PE table. Flat line vs curved table?

[Nastruck]

So this may have been answered before but maybe not straight forward. Been little curious cause stock GM tunes have a curved PE table usually. When I'm tuning camed vehicles I usually stick with one AFR across the board but without ever having any of my tunes on the dyno I'm probably leaving some power on the table. Going to list a couple questions/scenarios and see what's the best info I get from the more advanced tuners.

So tuning a stock GM vehicle for more power with the stock cam is it better to find my max lean area and follow the same factory curve pattern cause they already determined where the max torque and max power range is for best fuel economy but just lean it out with the same curve?

On a cammed vehicle I usually stick with a flat afr and they run pretty hard but recently started thinking maybe I should follow a pattern like the factory does except using the VE table to determine where I want my lean/rich curve to come in at. Once the VE table is dialed in you can see where the cam really comes in and power falls off or in my trucks case see where it really loads up on the big stall converter.

So I was thinking with a flat PE table I'm probably losing torque in some spots and peaking in one section then falling again in another going this route. I may be completely wrong or this might not make sense to most people so open to criticism but looking for good info from maybe some more advanced tuners that's had different setups on the dyno that can prove this or no.

[LSxpwrdZ]

In my experience the LS engine makes great power in a wide range of lambda. However I always tend to command a bit richer mixture around peak tq then lean back out as peak hp approaches.

Those of you that don't have a TQ curve on a dyno to look at to see peak tq I'll give you a little trick. Plot g/cyl (Cylinder Airmass) on the Chart vs Time graph and do a WOT pull in one gear on the street from 2k rpm up to redline. The curve you see is a perfect representation of what the torque curve will look like on the dyno. Another one to look at is the injector pulsewidth. You'll notice IPW and g/cyl mimic the same curve. This is because it is directly representing the amount of air and/or fuel entering the cylinder each cycle.

[Area47]

giving the engine what it wants in terms of the pe, or maf curve will yield more power and more torque time and time again. flat is lazy.

[Nastruck]

I'll check into that James when my transmission is back in the truck

[mcfarlnd]

I always try to get a few runs on the dyno and follow the theory: Rich best torque to lean max power. I street tune all my vehicles and until I'm able to get it on a dyno, it is a flat PE curve. I like what LsxpowrdZ said, will have to try that out although when richening up the mixture, you don't know how much to fatten it unless it's on a dyno i.e. Following an airmass curve and you don't know when you start losing torque/power from the enrichment.

[ddtech]

Flat is not lazy infact, thats when the maf and what not is dialed in correctly.

#stoprapingthepetable


Spend the time to get the maf curve correct so u target 1 afr pe.

[Higgs Boson]

Flat is not lazy infact, thats when the maf and what not is dialed in correctly.

#stoprapingthepetable


Spend the time to get the maf curve correct so u target 1 afr pe.

what if the maf is perfectly tuned on a flat PE table and then you can alter the pe table (ie. richen it up around peak torque and lean it out up top or something else) and find more power at given RPM ranges not unlike more or less spark at different RPM ranges to find the best spark lead and AFR combination at each RPM (range) to optimize the combination?

I always tune to a flat PE but PE can be changed after that.

[ddtech]

Sure theres always exceptions..but im talking about people not giving a shit to the curve.. lol

[Area47]

Sure theres always exceptions..but im talking about people not giving a shit to the curve.. lol

as was i. i see it all the time when pe is tanked to get a certain afr/lambda, and the maf does not match it, or even close. i just didn't go into more detail about it.

[Nastruck]

Yea I always dial in my VE or MAF table no matter what. I don't cheat the PE to get a certain Afr to get around modifying the VE/MAF table. Just curious what most tuners with more experience go with as far as PE table. Flat or starting with a rich curve and leaning out up top

[motorheadmike]

In my experience the LS engine makes great power in a wide range of lambda. However I always tend to command a bit richer mixture around peak tq then lean back out as peak hp approaches.

Those of you that don't have a TQ curve on a dyno to look at to see peak tq I'll give you a little trick. Plot g/cyl (Cylinder Airmass) on the Chart vs Time graph and do a WOT pull in one gear on the street from 2k rpm up to redline. The curve you see is a perfect representation of what the torque curve will look like on the dyno. Another one to look at is the injector pulsewidth. You'll notice IPW and g/cyl mimic the same curve. This is because it is directly representing the amount of air and/or fuel entering the cylinder each cycle.

But... but... but... isn't that raping the PE table? LOL!

[LSxpwrdZ]

But... but... but... isn't that raping the PE table? LOL!

LOL, not when I'm commanding it and achieving it. Now throwing 1.75 in the table to add fuel at 6000rpm because a MAF is maxed out would classify as PE raping to me.

[motorheadmike]

LOL, not when I'm commanding it and achieving it. Now throwing 1.75 in the table to add fuel at 6000rpm because a MAF is maxed out would classify as PE raping to me.

Yeah, I can see that being a problem.