springer_4

iTrader: (9)

Already have a Frost Mail Order tune, for Basic bolt on's LS6 Intake and LS6 Cam. Hence after only 400 miles, I'm doing another rebuild, everything will be the same except for going .025 over bore and the new addition of a set of 243 heads. So send off and get a retune or would the one I be just fine?

Firebirdmuscle

iTrader: (16)

I would have to say retune becuase those 243s are going to flow more than your stock heads.

redtan

iTrader: (5)

You will most definitely need a retune.

springer_4

iTrader: (9)

Thanks for the response guys,

DANOZ28

iTrader: (1)

could someone explain why he would need a new tune? i wouldn't think heads only would lean him out that much from his current A/F ratio. & doesnt the computer learn & adjust for that small of a change? different story if he only had a stock tune.

thunderstruck507

iTrader: (18)

the computer can learn part throttle air fuel changes but if it adds fuel to part throttle because it's leaner it will add that much to WOT just to be safe

without tuning for major component changes you are either sacrificing part of the gain from the parts or possibly even making less power than before if the swing is big enough

243 heads have more flow and more compression, the car will most likely run great with them but will also most likely be leaving power on the table...the only way to know is to scan the car to view fuel trims and check for spark retard

redtan

iTrader: (5)

It does to a certain degree at part throttle. And even then, it's not really called "learning" more so adjusting. You want your PCM to adjust as little as possible, thus you don't want fuel trims in the 20s just to get it to where it's supposed to be.

At full throttle though it doesn't learn squat, so you'd need a re-tune if you wanted to get on it at all...otherwise you'd burn a piston real quick.

thunderstruck507

iTrader: (18)

Forgot to mention it would be less likely to need a retune if had been dyno tuned, but a mail order tune may or may not be spot on for what you already have. You would be surprised how different cars with the same components installed can behave.