MicroSquirt.com read only forum (Jan.15,2018)

i red in the tuning manual that req fuel is the amount of fuel required for 100% ve....

heres my questions....

for a motor runing 15psi, wouldnt 100% ve be at normal n/a ambient presure, and 200% ve be at 15 psi?


also, i have my ve map now set at 100@15psi, with a 9ms req fuel with 42# injectors... i beleve that 9ms isnt enuf for 15psi.....

any help?

req_fuel is just a number to base the fuel calculations on. It doesn't have to be your pulse width at full power. This is why you can go over 100% in the VE table to add more fuel.

I like to setup my VE table so that its around 100 at 0psi, over 100 for boost and under 100 for vacuum. You can do it any way you want, it won't make any difference because the final calculated will still come out the same.

the req_fuel means that at VE=100 and MAP=101kPa the fuel pulse will be req_fuel long.

So at VE = 100 and MAP = 151kpa (7 psi boost) the fuel pulse will be
1.5 x req_fuel

As you tune you will probably(hopefully) get VE > 100 in places were the valve overlap and intake/exhaust resonance is forcing more than theoretical 100% air volume.

You also will want your VE a bit higher at boost in order to give a richer mixture.

9ms sounds reasonable for req_fuel. You just need to toon and analyze datalogs to dial in the VE table now.

that makes a little more since. i think ill with 100ve @100kpa and 200ve@205kpa.....

i think my major problem is with timing. ive found all sorts of maps from others with the same motor, but all the maps are way way different and all ahve different results.

Timing is usually pretty different for different engines. It depends a lot on your engine characteristics like comp ratio, cylinder head design, etc. It's best to tune it on a dyno. Tune for the least timing advance that gives you the most torque without detonating.