AEM wideband placement
03-16-2008, 02:38 AM
#1
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AEM wideband placement i dont know if this is the right section to put this thread, so mods if you feel like moving it thats fine
but i was helping to put texas speed headers and x pipe on a friends 98 vette eariler tonight and a question came up.
where is the optimal place to put a single AEM wideband in the exhaust?
we had talked about drilling a hole in the center of the top of the X and putting it in there but wanted to double check and ask someone where the best to place to put it
so anyone give me some info that'de be great because tomorrow we're goin to finish up the car and get the wideband in there and everything.
but i was helping to put texas speed headers and x pipe on a friends 98 vette eariler tonight and a question came up.
where is the optimal place to put a single AEM wideband in the exhaust?
we had talked about drilling a hole in the center of the top of the X and putting it in there but wanted to double check and ask someone where the best to place to put it
so anyone give me some info that'de be great because tomorrow we're goin to finish up the car and get the wideband in there and everything.
03-16-2008, 09:58 PM
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wideband needs ot be installed in front of the cats. As vertical as possible. So basically if you have room to screw it in from the top thats perfect. As close to the headers as possible in the X pipe.
03-17-2008, 04:19 PM
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That makes sense. I couldn't come up with a single reason it would read any different dependent upon position. As long as you're less than 90 degrees off vertical you should be fine.
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03-18-2008, 12:41 AM
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If one of the banks is off you know you have an issue. Really the best would be to have widebands in the headers, 8 total Also EGTs are a good idea. This is a better indication of tune then A/F.
03-18-2008, 04:51 AM
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03-18-2008, 11:32 AM
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8 O2's would be ideal. My race cars have all had egt's but they typically run so rich they burn in the pipe which gives you an artificially high temp. It's a good way to balance out your cylinders, but not always a clear correlation to to what the O2's read.
03-18-2008, 12:05 PM
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What do you mean by they burn in the pipe?
03-18-2008, 01:21 PM
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By the time you're exhausting your gasses, the fuel hasn't had sufficient time to "burn out." The combustion is finished as the gasses run through the exhaust system.
03-18-2008, 04:26 PM
#16
With late ignition timing (retarded) and rich mixtures, you can have unburnt fuel burning in your exhaust. Early opening exhaust valves also exhibit this condition.
If you have the opportunity to measure EGT's incrementally going from a lean to rich condition you will see high EGT's from a lean combustion condition at the start. As you richen up the mixture you will see the EGTs start to drop. When you start getting very rich (lets say 11:1 for an example), you will have excess fuel burning in the pipe, elevating your EGTs.
Of course, Ignition and Exhaust valve timing will have an effect on the above.
If you have the opportunity to measure EGT's incrementally going from a lean to rich condition you will see high EGT's from a lean combustion condition at the start. As you richen up the mixture you will see the EGTs start to drop. When you start getting very rich (lets say 11:1 for an example), you will have excess fuel burning in the pipe, elevating your EGTs.
Of course, Ignition and Exhaust valve timing will have an effect on the above.
03-18-2008, 07:04 PM
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With late ignition timing (retarded) and rich mixtures, you can have unburnt fuel burning in your exhaust. Early opening exhaust valves also exhibit this condition.
If you have the opportunity to measure EGT's incrementally going from a lean to rich condition you will see high EGT's from a lean combustion condition at the start. As you richen up the mixture you will see the EGTs start to drop. When you start getting very rich (lets say 11:1 for an example), you will have excess fuel burning in the pipe, elevating your EGTs.
Of course, Ignition and Exhaust valve timing will have an effect on the above.
If you have the opportunity to measure EGT's incrementally going from a lean to rich condition you will see high EGT's from a lean combustion condition at the start. As you richen up the mixture you will see the EGTs start to drop. When you start getting very rich (lets say 11:1 for an example), you will have excess fuel burning in the pipe, elevating your EGTs.
Of course, Ignition and Exhaust valve timing will have an effect on the above.
I have never tuned with them, but I talked to one of the viper engine engineers at one point. They basically said on their engines thats the proper way to tune them.
03-19-2008, 12:32 AM
#18
Yes, If you have the ability to tune by cylinder, exhaust temps are a good way to go. An O2 per cylinder will arguably give you better results. Ideally, cylinder pressure would give you the most accurate results, although plumbing is a pain when drilling and tapping the cylinder heads. On my latest race car I have one pressure transducer/TC tap in each of my heads for simplicity. I'm a former GM Test Engineer and get carried away with instrumenting the race car sometimes. In my case I'm looking at cylinder pressure and temperatures when different fuels are used.
Unfortunately, with any of these methods, the only ***** you have to tweak without playing with your intake/head ports is fuel and timing.
Unfortunately, with any of these methods, the only ***** you have to tweak without playing with your intake/head ports is fuel and timing.
Last edited by TT632; 03-19-2008 at 12:40 AM.
03-19-2008, 01:10 AM
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Yes, If you have the ability to tune by cylinder, exhaust temps are a good way to go. An O2 per cylinder will arguably give you better results. Ideally, cylinder pressure would give you the most accurate results, although plumbing is a pain when drilling and tapping the cylinder heads. On my latest race car I have one pressure transducer/TC tap in each of my heads for simplicity. I'm a former GM Test Engineer and get carried away with instrumenting the race car sometimes. In my case I'm looking at cylinder pressure and temperatures when different fuels are used.
Unfortunately, with any of these methods, the only ***** you have to tweak without playing with your intake/head ports is fuel and timing.
Unfortunately, with any of these methods, the only ***** you have to tweak without playing with your intake/head ports is fuel and timing.
Btw your hardcore
03-19-2008, 10:19 AM
#20
Yes, that would be the best use of your EGTs. Another benefit is finding out if you have a cylinder going south, or just a bad plug, wire or something else(TC probe going bad). Typically, I would run a real time trace of the exhaust temps before or after a pass to gauge the health of the motor.
Comparisons of your O2s can can also clue you in, just bank to bank and not individual cylinder.
Enough for now, Sorry to high jack the thread.
Last edited by TT632; 03-19-2008 at 11:43 AM.
