Auto GXP dynographs

I1ULUZ · 06-19-2009, 03:11 PM

Does anyone have a DynoJet dynograph from a GXP Auto they could post. Also if it was on a 224 or 248 model.

Here is my other thread about what is going on with the car. GMPP dyno results, not impressive AT ALL

There was a P0341 Camshaft Position code set, GM called it a "ghost" code they know about but can't figure out why it is set or how to keep it from coming back. The TAC "expert" said if it comes back again, to take it to a Pontiac dealership so they can compare the engine parameters with another GXP. Which in my book is BS, so much for being a Tech Assistance Center. Also the TAC has NO information about the GMPP tune or could provide any help on it to the Tech.

The Service Tech first used an over the air device vice the Tech II to load the program and it may have had an error, yesterday he loaded it using the Tech II as a pass-thru and it is a little better.

But getting it on the dyno today it's still not making the HP/TQ I believe it should. The new best was 225.40rwhp and 216.34 Tq which seems really low compared to other dynographs I have seen on here, but they are manual cars.

Trying to figure out what exactly is going on with the car. Here is the latest dynograph. Comments are always welcome. Sort of feel

and

Oh yea, after this set of pulls, we changed the stock exhaust out on the dyno with the Magnaflow catback and lost HP/TQ.

The other thing I have noticed on the dyno you have to beat the living snot out of it to make good power, takes 5-8 pulls before it will lay down it's best numbers. What is that about? Then after it makes it's highest number the AFR goes rich and power drops.

LatinVenom · 06-19-2009, 06:17 PM

The tech should have use pass-thru to do the download.
As for the Dyno, it really has no meaning, why, because you do not have data from before the GMPP caned tune.
How does it feel to you now, compared to before the GMPP caned tune?.
You seem to be aware of 1/4 times from your signature, why not take it to the track and see what it can do.
You know with the weight of our car and the GMPP caned tune, it should post in the high 13's.
A few passes on the track should give you some good feed back.

I1ULUZ · 06-19-2009, 09:05 PM

Quote:

Originally Posted by LatinVenom

As for the Dyno, it really has no meaning, why, because you do not have data from before the GMPP caned tune.

Yea you could say I've been to the track once or twice. To be honest, the Solstice does not feel very fast to me, then again owning a 11 and a 9 second car most fairly stock cars won't.

I also hate going to open track nights, it's always crowded and you might get 3 or 4 runs in, vice a track rental when you can get 30 if you feel like beating on the car.

Stock dynograph.

GS Stage 1 · 06-19-2009, 10:11 PM

I am thinking there is something not correct with the flash (assuming you have run at least 10-15 key cycles of spirited driving before getting on the Dyno). Because your torque is coming in lower than HP. The numbers are supposed to be 290 HP and 325 Torque for the automatic. Automatics are notorious for not working on a Dyno worth a damn because the torque converter tends to never lock up completely. But I would think that what ever peak numbers you have, you would still see about at 45 point advantage for the Torque.

I1ULUZ · 06-19-2009, 11:10 PM

Quote:

Originally Posted by GS Stage 1

I am thinking there is something not correct with the flash (assuming you have run at least 10-15 key cycles of spirited driving before getting on the Dyno). Because your torque is coming in lower than HP. The numbers are supposed to be 290 HP and 325 Torque for the automatic. Automatics are notorious for not working on a Dyno worth a damn because the torque converter tends to never lock up completely. But I would think that what ever peak numbers you have, you would still see about at 45 point advantage for the Torque.

That is one theory I have been tossing around among my friends, thinking that the dyno can't load the engine up enough like in a manual car. That is why I am trying to find another auto car to compare dynographs with. Least I can see the shape of the curves. My graphs seem really smooth compared to other LNG graphs I have seen online. Even with smoothing turned down to zero. The dyno I've been using is a 224 model thinking about using the local 248 with heavy drums to see if that would load up the engine better.

We have even gone so far as to run it up though the gears on the dyno to see what it does. Get some torque spikes but nothing close to what I would expect. But you can see torque management kicking it before and after the shift.

If anyone can give me some advice on how to keep it from dropping down a gear would be great too.

LatinVenom · 06-20-2009, 09:59 PM

You did gain 13 RWHP and 16 of torque from stock.
I have seen 20 - 30 for a standard transmission car with the GMPP for the RWHP.

I1ULUZ · 06-21-2009, 08:04 AM

Quote:

Originally Posted by LatinVenom

You did gain 13 RWHP and 16 of torque from stock.
I have seen 20 - 30 for a standard transmission car with the GMPP for the RWHP.

And I would expect the same amount of HP gains even from an Auto as the manual, looking for the amount of change not the number, that is not even 50% of the claimed gain and less than 30% expected gain in Tq.

We all buy HP but drive Tq. I rather love torque, the Ram 3500 along with the Touareg are both diesels. My Vette is an Auto it has nothing compared to this type of drivetrain loss.

But if I can see another auto dynograph I would feel better about the lack luster performance gain I saw out of the GMPP kit.

Am I missing something in my methodology?

scdyne · 06-21-2009, 02:42 PM

You need to run a scanner and watch TCCC lockup. You'll quickly see 2 thing's;
1. The TCCC never fully locks up
2. The % of difference between Input and output RPM's are different on the street than they are on most dynos.

One solution would be to run it in "I" mode on the dyno and that may help a little or use a good scanner to both force TCCC lock to 100% and 4th Gear.

I1ULUZ · 06-21-2009, 06:38 PM

Quote:

Originally Posted by scdyne

You need to run a scanner and watch TCCC lockup. You'll quickly see 2 thing's;
1. The TCCC never fully locks up
2. The % of difference between Input and output RPM's are different on the street than they are on most dynos.

One solution would be to run it in "I" mode on the dyno and that may help a little or use a good scanner to both force TCCC lock to 100% and 4th Gear.

We have been running it in "I". But I will see if I can get a friend's Tech II that should be able to lock the converter. HPT hasn't cracked enough of the program to let me scan that. But this advice is exactly what I am looking for to figure this issue out. THANKS!!!

topdowneh · 06-24-2009, 07:30 PM

I have an automatic 07 GXP with a few mods (see signature below) and have an appointment to have it dyno tested at 6 PM, July 9th at DL Motorsports in Burlington, Ontario. It is a DynoJet machine and I plan on running it in 4 which, I assume, should put it in 4th gear which is 1:1 and direct drive with no gearing. I will post the results as soon as I get them. I am really curious as to what the results will be and how they compare to your GXP dyno graphs.

Since the mods, the power of the GXP has improved dramatically - turbo boost pressure has increased from 100 to 145 kPa and I now get a healthy cherp when the tranny shifts into 3rd gear as the tires spin.

I1ULUZ · 06-25-2009, 01:32 AM

Quote:

Originally Posted by topdowneh

I have an automatic 07 GXP with a few mods (see signature below) and have an appointment to have it dyno tested at 6 PM, July 9th at DL Motorsports in Burlington, Ontario. It is a DynoJet machine and I plan on running it in 4 which, I assume, should put it in 4th gear which is 1:1 and direct drive with no gearing. I will post the results as soon as I get them. I am really curious as to what the results will be and how they compare to your GXP dyno graphs.

Since the mods, the power of the GXP has improved dramatically - turbo boost pressure has increased from 100 to 145 kPa and I now get a healthy cherp when the tranny shifts into 3rd gear as the tires spin.

I look forward to seeing your graphs and how the operator keeps it from kicking down into 3rd. Is it a small drum 224 model or a large drum 248 model?

If you can take a memory stick and download your dyno data and email it to me so I can look at it on the DynoJet software. I can overlay it with my pulls to see where the exact difference is at.

Thanks in advance and Good Luck!!!

topdowneh · 06-25-2009, 07:05 AM

Quote:

Originally Posted by I1ULUZ

I look forward to seeing your graphs and how the operator keeps it from kicking down into 3rd. Is it a small drum 224 model or a large drum 248 model?

If you can take a memory stick and download your dyno data and email it to me so I can look at it on the DynoJet software. I can overlay it with my pulls to see where the exact difference is at.

Thanks in advance and Good Luck!!!

Hi 1ULUZ,

I will call them to see what drum size they have and what they plan on doing to keep the car from downshifting into 3rd and also how many automatics they have tested and what are the corresponding problems with automatics. Also, I will see if I can download the data with a memory stick. These guys are very busy in the Dyno business and have a lot of experience. I had to wait until July 9th for my test.

Also, I am thinking of taking the GXP to the local strip to get some 1/4 mile times. Should be very interesting.

topdowneh · 07-03-2009, 02:37 PM

Quote:

Originally Posted by I1ULUZ

I look forward to seeing your graphs and how the operator keeps it from kicking down into 3rd. Is it a small drum 224 model or a large drum 248 model?

If you can take a memory stick and download your dyno data and email it to me so I can look at it on the DynoJet software. I can overlay it with my pulls to see where the exact difference is at.

Thanks in advance and Good Luck!!!

Hi Chris,

Just got back from DL Motorsports to ask them the above questions in person.
They will try to run in 3rd and 4th - which ever gear will provide the best numbers
The dynojet unit is a 248 model.
Yes, they said that I could download the runs onto a memory stick so that I could email them to you for you to compare with your runs.

Take care,

Rick

I1ULUZ · 07-03-2009, 07:28 PM

Quote:

Originally Posted by topdowneh

Hi Chris,

Just got back from DL Motorsports to ask them the above questions in person.
They will try to run in 3rd and 4th - which ever gear will provide the best numbers
The dynojet unit is a 248 model.
Yes, they said that I could download the runs onto a memory stick so that I could email them to you for you to compare with your runs.

Take care,

Rick

Rick

That is great news. I have pushed this issue up to GM Powertain level via the Area Service Manager. Waiting to hear something back. With your data either proving it's only my car or it's an auto issue only then it should help my case.

While at the local dealership the Service Manager said he has seen a few cars where the high pressure fuel pump has been an issue. My graph does show it's leaner than a LNF engine with an aftermarket tune on it. One would think that GM would make it run richer to be safe.

Chris