Discussion of Chassis Setup for 8 Sec. Assault

DCVING 6 said:
Is it hard to stage the car with it jumping so much initially against the t brake?
Click to expand...
I agree. That is something that I'll be working on in the near future. I need to install a braking system pressure gauge first.
One thing I was thinking of, what if the rocking is timed so that when the car launches, the car is rocking towards down track? It would be like getting a little extra push off the line, wouldn't it? Not that I'm promoting rocking the car at the line, but I just thought that idea was interesting.
 
I was just thinking of another thing. If the momentum of the rocking of the car was towards the burn out box when the car launched, wouldn't that promote weight transfer to the rear tires and thus tire plant?
Sounds like a win/win no matter which direction the car is rocking when the transbrake releases.
 
DonWG said:
I was just thinking of another thing. If the momentum of the rocking of the car was towards the burn out box when the car launched, wouldn't that promote weight transfer to the rear tires and thus tire plant?
Sounds like a win/win no matter which direction the car is rocking when the transbrake releases.
Click to expand...

When I saw the video I was actually wondering if that was planned. Watched it a few times and it is pretty close to rebounding up a tad as you leave. Interesting.
 
Here's a track photo of the car from the last time out.

Pete Liebig Photography - Snapshots!!
Click on drag racing, then click on 4th Annual Goblin Gambler, then go to photo number 309.
Photo number 308 shows a little more the amount of slick wrinkle just after the initial hit on the chassis.

The attitude of the car looks good to me. I like this wheelie bar setting. The next time out I'm going to try one more turn on 'em along with a little more power through the launch.
 
DonWG said:
The attitude of the car looks good to me. I like this wheelie bar setting. The next time out I'm going to try one more turn on 'em along with a little more power through the launch.
Click to expand...

Car looks great, seems to hook nice, leave nice and level. From the pics it looks like it would make a nice straight pass and not be a handful at all. Nice work Donnie, can't wait to see it in person!
 
Squid4life said:
Car looks great, seems to hook nice, leave nice and level. From the pics it looks like it would make a nice straight pass and not be a handful at all. Nice work Donnie, can't wait to see it in person!
Click to expand...
Thanks. It does handle very nice. The wonders of having the right chassis components, I guess.
 
Well, no new best numbers for the car, but it maintained and didn't fall back any.
After repairing 3 of the nitrous nozzles, the tuneup has changed a little during nitrous activation. How do I say this,... IT'S BETTER!!!
The boost buildup is on a steeper ramp. The boost is reaching 145 kPa before 5000 rpm! The car is launching from the line at over 280 kPa!
The car is now leaving the starting line at Full Song.
I tried a lower tire pressure (9.25 psi), and I think I'll be going back up to 10 psi. The car was a little more loose on the top end, and judging from the videos of the launch, leaving at 280 kPa with 9.25 psi tire pressure is annihilating the sidewalls.
The staging creep is dialed in. It works fantastic. After I stage the car, I go WOT. That activates the nitrous. As rpm begins to climb and passes 2800 rpm, the creep feature is activated and the car stages. There is still a little rocking, but it's very minor compared to the last time out with the car, and it seems to be a shallow stage. Definitely not a deep stage.
 
DonWG said:
Well, no new best numbers for the car, but it maintained and didn't fall back any.
After repairing 3 of the nitrous nozzles, the tuneup has changed a little during nitrous activation. How do I say this,... IT'S BETTER!!!
The boost buildup is on a steeper ramp. The boost is reaching 145 kPa before 5000 rpm! The car is launching from the line at over 280 kPa!
The car is now leaving the starting line at Full Song.
I tried a lower tire pressure (9.25 psi), and I think I'll be going back up to 10 psi. The car was a little more loose on the top end, and judging from the videos of the launch, leaving at 280 kPa with 9.25 psi tire pressure is annihilating the sidewalls.
The staging creep is dialed in. It works fantastic. After I stage the car, I go WOT. That activates the nitrous. As rpm begins to climb and passes 2800 rpm, the creep feature is activated and the car stages. There is still a little rocking, but it's very minor compared to the last time out with the car, and it seems to be a shallow stage. Definitely not a deep stage.
Click to expand...


Awesome results. I cannot even imagine leaving the line that hard! 280 kPa is about 42psi if the conversion is correct. Yikes, that is sick! Nice work on the nozzles too, I looked at the build post. Man, mad skills Donnie!

Quick 8, here comes Donnie! :biggrin:
 
Squid4life said:
Awesome results. I cannot even imagine leaving the line that hard! 280 kPa is about 42psi if the conversion is correct. Yikes, that is sick! Nice work on the nozzles too, I looked at the build post. Man, mad skills Donnie!

Quick 8, here comes Donnie! :biggrin:
Click to expand...
You have to subtract 100 kPa from that for the atmospheric value. The amount of boost over atmospheric was 180 kPa. That translates to 26 psi boost pressure. I think it's too much. The 60' didn't increase and the car didn't carry the front wheels as well as when launching at the lower settings. I'm going to find some conservative settings for Pinks this week.
 
26 would still be killer off the line. That is pretty high and a testament to how well you have the car set up. I can't imagine most cars being able to leave with that amount of boost and it sticks. I think it is official, you can never sell your car. It would take a team of NASA engineers and MIT graduates to tune it! ;) Can't wait to see it at Pinks!
 
charlief1 said:
Did you soften the front up any Donnie?
Click to expand...

No I didn't. I left all other settings alone, except for the wheelie bars being one turn higher than the last time out.
What I observed from the video is that the harder launch wrinkled the tires enough to cause the wheelie bars to hit the ground sooner due to the rear of the car dropping closer to the ground, resulting in the front tires being carried for a shorter distance and maybe only a couple inches off the ground when they were carried. I had no white stripes on the tires, so I couldn't judge the wheel spin at the launch, but I bet it was excessive.
 
I just reviewed the pass where I was leaving at high boost. You can see the rearend of the car swing to the left, then to the right as the car makes it through the first 60 feet. Obviously, I was losing traction at the launch even though the sidewalls were being squished into the track.
 
The high boost launch test.

[YOUTUBE]http://www.youtube.com/watch?v=d18L79F7zJQ[/YOUTUBE]
 
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