difference in tuning FI vs NA?

[da_vato]

Can anyone tell me the major differences in tuning for boosted vs bolt on big power adders like a Cam or nitrous? There is a local tuner that all of the corvette guys go to but he has stated that he will not touch forced induction at all.

With the generosity of this board I have been working through the tuning of my forced induction application but I do not see what the big difference would be other than I obviously would not hit higher air calculations. As far as I can tell the PCM is still taking the same inputs to make calculations to spit out fuel. I understand that a Cam would change when and how long the valves open but I can't see that being more difficult than forced induction....

[SultanHassanMasTuning]

FI: unlike NA where its Pulling Air into the engine, key word is Forced. There are many changes to be made to compensate for at minimum fuel and timing.

[redhardsupra]

I like to think of NA as a case of really lousy FI

[DSteck]

It's all the same to me. You have different target AFR for power enrichment, and your timing changes, but the process is the same.

[ElecTech]

Sounds to me like he just doesn't want to mess with the chance that something catastrophic happens with the FI and he has to try and make it right. NA is much more forgiving to "good enough" calibrations. FI can go wrong in a hurry, not to mention, can take a little more time. I think the biggest peeve I have is that everyone likes to install there own stuff and then show up and say "its ready for a tune!" and it ends up being a mechanical nightmare.

[robbyredneck]

Sounds to me like he just doesn't want to mess with the chance that something catastrophic happens with the FI and he has to try and make it right. NA is much more forgiving to "good enough" calibrations. FI can go wrong in a hurry, not to mention, can take a little more time. I think the biggest peeve I have is that everyone likes to install there own stuff and then show up and say "its ready for a tune!" and it ends up being a mechanical nightmare.

god isnt that the truth

[PST]

The only thing more 'risky' in my opinion is setting the timing. And in that regard, its not really the main timing maps so much as the modifier tables. Things can get real hot when one of you vette drivers goes out and plays autobahn on the freeway. Most failures I've seen by other tuners is in not properly preparing the tune for such situations. And these situations cant be properly replicated on your average dyno. Think long wot 2nd through 5th gear pulls. Illegal as it may be, as a tuner you have to expect this stuff to happen. Whether your customer is a 60yr old man or a 16yr old girl. Prepare for the worst so your tune is ready for anything.

[da_vato]

It's all the same to me. You have different target AFR for power enrichment, and your timing changes, but the process is the same.

This is exactly what I was thinking as I've been going through but I'm not very experienced.