Boost levels and Atmospheric Conditions thread - Pontiac Solstice Forum
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post #1 of 60 (permalink) Old 02-18-2009, 11:33 AM Thread Starter
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Boost levels and Atmospheric Conditions thread

Hey all fellow Solstice GXP and SKY RL owners with the LNF engine!

I would like to start keeping track of some boost information and see if I can correlate DIC boost levels with atmospheric conditions.

To get to that, I need to acquire data from as many of us that are willing to participate. Here is what I would propose:

- We use a standard procedure, simple in nature, to note the maximum DIC boost level.

- Simply run the procedure, note the local date and time, and the nearest airport.

Post the information here in the following format:

Boost level sustained:
Peak boost noted if different than the sustained level:
Date and time:
Nearest airport: (you can also note the city and state, or find nearest ASOS/AWOS via AirNav)
Performance Modifications: (stock, exhaust/intake, stage kit or tune, etc.)

It is that simple. I can calculate the rest from there. I plan on trying to plot the boost pressure and density altitude to see if I can tell what is normal and what different modifications mean.




The procedure:
-Make sure your car is warm. DIC coolant temperature should be >185F
-Set your DIC to monitor boost. Be sure to wait until the display is active (displaying the PSI, not "BOOST" when the gage is initiating)
-Start the procedure in 3rd gear at 30-35 MPH (approximately 2000-2500 RPM)
-Go to Wide Open Throttle (WOT)
-Note the sustained and peak values you see on your DIC. Accelerate to as high a speed as you are comfortable.
-watch out for deer, pedestrians, other cars and curves. Maintain control of your car at all times, and obey traffic laws where applicable.
-Note the date and time.


Keep in mind that you may see a traction light, so you may want to do this in competitive mode to avoid this happening. If the traction control becomes active, you will lose your boost gage to the superceding traction control message.


For example, on the way in on the morning of 2/17/09:

Boost level sustained: 22
Peak boost level: same (22PSI, solid)
Date and Time: 2009.02.17 06:53 EST
Nearest Airport: Howell or Pontiac (KOZW or KPTK, Milford Proving Ground is 1/2 way between)
Performance Modifications: GM PUpgrade Kit, 6 shortening wastegate turns from stock, stock intake/exhaust

From that, we can determine the weather conditions and calculate the density altitude is -1456' for this run.


I am especially interested in stock vehicles. I think a typical LNF car is not going to be too far away from this:

-2000' (cold day below freezing) 14-15 PSI
-1000' (15-16)
0' (16-17)
+1000' (17~18)
+2000' 19 PSI (close to SAE J1349 standard)
+4000' 20 PSI
+6000' 20~21 PSI

I am a GM Engineer.

I do not claim to be a GM representative, all of my postings are my own interpretation and personal opinions.

I am a proud Solstice GXP owner (Flash). My wife, A FORMER GM engineer, is a proud Solstice GXP Coupe owner (Wicked).

My other hobby: hot turbo wastegate nut adjustment.
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post #2 of 60 (permalink) Old 02-19-2009, 04:38 PM
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Boost level sustained: 19 psi
Peak boost noted if different than the sustained level: 20
Date and time: 2/19/2009 3:30 pm
Nearest airport: MKE (Milwaukee, WI)
Performance Modifications: GM PUpgrade Kit, Waste gate 4 turns. No other mods

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post #3 of 60 (permalink) Old 02-20-2009, 02:21 PM
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My Car

08 Redline 5-speed manual

Boost level sustained: 21 psi
Peak boost noted if different than the sustained level: 23 psi
Date and time: 2/20/2009 12:30 P.M. MST
Nearest airport: Fort Collins/Loveland CO regional
Performance Modifications: GM PUpgrade Kit, Waste gate 2 turns. No other mods


DIC showed outside temp as 50 degrees F.

Last edited by GS Stage 1; 02-20-2009 at 02:26 PM.
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post #4 of 60 (permalink) Old 02-20-2009, 02:25 PM
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My Wife's Car

08 Redline 5-speed manual

Boost level sustained: 17 psi
Peak boost noted if different than the sustained level: 19 psi
Date and time: 2/20/2009 12:55 P.M. MST
Nearest airport: Fort Collins/Loveland CO regional
Performance Modifications: No mods


DIC showed outside temp as 50 degrees F.

An interesting thing I noticed with her car. Starting out, it peaked at the 19, then dropped to 16, then continuously gained steadily going up in the rpm till it just hit 18 right before redline. So I called it 17.

With my car; it would peak at 23, with flickers of 24, then drop to 22, then continuous steady drop going up in the rpm till it just hit 19-20 right before redline. So I called it 21.

Do you think this is because the GM tune is adding so much torque lower in the power band that you get more of a "launch" when going WOT in 3rd from 2500 rpm? And therefore it doesn't have to demand as much boost later in the rpm range to achieve max A/F ratio? Or do you think this is the difference between the stock version having the "torque limitation" engaged, resulting in reduced boost at the beginning of the launch, but allowing it to command a little more as torque drops going up in RPM. I am tending to lean this way, because of how "flat" the torque curve is on the stock tune.

I had never tried the load test in 3rd at 35 mph before today. So I had never noticed this difference in the two cars. Both cars seem to react about the same way when doing a load test in 4th at 60 mph. They will both peak then drop 1-2 psi, then hold steady all the way to 100 mph, without the noticeable change in boost pressure, either down or up. (I bet if I had balls enough to hold either one to 130 mph in 4th today, then I would see the boost drop off. But I save that kind of testing for more law enforcement scarce areas. LOL)

Last edited by GS Stage 1; 02-22-2009 at 09:33 AM.
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post #5 of 60 (permalink) Old 02-23-2009, 10:59 AM Thread Starter
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Info so far:


Typhoon:

Boost level sustained: 19 psi
Peak boost noted if different than the sustained level: 20
Date and time: 2/19/2009 3:30 pm
Nearest airport: MKE (Milwaukee, WI)
Performance Modifications: GM PUpgrade Kit, Waste gate 4 turns. No other mods


METAR KMKE 192052Z 30017G24KT 10SM FEW031 M06/M16 A3001 RMK AO2 SLP175 T10611161 55003
METAR KMKE 192152Z 28013G20KT 10SM FEW031 M06/M16 A3001 RMK AO2 SLP175 T10561161
Elevation: 723 ft.


Density Altitude -1780.6 ft

Absolute Pressure (station pressure) 29.235 in Hg (14.35 PSI)

Relative Density (ISA) 105.31%
Actual Density (kg/m^3) 1.2901
Relative Humidity Relative Humidity = 45%

19PSI (DIC) = 33.4 PSI abs / 2.24 bar
20 PSI (DIC) = 34.35 PSI abs / 2.37 bar
=================

GS Stage 1

08 Redline 5-speed manual

Boost level sustained: 21 psi
Peak boost noted if different than the sustained level: 23 psi
Date and time: 2/20/2009 12:30 P.M. MST
Nearest airport: Fort Collins/Loveland CO regional
Performance Modifications: GM PUpgrade Kit, Waste gate 2 turns. No other mods


DIC showed outside temp as 50 degrees F.


Elevation: 5016 ft.
METAR KFNL 201935Z AUTO 29037G45KT 10SM CLR 12/M16 A2985 RMK AO1

Density Altitude 5931.6 ft

Absolute Pressure (station pressure) 24.82 in Hg (12.2 PSI)

Relative Density (ISA) 83.76%
Actual Density (kg/m^3) 1.0260
Relative Humidity Relative Humidity = 12%

21 PSI (DIC) = 33.2 / 2.29 bar
23 PSI (DIC) = 35.2 / 2.43 bar
==================

GS Stage 1 Wife

08 Redline 5-speed manual

Boost level sustained: 17 psi
Peak boost noted if different than the sustained level: 19 psi
Date and time: 2/20/2009 12:55 P.M. MST
Nearest airport: Fort Collins/Loveland CO regional
Performance Modifications: No mods

METAR KFNL 201955Z AUTO 28031G45KT 10SM CLR 12/M14 A2984 RMK AO1



Density Altitude 5947.7 ft

Absolute Pressure (station pressure) 24.811 in Hg (12.2 PSI)

Relative Density (ISA) 83.72%
Actual Density (kg/m^3) 1.0255
Relative Humidity Relative Humidity = 15%
29.2 2.013269044
31.2 2.151164184


17 PSI (DIC) = 29.2 PSI abs / 2.01 bar
19 PSI (DIC) = 31.2 PSI abs / 2.15 bar
==================


My run was

Boost level sustained: 22
Peak boost level: same (22PSI, solid)
Date and Time: 2009.02.17 06:53 EST
Nearest Airport: Howell or Pontiac (KOZW or KPTK, Milford Proving Ground is 1/2 way between)
Performance Modifications: GM PUpgrade Kit, 6 shortening wastegate turns from stock, stock intake/exhaust


Density Altitude -1456 ft

Absolute Pressure (station pressure) 29.088 in Hg

Relative Density (ISA) 104.33%
Actual Density (kg/m^3) 1.2780
Relative Humidity Relative Humidity = 79%

22PSI(DIC) = 36.29 PSI abs / 2.5 bar

I am a GM Engineer.

I do not claim to be a GM representative, all of my postings are my own interpretation and personal opinions.

I am a proud Solstice GXP owner (Flash). My wife, A FORMER GM engineer, is a proud Solstice GXP Coupe owner (Wicked).

My other hobby: hot turbo wastegate nut adjustment.
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post #6 of 60 (permalink) Old 02-23-2009, 06:30 PM
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Interesting stuff, Flash.

Assuming I understand this correctly: So even with your WG set as tight as it is, you still have a lot of room before the 3 bar limit. But of course there is still that pesky max manifold pressure limit and max turbo RPM limit imposed by the ECM. I sent you a PM also.

Last edited by GS Stage 1; 02-23-2009 at 06:39 PM.
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post #7 of 60 (permalink) Old 02-24-2009, 09:47 AM Thread Starter
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Quote:
Originally Posted by GS Stage 1 View Post
Interesting stuff, Flash.

Assuming I understand this correctly: So even with your WG set as tight as it is, you still have a lot of room before the 3 bar limit. But of course there is still that pesky max manifold pressure limit and max turbo RPM limit imposed by the ECM. I sent you a PM also.
As always, the overboost code is the difference between COMMANDED boost and ACTUAL boost. You are right, though, there is always the turbine speed limit, and the detonation map limit, which dials back if you approach conditions favorable to detonation. Not that I am anywhere near that level yet.



This morning, it was f'ing cold:

Boost level sustained: 19
Peak boost level: same (21PSI, intermittent)
Date and Time: 2009.02.24 07:15 EST
Nearest Airport: Howell or Pontiac (KOZW or KPTK, Milford Proving Ground is 1/2 way between)
Performance Modifications: GM PUpgrade Kit, 6 shortening wastegate turns from stock, stock intake/exhaust


Density Altitude -3110.3 ft

Absolute Pressure (station pressure) 29.35 in Hg

Relative Density (ISA) 109.42%
Actual Density (kg/m^3) 1.3404
Relative Humidity Relative Humidity = 85%

19 PSI (DIC) = 33.4 PSI abs / 2.30 bar
21 PSI (DIC) = 35.4 PSI abs / 2.44 bar

I am a GM Engineer.

I do not claim to be a GM representative, all of my postings are my own interpretation and personal opinions.

I am a proud Solstice GXP owner (Flash). My wife, A FORMER GM engineer, is a proud Solstice GXP Coupe owner (Wicked).

My other hobby: hot turbo wastegate nut adjustment.
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post #8 of 60 (permalink) Old 02-24-2009, 09:49 AM
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Boost level sustained: 23 psi
Peak boost noted if different than the sustained level: 23
Date and time: 2/24/2009 5:3450 am
Nearest airport: Centenial Denver
Performance Modifications: GM PUpgrade Kit, Solo high flow cat, Magnaflow, Dejon charge tubes, CAI, intercooler.
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post #9 of 60 (permalink) Old 02-25-2009, 09:20 AM
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This morning's results

Boost level sustained: through 1st and 2nd gear 18 pounds. 3rd and 4th gear 23 psi
Date and time: 2/25/2009 5:45 am
Nearest airport: Centenial Denver
Performance Modifications: GM PUpgrade Kit, Solo high flow cat, Magnaflow, Dejon charge tubes, CAI, intercooler.
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post #10 of 60 (permalink) Old 02-26-2009, 12:35 PM Thread Starter
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Rob the Elder:

Boost level sustained: 23 psi
Peak boost noted if different than the sustained level: 23
Date and time: 2/24/2009 5:3450 am
Nearest airport: Centenial Denver (5885 ft)
Performance Modifications: GM PUpgrade Kit, Solo high flow cat, Magnaflow, Dejon charge tubes, CAI, intercooler.

Density Altitude 5844.6 ft

Absolute Pressure (station pressure) 24.14 in Hg

Relative Density (ISA) 83.98%
Actual Density (kg/m^3) 1.0287
Relative Humidity Relative Humidity = 70%

23 PSI DIC = 34.86 PSI absolute / 2.4 bar

======================

Boost level sustained: through 1st and 2nd gear 18 pounds. 3rd and 4th gear 23 psi
Date and time: 2/25/2009 5:45 am
Nearest airport: Centenial Denver
Performance Modifications: GM PUpgrade Kit, Solo high flow cat, Magnaflow, Dejon charge tubes, CAI, intercooler.

Density Altitude 5994.8 ft

Absolute Pressure (station pressure) 24.182 in Hg

Relative Density (ISA) 83.59%
Actual Density (kg/m^3) 1.0240
Relative Humidity Relative Humidity = 38%

23 PSI DIC = 34.88 PSI abs / 2.4 bar

======================


I remember something about boost in 1st/2nd gear, but it slips my mind right now. There is an explanation about why the boost is lower in those gears.

I am a GM Engineer.

I do not claim to be a GM representative, all of my postings are my own interpretation and personal opinions.

I am a proud Solstice GXP owner (Flash). My wife, A FORMER GM engineer, is a proud Solstice GXP Coupe owner (Wicked).

My other hobby: hot turbo wastegate nut adjustment.
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post #11 of 60 (permalink) Old 02-26-2009, 01:26 PM Thread Starter
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It appears that nearly untouched PUpgrade Kit cars have a target boost of about 2.3 bar, and maybe another .1 bar for efficiency upgrades like Rob the Elder's car. If you go extreme on the wastegate and are low enough density altitude to avoid knock, as high as 2.5 bar may be possible.

All absolute pressure, independent of current density altitude.

My checks on stock vehicles supports between 1.9 and 2.05 bar.

Furthermore, I can calculate a preliminary correlation of DIC displayed pressure and density altitude. It seems to work out to be approximately 2500 ft change in density altitude = 1 PSI change in DIC displayed output, the higher the DA, the higher the displayed boost.

In a weird and wacky way, if you have a good feel for your DIC and your car, you can use the boost as an approximation of density altitude, plus or minus about 1200 feet. LOL

On the assumption that the system is trying to boost to the same approximate mass air flow:

DA=7000', DIC displays +2 PSI from standard conditions
DA=4500', DIC displays +1 PSI from standard conditions
Standard (2000' DA)
DA=-500', DIC displays -1 PSI from std conditions
DA=-3000', DIC displays -2 PSI from std conditions



If the absolute pressure for a base car in standard conditions is 15PSI, then the DIC would display as follows:

DA=7000', 17 PSI
DA=4500', 16 PSI
Standard (2000' DA) 15
DA=-500', 14 PSI
DA=-3000', 13 PSI

and a PUpgrade Kit car DIC displayed boost might be something closer to:

DA=7000', 22 PSI
DA=4500', 21 PSI
Standard (2000' DA) 20
DA=-500', 19 PSI
DA=-3000', 18 PSI

And since we start to see turbine overspeed corrections in DA>8000', it appears that this is approaching the limit for the current turbine, or approximately 26 PSI boost over atmospheric.

I am a GM Engineer.

I do not claim to be a GM representative, all of my postings are my own interpretation and personal opinions.

I am a proud Solstice GXP owner (Flash). My wife, A FORMER GM engineer, is a proud Solstice GXP Coupe owner (Wicked).

My other hobby: hot turbo wastegate nut adjustment.
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post #12 of 60 (permalink) Old 03-11-2009, 08:06 AM
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The car appears to have stabalized at 20 pounds of boost through the first 3 gears and 23 pounds at WOT in 4th.

Fun times.
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post #13 of 60 (permalink) Old 03-14-2009, 09:45 AM
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Boost level sustained: 21
Peak Boost level: 23
Date and Time: 2009.03.13 13:45 PDT
Nearest Airport: San Francisco International KSFO (altimeter at TOT 30.19 | 43 ' above sea level)
Performance modifications: GMPP Upgrade Kit, 5 turns of wastegate from stock position

Side notes: Since new, the car has only been filled with Chevron with Techron 91 octane
Current mileage 2585

Test conditions: 1/2 mile straight frontage road, no traffic, 64 degrees F, clear and dry. Less than 5 miles south of runway 28 at SFO.

Wheeeeee
2008 GXP - Brazen Orange - purchased on the 4th of July
Loaded, GMPP 290hp upgrade + AVIC Z3 Navigation
so I can always find my way home after a great day in my Solstice
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post #14 of 60 (permalink) Old 03-14-2009, 03:41 PM
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Is this only for people with GMPP upgrade kit??

I have westers tune.


Boost level sustained: 22
Peak Boost level: 25
Date and Time: March 14th, 2009......1PM PST
Nearest Airport: El Monte Airport (KEMT) Elevation AMSL 90.2 ft / m
Performance modifications: Dejon intake/spring/IC. Westers Race Tune (91 octane), WG shortened to only 4 threads showing.

Side notes: Current mileage 15,200

2008 Deep GXP Manual.

Last edited by Deep-GXP; 03-14-2009 at 03:56 PM.
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post #15 of 60 (permalink) Old 03-16-2009, 06:25 AM Thread Starter
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Not necessarily, Deep. Anyone who has a boosted car - even stockers.

I am a GM Engineer.

I do not claim to be a GM representative, all of my postings are my own interpretation and personal opinions.

I am a proud Solstice GXP owner (Flash). My wife, A FORMER GM engineer, is a proud Solstice GXP Coupe owner (Wicked).

My other hobby: hot turbo wastegate nut adjustment.

Last edited by Flash's Owner; 03-16-2009 at 06:33 AM.
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