Dr. Gräfenberg

How can I find out the size of my MAF on the 98 A4 1.8T, so I could match it to larger injectors from TT (386cc)and possibly use the TT MAF if it fits, and hence increase the turbo size accordingly (K04 or K04/T28 hybrid).

Thanks in advance.

Jamez

get a maf-housing and injectors to match so that fueltrims are kept minimum...

your MAF housing is probably 63mm. (take it out and measure to be sure)
find your old injectors flow here:
<a href="http://clam.rutgers.edu/~dreadsct/resell/1.8T_injectors.htm">injector database</a>

then you can calculate the "most" correct maf-hosing for 386cc like this:

newmaf = sqrt((newinjector/oldinjector) * (oldmaf)*(oldmaf))



I did somewhat this.
I changed to a 76mm housing, ~50% larger than stock, and 440cc injectors @4bar.
I should be way rich, but I was running way lean on idle, but WAY rich up top, since fueltrim added even more.
Linerity is crappish.
But, you could be lucky...
I had to remap.

good luck.

Jamez.