how do you determine which AFR's to run?
#1
Tour de Franzia
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how do you determine which AFR's to run?
I've heard so many different schools of thought on this that I don't really know what's right or wrong anymore. A well known miata shop owner told me today that 13.4 was too lean for 100kpa full throttle and told me to go 11.0:1 or richer from 6psi+.
if someone has a target ego table, that would be great too, but please explain what ratios at rpm and load, and why.
if someone has a target ego table, that would be great too, but please explain what ratios at rpm and load, and why.
#2
Boost Czar
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11.0:1 or richer?! no.
there's no reason to ever get close to 11.0:1. boost or not. its a waste of gas and does nothing. its doesnt cool the charge, slow the burn or anything but waste gas.
the point of the extra fuel is to slow the burn and to add some additional cooling to prevent detonation. Between 12-12.5:1 is perfectly safe, fool around with what gives you the best torque that you are happy with.
From what I've seen on the dyno the stock AFR gets to 12.5:1 at WOT N/A, which I don't see a problem with being between 13-13.5:1 to give you more power. The same car at 11:1 or richer would most likely be down 10hp.
detonation can be dealt with by your spark tuning.
there's no reason to ever get close to 11.0:1. boost or not. its a waste of gas and does nothing. its doesnt cool the charge, slow the burn or anything but waste gas.
the point of the extra fuel is to slow the burn and to add some additional cooling to prevent detonation. Between 12-12.5:1 is perfectly safe, fool around with what gives you the best torque that you are happy with.
From what I've seen on the dyno the stock AFR gets to 12.5:1 at WOT N/A, which I don't see a problem with being between 13-13.5:1 to give you more power. The same car at 11:1 or richer would most likely be down 10hp.
detonation can be dealt with by your spark tuning.
#4
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Thanks a ton for that, imma use it when I get my MS running.
11.0:1 or richer?! no.
there's no reason to ever get close to 11.0:1. boost or not. its a waste of gas and does nothing. its doesnt cool the charge, slow the burn or anything but waste gas.
the point of the as fuel is to slow the burn and to add some additional cooling. between 12-12.5:1 is perfectly safe, fool around with what gives you the best torque that you are happy with.
IIRC the stock AFR gets close to 12:1 at WOT N/A, which I don't see a problem with being between 13-13.5:1 to give you more power.
detonation can be dealt with by your spark tuning.
there's no reason to ever get close to 11.0:1. boost or not. its a waste of gas and does nothing. its doesnt cool the charge, slow the burn or anything but waste gas.
the point of the as fuel is to slow the burn and to add some additional cooling. between 12-12.5:1 is perfectly safe, fool around with what gives you the best torque that you are happy with.
IIRC the stock AFR gets close to 12:1 at WOT N/A, which I don't see a problem with being between 13-13.5:1 to give you more power.
detonation can be dealt with by your spark tuning.
#5
I've read several different numbers as well so I'd start with an AFR around 12 like brain and adjust only for knock (assuming your timing is okay and probably making it a bit richer if you get knock since you'll be tracking it) or even better, for max power on the dyno (within reason). As long as you don't have detonation and are running a reasonable afr, I don't think there is one number that is perfect for all setups.
#9
In all seriousness, going too rich doesn't gain all that much safety either. There was a good article on Innovate's site about how adding more fuel beyond a certain point really doesn't do anything for you. Edit: I found it.
http://www.innovatemotorsports.com/resources/rich.php
#12
That's why my GReddy setup made ~20-ft-lbs more torque.
In all seriousness, going too rich doesn't gain all that much safety either. There was a good article on Innovate's site about how adding more fuel beyond a certain point really doesn't do anything for you. Edit: I found it.
http://www.innovatemotorsports.com/resources/rich.php
In all seriousness, going too rich doesn't gain all that much safety either. There was a good article on Innovate's site about how adding more fuel beyond a certain point really doesn't do anything for you. Edit: I found it.
http://www.innovatemotorsports.com/resources/rich.php
i looked at some logs and i'm losing boost in that range, it spikes up, then dips and creeps back up later. i've also talked to a couple tuners and they say to load up with fuel around peak torque and little before to spool the turbo faster.
#15
Why dont you have it tweak while in boost as well? I mean your afr table is setup for it.
I know I have read somewhere, some people say its not good, but I wonder why not. If its setup right, it should only be a benefit. If you think it will have to much authority, you can tweak the sensativity with the ego limit.
In my mind right now. I figure ill have it run correction up to 200kpa. But ill set the "change ego limit above" in Lamda AFR settings to 101. Then the Ego limit to 5. That should change the authority from 10 to 5 when in boost.
What is open loop 02 correction(found in open loop settings)? I thought that o2 correction only happens in closed loop and if the car is in open loop no correction is made.
I know I have read somewhere, some people say its not good, but I wonder why not. If its setup right, it should only be a benefit. If you think it will have to much authority, you can tweak the sensativity with the ego limit.
In my mind right now. I figure ill have it run correction up to 200kpa. But ill set the "change ego limit above" in Lamda AFR settings to 101. Then the Ego limit to 5. That should change the authority from 10 to 5 when in boost.
What is open loop 02 correction(found in open loop settings)? I thought that o2 correction only happens in closed loop and if the car is in open loop no correction is made.
#16
Boost Czar
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boost is easy to tune. If you watch your logs, the fueling just needs one row to read across. The rest of the rows (below 3000RPM) is just to smoothly increase the AFR to 12:1.
for example, I typically see this line while WOT:
for example, I typically see this line while WOT: