PE time :)
11-07-2005, 10:14 PM
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PE time :) yes or no...
when messing with my pe and open loop eq ratio
to basically decide what i want my a/f to be id do the following equation right?
14.7/1.091 to get an a/f of 13.4 correct?? if so, is that it for WOT PE wise, on top of ve and timing that is???
when messing with my pe and open loop eq ratio
to basically decide what i want my a/f to be id do the following equation right?
14.7/1.091 to get an a/f of 13.4 correct?? if so, is that it for WOT PE wise, on top of ve and timing that is???
11-07-2005, 10:49 PM
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why do you say that?? do i have it all wrong?? ive spoken (aim) with quite a few of the guys that beta tested 2.0. Ive asked away as well as spent most of my time underway reading the how to's, old posts and all that other stuff. I just now started playing with the software and stuff started making more and more sense so i thought.
11-07-2005, 11:05 PM
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I don't think 13.4 is a good AFR to plug into your car unless you do it in increments on a dyno or at a track to insure that you even need it. A good AFR for your car isn't something that you can just say, hey I think I'm going to run this AFR because so and so ran it. Going lean is the number one way to hurt your engine. I would set it up with 12.9/13.0 and call it a day until you toss it on a dyno.
There is a broad range of AF ratios where your car will make about the same power, you want to be at the bottom of that band. You won't make or lose a lot of power due to A/F ratio, timing has more to do with power.
I watched a demonstration where they had a car strapped to a steady state dyno using a Motec stand alone, they moved the A/F ratio up and down and you could look at the output on the dyno to see how much power it was making while the car was held in the same rpm/map. The car made as much power at 12.4 as it did all the way up into the 13s until you could hear it ping.
All I'm saying is make sure you know what you're doing, and that I would never recommend that anyone run that high unless they put it on a dyno and know that its worth the risk.
There is a broad range of AF ratios where your car will make about the same power, you want to be at the bottom of that band. You won't make or lose a lot of power due to A/F ratio, timing has more to do with power.
I watched a demonstration where they had a car strapped to a steady state dyno using a Motec stand alone, they moved the A/F ratio up and down and you could look at the output on the dyno to see how much power it was making while the car was held in the same rpm/map. The car made as much power at 12.4 as it did all the way up into the 13s until you could hear it ping.
All I'm saying is make sure you know what you're doing, and that I would never recommend that anyone run that high unless they put it on a dyno and know that its worth the risk.
11-07-2005, 11:09 PM
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my bad. i didnt mean thats the a/f i was going to use. I was just using that as an example to see if i had the equation right 
I know not to run that lean 
but this now worries me because this is what my PE is set to and has been:
1.09082 1.09082 1.09082 1.09082 1.09082 1.09082 1.09082 1.09082 1.09082 1.07910 1.07910 1.07910 1.07910 1.07910 1.07910 1.09082 1.09082 1.09082 1.09082
Like i said, ill have Ed there, but he's more familiar with the older way of tuning. He doesnt know the ve portion very well. Im just trying to make sense of it all so when we get together, I can explain it better and have a better understanding of whats going on.
I know not to run that lean but this now worries me because this is what my PE is set to and has been:1.09082 1.09082 1.09082 1.09082 1.09082 1.09082 1.09082 1.09082 1.09082 1.07910 1.07910 1.07910 1.07910 1.07910 1.07910 1.09082 1.09082 1.09082 1.09082
Like i said, ill have Ed there, but he's more familiar with the older way of tuning. He doesnt know the ve portion very well. Im just trying to make sense of it all so when we get together, I can explain it better and have a better understanding of whats going on.
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11-08-2005, 05:31 PM
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Bombguy, that is an intersting example. Unfortunately, some of us need to conserve fuel during sprint races, and need to be on the "lean" side of things. Would you happen to remember the exact "13s" that ping started. I've run my engines at AFR's great than 14.0, and while I have the retard programmed out (don't know if it was pinging or not), I've never hurt an engine due to it running lean. I've been trying to determin the absolute leanest you can safely run, but haven't gotten answers consisten with my personal experience.
Thanks!
Thanks!
11-08-2005, 10:04 PM
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your right that is how the pe table commands desired afr.
People say you should command 13:1 because it provides the best power and it is the safest. If you want to run leaner you will be more prone to detonation and heat but as long as your timing levels are safe and fueling consistent have at it.
Engines didnt always have knock and 02 sensors; on an NA engine I dont think there is as much to worry about with catastrophic failure from detonation as everyone would like to believe especially with the compression ration under 11:1. Ive always heard that rings tend to go before the piston is actually compromised from detonation. Of course detonation can get so bad its turns into preignition then your gonna have problems. But late model engines can stand up to moderate amounts of detonation for a long time.
My .02
People say you should command 13:1 because it provides the best power and it is the safest. If you want to run leaner you will be more prone to detonation and heat but as long as your timing levels are safe and fueling consistent have at it.
Engines didnt always have knock and 02 sensors; on an NA engine I dont think there is as much to worry about with catastrophic failure from detonation as everyone would like to believe especially with the compression ration under 11:1. Ive always heard that rings tend to go before the piston is actually compromised from detonation. Of course detonation can get so bad its turns into preignition then your gonna have problems. But late model engines can stand up to moderate amounts of detonation for a long time.
My .02
11-09-2005, 04:35 PM
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our engines run 12:1 compression, forged rods/pistons, 104 octane fuel, tons of spark advance (don't have my tables in front of me, but 28-32ish), with good pumps and injectors.
I ran almost a full season, including a race win and track record, in 2002 with my AFR dead on 14.7. I was running an ASA computer, and nobody told me it was designed for 58psi fuel pressure (mine was set at stock 52). I finally got LS1edit, but ordered the wrong year (again, nobody told me the ASA computers were 2000-VIN, my car had originally been 01). By the time I finally bumped the PE table, the season was just about over.
I did have two engine "failures". BAck in 01, a batch of lifter "guides" (the plastic pieces) were molded with one of the bores rotated 10 deg off from square. After exactly 2 races, the lifter fails and destroys the camshaft. In both cases, I was able to continue with a new camshaft, lifter and guide (not fun at the track on a Vette, I must add), but the block was not usable for a rebuild due to the damage.
Sorry for the side track, but just showing that even a bad AFR isn't necessarily the worst problem you can have.
I ran almost a full season, including a race win and track record, in 2002 with my AFR dead on 14.7. I was running an ASA computer, and nobody told me it was designed for 58psi fuel pressure (mine was set at stock 52). I finally got LS1edit, but ordered the wrong year (again, nobody told me the ASA computers were 2000-VIN, my car had originally been 01). By the time I finally bumped the PE table, the season was just about over.
I did have two engine "failures". BAck in 01, a batch of lifter "guides" (the plastic pieces) were molded with one of the bores rotated 10 deg off from square. After exactly 2 races, the lifter fails and destroys the camshaft. In both cases, I was able to continue with a new camshaft, lifter and guide (not fun at the track on a Vette, I must add), but the block was not usable for a rebuild due to the damage.
Sorry for the side track, but just showing that even a bad AFR isn't necessarily the worst problem you can have.
11-09-2005, 10:28 PM
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The guy that told me that story was Ben Strader, he does the EFI university classes and used to do race engine development for Porsche. I haven't done any of that type of testing myself, just sharing some info that I heard.
Yeah, I could see for race engines where fuel consumption is an issue that would be benificial. But for non-competition stuff where you'd like your engine to last a while its food for thought. I forget the exact time frame, but the engines were ran for several hours at high rpm on an engine dyno I believe.
Yeah, I could see for race engines where fuel consumption is an issue that would be benificial. But for non-competition stuff where you'd like your engine to last a while its food for thought. I forget the exact time frame, but the engines were ran for several hours at high rpm on an engine dyno I believe.
11-09-2005, 10:36 PM
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David, I don't remember what AFR it started pinging at, but it wouldn't really be relevant. Every engine build is going to be different in tolerances, and honestly the more powerful an engine is the narrower your optimal AFR will be. I'd bet your engine probably has a .3-.4 tolerance or so where it makes the best power. A stock or near stock LS1 probably has a much wider band.
In your case, if I were tuning your car, especially since your in competition, I'd sit with the car on a brake dyno for hours mapping every cell in existence using the limited bi-directional controls that available tuning software has.
Do they let you run standalones or are you limited to OEM-like PCMS?
In your case, if I were tuning your car, especially since your in competition, I'd sit with the car on a brake dyno for hours mapping every cell in existence using the limited bi-directional controls that available tuning software has.
Do they let you run standalones or are you limited to OEM-like PCMS?