How does the Viper motor make more HP with out "computer adjustments"?

[Greg D]

How does the Viper motor make more HP with out \"computer adjustments\"?

Since the Viper's EFI system doesn't use a MAF sensor, I assume the EFI system is of the speed density variety. That said (or assumed) how does the engine make more power by increasing breathing capability either on the intake side (K&N's and smooth tubes) and/or the exhaust side (free flowing cats, 3" cat back systems etc...)?
I am under the impression that a speed density FI system calculates the amount of fuel needed by: the program in the computer, position of the TPS, water temp of engine, engine vacuum, engine speed and, under part throttle conditions, the O2 sensor/s. (are there any inputs I missed?)
How does the engine "know" if it needs more fuel (to go along with the additional air provided by the better breathing of the above mentioned mods) at full throttle to make more HP?
I realize the mods I mentioned above do produce more torque and HP but can't figure out how with out changing the "program" in the ECU.
Is the ECU programmed on the rich side? If so, does that mean we are "leaning out" the mixture to get the additional HP from the above mentioned mods??

 

[lleone]

Re: How does the Viper motor make more HP with out \"computer adjustments\"?

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Greg D:
Is the ECU programmed on the rich side? If so, does that mean we are "leaning out" the mixture to get the additional HP from the above mentioned mods??
<HR></BLOCKQUOTE>

The stock ECUs run rather rich as I understand it. Your assumption about "leaning out" the mix would be my guess, but don't quote me on it.

 

[Ulysses]

Re: How does the Viper motor make more HP with out \"computer adjustments\"?

I think you answered your own question. I believe the O2 sensors play a big part in determining what is needed. There are predetermined A/F ratios for a given condition. The computer doesn't really try to create the best HP, but tries to keep within predetermined parameters that someone has programmed and believes optimum for a given condition(but not necessarily optimum power).

 

[Greg D]

Re: How does the Viper motor make more HP with out \"computer adjustments\"?

I understand O2 sensors control the A/F mixture, but they only work at part throttle, not full throttle.
It seems like you would need a "real time" O2 sensor like the Horiba and something like the VEC1 to adjust the A/F mixture so you could tune each and every mod to gain it's max HP.
Has anyone out there actually tried this? If headers bring 35-50 HP gains with out recalibrating the PCM, imagine what gains could be had if the PCM was recalibrated to ensure max gain.

 

[rgifford]

Re: How does the Viper motor make more HP with out \"computer adjustments\"?

The viper does not have a knock sensor, Correct. This I assumes is the reason for the rich mixture....