due to the aggressive ignition advance used.

Tuning notes

This program is a highly optimized version of the K20A2-4 program. Ignition was retarded from 1800-2200 rpm as 91 octane and 11.5 compression caused knocking. This (and the knock sensor retarding the ignition) is the cause of the slight low RPM power drop.

Fuel was added to all high cam fuel map. Additional fuel was needed above 8500 rpm where the engine ran very lean. Part of the reason additional fuel was needed was that the Hondata gasket was providing colder air while the ECU was providing the same fuel. The Hondata gasket caused the engine to run about 0.2 points of an air fuel ratio leaner.

Cam timing has been highly optimized for this engine. The intake cam can move 50 crank degrees. 25 degrees of movement is needed to generate the best high cam power figures.

We tested a 64 mm (+2 mm) bored and tapered throttle body. It produced statistically insignificant results (+ 1 HP from 7500 rpm up.) We have seen combinations (short ram cold air 50 cm straight velocity stacks on a K20A engine mounted in a Lotus.) where the bored throttle body makes a difference.

Dynojet comparison

These three programs were also tested on the Jackson racing dynojet.

Note that this car had heavy 19” wheels and tyres. The gearbox also has different ratios to the type S. The time taken to make the acceleration is longer than the Dynapack. This will also affect power readings. Dynojet testing was done the day after the Dynapack testing that generated the graphs above.

For consistency in dyno testing we suggest you follow the dyno procedure outlined here.

How does this compare to the Type S?

An RSX Type S with CAI, Hondata flash program and stock exhaust makes between 190-200 peak HP on the Dynapack. When examining these figures take into account that the ITR had a cat back, giving it a few more HP, and the RSX's engine had only a few miles giving it a few less HP.

You can see that the main improvements are on the high cam by the amount of 15-20 HP.

Rev limits and Valve springs

Based on information from TODA Japan, the Type-S and Type-R have the same exhaust valve springs. However the intake side uses F20C (S2000) intake springs for the outer spring and a Type-R for the inner spring. TODA also mentioned that Honda is now using single springs of a higher grade material for the newer Type-R's.

The interpretation here is that the stock valves are good. We have had a test vehicle (K20A2 in a Civic Si) running with an 8900 Rev limit for 2 months now. In this car you change gear when the Rev counter points to 20 mph!

Any increase in RPM limit though is at your own risk. If you suffer engine damage that is related to excessive revs Honda / Acura will not cover your warranty. If this of a concern, upgrade your valve train or use a program with a stock rev limit.

Thanks

Shawn Church Automotive for the Dyno facilities, testing and useful feedback. Shawn has a lot of RSX dyno plots on his Dynapack dyno if you would like to compare your RSX's performance and you live in California.