aleks77

I changed my turbo, to a slightly bigger one, almost identical to my old one. Now im curious if i need a re-tune if my AFRs are pretty much identical to my old turbo? I did 1 run 3rd and 4th gear, and the AFR was bang on 11.4-11.8. Is this all i have to worry about, or could have timing been effected also?

This turbo seems like it spools a little later.

Silva Bullit DC4

I'd say yes, retune. What are the dimensions on the old and new turbo?

AdamB18C1EK

well. if your spool is earlier/later id venture to say you should get it tuned because your car is A. going to need more fuel because there will be more CFM. and B. ignition and fuel tables will need to be changed because the turbo spools differently. and C. for the love of god why would you beat on your car without knowing, or having your tuner at least take a look at it?

Tony the Tiger

As a rule of thumb, always get it retuned, or at least verified by your tuner at the dyno.

You may think your AFR's are the same because you could be running it at a sweet spot when either turbo was pushing the same amount of power/airflow; it could be totally different during spool-up or spool recovery between shifts and that's all it takes to pop something in the motor. You will never be able to keep an eye on the AFR all the time when you start ramming through the gears.

aleks77

alright thank you guys, i made an appointment for next wendsday. The weather is really shitty right now, so i think the only option is to hit the dyno and tune it, its been fully tuned on the street already with the old turbo. Not sure if it needs more street tunning or dyno will suffice?

TheShodan

iTrader: (14)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by aleks77 &raquo;</TD></TR><TR><TD CLASS="quote">alright thank you guys, i made an appointment for next wendsday. The weather is really shitty right now, so i think the only option is to hit the dyno and tune it, its been fully tuned on the street already with the old turbo. Not sure if it needs more street tunning or dyno will suffice?</TD></TR></TABLE>

That will be up to the tuner, and the turbo that you changed to. Anytime that you change Air (CFM volume) or fuel (injector size, and flow rate) it is necessary to retune.

aleks77

alright thanks guys, i did a couple of 2nd gear pulls before this thread, and afr was always under 12, usually 11.4-11.7, i thought this was ok but i wont boost at all anymore as there are other factors, i just hope i didnt [freak] up my motor from those 5-6 pulls

done

Your probably fine. Your fuel/timing maps just probably need a little adjusting in the spool up range..