So, just to start a small discussion/ see what people who DO know more or the same amout about cars as me weigh in and think.

If you have a newer car with a computer and you mod it without modding the computer, what kind of gain are you getting in reality?

For example, I know that a cars computer has a set air/fuel ratio curve to abide by to keep the engine running optimal. That being said, let's say you upgrade the intake, exhaust, and port the heads, what are you really gaining? I know you are helping the car breath better, so you have to be gaining something, but the computer also is trying to adjust to get back to that curve isn't it? Or does it reprogram/ relearn the timing curve to adjust for the modifications?

If indeed it does adjust the timing, how long do you drive it until it finds what is best?
I know you should get a pcm tune when modding for best performance, but simple bolt ons, I usually don't.
When going into a turbo, I usually suggest getting a tune then.

Thoughts? Opinions?

 

You're thinking is correct. In order to see the best performance you will want to tune the PCM. However, you still will see gains even if you don't have the PCM. A situation like this could be that if your car is already seeing KR from the factory, the mods that you do to it will reduce/eliminate the KR which will help your engines performance.

Also, lighter weight components (such as lighter pulleys, rockers, valves, etc) will make your engine work less and that also gives power. I saw gains when I was NA and installed mods and still saw gains without tuning the PCM, but it was always better after the tune. You see the full potential after the tune.