# Advanced Engineering Tech - Formula for exhaust density relative to temp.

xfactor_pitbulls
09-15-2010, 04:13 PM
I looked through J-rods formula thread and online alittle, cant find what I am looking for. For a 93 octane stoich value what percentage increase and decrease of density will be seen from a constant say 12:1 AFR by temperature? Any help would be appreciated.

crazydavez28
09-20-2010, 04:02 AM
ideal gas law. you'll have to calculate an m and R for that specific mixture i'm assuming that may be a hang-up in the process.

PV=mRT

but you probably want

P= Density*(R/M)*T
Again you'll need the specific R and M for the mixture

justoyz2
10-17-2010, 04:54 PM
Density? What is your end result. I think you are trying to determine what A/F you will have with 12 to 1 compression while using 93 Oct fuel?

If this is your true question, you can only answer is you are in one specific location and the weather condition stay exactly as it is when you capture your first reading.

Dew point, humidity, elevation and temperture determines the A/F at a given moment in time.

I have a closed loop system that manages my A/F ratio via dwell time thru my injectors.
It changes so fast it's unreal.....

xfactor_pitbulls
10-23-2010, 01:40 PM
Density? What is your end result. I think you are trying to determine what A/F you will have with 12 to 1 compression while using 93 Oct fuel?

If this is your true question, you can only answer is you are in one specific location and the weather condition stay exactly as it is when you capture your first reading.

Dew point, humidity, elevation and temperture determines the A/F at a given moment in time.

I have a closed loop system that manages my A/F ratio via dwell time thru my injectors.
It changes so fast it's unreal.....