I see the term "air-fuel ratio" used alot, and while I understand what the ratio actually is, I'm having a hard time understanding what is all about. I understand that it is the relationship of "air to fuel", but what does that mean?

What are the benefits/drawbacks to a good/poor ratio? How do you know what a good ratio is? What affects the outcome of the ratio? How does one take a "bad" ratio and tune it to a "good" one? How does someone know that they have a bad ratio?

I know that these are probably really basic questions, but I just haven't seen the answers yet while searching. Thanks for the info!

 

ok on a gasoline engine the "idel" A/F ratio is 14.7:1, on most cars this is hella lean, on a N/A car you want about 13.5:1 and on a turbo car you want around 12.5:1. If you running too lean (ie. 14.7:1 and need 13.5:1) you add more fuel with a V-AFC or simmilar product, the oppisite is for running rich, thats the basics

 

OK cool! Thanks! But now, how can I find out what my ratio is? What engine add-ons will affect this ratio?

 

It really depends on what you have all done to the motor. There are a couple different ways to monitor your A:F, number one is go to a dyno that is wideband capable (maybe all you need for a couple hours of simple tuning) or you could buy a wideband system. This is where it can get expensive. I haven't actually worked with the Innovative LM-1 but everything that I've seen/heard about it seems cool and you definately can't beat the price (~$350). If you're running Hondata or something of the like it is possible to use a PLX device in which you can tie a wideband in to monitor or datalog the output. Probably one of the most expensive ways possible is to run a MoTeC PLM (basically does the same thing as a the PLXApp002). If this is going to be a one time thing, atleast for awhile I would probably just have take your car to a shop with a dyno that monitors your A:F via a wideband. Just my $0.02