A Discovery: More Ponies after I/H/E

[AcesHigh]

Hey everyone. Nope, I'm not quite dead yet .

After studying several h22a dyno charts and consulting with a few tuner friends, I made a rather suprising discovery. On an average h22a with a standard short ram/CAI, minimally bored out header, and larger exhaust system, a dyno using a wideband O2 sensor showed the following on an AFR chart:

Idle to 800RPM~ 15.3:1
800RPM to 4800RPM ~ 14.6:1
VTEC to Rev Limit ~ 10.3:1

Did you catch that drop? On some of the dyno charts I looked at, the AFR past VTEC crossover was even lower. So why the drop, and what does it mean? Well, it means as the h22 climbs higher in RPMs it is running richer and richer. The stock p13 ECU is programmed to dump extra fuel as the RPMs get higher to protect the engine from detonation. More fuel than needed, however, reduces horsepower because it lowers combustion temperature (which is why you should NEVER mess with your fuel unless you know how to properly tune it).

Anyways, what this means for us is that there is power to be reclaimed, and rather inexpensively too. What you need to do to lean your AFR safely is have a Fuel Pressure Regulator (FPR) that can be adjusted, a cheap fuel gauge, and a VAFC. The original is good enough, you don't need VAFCII.

You have to take your car to a dyno and hook it up to a wideband O2 sensor (most dyno places should have one handy). Do a printout of your AFR chart and the numbers should be close to the ones above. You have to take out a little extra fuel at the top end so that your AFR sits at about 13.0:1 to 13.5:1 at VTEC. The AFR number will depend on how many mods you have on your car and ultimately whichever makes more horsepower for your setup.

This works for stock h22a's, and maybe even h23a too, but it is best if there are freeflow (I/H/E) mods. You can free up about 10-20whp on a mild setup, not bad for a couple hundred dollars investment.

Cheers.

[Phunyguy]

excellent research! that may be my deciding factor for going turbo or not... I know N/A has alot of potential too. I was going to build my motor for mild turbo, and spend 3-4 grand on turbo... i could also take that 3-4 grand and dump that much more on the engine, instead of turbo, making it stronger for higher compression and maybe NOS. That's where my questions come in, If I had a setup with 11:1 - 11.5:1 compression with a ported / polished head, ported / polished intake manifold, AEM short ram - ductile iron sleeves, enough fuel flow, fully built head capable of 10k-11k rpm or more... hondata system to tune it... what kind of power could i be looking at? i knew someone with a redline of like 12,400 on his H22... he didn't have a bunch of horsepower but he had such a high redline that he didn't shift as fast and was blowin people away. It was creepy to watch the tach just goin up and up and gettin thrown back in the seat even more as the engine starts to scream for more. I almost downloaded into my skivvies.