Question: Air Fuel Ratio 3.8
10-20-2009, 11:58 AM
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Question: Air Fuel Ratio 3.8
Does anybody know what is the correct Air Fuel ratio for a 3.8 engine under full load?
Last edited by HansB; 10-20-2009 at 05:50 PM.
10-26-2009, 01:07 PM
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You can look www.911chips.com dynos graphs,then you can ask them.My car is 3,6 lt. 12,5 comp. with wild cams my Afr is always shows nearly 13 on all rpm levels.
10-27-2009, 11:02 AM
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The correct air fuel ratio for a 3.8 engine depends on a number of factors including the load on the engine, the design of the engine, the cooling of the engine, etc. If you want to speak in general terms, here is what I've found. The 3.8l factory engine can be run as lean a .92 lambda, however, it tends to make peak power at .89 lambda, and I run them at .88 lambda because they run slightly cooler on the cylinder head temps which I seem to have a problem with on the high output 3.8 engines. This is at full throttle. At light load (< 30-40% throttle depending on engine) I run the engines a 1.0 lambda. If I tune an engine using leaded fuel (which I do not like) I might run it slightly leaner due to the cooling properties of the lead content.
I hope this helps.
I hope this helps.
10-27-2009, 11:06 AM
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This topic is covered, in general terms, on page 175 of the Bruce Anderson book and with possible variation on page 147. In short: 14 is target ratio for perfect combustion (1.0 lambda), 16 produces better fuel economy and 12 or less for more torque.
http://books.google.com/books?id=xHe...age&q=&f=false
http://books.google.com/books?id=xHe...age&q=&f=false
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10-27-2009, 02:42 PM
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