Some boost and VE issues

[Whippled 496]

I am trying to work out a few bugs in my tune and can not figure out a few issues that i have been having for a little while now. Hopefully someone here can lend a hand. My details:

8.1L / Allison
Whipple supercharged @ ~6.5lbs
A2W intercooler
SD tune w/ EFILive COS3

so here are my two issues:

1. I can not get past 145kPa no matter what pulley i use. I have tried 2.75", 2.625", and 2.50" and all give me right around 143-145kPa, then drop off to around 135kPa after a few seconds. The belt is tight, and has pretty good wrap around the pulley (as good as you can have with that small of a pulley anyway). There are no leaks, at least none that are identified by the scan tool in EFILive. I tried pulling the intake tubing off to see if there was a restriction coming in but it made no difference. So not really sure what to do here.

2. I have my AutoVE done for the most part and was working on tweaking some of the boostedVE table (A0009) because I had a few lean spots (1.02 -1.03 BEN's). This is when i noticed that my commanded VE (A0009) was quite different than what the scan tool was recording in those respective cells. My IATs were low enough that A0014 should not be having an effect on the cells and my ECTs were high enough that A0008 should not be having an effect either. Is there other places in this COS that effect final VE calculation?

Here is a tun/log file to look at, check frames 5810 - 5875 for examples.

http://www.pasadenatownhall.com/tun_log.zip

[Whippled 496]

matter of fact, it seems that there are quite a few places, even in the mainVE that dont seem to be matching correctly. There must be another table i am missing someplace that is making calculations.

[hquick]

Strange...I seem to be seeing the same thing (145Kpa max). I just assumed that was the limit for me...maybe not.

[Whippled 496]

Been looking over this for a couple days now and not finding anything that should be a factor in the calculations. Still dont know why they differ so much. Anyone else have any luck?

[onfire]

Which map sensor are you using?

Try some VHT on the belt for one run and see if the kPa's jump up. That will eliminate the belt if it is not slipping.

[hquick]

Pretty sure this is the part number of the sensor I'm using.
12580698

[Delco]

I am trying to work out a few bugs in my tune and can not figure out a few issues that i have been having for a little while now. Hopefully someone here can lend a hand. My details:

8.1L / Allison
Whipple supercharged @ ~6.5lbs
A2W intercooler
SD tune w/ EFILive COS3

so here are my two issues:

1. I can not get past 145kPa no matter what pulley i use. I have tried 2.75", 2.625", and 2.50" and all give me right around 143-145kPa, then drop off to around 135kPa after a few seconds. The belt is tight, and has pretty good wrap around the pulley (as good as you can have with that small of a pulley anyway). There are no leaks, at least none that are identified by the scan tool in EFILive. I tried pulling the intake tubing off to see if there was a restriction coming in but it made no difference. So not really sure what to do here.

2. I have my AutoVE done for the most part and was working on tweaking some of the boostedVE table (A0009) because I had a few lean spots (1.02 -1.03 BEN's). This is when i noticed that my commanded VE (A0009) was quite different than what the scan tool was recording in those respective cells. My IATs were low enough that A0014 should not be having an effect on the cells and my ECTs were high enough that A0008 should not be having an effect either. Is there other places in this COS that effect final VE calculation?

Here is a tun/log file to look at, check frames 5810 - 5875 for examples.

http://www.pasadenatownhall.com/tun_log.zip

What size whipple are you using , I suspect its the 2.4L which would be past max efficiency on a 8L , I found on the 383 spinning it past its rated limit I could get no more than 10 psi , dropping of to 6 psi in the upper rev range.

Your website pics dont work so I couldnt check out your setup

[Whippled 496]

What size whipple are you using , I suspect its the 2.4L which would be past max efficiency on a 8L , I found on the 383 spinning it past its rated limit I could get no more than 10 psi , dropping of to 6 psi in the upper rev range.

Your website pics dont work so I couldnt check out your setup

Im still working on the site pics, sorry. Its the standard 2.3L compressor, and I have a feeling i have reached its max capcity as well. I suppose I may as well pop the 2.75" pulley back on and save myself some heat build up because it gives me about 145kPa with that pulley as well. I did see it hit 149kPa today which is the most i have ever seen, but thats still less than 7lbs of boost, and still falls back to about 138-140kPa almost immediately. I will post up a log of todays run in a little while, got my best time today of 13.54 @ 99....not bad for a 7100lb gas truck. I am a little fuzzy on how to calculate compressor effeciency, how do you know when you have reached that point? How do i figure what the compressor is spinning (RPMs)?

[mistermike]

Im still working on the site pics, sorry. Its the standard 2.3L compressor, and I have a feeling i have reached its max capcity as well. I suppose I may as well pop the 2.75" pulley back on and save myself some heat build up because it gives me about 145kPa with that pulley as well. I did see it hit 149kPa today which is the most i have ever seen, but thats still less than 7lbs of boost, and still falls back to about 138-140kPa almost immediately. I will post up a log of todays run in a little while, got my best time today of 13.54 @ 99....not bad for a 7100lb gas truck. I am a little fuzzy on how to calculate compressor effeciency, how do you know when you have reached that point? How do i figure what the compressor is spinning (RPMs)?
Figuring compressor speed isn't too hard. You take the ratio of pulley circumference from the crank pulley to the drive pulley and multiply by engine RPM. If there's more than one belt, then you have to figure the intermediate ratios as well. Efficiency can be derived from the attached compressor map. The map only goes to 14,000 RPM, so I suspect spinning faster isn't likely to be productive, and even at that speed, adiabatic efficiency isn't in the sweet spot.