2.7 upgrade, tune question

[turbski]

So from what I have read I think I have already answered my own question but would like conformation from the experts. If I were to swap my block out for a 2.7 seta and put all my 2.5 bits back on, same turbo, same injectors etc how much re tuning would be required or would my current dyno tune be acceptable. Again this might be a noob question but Im going to ask regardless.

Thanks guys!

[Digitalwave]

You would need to retune the fuel table at at the very least.

[digger]

yeah its gonna need a retune to do a proper job, will probably run ok on same tune sub optimal

[turbski]

I kinda knew it would need a retune with all the changes, I was more curious if it would be ok to start it to seat the rings (if I can figure out which rings I need lol) before my dyno apt. Im gonna trailer the car up there either way just in case something does not go my way.

from what I have been exposed to no motor is ever the "same motor" once you pull it apart and rebuild. its going to need quite a few tweaks to be correct again.

[e30davie]

Got a wide band? you can tune it yourself to at least get it idling driving around. Idling and light throttle stuff should be relatively close. Its VE tuning after all, if you do your required fuel properly what you have will be in the ball park to get it running.

If in doubt, rev it out. (nah don't do that).

[digger]

I kinda knew it would need a retune with all the changes, I was more curious if it would be ok to start it to seat the rings (if I can figure out which rings I need lol) before my dyno apt. Im gonna trailer the car up there either way just in case something does not go my way.

from what I have been exposed to no motor is ever the "same motor" once you pull it apart and rebuild. its going to need quite a few tweaks to be correct again.

i ran in my 3.1L on stock chip and motronic iirc, just had proportionly larger injectors and the O2 did the rest. a little lean on WOT but thats not an issue as not flogging the shit out of it for extended periods

[turbski]

Good to know, I will try to keep some pictures going and maybe do a small build thread. Car had come along nicely up until the knocking and smoking. LOL. I just wanted to make sure it would be cool to start it and maybe get the rings seated if at all possible. We had toyed around with the idea of putting a slightly smaller turbo on to move the power band lower into rpm range but its kinda out of the budget right now. Im pulling the head off original motor this morning so ill grab a few pics of anything I find