ALT Posted April 27, 2008 Share Posted April 27, 2008 Attached is the AFR data from my recent dyno run. Any of you technical people have any comments / suggestions? Quote Link to comment Share on other sites More sharing options...
Ekona Posted April 27, 2008 Share Posted April 27, 2008 Runs quite rich, doesn't it? 11-11.5 is what I'd expect an FI engine to run, not an NA one. How did they get the AFR? Sniffer at the exhaust tip, or have you had a separate hole for a proper wideband sensor added before the cats? Quote Link to comment Share on other sites More sharing options...
ALT Posted April 27, 2008 Author Share Posted April 27, 2008 Runs quite rich, doesn't it? The engineer at Crazy Horses was surprised. Also surprised at how variable the mixture is between 3000 and 6000 rpm. How did they get the AFR? Sniffer in the end of the exhaust. So is this something to be concerned about? Should I do anything about it? Quote Link to comment Share on other sites More sharing options...
Ekona Posted April 27, 2008 Share Posted April 27, 2008 Not really worried about as a sniffer can only detect so much as it's post-cat, but assuming it's close enough to the true reading it's getting dangerously rich at the top end, possibly getting towards bore wash perhaps? Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted April 27, 2008 Share Posted April 27, 2008 Certainly the numbers are a bit rich but a sniffer is really not that accurate and as Dan says bore wash is a strong possibility at top end if you are actually running that rich. Most of the tuner guys that use a sniffer would probably use an Innovate LM1 AFR meter and for speeds sake would use the sniffer but it can also be hooked up to a Bosch Wideband Sensor which would give you an accurate reading. If you are concerned then I would recommend that you get that done. Quote Link to comment Share on other sites More sharing options...
Ekona Posted April 27, 2008 Share Posted April 27, 2008 LM1 Terrific piece of kit. Quote Link to comment Share on other sites More sharing options...
sinbad Posted April 27, 2008 Share Posted April 27, 2008 Runs quite rich, doesn't it? 11-11.5 is what I'd expect an FI engine to run, not an NA one. How did they get the AFR? Sniffer at the exhaust tip, or have you had a separate hole for a proper wideband sensor added before the cats? my DC5 ran around that mark? Quote Link to comment Share on other sites More sharing options...
AndySpak Posted April 27, 2008 Share Posted April 27, 2008 What should it be in a Zed? Quote Link to comment Share on other sites More sharing options...
Ekona Posted April 28, 2008 Share Posted April 28, 2008 Stolen from Wiki: In Naturally Aspirated engines powered by octane, maximum power is frequently reached at AFRs ranging from 12.5 - 13.3:1 I'd be expecting to see the lower end of that scale for an OEM tune, but certainly not in the 11s. Quote Link to comment Share on other sites More sharing options...
ALT Posted April 28, 2008 Author Share Posted April 28, 2008 Stolen from Wiki: In Naturally Aspirated engines powered by octane, maximum power is frequently reached at AFRs ranging from 12.5 - 13.3:1 I'd be expecting to see the lower end of that scale for an OEM tune, but certainly not in the 11s. Ok. So there is some doubt about the accuracy of the data (although the reading at idle looks about right). Is there any way a standard garage (without all the fancy tuning gear) could check this for me? If the mixture genuinely is rich, what could be the reason? Could this be a symptom of restricted airflow, for example, a blocked filter? Would it be worth me replacing my standard paper filter with a high flow K&N, for example? Has anyone else had this measurement done on their car? Do the data look similar? Quote Link to comment Share on other sites More sharing options...
djtimo Posted April 28, 2008 Share Posted April 28, 2008 13:1 AFR for a NA car dude, best power and fuel economy! Quote Link to comment Share on other sites More sharing options...
sinbad Posted April 28, 2008 Share Posted April 28, 2008 Yes your right power will be achieved between 12.5 - 13.3:1 but the standard map isnt trying to acheive maximum power. Its a standard Nissan map that has to be able to run in all conditions and be able to cope with extremes in weather, different quality/octane fuel etc.. plus at peak it will run rich as a saftey feature? Saying that the map does look slighty rich. altheo45 - replacing the filter wouldnt have any adverse affects. Has anyone else got a standard AFR map to compare? Quote Link to comment Share on other sites More sharing options...
Carlo Posted July 14, 2020 Share Posted July 14, 2020 2008 350zHR. Custome made long tube headers and hoping to get 3" / 76mil intakes and tune. But need to know what the AF ratio should be without melting down the motor or wasting gas but for best performance Quote Link to comment Share on other sites More sharing options...
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