lets say i get my car tuned, then somewhere down the road i wind up doing a .5mm overbore. maybe from 84-84.5mm. is that a concerning difference that i should retune, or is it negligable. im just speaking theoretically here...thanks

 

If compression doesn't change then don't worry about it. Wouldn't hurt to throw a wideband on it and make sure A/F's are in order.

 

im sure a quick 15 minute check by the tuner wouldnt hurt with all that money

shouldnt take long since its a small change

 

yeah, my concern would be that my tuner would be hours away and super booked to make scheduling hard to do, especially with my work schedule

 

The fuel increase isnt much and the timing requirements will increase. So if your timing was unchanged it would be more conservative but less ideal for a bigger bore.

 

good answer muckman. i just recently went from 81 to 84mm and am still unsure of how much more timing is justified? i had trouble on the dyno so im still conservative ( 18* total at 12 psi boost)