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hi looking for abit of advice. have mapped my current mx5 turbo build with a td04l 13t and is sat mint on my targeting and mapping. am looking at using the same turbo and changing out the intake impeller for a 19t upgrade and housing,when it comes to the mapping what areas am I going to have to correct and consider in checking after doing this mechanical change to the turbo? being I already have it homed in.
There's probably a SLIGHT lag difference compared to the smaller 13T. So you're fueling and timing will need to be massaged to match. I don't think you will have to do anything too drastic (they are pretty similar turbos). You could always pull a few degrees out of your boosted section as well as richening it up a bit, start at a reasonable boost level and work up from there. I'm sure more experience people will chim in, but that's what I would do.
You will probably need a bit more fuel in the top end if it was near choke flow with the smaller compressor. You may still be effectively turbine limited though if EMP:IMP was going up in the top end.