Finally got to run the 1/4 mile!

[LeadSled1]

Originally Posted by GhostRL

Sidejam: You're slow in the last part of the track because 1: the turbo runs out of air in fourth gear and 2: fourth gear is a terrible ratio for the 1/4 mile. Switch to a smaller rear tire and you'll move through it faster. I use 26" drag radials which effectively increase your rpms crossing the traps. (vs 28.5" stockers)

Keep practicing

Interesting, what is the rpm at the traps with stock tires?

Does anyone make a rear gear set for these cars? I also wonder how the Redline would run with the NA rear gear set (3.9X versus the stock 3.7X)?

Bogie, do you want to calculate what the engine RPM is in 4th gear at 100mph?

[RedHeaded RedLine]

Originally Posted by sidejam

Here's my timeslip and a vid of the run (I'm car R202):Keep in mind please that the track is at 3200 ft elevation. There was a stock Solstice GXP that ran a best of 14.6. Assuming he's a decent driver, this gives me an idea what the Sky RL would do at this altitude.

13s are in your future for sure. If you get the 60' under 2.0, you are set. What tire pressure were you running? -J

[Bogie]

Originally Posted by LeadSled1

Interesting, what is the rpm at the traps with stock tires?

Does anyone make a rear gear set for these cars? I also wonder how the Redline would run with the NA rear gear set (3.9X versus the stock 3.7X)?

Bogie, do you want to calculate what the engine RPM is in 4th gear at 100mph?

With a 3.7 final gear ratio and assuming a loaded stock tire of 25.81, 4th gear at 100 mph will occur at 4817 RPM.

With 3.9 final gear ratio under same conditions as above, 4th gear at 100 mph will occur at 5077 RPM.

[sidejam]

Originally Posted by RedHeaded RedLine

13s are in your future for sure. If you get the 60' under 2.0, you are set. What tire pressure were you running? -J

I set the tire pressure to 42 psi in the front, and 26 psi in the rear.

[Leather]

Originally Posted by Leather

I have never raced before but would like to try it. What days does Racecity let people test their skillz? I looked online but was unsure, it looks like the cost is $25 a run.

Maybe my question got overlooked

[sidejam]

Originally Posted by Leather

Maybe my question got overlooked

Shoot!!! Sorry!!!

Race City is open to street cars Friday night. You have to go through a tech inspection, pay $25, and since we have convertibles, you need a helmet regardless of what times you run.

I'm not going this coming weekend since I'll be in Edmonton, but I'm hoping to go the following weekend. Send me a PM if you're going to go and we can meet up!

[Antonio]

Originally Posted by sidejam

I set the tire pressure to 42 psi in the front, and 26 psi in the rear.

much too high. Next time I'd lower the rear pressure to about 21

[Robotech]

Bill...I'm not sure what adjustments the PCM can make for altitude...less air = less fuel = less power if I remember correctly, yes? The PCM should pull fuel because of the lower MAF readings but that should still result in less power output from the engine IF I remember correctly...which...yea...never a sure thing with me.

[Leather]

Originally Posted by sidejam

Shoot!!! Sorry!!!

Race City is open to street cars Friday night. You have to go through a tech inspection, pay $25, and since we have convertibles, you need a helmet regardless of what times you run.

I'm not going this coming weekend since I'll be in Edmonton, but I'm hoping to go the following weekend. Send me a PM if you're going to go and we can meet up!

Thanks for the information sidejam. I am unsure when I can make it but I will PM you when I do.

[RedHeaded RedLine]

Originally Posted by sidejam

I set the tire pressure to 42 psi in the front, and 26 psi in the rear.

Good place to start! Get friendly with one of the big boys there and borrow a pyrometer. Most people are eger to help until you threaten to outrun them.
Even temps across the rear says 'just right'. -J
BTW our 1/8 $20 all you could run all night. Man! we miss that track!

[EcoBoost]

Originally Posted by Bogie

The curious engineer that I am, what adjustments does the car make at altitude?

Two methods, one most conventional, one most unprecedented:

Conventional: The PCM's barometric pressure readings will detect the lower atomospheric pressure.

Unprecedented: Targeted airflow. As the reduced air density attributable to the higher altitude is interpreted by the PCM, it will increase boost pressure to compensate and return the airflow to its intended value.

[EcoBoost]

Originally Posted by Robotech

Bill...I'm not sure what adjustments the PCM can make for altitude...less air = less fuel = less power if I remember correctly, yes? The PCM should pull fuel because of the lower MAF readings but that should still result in less power output from the engine IF I remember correctly...which...yea...never a sure thing with me.

See my reply to Bogie just above

[sidejam]

Originally Posted by EcoBoost

Unprecedented: Targeted airflow. As the reduced air density attributable to the higher altitude is interpreted by the PCM, it will increase boost pressure to compensate and return the airflow to its intended value.

That's interesting... So in stock form, should my car still be able to run a 14.0 at this altitude? There was a bone stock Solstice at the track the same day, and the best he could run was a 14.6. I do realize that varying track conditions could alter a time by as much as half a second or even more.

It'd be nice to think that on a better day, if the stock Solstice could get down to a 14.0, I might be able to get a mid to high 13. Either way, I'm going to keep on racing at this altitude. I don't really have to much of a choice. If time allows me, I want to go to a lower altitude track. I guess that would be the real test.

Thanks for the info though!

[EcoBoost]

Originally Posted by sidejam

That's interesting... So in stock form, should my car still be able to run a 14.0 at this altitude? There was a bone stock Solstice at the track the same day, and the best he could run was a 14.6. I do realize that varying track conditions could alter a time by as much as half a second or even more.

It'd be nice to think that on a better day, if the stock Solstice could get down to a 14.0, I might be able to get a mid to high 13. Either way, I'm going to keep on racing at this altitude. I don't really have to much of a choice. If time allows me, I want to go to a lower altitude track. I guess that would be the real test.

Thanks for the info though!

Yes, that's the theoretical ideal as intended by GM and Bosch (the manufacturer of the engine management). Now, in the unforgivingly accurate world of drag strip timing, the ability to run just as hard at 4,000 feet altitude as one could at sea level may pale somewhat. Nonetheless, the fact is...the technology is on your side, and as compared to earlier cars that did not have this compensation feature, you are way ahead of the game insofar as high altitude performance.

[AWSM502]

Hello all. I don't want to hijack this post, but it seemed a good place to ask this question.

What launch technique is the best to use with an automatic? My wife (AWSM Sky) has a stock R/L with Magnaflow exhaust and an auto, and is running 14.2 - 14.3's with an average 60ft time of 2.2 sec. That is at a 600ft high track, in about 60deg air. Traction and stability control off.

The biggest issue it seems is she can't build boost off the line even brake torquing. Should she be able to, or is their a safety in the stock ECM?

Can you shift these cars manually? If launching in "Low" or 'Intermediate", will it still try to upshift?

FYI - Stock she would only build 17psi through the traps. With the Magnaflows, she is up to 20psi. She's about 0.2 sec. quicker with the Magnaflows, but her 60ft times are still the same due to the lack of boost.

Thanks!

Keith

[RedHeaded RedLine]

Originally Posted by AWSM502

Hello all. I don't want to hijack this post, but it seemed a good place to ask this question.

What launch technique is the best to use with an automatic? My wife (AWSM Sky) has a stock R/L with Magnaflow exhaust and an auto, and is running 14.2 - 14.3's with an average 60ft time of 2.2 sec. That is at a 600ft high track, in about 60deg air. Traction and stability control off.

The biggest issue it seems is she can't build boost off the line even brake torquing. Should she be able to, or is their a safety in the stock ECM?

Can you shift these cars manually? If launching in "Low" or 'Intermediate", will it still try to upshift?

FYI - Stock she would only build 17psi through the traps. With the Magnaflows, she is up to 20psi. She's about 0.2 sec. quicker with the Magnaflows, but her 60ft times are still the same due to the lack of boost.

Thanks!

Keith

Start in ‘I’, (low will not shift), in either ‘traction off’ or ‘competition’. After a couple of shift get into 4th. I have found that trying to hold boost against the brake full throttle doesn't work and the turbo blows off. I bring the RPM's to ~2100. As you are holding against the brake let the car creep. This will allow the boost to stay up. A little rough on the brakes & Torque Converter but hey, that is what a warranty is for. On the 3rd amber, floor the gas and take your foot off the brake. The fastest way to move you foot off the brake is to move it sideways not back at you. I have found that leaving it in ‘I’ for the launch provides the best result. The shifter is more suited to holding gear on back country roads, not quick shifting down a strip. -J