is 10.2 a safe afr?
12.5
is about the most you can get from fuel burn but leaves no margin of safety, esp under boost.
12.0
is slightly less productive, but with more room for error (timing, miss, spikes, whatever) however tune will need to be perfect, water inj or racegas is suggested, and 93 oct would be pushing it
11.5 - 12.0
a good target, with optimal timing however
10.0 - 10.5
- this here are bubba tune
is about the most you can get from fuel burn but leaves no margin of safety, esp under boost.
12.0
is slightly less productive, but with more room for error (timing, miss, spikes, whatever) however tune will need to be perfect, water inj or racegas is suggested, and 93 oct would be pushing it
11.5 - 12.0
a good target, with optimal timing however
10.0 - 10.5
- this here are bubba tune
You hit the nail on the head.CJ
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But, your question was asking if it was safe, YES your current tune is safe....very safe. If you are asking to tune even richer, i would not do that. You can actually cause a knock condition if you are running too rich. If you do anything, do what i recommend.
Good luck!
CJ
It's been my experience that fuel doesn't cause knock, it quells it, and I'm not just talking about EVOs, same with other cars.
I have preached(and argued) that running a richer AFR is the best for safety, as it cools the intake charge, lowers the charge density, slows the burn rate, resulting in more advanced ignition timing, which places the burn later in crank angle, where there is more leverage on the crank, resulting in more power(when properly done). I have said this many times and have argued with many tuners on this site(and others and in person) about this FACT, when they decided to tune @ 11.8-12.0:1 on pump gas. Running a slighty richer AFR deffinatly has it's advantages and this is the way i tune. So please, don't confuse this with what i'm about to say........
Running too rich can cause problems of it's own. For instance, if you run so rich, to the point that the plugs are just on the verge of fouling out, carbon deposits can and will form in the combustion chamber. They will form on the plug and on the valve releifs of the pistons, ect. If the rich condition is not enough to foul the plugs and the plug are still able to operate at self cleaning temp....these carbon deposits can actually get red hot, which can cause pre-ignition as these hot spots of carbon deposits ignite the air/fuel mixture prematurely(before the scheduled spark). This causes multiple flame fronts, which ultimatly collide together, causing knock(in this case, pre-ignition).
Of course, this is rare as most super super rich condition foul the plugs, causing misfires. But it can happen.......trust me.
Running super rich can also cause other problems as well. It can cause bore wash. If you run too rich for too long, the fuel washes past your rings and into your oil. As this is happening, the fuel is washing away the oil film on the piston skirts, cylinder walls and rings. The fuel content in your oil is bad because fuel is not a good lubricant. There is always going to be fuel content in your oil, especially in a turbocharged engine. But, it's not a good thing at all and the more thats there, the faster your oil gets "dirty". This hurts your oil's performance and will show up in a oil anylisis. This is bad thing...this will effect your engine's longetivity if not kept in check.
CJ
Running too rich can cause problems of it's own. For instance, if you run so rich, to the point that the plugs are just on the verge of fouling out, carbon deposits can and will form in the combustion chamber. They will form on the plug and on the valve releifs of the pistons, ect. If the rich condition is not enough to foul the plugs and the plug are still able to operate at self cleaning temp....these carbon deposits can actually get red hot, which can cause pre-ignition as these hot spots of carbon deposits ignite the air/fuel mixture prematurely(before the scheduled spark). This causes multiple flame fronts, which ultimatly collide together, causing knock(in this case, pre-ignition).
Of course, this is rare as most super super rich condition foul the plugs, causing misfires. But it can happen.......trust me.
Running super rich can also cause other problems as well. It can cause bore wash. If you run too rich for too long, the fuel washes past your rings and into your oil. As this is happening, the fuel is washing away the oil film on the piston skirts, cylinder walls and rings. The fuel content in your oil is bad because fuel is not a good lubricant. There is always going to be fuel content in your oil, especially in a turbocharged engine. But, it's not a good thing at all and the more thats there, the faster your oil gets "dirty". This hurts your oil's performance and will show up in a oil anylisis. This is bad thing...this will effect your engine's longetivity if not kept in check.
CJ
Last edited by iTune; May 21, 2007 at 07:10 PM.
Evolving Member
Joined: Mar 2007
Posts: 434
Likes: 1
From: Mexico
Here are the game rules:
Monitor your exhaust temp & knock activity.
Rich mixture = coolest exhaust temp
Lean mixture= hi gas temp (and so turbo boost / less turbo lag).
Too lean = knock
So try to go down and come back when detecting knock / detecting too high exhaust temps.
Cheers.
Monitor your exhaust temp & knock activity.
Rich mixture = coolest exhaust temp
Lean mixture= hi gas temp (and so turbo boost / less turbo lag).
Too lean = knock
So try to go down and come back when detecting knock / detecting too high exhaust temps.
Cheers.
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