Air/Fuel question about LT1s
Thread Starter
Joined: Jan 2005
Posts: 1,475
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From: Munfordville KY
Air/Fuel question about LT1s I got my car dynoed this weekend, and was going to have a little tuning done, but the dyno shop couldn't find his obd1 cable. I dynoed 310.1 hp and 317.8 tq at the tires. My air/fuel was at 12.4. What is the optimal air fuel for an LT1 Na car?? The reason I'm asking, is my buddy's car was pulling awesome #'s with his air fuel setting at 14.0.
Could I gain any power safely by leaning the car out some?? Thanks
Matt
Could I gain any power safely by leaning the car out some?? Thanks
Matt
TECH Enthusiast
Joined: Jul 2003
Posts: 697
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From: Evansville, IN
Yeah you may get higher numbers running that high, but it gets pretty dangerous running that lean. His fuel pump is probably going out. You might be able to go a little higher but I would not suggest 14.
do not run a 14.7:1 AFR during WOT you will blow the engine and burn the cats up. there is a reason the AFR is commanded down to 13:1 or lower from the factory during WOT passes. it is to keep the engine together.
you will need to have your car dyno tuned to find out what it likes. some cars start knocking at 13:1 others can go 13.5:1 and not have problems. every car is different. for a genral rule of thumb though, i would not go leaner than 13 or 13.2:1. the few extra ponies your going to get out of it by pushing it leaner is not worth the possibility of blowing the engine.
you will need to have your car dyno tuned to find out what it likes. some cars start knocking at 13:1 others can go 13.5:1 and not have problems. every car is different. for a genral rule of thumb though, i would not go leaner than 13 or 13.2:1. the few extra ponies your going to get out of it by pushing it leaner is not worth the possibility of blowing the engine.
Originally Posted by FlamingChicken
the perfect a/f ratio is 14.7:1. at least for stock cars...
You definetly don't want that on a dyno reading.
A 14.7-1 air/fuel ratio is offen refered to as stoichiometric and is theoretically the best burn rate for emmisions at part throttle settings. This in no way is ggod for power production. Really somewhere in the low 13's is going to be the best depending on what your engine wants.
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My car gained 15 RWHP leaner it from 12.5 to 13.0 to 1. I lost power going leaner. HOWEVER, every car is different. Different mods will demand the optimum air/fuel ratio. Generally, though, "lean is mean" which is good for horsepower. Most engines will make the best power between 13 and 13.5 to 1.