AFR tuning theory
#32
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#34
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I know of a certain tuner that's running 12.8 afr's at 14-17psi and he swares that no damage is being done because there's no knock on his logs. Poor guy learned the hard way that burnt valves and butted piston rings are not from knock!
Last edited by crispeed; Feb 1, 2010 at 10:56 PM.
#36
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Egt's are not only effected by afr's. Ignition timing and load just to name a few have a greater affect on egt's than afr's. Every application is different so egt data will differ a lot. The fuel you're using also effect egt's. You can't really compare egt's from another application. Not even going to get into the differences in the measurement devices and their position in the exhaust system use to capture egt's.
Last edited by crispeed; Feb 1, 2010 at 10:42 PM.
#39
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Actually it does because it's not only the piston you gotta worry about. The piston-to-wall clearances and rings are adjusted for the level of power output. The fuel you're using also have a great affect on those build specs. Once piston sealing is compromised then everything goes downhill form there. Oil contamination does wonders for breaking down fuel. It's also greatly effects the egt's and afr's your're recording. Tuning two strokes is just one example where you cannot rely on afr and knock recording equipment. Egt's play a more important role there.
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#42
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anways, back on topic...
I think we can all agree that this thread basically revolves around running 11:1 vs 12.5:1
richer = safer?
leaner = cleaner + more power but at what cost?
is it realistic to run 12.5:1 AFR's on a daily driver using pump??
forgetting about fuel quality and mixture perfection, what about EGT's? Is there anything else we need to consider?
this is for pump fuel (91 or 93oct) and based on the Evo engine (4g63 or 4b11) for those that want to argue about AFR's on other engines/fuels...
I think we can all agree that this thread basically revolves around running 11:1 vs 12.5:1
richer = safer?
leaner = cleaner + more power but at what cost?
is it realistic to run 12.5:1 AFR's on a daily driver using pump??
forgetting about fuel quality and mixture perfection, what about EGT's? Is there anything else we need to consider?
this is for pump fuel (91 or 93oct) and based on the Evo engine (4g63 or 4b11) for those that want to argue about AFR's on other engines/fuels...
#45
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anways, back on topic...
I think we can all agree that this thread basically revolves around running 11:1 vs 12.5:1
richer = safer?
leaner = cleaner + more power but at what cost?
is it realistic to run 12.5:1 AFR's on a daily driver using pump??
forgetting about fuel quality and mixture perfection, what about EGT's? Is there anything else we need to consider?
this is for pump fuel (91 or 93oct) and based on the Evo engine (4g63 or 4b11) for those that want to argue about AFR's on other engines/fuels...
I think we can all agree that this thread basically revolves around running 11:1 vs 12.5:1
richer = safer?
leaner = cleaner + more power but at what cost?
is it realistic to run 12.5:1 AFR's on a daily driver using pump??
forgetting about fuel quality and mixture perfection, what about EGT's? Is there anything else we need to consider?
this is for pump fuel (91 or 93oct) and based on the Evo engine (4g63 or 4b11) for those that want to argue about AFR's on other engines/fuels...
It depends greatly on the material that the pistons are made off and how well the engine components transfer heat to the cylinder walls and head..
Our sales guy has a stock 1JZ swapped SC300 that runs on Q16, his AFRs are at 13.0 at 24PSI of boost and hes been running with no issues.. Our shop race car (900+ HP RSX) runs 13.0 - 13.4 AFRs with no issues.. Now granted the shop car is built, but the 1J is completely stock..
Our old shop race car was 11.5:1 compression motor with 28PSI of boost running 13.0 all the way down the track.. Never had an issue with pistons or valves.
http://www.youtube.com/watch?v=pWsXy6qYmQA RSX
http://www.youtube.com/user/Bugermass#p/u/6/qFuv-DyWjRk Old shop car.