Don't know about the 06+ ECU advantages, other then mostly what's been reported is they are generally running too lean already. Mechanically what's different is the TB size which has increased from 64mm from 00-05 to 68mm opening 06+.

 

...which to take advantage of a larger tb, they'd likely need to make some tuning changes to ecu to make more power.

So one could note the '06+ ecu change, and note the slight power increase, and improperly attribute power to ecu by itself.

 

Strange that Honda rates them all at the same peak power.

-- Chuck

 

Yeah well I figure they are thinking if your talking 2-3whp/margin of error in each series of changes, no sense in announcing it and trying to market. Just chalk it up as improved efficiencies through the evolution of the car. It did go through 3 fairly significant evolution changes with the engine displacement, induction and ecu, but not enough to market it. I do remember something about the last year or two of production they switched to advertising SAE output of 238hp, not sure what that was about exactly. Seems even less accurate on actual output when you consider average wheel reported and 15/17% drivetrain loss.

 

There was a change in how SAE measures and rates hp that accounts for the reduction in rated output.

 

Regarding the identical power ratings: Given that Honda continued to sell the AP1/F20C in Europe through 2009, I'm sure they didn't want to advertise that the AP2/F22C was significantly stronger -- no sense risking Euro customers feeling like they got a "lesser" motor. And while I'd assume that at least the '06+ DBW F20Cs got some ECU tweaks, they were never going to be as powerful as the F22C ("there's no replacement for displacement").

 

^^ what he said.

 

I don't think the Japanese think about horsepower the way Americans and some others do. Just look at cars like the BRZ, Miata, even the new Supra, etc, and the "gentlemen's agreement" in the 90s.

They are focused on the driving experience, so in the case of the S2000, while the car kept getting refined, added power was not really a selling point.

 

I do not think I have even been on a car related forum where I did not see claims of "factory freaks" that made 20 WHP more than other known specimens. Way too much variability in dynos, operators and conditions to put much weight on that.

 

Power is a number. Essentially Torque x RPM with a factor depending on imperial horsepower or metric kilowatts notation.

The "small" engine will rev higher. Lower torque x higher rpm can easily match higher torque x lower rpm, it's just math. (Torque is the only measurable.) Both engines are rated at the same maximum power, the only number that gets advertised.

-- Chuck