Discussion about PE Modifier Based on RPM (B3618)

[Kevin Doe]

I am completely done with the VE table for the time being. I have every possible cell within 1% and now I'm moving onto really making some power from the tune.

I want to change my PE modifier based on RPM ( B3618 ), but I want to do so in an intelligent manner.

Theory tells me that you make max torque under the curve when you make the car richest at max torque, then lean it out afterwards.

I was thinking in the 12.75:1 range before max torque, then ramp to 12.5 at max torque, then ramp back to 13:1 after peak torque. Does anyone have any thoughts on this subject. I searched and didn't find much on the subject. Joecar had one post where he posted a screenshot of his curve, and it looked like a nice curve, maybe a bit on the rich side.

Anyone care to post your PE modifier based on RPM ( B3618 ) tables for comparison/ideas.

Thanks,
Kevin

[rally1]

Those sound like good numbers to aim for, I also go richer again once I reach peak power but it would be interesting to here from others about whether or not they do that .
You have to keep in mind all engines are slightly different in there fuel requirements to produce maximum power so trial and error on the dyno is the best way of finding the ideal fuel mixture.
You may find you can increase power by going a bit leaner around peak torque but I would say not a lot.

[WHYTRYZ06]

At what RPM do you consider max tq.... when does the PE actually start to kick in?? 4000rpm???

[SOMhaveit]

That seems close to the number I keep seeing in the tuning documents I've been able to find.

My max torque is very near 5200 RPM's, so I believe I set up for 12.8 up to 5200, then 13.1 up to Max HP (5900 RPM), then 12.5.

Problem I have is that even after AutoVE and MAF calibration, going back to closed loop I have positive LTFT's adding more fuel during WOT PE enrichment. In SD I was right on the money every time.

[Kevin Doe]

Could you post up a screen shot of the curves? I'm curious what works better. A linear ramp to peak torque then back down, or more of a hump that follows the torque curve? Yeah, dyno will be the deciding factor, but I'd like to get close before I get on the dyno and spend a ton of cash. On the street I'll be able to look at elapsed times. Say start a WOT pull in 3rd gear at 1500 rpms, and watch the elapsed time. I could look at elapsed times through each thousand rpms, and compare back to back runs to look for improvements.

[SOMhaveit]

Sorry Kevin, I don't have a means of posting my dyno sheet. I just remember that after I had my car dynoed I looked at posts where people showed their dyno's and right around 5200 was where the torque was peaking. There are a bunch of dyno sheets on ls1tech you could look at.

It's my understanding strictly from reading tuning manifestos on the net that the the 12.8 AFR target under the torque curve is a street tune or Mustang dyno. I don't understand why, but the recommendation is that if it's being done on a dynojet you should target the 12.2 -12.5 range.

I had my car dynoed before I got EFILive, so I wasn't doing the tuning. The guy who had previously tuned my car did then and really had it way too rich - around 11.0/1.

I did find an MS4 dyno sheet on LS1Tech and it looks like peak torque is close to 5200 and peak HP is around 6300. You might try 12.8 to 5200, 13.0 to 6300 and then 12.5 - tuning on the street.

I didn't try to make a curve regarding AFR, it's linear and abrupt. I've never seen anything about a graduated or curved AFR effect.

[stigmundfreud]

thats my ls1 which was at that time commanding 12.6 through the range. The dyno run was more a case to check my commanded fueling matched which this hopefully shows the case

Rather than ramping in and out as its NA I've now gone for 12.95 through the range to take another run on the dyno. For me I cant find the time to spend too much chacing optimum, I'm happy with the results as is so the comprrison going to 12.95 should be good to see.

I've used 12.95 as that matches the maximum called in my 3605 table. The next run however will be whilst using the MAF too - something I'm just starting to scale.

[Kevin Doe]

I"m lookin to see peoples B3618 curves. NOT the acual feedback. I'm assuming we all have our VE tables good enough that the acutal is withiin 1% of the commanded.

Here is my B3618 for reference. No KR, seems to run very strong, and very good. I"m still tweaking, and will probalby lean it out more, but this is my current table.



POST UP SCREEN shots and comments regarding to how well it is working, and your observatoins please.

[joecar]

At low rpm (high gear), you might want a little richer for throttle tip-in.