Hallo,

i have a very strange question but i'am curious so i ask it anyway.
last week we tuned a friends car on the street and with a wideband (dyno was to expensive for him)

so we made a few runs with constand load (~1000mbar) over the whole rpm range and adjusted the mixtrue to
correct it so what we want (in this case something around 13:1)

then we made a few runs at 500mbar (absolute) and timmed the mixture to 14,7:1.

until now everything works very well and after we found the correct values for 1000mbar and 500mbar
i extrapoleate the columns in between linear to get a constant mixture over the full map.
this was also successfull so we get a constant mixture (only had to make some little modifications but
nothing big)

and now it comes to whats a bit strange for me.

when i look at a stock NA Map the rising as allmost linear. For example: if i take a fuelvalue anywhere in
the map and then look at the column for double the map pressure i will find a value nearly double that high
then in the first cell.

i.e. 500mbar = fuelvalue 200 -> 1000mbar fuelvalue 400 (just an example)

in the stock fuel map there are light fluctuations from this but aas a ruel of thumb it works like this.

when i now look at the fuelmap of my friends car which has a absolut contant mixture (14.7:1 in Openloop
from 200-700mbar absolute pressure) the rising of the fuelvalues are not like in the stock map.
they are about 40% HIGHER

i.e. 550mbar = fuelvalue 152 -> 1100mbar fuelvalue is 560 (real value) but when i look at a stock
map i would see 304 instead of 560 which is an extreme difference...

maybe some of you can explain this to me? its not that i think i made something wrong because we looked
at the mixture for some times during driving in openloop and the mixture is the best i've ever seen.
totaly constand all over the map but i have no explanation because of the strange math on the map.
i just want to understand why this engine is so totaly different then the stock NA engine?

if it helps i can post some pictures of the map's but for general this explanation should be ok i think.

Thanks
Malte.