iwannarace

Hey guys,

Neptune-noob here. I've read most of the intro-faq's in most of the tuning forums and spent tons of time searching but haven't been able to find what I'm looking for.

Basically, I just want to see the Target a/f ratio map of someone with a tuned n/a b20/vtec. Would appreciate some help, thanks!

LTCxD2B

The target a/f should be stoich and a little rich under the max load area so about 13.8 up top but every engine varies and can need more or less fuel to make the most power without knock. Which is the goal .... Pgmfi.org (spelling?) has base maps u can download and look at

iwannarace

Thanks for the response. Went to Xenocrome and just spent the last hour trying to figure out how to open the .bin files all the maps are in... I'm on a MacAir using the latest MacOS. Help??

LTCxD2B

Won't work on Macs I have one and I still haven't found a bin reader that was useful so I dual boot windows ... What software was used for the map chrome?

Masterl1nk

If stock cams, idling would be near 14.5~14.7, cruising at 30-70kpa, for good fuel economy would be 14.7~15.2 and in WOT, most power would be find at 13.0~13.5, leaner would melt pistons (at high loads/high rpm)

iwannarace

I'll target 13.0 @ FT for now. Less interested in peak power for now, more interested in not melting pistons.

GhostAccord

If you don't want to melt pistons I would suggest the installation of an exhaust gas temperature (EGT) or cylinder head temperature (CHT) sensor for monitoring combustion chamber temps in relation to AFRs. A knock sensing device wouldn't hurt ether.

Like mentioned above, every engine is different and just because you set 13:1 AFR as a goal. That doesn't mean you are not going yo do damage to the piston/engine. Timing also comes into play here as well.

blackeg

i really feel an egt is as necessary as a wideband. it helps with knowing the right afr and maybe even more for timing. when cruising and the tune is solid the egt will plateau and hold. just think of it as another way to double check the tune.

i just got knocksense myself. its a bit finicky at first but helpful once u get it dialed in. match the sensors activity to what the plugs are doing again its just a great way to doublecheck

VegasInvasion

this is a really arbitrary question. you didn't say what your compression is, what your altitude is, cam or porting, exhaust type... all these things affect the ideal AFR for any engine.
But as a general rule of thumb, I typically start at a safe 12.5:1 at full load then lean out until it stops making power (or starts knocking).
if it's over 12:1 compression ratio, I'll start at 11.5:1 AFR since knocking is more prominent.
if you haven't read the manual in my signature, read it first. it's the same concepts across all honda tuning platforms.