How lean is too lean???
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How lean is too lean???
I'm trying to educate myself and learn more about my FD. So far, others have tuned it, but I'd like to learn more about it myself. At the moment, my A/F ratio is at about 11 for most of my curve. I know this robs me of some power, but how lean can I go without killing my engine?
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Venting the stock BOV wont help since it is not setup as a diverter valve (such as DSM's). 11:5-12:1 is about where you want your air fuel ratio at. Running your car leaner isn't going to increase your power, its just going to hurt, more fuel is better, too much fuel is bad. What kind of setup are you running anyways that others have to tune it?
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Venting the stock BOV wont help since it is not setup as a diverter valve (such as DSM's). 11:5-12:1 is about where you want your air fuel ratio at. Running your car leaner isn't going to increase your power, its just going to hurt, more fuel is better, too much fuel is bad. What kind of setup are you running anyways that others have to tune it? If it was professionally dyno tuned, your car should be just where it should be. I dont understand how someone else could tune your car otherwise unless your using other peoples fuel maps or something, which is not a good way to go.
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Rotaries don't make a ton of power by leaning them out much further than that. My buddy Eric's car only picked up 7whp going from 11:1 to 12.5:1. It's not worth it. If you're at 11:1 that's fine, keep it there.
#7
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Originally posted by kyle@insight
Rotaries don't make a ton of power by leaning them out much further than that. My buddy Eric's car only picked up 7whp going from 11:1 to 12.5:1. It's not worth it. If you're at 11:1 that's fine, keep it there.
Rotaries don't make a ton of power by leaning them out much further than that. My buddy Eric's car only picked up 7whp going from 11:1 to 12.5:1. It's not worth it. If you're at 11:1 that's fine, keep it there.
My experience is good power is available leaning from 11.1 to 11.6 / 11.8. That is my limit, but I feel confident about my set up.
YMMV. Use caution, the leaner you run, the less tolerance you have for an anomaly, i.e., overboost, timing error, etc.
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Originally posted by mmaragos
YMMV. Use caution, the leaner you run, the less tolerance you have for an anomaly, i.e., overboost, timing error, etc.
YMMV. Use caution, the leaner you run, the less tolerance you have for an anomaly, i.e., overboost, timing error, etc.
#10
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Originally posted by tomaszjc7
I dont think we have timing problems....
I dont think we have timing problems....
Don't believe me? Go swap your plug wires and see how many miles you can drive .
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Originally posted by GoodfellaFD3S
Don't believe me? Go swap your plug wires and see how many miles you can drive .
Don't believe me? Go swap your plug wires and see how many miles you can drive .
Even though I dont know exactly what would happen if someone were to do that (I can take a wild guess though), I dont think we should say that. Hopefully no one is gullible enough to try it just to see what happens.
**ludeowner goes to swap his leading and trailing plug wires**
#12
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Originally posted by ludeowner
Even though I dont know exactly what would happen if someone were to do that (I can take a wild guess though), I dont think we should say that. Hopefully no one is gullible enough to try it just to see what happens.
**ludeowner goes to swap his leading and trailing plug wires**
Even though I dont know exactly what would happen if someone were to do that (I can take a wild guess though), I dont think we should say that. Hopefully no one is gullible enough to try it just to see what happens.
**ludeowner goes to swap his leading and trailing plug wires**
That's why when you're doing your own plugs, always do one wire at a time. The leading plugs fire off of the same coil, so swap those bad boys to your heart's content.....
#15
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Originally posted by homie
Actually I just checked and my A/F is at 12. Is that too lean?
Actually I just checked and my A/F is at 12. Is that too lean?
Last edited by GoodfellaFD3S; 07-17-03 at 03:05 PM.
#16
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Originally posted by homie
FYI - I'm measuring A/F at the tailpipe and not the downpipe...if that helps any.
FYI - I'm measuring A/F at the tailpipe and not the downpipe...if that helps any.
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Originally posted by homie
I'm at 1 bar, pushing 360rwhp. 14 A/F @4100 rpm, 13 A/F @5000 rpm, 12.5 A/F @5500 rpm, 11.9 A/F @6000-7500 rpm.
I'm at 1 bar, pushing 360rwhp. 14 A/F @4100 rpm, 13 A/F @5000 rpm, 12.5 A/F @5500 rpm, 11.9 A/F @6000-7500 rpm.
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Thats a kaboom tune. You're way lean at peak torque. You could probably get away going the other way (ie 11.0-11.5 through peak torque, then up to 12.0 in the high revs)
#20
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Originally posted by homie
I'm at 1 bar, pushing 360rwhp. 14 A/F @4100 rpm, 13 A/F @5000 rpm, 12.5 A/F @5500 rpm, 11.9 A/F @6000-7500 rpm.
I'm at 1 bar, pushing 360rwhp. 14 A/F @4100 rpm, 13 A/F @5000 rpm, 12.5 A/F @5500 rpm, 11.9 A/F @6000-7500 rpm.
#22
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Go with what Marshall said. You need to richen up the area on the map that corresponds with your dyno plots peak torque. If its at 5000 rpms, then that is where you need to be 11.4 or richer depending on your car. Assuming your running twins sequentially, 5000 is around the peak torque and your pretty damn lean (13 to 1) at that point. Richen that thing up to to 5000 rpms and you can raper it off to redline with maybe 11.8 to 11.6 at that point.
Right now your playing with a time bomb and need to tell the "tuner" to add some fuel or its rebuild time.
Tim
Right now your playing with a time bomb and need to tell the "tuner" to add some fuel or its rebuild time.
Tim
#23
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One other point......measuring from the tailpipe is fine, but make sure that you don't have an exhaust leak. This can cause you to show a richer reading than you're actually getting from your motor......
#24
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Originally posted by GoodfellaFD3S
One other point......measuring from the tailpipe is fine, but make sure that you don't have an exhaust leak. This can cause you to show a richer reading than you're actually getting from your motor......
One other point......measuring from the tailpipe is fine, but make sure that you don't have an exhaust leak. This can cause you to show a richer reading than you're actually getting from your motor......
I am not sure how a leak will make you read richer or leaner (leaner was said before). Air will not leak in, exhaust gas will leak out, but if it is going to read richer the assumption would have to be that just the O2 is leaking out? I don't see how that can happen.
Maybe I am not seeing/understanding something...
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Originally posted by mmaragos
I am not sure how a leak will make you read richer or leaner (leaner was said before). Air will not leak in, exhaust gas will leak out, but if it is going to read richer the assumption would have to be that just the O2 is leaking out? I don't see how that can happen.
Maybe I am not seeing/understanding something...
I am not sure how a leak will make you read richer or leaner (leaner was said before). Air will not leak in, exhaust gas will leak out, but if it is going to read richer the assumption would have to be that just the O2 is leaking out? I don't see how that can happen.
Maybe I am not seeing/understanding something...