someone please explain air fuel ratio
Mar 21, 2006, 12:15 PM
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Originally Posted by deadbeatrec
he didnt know what was going on other than the high flow cat messing things up. since then i have taken the hfc off and replaced it with a test pipe. feels strong and i dont feel any loss of power up top what so ever. but i hate to get on it when i dont know if im still having the knock sensor issues, so i drive like a g-ma all the time. he basicly told me to get rid of the cat and see how it feels. that and get some cams and come back for a retune.
It would be interesting to get re-dynoed ...
Also, something like this TurboXS knock lite might also be a great monitoring tool for peace of mind to know whether or not you are suffering from knock.
Mar 21, 2006, 12:26 PM
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the test pipe sounds amazing, just thought i would share. and that seems like an interesting tool. works off of sound, hum? how accurate is it? also how much is it and how do u hook it up? stick a mic under the hood, haha.
Originally Posted by joshd
Sounds like the test pipe was the right move
It would be interesting to get re-dynoed ...
Also, something like this TurboXS knock lite might also be a great monitoring tool for peace of mind to know whether or not you are suffering from knock.
It would be interesting to get re-dynoed ...
Also, something like this TurboXS knock lite might also be a great monitoring tool for peace of mind to know whether or not you are suffering from knock.
Mar 21, 2006, 01:20 PM
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Originally Posted by deadbeatrec
the test pipe sounds amazing, just thought i would share. and that seems like an interesting tool. works off of sound, hum? how accurate is it? also how much is it and how do u hook it up? stick a mic under the hood, haha.
I believe the knock lite just splices in to your factory knock sensor. There is some period where you train the device to know your engine sound (like revving in neutral or something), and then from that point forward, if the knock voltage goes over the learned threshold, the light comes on ... pretty slick and simple really. If you're paranoid about knock (who isn't), it seems like good peace of mind.
Mar 21, 2006, 02:16 PM
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it depends on your level of mods and your boost level, but
12.5-13:1 will blow your to pieces.
11.5~11.8 will be somewhat idea before you start getting detonation.
You want to be richer as the RPM climbs higher.
mine hangs around 11.5 at 7000rpm and well, mostly 11.5.
I would rather be blowing backfires than leaning out and blowing the pistons in pieces.
ideally, 11:1 is extremely rich and a if i were tuning my own car i would aim closer to 12-12.5:1. running that rich you can run the risk of washing your cylinder walls with the fuel. interestingly, if you used E85 as a fuel, you could run right on stoic. ratio and be fine because the fuel itself cools the air far greater then gasoline does (you wouldn't even need an intercooler for moderate boost levels). thats why the alcohol injection kits are a hot commodity for running high boost.
basically what it boils down to, you don't need to run 11:1 A/F. if you don't know what you are doing with tuning, then certainly stay super rich to sort of "mask" your errors. the factory tunes really rich for safety and reliability, but 11:1 ratio is not a max power tune (IIRC lambda of .85-.9 is ideal, which will put you at 12.5-13:1. if you are going to tune for that range, you need to be spot on with your A/F ratios... you need to know the latency of the sensor and readout, you need to know what timing you can run, and you need to know how consistant your boost is. boost spikes with A/F ratios close to stoic will be disasterous if you didn't tune for them.
this is only the tip of the iceburg really. i suggest reading some books on it if your interested in tuning your own car.
basically what it boils down to, you don't need to run 11:1 A/F. if you don't know what you are doing with tuning, then certainly stay super rich to sort of "mask" your errors. the factory tunes really rich for safety and reliability, but 11:1 ratio is not a max power tune (IIRC lambda of .85-.9 is ideal, which will put you at 12.5-13:1. if you are going to tune for that range, you need to be spot on with your A/F ratios... you need to know the latency of the sensor and readout, you need to know what timing you can run, and you need to know how consistant your boost is. boost spikes with A/F ratios close to stoic will be disasterous if you didn't tune for them.
this is only the tip of the iceburg really. i suggest reading some books on it if your interested in tuning your own car.
11.5~11.8 will be somewhat idea before you start getting detonation.
You want to be richer as the RPM climbs higher.
mine hangs around 11.5 at 7000rpm and well, mostly 11.5.
I would rather be blowing backfires than leaning out and blowing the pistons in pieces.
Mar 21, 2006, 04:06 PM
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Originally Posted by joshd
Some good info in your post, thanks. Just one point of potential clarification. I may be wrong on this, so feel free to correct me.
My understanding is that the two phenomenon: pre-ignition and detonation are actually two separate (bad) things that can occur in an internal combustion engine.
Pre(auto)-ignition, as you state, is when the mixture spontaneously combusts prior to the spark event due to a high heat/low octane (or combination thereof) situation.
Detonation on the other hand, I think, is an uncontrolled (too fast) burn of the mixture after being ignited by the spark.
Both of these are very bad obviously and can happen more frequently in turbo cars, but I think you might have these two conditions somewhat mixed together in your description above.
Also, my understanding is that fuel doesn't really lower intake temps much at all, that is a bit of a misnomer. Extra fuel I believe slows the burn which helps to prevent detonation. This is different than water/alky, which have much higher specific latent heat of vaporization (water having the highest i think) and can both lower intake temps a significant amount.
Anyway, just rambling here and trying to galvanize my own knowledge. Feel free to point out my mistakes
My understanding is that the two phenomenon: pre-ignition and detonation are actually two separate (bad) things that can occur in an internal combustion engine.
Pre(auto)-ignition, as you state, is when the mixture spontaneously combusts prior to the spark event due to a high heat/low octane (or combination thereof) situation.
Detonation on the other hand, I think, is an uncontrolled (too fast) burn of the mixture after being ignited by the spark.
Both of these are very bad obviously and can happen more frequently in turbo cars, but I think you might have these two conditions somewhat mixed together in your description above.
Also, my understanding is that fuel doesn't really lower intake temps much at all, that is a bit of a misnomer. Extra fuel I believe slows the burn which helps to prevent detonation. This is different than water/alky, which have much higher specific latent heat of vaporization (water having the highest i think) and can both lower intake temps a significant amount.
Anyway, just rambling here and trying to galvanize my own knowledge. Feel free to point out my mistakes
"4.1.4 Detonation or abnormal combustion
Detonation occurs in the combustion process when the advancing flame front, which is pressurizing and heating the unburned mixture ahead of it, does so at such a rate that the unburned fuel in that zone achieves it's auto-ignition temperature before the arrival of the actual flame front. The result is that the unburned mixture combusts "spontanously" and over the entire zone where the auto-ignition temperature has been achieved..."
depending on how you interpret that, we are both right. my interpretation is they are the same thing. you get pre-ignition in detonation due to temps being to high.
and yes, even gasoline has a latent heat of vaporization that does cool the air slightly (not near as much as alcohol fuels though).
Mar 21, 2006, 04:28 PM
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Originally Posted by joshd
Also, my understanding is that fuel doesn't really lower intake temps much at all, that is a bit of a misnomer. Extra fuel I believe slows the burn which helps to prevent detonation. This is different than water/alky, which have much higher specific latent heat of vaporization (water having the highest i think) and can both lower intake temps a significant amount.
Mar 21, 2006, 06:17 PM
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Originally Posted by KevinD
taken out of "design and simulation of four-stroke engines" by gordon Blair:
"4.1.4 Detonation or abnormal combustion
Detonation occurs in the combustion process when the advancing flame front, which is pressurizing and heating the unburned mixture ahead of it, does so at such a rate that the unburned fuel in that zone achieves it's auto-ignition temperature before the arrival of the actual flame front. The result is that the unburned mixture combusts "spontanously" and over the entire zone where the auto-ignition temperature has been achieved..."
depending on how you interpret that, we are both right. my interpretation is they are the same thing. you get pre-ignition in detonation due to temps being to high.
"4.1.4 Detonation or abnormal combustion
Detonation occurs in the combustion process when the advancing flame front, which is pressurizing and heating the unburned mixture ahead of it, does so at such a rate that the unburned fuel in that zone achieves it's auto-ignition temperature before the arrival of the actual flame front. The result is that the unburned mixture combusts "spontanously" and over the entire zone where the auto-ignition temperature has been achieved..."
depending on how you interpret that, we are both right. my interpretation is they are the same thing. you get pre-ignition in detonation due to temps being to high.
Mar 21, 2006, 06:41 PM
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Originally Posted by 32 psi daily
it depends on your level of mods and your boost level, but
12.5-13:1 will blow your to pieces.
11.5~11.8 will be somewhat idea before you start getting detonation.
You want to be richer as the RPM climbs higher.
mine hangs around 11.5 at 7000rpm and well, mostly 11.5.
I would rather be blowing backfires than leaning out and blowing the pistons in pieces.
12.5-13:1 will blow your to pieces.
11.5~11.8 will be somewhat idea before you start getting detonation.
You want to be richer as the RPM climbs higher.
mine hangs around 11.5 at 7000rpm and well, mostly 11.5.
I would rather be blowing backfires than leaning out and blowing the pistons in pieces.
Mar 22, 2006, 04:37 AM
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as for a sound clip, dont have one right now but it sounds really mean. exhaust is completly done from the manifold back and it growls like no other. very deep, no ricer screams, more like an sti with a turboback.
as for the knock, i think im going to go the light route or get an aem uego. thanks again guys
as for the knock, i think im going to go the light route or get an aem uego. thanks again guys
Originally Posted by joshd
sound clip?!?!?!
I believe the knock lite just splices in to your factory knock sensor. There is some period where you train the device to know your engine sound (like revving in neutral or something), and then from that point forward, if the knock voltage goes over the learned threshold, the light comes on ... pretty slick and simple really. If you're paranoid about knock (who isn't), it seems like good peace of mind.
I believe the knock lite just splices in to your factory knock sensor. There is some period where you train the device to know your engine sound (like revving in neutral or something), and then from that point forward, if the knock voltage goes over the learned threshold, the light comes on ... pretty slick and simple really. If you're paranoid about knock (who isn't), it seems like good peace of mind.
Mar 22, 2006, 05:47 AM
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I have the AEM UEGO and you mount it on the DP before the cat. AEM recommends 24" from the turbo I believe. I dont think mine is quite that far away but its been on for 10k miles w/o a single problem.
Mar 22, 2006, 07:10 AM
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Originally Posted by deadbeatrec
as for the knock, i think im going to go the light route or get an aem uego.
Mar 22, 2006, 07:59 AM
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u dont have to have AEM EMS to use the uego do u? EMS is a stand alone system isnt it? i have a flash and do not have the money to get a stand alone.
also does anyone know where is can get that light and any instructions on how to install it?
edit: found the light for like 122 but still need any install directions anyone might have. thanks
also does anyone know where is can get that light and any instructions on how to install it?
edit: found the light for like 122 but still need any install directions anyone might have. thanks
Originally Posted by Gsxfury
AEM EMS and uego perfect combine to monitor a/f, mine has been perfect and I wouldnt choose any other type of set up
Last edited by deadbeatrec; Mar 22, 2006 at 08:16 AM.
Mar 22, 2006, 10:06 AM
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Originally Posted by deadbeatrec
u dont have to have AEM EMS to use the uego do u? EMS is a stand alone system isnt it? i have a flash and do not have the money to get a stand alone.
also does anyone know where is can get that light and any instructions on how to install it?
edit: found the light for like 122 but still need any install directions anyone might have. thanks
also does anyone know where is can get that light and any instructions on how to install it?
edit: found the light for like 122 but still need any install directions anyone might have. thanks
Mach V link
or you can just buy it direct from TurboXS
I'd be tempted to give Dan the business though ... I met him yesterday and he seems like a great guy.
As for the UEGO, no you do not need the stand alone EMS to make it work!
There are other options too, for example the Innovative stuff:
Innovative LC-1 controller with XD-16 gauge kit
Have fun!