Proper AFR with a pulley cobra...

[sykal]

what would be a SAFE AFR with a 2.76 pulley?

would running something like 10.5-11.0 be TOO rich?
i really don't care about making 460+- rwhp.
id be happy with 430.

would a very rich tune be able to push me there?
i just don't want nothing breaking on any 4th gear runs.

i hear even top speed runs are fine on a stock tuned car, so i figured since they are tuned pig rich, if i continue to tune it pig rich, i should be fine...no?

 

[03cobra#694]

I`m @ around 11.7 @WOT with 22* timing.

 

[sykal]

I`m @ around 11.7 @WOT with 22* timing.

i just wouldn't feel comfortable with that.

i just want to know what would be the real threshhold on a "too rich" tune.

 

[Jomo1994z71]

I have a very conservative tune of 21 degrees of timing with an A/F of around 11.5@WOT

 

[venom1997]

10.5-11 isnt extremely rich at all

 

[jm@ReischePerf]

I think low 11s is probably what you're looking for.

 

[Blownsob]

Yeah, 11.5 is just about as perfect as you can get.

 

[Posi]

I'd go 11.5 if you're a little nervous. By running rich you're doing nothing to help deter the high speed blow ups. By letting out of it you'll save the engine. Or you could do high speed pulls everyday and you never know it might not blow or lock up. Most of us won't do it though with all the ones that's started threads and that's what they were doing when the engine let go.

 

[96stanggt]

i just wouldn't feel comfortable with that.

i just want to know what would be the real threshhold on a "too rich" tune.

That's still a rather safe tune. The recommended AFR for forced induction vehicles is actually 12.5, it has become generally accepted with these cars to run them in the mid-hi 11's for safety reasons. A tune with AFR in the mid 11's is plenty safe, running too rich can hurt a motor just as quick as too lean. If your tuner can keep you between 11.1-11.5 you should get well over the numbers you're looking for and be PLENTY safe.

 

[sykal]

thanks a lot for the info everyone.

ill try to push between 11.0-11.5.

thanks a bunch again.

 

[Posi]

Good luck with your car.

 

[TermySnake]

the stock tune goes way rich in the top rpm, ford says: to save the cats from getting destroyed by the heat. our piston to wall clearence are too tight that our lousy pistons expands & hit them once the heat does it effect on them, :uh oh:i'm not talkin about 11.0-11.5 AFR in the high RPM, the stock tune runs more richer.:read:

 

[sykal]

the stock tune goes way rich in the top rpm, ford says: to save the cats from getting destroyed by the heat. our piston to wall clearence are too tight that our lousy pistons expands & hit them once the heat does it effect on them, :uh oh:i'm not talkin about 11.0-11.5 AFR in the high RPM, the stock tune runs more richer.:read:

how rich exactly?
maybe i should tune it to around 8/9.0 in the high rpms?...

 

[TermySnake]

how rich exactly?
maybe i should tune it to around 8/9.0 in the high rpms?...

I don't now exactly! the only way to know is to dyno your car & see the after dyno results in the dyno sheet (AFR includes).

The point is... u don't do a fifth or 6th gear pulls. Nobody want's to risk blowing thier motor, just for an extra few secs.:bash: look at the bright sight, u don't need to speed more than 130-140. 160 is extremly dangerous on the streets.. imagine u blow out your front tires at those speed god forbid. it's a game over for you:cryying: :loser:

 

[sykal]

I don't now exactly! the only way to know is to dyno your car & see the after dyno results in the dyno sheet (AFR includes).

The point is... u don't do a fifth or 6th gear pulls. Nobody want's to risk blowing thier motor, just for an extra few secs.:bash: look at the bright sight, u don't need to speed more than 130-140. 160 is extremly dangerous on the streets.. imagine u blow out your front tires at those speed god forbid. it's a game over for you:cryying: :loser:

honestly, i dont plan on doing 5th or 6th gear pulls.

i do want the ability to do 1-4th back to back if i want though.

these cars don't blow up stock if they do high speed runs, which leads me to believe its all in the tune my friend.

pig rich stock, make it pig rich modded. so you sacrifice some hp, who gives a crap...you save your motor.

id rather have 425/430 HP and not worry about a thing, than push 460/470 and pray nothing breaks everytime i stomp it.

 

[jm@ReischePerf]

By running rich you're doing nothing to help deter the high speed blow ups.

Adding unburnt fuel should help lower the EGTs which should lower the risk of melting down a piston but how much this helps with these P/E tolerances I'm not sure.

 

[Posi]

^Prove it lol. I know what you are saying but being in the upper rpm's after going 1st - 4th I don't think the pistons are going to know the difference. They are going to be hot and adding that small amount of fuel only in the upper rpm's is not going to cool the piston down. At least I don't see how.

I can't prove it either but we could argue until we're blue in the faces. Bottom line is you might damage the motor and you might not.

 

[jm@ReischePerf]

^Prove it lol.

So you don't think running a richer A/F helps at all? You do agree that added fuel lower EGTs though?

 

[Posi]

I'm saying I don't think that it will cool down the piston that much. I've been working with metal mostly my whole life and if you only add a little cooling to it, it's not going to cool it down much. I've dealt with Aluminum a bunch also and it takes a lot to cool it down. Let alone as it's still trying to conduct heat. Aluminum is about the most conductive material and if things are hot around it, it's going to soak that heat up also. It just seems like a losing battle.

Like I said though I'm not saying you are wrong at all. Just my opinion is all on the cooling effect of it.

 

[sykal]

I'm saying I don't think that it will cool down the piston that much. I've been working with metal mostly my whole life and if you only add a little cooling to it, it's not going to cool it down much. I've dealt with Aluminum a bunch also and it takes a lot to cool it down. Let alone as it's still trying to conduct heat. Aluminum is about the most conductive material and if things are hot around it, it's going to soak that heat up also. It just seems like a losing battle.

Like I said though I'm not saying you are wrong at all. Just my opinion is all on the cooling effect of it.

can you explain why stock cobras can do 160 until they run out of fuel with no problems then?