L30 / L31 "base engine friction torque vs rpm vs vacuum" table

[1project2many]

Does anyone know how GM populated this table? It seems like the L30 and L31 tables should have some type of relationship that's easy to see. Base engine friction seems like it's going to be affected by stroke and bore more than anything else. The L30 and L31 are very similar, with the only major difference being the bore and possibly a slightly smaller cam on the L30. Yet comparing this table between the two engines shows some unexpected differences. Has anyone played with this or maybe heard something about how the tables were developed? Any theories???

[Hog]

Does anyone know how GM populated this table? It seems like the L30 and L31 tables should have some type of relationship that's easy to see. Base engine friction seems like it's going to be affected by stroke and bore more than anything else. The L30 and L31 are very similar, with the only major difference being the bore and possibly a slightly smaller cam on the L30. Yet comparing this table between the two engines shows some unexpected differences. Has anyone played with this or maybe heard something about how the tables were developed? Any theories???

L30 and L31 use teh same 191/196º .412".428" 111ºLSA cam. Same cam used in the 1994-96 Impala SS/Caprice/Roadmaster/Cadillac GEN 2 5.7's with iron heads as well as the 94-96 GEN 2 4.3 V8(VEE eight) Caprice engine(200hp). That cam was pretty popular.

Between the L30 and L31, I'd think the L31 would have slightly more friction due to the greater ring/bore contact vs. the smaller bore L30, but who knows.

So I looked it up, here you go.

Vortec 350 L31
0-400-800-1200-1600-2000-2400-2800-3200-3600-4000-4400-4800-5200-5600 rpm
14.00 17.00 20.30 23.70 26.59 31.00 38.41 45.91 54.00 61.30 68.59 75.09 82.00 89.00 96.00 0kpa
17.16 20.92 25.09 28.09 29.92 34.08 41.31 49.89 57.72 62.27 69.67 75.05 80.61 87.59 94.55 20kpa
19.83 24.77 30.52 33.13 33.44 36.64 43.61 52.70 61.23 63.66 70.48 75.20 79.92 84.77 91.64 40kpa
23.33 30.36 34.78 37.27 36.86 39.05 45.56 55.08 62.70 65.13 70.78 74.09 77.83 81.94 87.27 60kpa
26.83 32.67 39.13 41.44 40.19 41.19 47.03 55.91 61.98 64.39 69.31 71.16 75.05 79.11 84.36 80kpa
29.17 35.63 42.25 43.91 41.80 41.69 47.31 55.16 61.39 63.08 65.44 69.50 73.66 77.70 82.91100kpa

Vortec 305 L30
15.92 16.92 18.11 21.36 26.09 30.70 35.25 40.69 47.50 55.28 62.39 69.86 77.03 84.00 91.00
19.77 20.77 22.13 25.00 29.42 33.78 38.09 42.53 48.73 56.27 63.20 69.56 76.94 83.80 90.41
23.39 24.39 25.86 28.72 32.75 36.70 41.50 44.94 49.95 57.23 64.16 69.73 77.42 83.00 89.50
27.47 28.47 29.53 31.98 35.88 39.34 44.44 47.47 51.31 58.08 65.42 69.55 76.52 80.00 87.00
30.63 31.63 32.91 34.97 38.56 41.52 46.09 49.17 51.70 58.28 64.25 68.75 72.70 77.00 82.00
33.59 34.59 35.91 37.70 41.09 43.50 47.59 50.70 52.09 58.41 63.80 68.00 70.00 73.00 76.00

Vortec 454 L29
22.39 27.09 31.88 34.67 40.72 48.83 59.95 75.03 90.53 104.47 114.80 121.06 125.23 131.30 136.55
27.98 31.44 35.17 37.11 43.08 50.36 60.77 75.53 89.91 104.05 114.48 120.72 124.75 130.83 135.16
39.19 42.92 44.77 43.95 49.23 55.50 63.86 77.08 89.91 103.20 113.75 119.70 123.77 128.45 131.91
48.14 49.86 51.16 50.30 56.42 61.67 67.98 79.14 89.91 102.16 112.19 117.97 121.33 124.64 127.27
54.86 55.92 56.48 55.09 64.63 68.88 72.09 81.70 89.81 99.42 107.92 112.89 114.48 118.94 120.77
52.63 53.11 54.36 50.80 54.36 60.64 74.16 79.14 87.33 93.11 99.14 102.72 106.66 107.52 111.47

peace
PAuly

[Fast355]

L30 and L31 use teh same 191/196º .412".428" 111ºLSA cam. Same cam used in the 1994-96 Impala SS/Caprice/Roadmaster/Cadillac GEN 2 5.7's with iron heads as well as the 94-96 GEN 2 4.3 V8(VEE eight) Caprice engine(200hp). That cam was pretty popular.

Between the L30 and L31, I'd think the L31 would have slightly more friction due to the greater ring/bore contact vs. the smaller bore L30, but who knows.

So I looked it up, here you go.

Vortec 350 L31
0-400-800-1200-1600-2000-2400-2800-3200-3600-4000-4400-4800-5200-5600 rpm
14.00 17.00 20.30 23.70 26.59 31.00 38.41 45.91 54.00 61.30 68.59 75.09 82.00 89.00 96.00 0kpa
17.16 20.92 25.09 28.09 29.92 34.08 41.31 49.89 57.72 62.27 69.67 75.05 80.61 87.59 94.55 20kpa
19.83 24.77 30.52 33.13 33.44 36.64 43.61 52.70 61.23 63.66 70.48 75.20 79.92 84.77 91.64 40kpa
23.33 30.36 34.78 37.27 36.86 39.05 45.56 55.08 62.70 65.13 70.78 74.09 77.83 81.94 87.27 60kpa
26.83 32.67 39.13 41.44 40.19 41.19 47.03 55.91 61.98 64.39 69.31 71.16 75.05 79.11 84.36 80kpa
29.17 35.63 42.25 43.91 41.80 41.69 47.31 55.16 61.39 63.08 65.44 69.50 73.66 77.70 82.91100kpa

Vortec 305 L30
15.92 16.92 18.11 21.36 26.09 30.70 35.25 40.69 47.50 55.28 62.39 69.86 77.03 84.00 91.00
19.77 20.77 22.13 25.00 29.42 33.78 38.09 42.53 48.73 56.27 63.20 69.56 76.94 83.80 90.41
23.39 24.39 25.86 28.72 32.75 36.70 41.50 44.94 49.95 57.23 64.16 69.73 77.42 83.00 89.50
27.47 28.47 29.53 31.98 35.88 39.34 44.44 47.47 51.31 58.08 65.42 69.55 76.52 80.00 87.00
30.63 31.63 32.91 34.97 38.56 41.52 46.09 49.17 51.70 58.28 64.25 68.75 72.70 77.00 82.00
33.59 34.59 35.91 37.70 41.09 43.50 47.59 50.70 52.09 58.41 63.80 68.00 70.00 73.00 76.00

Vortec 454 L29
22.39 27.09 31.88 34.67 40.72 48.83 59.95 75.03 90.53 104.47 114.80 121.06 125.23 131.30 136.55
27.98 31.44 35.17 37.11 43.08 50.36 60.77 75.53 89.91 104.05 114.48 120.72 124.75 130.83 135.16
39.19 42.92 44.77 43.95 49.23 55.50 63.86 77.08 89.91 103.20 113.75 119.70 123.77 128.45 131.91
48.14 49.86 51.16 50.30 56.42 61.67 67.98 79.14 89.91 102.16 112.19 117.97 121.33 124.64 127.27
54.86 55.92 56.48 55.09 64.63 68.88 72.09 81.70 89.81 99.42 107.92 112.89 114.48 118.94 120.77
52.63 53.11 54.36 50.80 54.36 60.64 74.16 79.14 87.33 93.11 99.14 102.72 106.66 107.52 111.47

peace
PAuly

As piston surface area increases so do the pumping losses. These losses become higher and higher as the vacuum increases and the piston has to fight increased resistance.

[1project2many]

So I looked it up, here you go.


Thanks.
Those tables match the ones I have here. I wonder if they're consistent across all L30 / 31 equipped trucks.


As piston surface area increases so do the pumping losses. These losses become higher and higher as the vacuum increases and the piston has to fight increased resistance.
Agreed. With so many similarities between engines it should be fairly easy to see this occurring by comparing tables but the comparison tells a different tale:

4142

[Hog]

An L31 should be similar to an LT1, but I cant find those tables in any LT1 calibration.

peace
Hog

[1project2many]

I expect they're part of the torque calculation for torque management. I don't remember seeing engine torque as an active variable in the LT1 calibrations. It may be part of the 4.3 calibrations so I'll check a few of them out.

[Fast355]

I expect they're part of the torque calculation for torque management. I don't remember seeing engine torque as an active variable in the LT1 calibrations. It may be part of the 4.3 calibrations so I'll check a few of them out.

IIRC there are several torque calibration tables in the 0411. One for the A/C, one for the accessories and an engine.

[1project2many]

Interesting. The tables above are form the 98 black box. I'll have to see if there are other tables to view.

[Hog]

Interesting. The tables above are form the 98 black box. I'll have to see if there are other tables to view.
Which are the same as the 1996 blackbox tables I posted.

peace
Hog

[1project2many]

Good to know. Thanks.

[Fast355]

This is some of the 0411 L31 stuff, it gets much more complex. Some of the even more complex modeling of the LSx engines is not enabled on the L31 van, such as A/C Torque vs A/C pressure. Much of the torque mapping is used to help control idle speeds and regulate torque delivery. Something as simple as an a/c clutch engaging or disengaging even above idle is smoothed by timing and IAC variation. That is one thing I noticed with the 0411, I can no longer feel the a/c clutch kick in or out. I can hear the clutch, but that is it. It even seems like the tune uses more throttle follower to compensate for the decreased torque off-idle.

[1project2many]

Some of the even more complex modeling of the LSx engines is not enabled on the L31 van, such as A/C Torque vs A/C pressure.

I suspect that may be due to the number of non-GM companies involved in building and selling van chassis vehicles. I've got A/C systems here from four different companies and there are multiple variations even then. Some of our cutaway chassis run three condenser fans drawing 30-40A, with front and rear blowers adding another 15A or so through hybrid evaporators with orifice tube front and TSV rear units.

What I find interesting is how Ford has handled some of it. Upfitters (body builders) are advised to obtain Ford reprogramming equipment and to download various calibrations for modifications such as larger alternator, dual alternator conversion, dual a/c systems, and possibly others. Much better IMO.

Hmmm... I'd like to meet the guy who's job was to motor an L31 to 8000 rpm to measure friction torque. ;)

If we ever get unburied from snow (we're only 8" from a record February, and they're predicting 6"-12" today and tonight) I'll check out some of my van cals just to see if there are any variations.

The ultimate goal here was to try and develop a model for the 3" stroke engine in my Suburban. It seemed so simple in the beginning...

[Fast355]

I suspect that may be due to the number of non-GM companies involved in building and selling van chassis vehicles. I've got A/C systems here from four different companies and there are multiple variations even then. Some of our cutaway chassis run three condenser fans drawing 30-40A, with front and rear blowers adding another 15A or so through hybrid evaporators with orifice tube front and TSV rear units.

What I find interesting is how Ford has handled some of it. Upfitters (body builders) are advised to obtain Ford reprogramming equipment and to download various calibrations for modifications such as larger alternator, dual alternator conversion, dual a/c systems, and possibly others. Much better IMO.

Hmmm... I'd like to meet the guy who's job was to motor an L31 to 8000 rpm to measure friction torque. ;)

If we ever get unburied from snow (we're only 8" from a record February, and they're predicting 6"-12" today and tonight) I'll check out some of my van cals just to see if there are any variations.

The ultimate goal here was to try and develop a model for the 3" stroke engine in my Suburban. It seemed so simple in the beginning...

On the same token, I would like to tweak my tables for the LT4 cam....I wonder how much a cam changes that model.....

[1project2many]

Hmmm..... Good question. Typically I'd expect it see an inverted version of the torque curve in the tables but with the highs and lows where they are in this table I really don't know what's going on.

[EagleMark]

I think his picture is HP Tuners and I don't know what they use? The numbers from TunerCat look to be percent?. In EFI Live most of this is done in Eq Ratio or Grams*Kelvin/kPa and really confuses you.

I have no idea, have not worked on this? Just looked an EFI Live has nothing, well it's as worthless as tits on a bull for vortec anyway...

[Hog]

Hmmm... I'd like to meet the guy who's job was to motor an L31 to 8000 rpm to measure friction torque. ;)


The ultimate goal here was to try and develop a model for the 3" stroke engine in my Suburban. It seemed so simple in the beginning...
Well we know they didnt use a "blackbox" PCM to rev that high with the L31.

3" stroke ehh, to bad we couldnt get the data for a 94-96 L99 4.3 GEN 2 engine as it uses the 3" stroke crank.

peace
Hog

[Fast355]

Well we know they didnt use a "blackbox" PCM to rev that high with the L31.

3" stroke ehh, to bad we couldnt get the data for a 94-96 L99 4.3 GEN 2 engine as it uses the 3" stroke crank.

peace
Hog

Pauly,

Have a better plan to investigate. Someone find me a HP Tuners .bin file for the same year 4.8 and 5.3 trucks and I will have a peak. Those two engines are identical minus the crankshaft and rods.