Max lean burn horsepower with VX engine.

[Clev]

Originally Posted by basjoos

I can monitor lean burn on the SuperMID where the injector pulsewidth drops or jumps 2.0 usec as it enters or leaves lean burn when the pulsewidth reaches 6.1usec in lean burn (it jumps up to 8.0 usec as it leaves lean burn). I can also feel a sag or surge as it transisitions into or out of lean burn. Vtec-e kicks in at 2500rpm, but the pulsewidth on the MID doesn't change indicating a drop out of lean burn when it engages and I don't feel the surge that indicates it dropping out of lean burn. I haven't been able to do a long enough run at 80mph spend time trying to transistion in and out of lean burn through the 6.1usec threshhold. At 80mph the rpms are almost 2800.

Interesting. If it's RPM-independent, maybe a vacuum gauge would help. If you could determine that a specific point of vacuum corresponds to entering/leaving lean-burn, you could then mark the vacuum gauge at that point and have a nice easy-to-glance-at gauge that helps you stay in lean-burn.

[basjoos]

I'm planning to install a vacuum gauge, so it'll be interesting to compare the lean burn threshold on the vacuum gauge and the SuperMID.

[james]

I always imagined it was in the 20-28hp range...but I really have nothing that I am basing that on except feel. I can definately feel the engine going in and out of lean burn. Mine can do 75-80 without going out of lean burn. I can do over 3000 rpm and remain in lean burn...try it in 3rd gear. I usually keep it below 2500 but it can do higher. I also find that my vtec e does not feel like it changes to 4 valves/cyl until about 3500 or so. On another subject, for those VXers, I highly recommend climbing hills in 3rd with lean burn instead of 5th/full throttle. I dont have a super mid, but my mpg has gone up since I have done that.

[tim3058]

Originally Posted by Clev

Interesting. If it's RPM-independent, maybe a vacuum gauge would help. If you could determine that a specific point of vacuum corresponds to entering/leaving lean-burn, you could then mark the vacuum gauge at that point and have a nice easy-to-glance-at gauge that helps you stay in lean-burn.

So I just added a vacuum gauge on my Civic... looks like it is vacuum dependent, and I haven't (yet) noticed it responding to rpm. At cruising speed (anywhere from 50-65mph) any vacuum more than about 6in Hg keeps it in lean burn, anything less knocks it out... hope that helps.