PE vs RPM multiplier question.
01-27-2004, 04:57 PM
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Staging Lane
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PE vs RPM multiplier question. For all of you LS1EDIT gurus 
, is the multiplier value that you use to tune WOT linear with respect to AFR? In other words, if I increase the multiplier by 2% at a given RPM, will I get a 2% richer AFR at that RPM? My gut tells me no especially if the injectors are different, but I am not sure. What is the verdict? If not does anyone know the function for a stock 1999 fuel system?
I am preparing myself for a tuning session at the dyno and I would like: 1. To be in the ballpark. 2. To have a method figured out ahead of time to maximize my dyno time. Thanks
, is the multiplier value that you use to tune WOT linear with respect to AFR? In other words, if I increase the multiplier by 2% at a given RPM, will I get a 2% richer AFR at that RPM? My gut tells me no especially if the injectors are different, but I am not sure. What is the verdict? If not does anyone know the function for a stock 1999 fuel system?I am preparing myself for a tuning session at the dyno and I would like: 1. To be in the ballpark. 2. To have a method figured out ahead of time to maximize my dyno time. Thanks
01-28-2004, 12:19 PM
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Originally Posted by 1fastWS6
From what I've been told -yes- it is for small changes (<10%) then it starts to deviate. So, if you're 13.5:1 on the dyno and want to get to 12.5:1, you'll want to increase the PE multiplier by 8% or so. This should get you pretty close.
Thanks, makes sense.
01-28-2004, 06:27 PM
#4
the number is a divsor to calculate target air fuel ratio..
if you're using say 1.2403 as a value then take your stoich ratio on the main fuel table (should be14.737) and divide by 1.2403.. thats = 11.88:1 and that is your target ratio.. if your engine coolant temperature is outside of normal operating temperatures then it gets affected by the temperature adder (add the amount to the rpm number)
if the 11.8 turns out to be 12.0 a/f on the dyno etc. just keep that linear relationship in mind during adjustments (aim .2 low etc.)
if you are looking for max hp then you are looking for something on the par of 12.5 to .8 on the dyno but every car is different.
as you see the stock computer sets up slightly rich for safety.
if you're using say 1.2403 as a value then take your stoich ratio on the main fuel table (should be14.737) and divide by 1.2403.. thats = 11.88:1 and that is your target ratio.. if your engine coolant temperature is outside of normal operating temperatures then it gets affected by the temperature adder (add the amount to the rpm number)
if the 11.8 turns out to be 12.0 a/f on the dyno etc. just keep that linear relationship in mind during adjustments (aim .2 low etc.)
if you are looking for max hp then you are looking for something on the par of 12.5 to .8 on the dyno but every car is different.
as you see the stock computer sets up slightly rich for safety.
01-29-2004, 02:10 PM
#5
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Originally Posted by MIGHTYMOUSE
the number is a divsor to calculate target air fuel ratio..
if you're using say 1.2403 as a value then take your stoich ratio on the main fuel table (should be14.737) and divide by 1.2403.. thats = 11.88:1 and that is your target ratio.. if your engine coolant temperature is outside of normal operating temperatures then it gets affected by the temperature adder (add the amount to the rpm number)
if the 11.8 turns out to be 12.0 a/f on the dyno etc. just keep that linear relationship in mind during adjustments (aim .2 low etc.)
if you are looking for max hp then you are looking for something on the par of 12.5 to .8 on the dyno but every car is different.
as you see the stock computer sets up slightly rich for safety.
if you're using say 1.2403 as a value then take your stoich ratio on the main fuel table (should be14.737) and divide by 1.2403.. thats = 11.88:1 and that is your target ratio.. if your engine coolant temperature is outside of normal operating temperatures then it gets affected by the temperature adder (add the amount to the rpm number)
if the 11.8 turns out to be 12.0 a/f on the dyno etc. just keep that linear relationship in mind during adjustments (aim .2 low etc.)
if you are looking for max hp then you are looking for something on the par of 12.5 to .8 on the dyno but every car is different.
as you see the stock computer sets up slightly rich for safety.
So my stock settings are 1.2403 across the board, and the stoich ratio is 14.7. The wide band AFR shows me at 13.8 ish. That puts me nearly 2 points leaner than stock?? Seems a bit much but I guess I could have freed up 15% more air for WOT operation with cold air, 85mm MAF and ported TB. So by this logic the 1.2403 is acting more like 1.0652, the difference is .1751. If I added .1751 to the 1.2403 I should be back to 11.8ish number? But I really want 12.8 so I should add .0876. Looks good in theory. I'll try it and see what happens. Thanks a lot.
And in the end both of you are saying the same thing, and supporting stories is always good
Last edited by HellOnWeelz; 01-29-2004 at 02:19 PM.
