A/F Ratio Tuning

[figgie]

Too add

where does AFR come from? AFR is a derivative of Lambda.

lambda= actual AFR/stioch afr.

using gasoline/petrol.

lambda = 11.5 AFR / 14.7 AFR = Lambda .78.

So at stioch for Petrol/Gasoline

lambda = 14.7 AFR / 14.7 = Lambda 1

Methanol 6.4 AFR/ 6.4 AFR = Lambda 1
LPG 15.5 AFR / 15.5 AFR = Lambda 1
NitroMethane 1.7 AFR / 1.7 AFR = Lambda 1

everyone see a pattern? Regardless of fuel. At stoichiometry, Lambda will ALWAYS equal 1. Hence why you can tune any fuel using any familiar AFR scale. Like the Gasoline/Petrol AFR scale to tune E-85 or LPG.

 

[turbodriz]

Alright this is my question ..... When tunning in the mid to high 30psi i still want 11:5 afr ? I would'nt want numbers like 10:8 or so?

 

[figgie]

Alright this is my question ..... When tunning in the mid to high 30psi i still want 11:5 afr ? I would'nt want numbers like 10:8 or so?

It depends.

from a scientific point of view. The extra HC will drop the cylinder temps just slightly. Also depending how well the fuel is being atomized prior to it going into the cylinder, affects the lambda you will run.

New techniques are exherting higher and higher fuel pressures (talking about 100psi) and they are putting the injectors FURTHER away (unlike the 7m setup) from the head to help in the atomization process. Lots of cars are allowing for 12.x at WOT.

 

[Zazzn]

I wouldn't dare run anything above 12.2 if you are turning for power unless you have a EGT. I found most time's 12's gets you in to the 1650-1700 EGT range on stock ecu causing melt down.

I'd say 11.5 if you want to be safe.... I've never broke another engine since I watched that. my 2 Cents.... (and I've been around the block)