Effect of Temperature on AFR Distribution
Turbo Mini Forums

Following on from a discussion about the effect of temperature on AFRs on Graham T's testing, I though I would start a new thread.

As it was cold this afternoon, 12 Deg C, we took the 998 EFi turbo out and did some data logs. The plan is to take it out again in a few weeks on a hot afternoon to see if there is any difference.

The only changes from last year are a new FPR and now running two AEM widebands.

First log is a run through first and second, but I kept hitting the rev limiter, so it seems a bit squiffy, but you can see tyre spin in first and things warming up a bit:


Second log is a run through first, second and third. I still hit the soft limit, but its a bit cleaner. Getting a bit warm under the bonnet now:


Seems to be boosting a bit later than it used to, but runs fine.

So l will not make any adjustments now until we get a hot day log.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Who would believe that 2 weeks later, the temperature would have gone up by about 15 Degrees C !!

Only change is that I've changed the oil. finally put some CVT in it.

So we took another log:

A hard blast through 1st, 2nd and third. Sturgeo managed to get it to 6400rpm even with the rev limiter soft cut set at 6000rpm.

Intake temperatures got to around 50 Degrees C, but I'm not sure that there is much difference in the AFR spread.

We then took 5% out the VE table at the top end and took another log:

This is a run through 2nd, 3rd and a bit of 4th.

This certainly seems to have leaned off the inners and not the outers, so a bit less fuel and they may get even closer.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."