What causes exhaust flames?

[Matthew]

im not too sure about all that stuff, it just makes the most sense to me the way i explained it. im not smart enough with F/I to explain why it goes up then down etc etc.

 

[Brian MP5T]

Full Lean is 20 on the APEX-I TT

 

[Installshield 2]

Hey you two...Air/Fuel ratio...in the numerical order, the air molecules come first...Gasoline is a huge friggin' molecule...O2 is not...it takes 14.7 "moles" of oxygen to completely react with 1 mole of gasoline (moles are just the molecular weight of a said molecule in grams...easier to deal with when you are using lots of reactants like in an engine than figuring on trilliions of individual molecules...and also you can't have 14.7 molecules of anything, but you can have 14.7 moles)...So 13:1 is lean in that regard to a turbo'd engine...

Matt you have the theory dead on...Just had the numbers backwards..(thumb)

 

[Matthew]

dammit...so at say 100psi of fuel at 8psi of boost what is my ratio?

 

[MP3skaterNC]

thats fmu ratio's, totally different from actually air/fuel ratios. the less air you have to fuel, the richer you are. most turbo cars like a afr below 12.5 to make power, anything above that is risking detionation.

 

[Matthew]

werd...damn i need a w/b.

 

[simdrew]

im pretty sure its not. 12:1 FMU pushes more fuel because its 12 parts fuel to one part air. like if im at 64psi of fuel at 8psi of boost divide and you get 8:1...lean as hell...now im at 96psi of fuel and 8psi of boost its 12:1...

thats why less fuel is more susceptible to going boom! because say 8:1 is only 8 parts fuel to one part air, meaning there is a lot more air which is highly combustable in the fuel...where at 13:1 you only have one part air for every 13 parts of fuel.

You've got it backwards, it's an a/f ratio... 12:1 is 12 parts air to 1 part fuel.

 

[Matthew]

i realize that now i was thinking of FMU ratios like jamie said.

 

[Gen1GT]

(boom08)

 

[Matthew]

:wtf:

 

[Installshield 2]

(friday)

 

[pr5owner]

fart pipes

 

[Brian MP5T]

I have seen the baffles blow out of a mufler before. It wasn't flames but it was really funny!!

 

[TurfBurn]

Apparently with my car I can take my ignition cut and pull it down to like 4 K rev into it and it'l blow a massive fireball.. so said Terry sometime after I bought the car... never have done it though..

For our cars you want to run an AFR between 11.5 and 12.2 ideally. I run around 12.0 for the most part and will be tuning toward that. But yes you really do need a wideband to do any kind of actual tuning. I still highly recommend the PLX M-300... only 300 bucks... so can't beat that (at least not that I found)

Later.

Steve

 

[Brian MP5T]

I WANT FIREBALLS!!!!


(flame) (gun) (flame2) (flame) (rockon) (gun) (flame2)

 

[TurfBurn]

you can always be "one of those guys" and buy the fuel outlet sparker combination they sell on Ebay so you can be "just like" the guys in The Fast And the Furious

 

[WillisW555]

Yeah, you can buy a kit. I think it's crazy how big some of those flames are.

 

[pr5owner]

to my understanding rich = >14.7:1 and lean is <14.7:1

Rich means fuel burns in excess o2 as in more o2 than is needed
Lean means fuel burns in a lack of o2 as in not all fuel is burned

am i wrong?

 

[Installshield 2]

yeah...thats wrong...sort of...

rich and lean refers to lots of fuel and not a lot respectively...14.7:1 is nearly perfect amount of both for a perfect burn...14.7 parts AIR, and 1 part gasoline...the lower the number in front of the 1, the richer the mixture, because you have less air in the mixture...therefor more of a % of fuel per volume...

like chainsaws...a rich chainsaw runs all bad and smells real bad because the carb is letting way too much fuel in...but it runs cool...A lean chainsaw will hack anything up, but blow up and kill you....

 

[pr5owner]

oh okay so i had it rev, lean = more air to fuel and for rich its vise versa, so with a lean mixture its easier to blow up?