tuning and boost pressure.

[FATGTS-R]

ok

Just completed getting a major service, new brakes, fitting a bov and getting a full 3 inch exhaust system.

I am now ready to have my ecu chipped and have the car tuned properley.

My current way of boost control is a greddy under bonnet dial. ( still debating on changing to electronic control, but thats another thread ).

My question is this:

Lets say the car is tuned with the boost pressure at say 1.3 BAR and is running perfectly. If I decide to turn the boost pressure down to say 1.0 or 0.8 BAR will it still be in " tune "? As in will timing and a/f ratios still be spot on? Could it still detonate? I understand turning it up might not be recomended as detonation would be more likely but if the ceiling pressure is 1.3 BAR is anything lower going to still be spot on or will it only be at its most optimum efficiency at the pressure its tuned at?

[nitemare5]

no, the a/f ratios will differ and not be "in tune". as far as i know, i dont think detonation would be a problem as it'd be too rich rather then too lean, but im not an expert

[Emre]

http://www.skylinesaustralia.com/forums/fo...isplay.php?f=14

[FATGTS-R]

So people having a high/low boost controller are only in optimum tune at one of the settings, not both? Assuming there car has been tuned of course.

[Gizmo73]

This would depend on what ECU management they have chosen...

In the case of an ECU chip, this would be correct..

However, i believe a Power FC or similiar can have two maps for different boost settings..

[PranK]

test post - please ignore.

[Sydneykid]

Hi Guys, the Power FC mapping has a boost correction table, so you can tune it for any number of boost levels. When you think about it, that has to be the case, otherwise you would have to drive around at the one boost level all the time. We all know that doesn't happen.

Other tunable ECU's are exactly the same, even a chipped standard ECU would have a boost correction table.

Hope that answered FATGTSR's question.

[Emre]

Doesn't the load axis represent airflow which is directly related to boost pressure...?

[Sydneykid]

Hi Emre, yes the AFM is relevant but you can have different airflows at the same boost. For example 4,000 rpm at 1.5 bar might be the same airflow as 6,000 rpm at 1 bar. So the ECU uses both, plus of course throttle position, rpm, lambda, engine temp, etc etc. The ECU processes them all and uses the appropriate map.

[Emre]

Fark it,

I wrote my reply for the third time and it failed to post.