Discussion of Chassis Setup for 8 Sec. Assault

After studying the datalogs of the weekend, I found that the launches were at around 160s kPa MAP. I launched the car by feeling the engine and didn't wait long enough to have the MAP build to a higher level. I wasn't sure how well the new BOV staging boost level control system was going to work out so I played it safe and decided to work up slowly on the staging procedure to make sure I didnt' run into trouble.

I've been working more in the garage on the BOV staging tuneup and got the rpm and map to level out nicely at 5600-5700 rpm and 179-183 kPa MAP. The nitrous system acts to control the staging rpm and map level. Surprisingly the nitrous system gives a soft rev control. Very cool.

With more work done to the fuel table in the section leading up to and including where the engine will sit during staging, I've been able to increase the boost rise curve in relation to engine rpm. Using 145 kPa MAP as my benchmark with the 91mm, originally I would reach 145 kPa by a rpm that was in the 6,000s, then it went to 5700 rpm for a long time, then 5400, then 5200+, and now it's down to 5080 rpm. By 5700 rpm I'm now building 180 kPa MAP. Also, the ratio meter is now reading a flatline 14.64:1 through the whole ALS activation region showing in the datalogs. An interesting way to tune your high performance turbo engine. Tune to 14.64:1. :eek:
 
An interesting discovery this past week on my tire pressures. I purchased a certified digital tire pressure gauge and compared the readings of the new gauge to the readings from my old track gauges.
The old gauge I use for the slicks read 2 psi low compared to the new gauge. That makes some sense. Rear slick pressures have actually been 10.5 psi, not 8.5.
The old gauge I use for the front tires read 5 psi low compared to the new digital gauge.

Next time out, I'll be running with 5 psi more tire pressure in the front tires. Less rolling resistance. :biggrin:
 
New bests for the car after yesterdays test & tune. 5.651@126.756. New bests at half track also. 3.686@96.890.
The wheelie bar adjustment was raised two turns on the adjusters on each side. That let the car carry the wheels out a little longer. Finally got some video where I could see how the car is reacting at the launch.
The boost level through the 1-2 shift was around 260-270 kPa MAP. The boost level at launch was about 178-185 kPa MAP.
The 1-2 shift will definitely tolerate more power through the shift as the launch gets harder.
The plan is to raise the rpm and boost level at the launch by one psi. Rear tire pressure will also be lowered .5 psi. That will be 9.5 psi in the rear.
There is a little more work to do on the trans creep routine. The car is still deep staging (top bulb flickering). Best 60' of the outing was 1.307.
I was practicing for a pro light on a 3 amber tree and it looks like I've got it nailed down. From the point of final staging the car to the time the first bulb came down, the engine had reached launch rpm and boost level. There was even a sign in the datalog that the rpm and boost even had time to level out waiting for the first amber.
Always nice to leave the track with a new best(s).
 
Wow

a 5.65 in the 1/8th is 8.96 for the 1/4mi !!!!!!!!!according to wallace racing calculators

your 126.7 equates to 157.11 in the 1/4 mi.
 
The wheelie bar adjustment is now 7.5" rt, 8.0" lft side from ground to wheel axle centerline. That was after the two turn adjustment.
I'm going to crank one more turn into it for the next time out. 8.0" rt, 8.5" lft side.
The car is coming off the nitrous before the launch now. With the aux fuel activation point moved up higher into the map region, it's letting the O2 give me a cleaner reading of the top end. I've discovered a rich patch in the fuel table that I'll be working on leaning out the next time I get to the track. I love it when I find hidden treasures like this. The engine runs in this rich patch at 7200 rpm and lower and 220 - 305 kPa. That's most of first gear and better than half of second and third gear after the shifts. I predict another run of bests for the car the next time out. :cool:
 
The second pass in the video was after raising the wheelie bars the two turns.
 
Donnie et al,
A great book on aerodynamics of race cars is:

New Directions in RACE CAR AERODYNAMICS...Designing for Speed

by Joseph Katz published by Bentley Publishers. Should be available in most good bookstores or from www.Amazon.Com or direct from Bentley Publishers Home  -  Bentley Publishers - Repair Manuals and Automotive Books.

Link to Stan Davis' car is below:
http://www.turbobuick.com/forums/tu...-regal-complete-turbo-mag-write-up-video.html

I do have an original issue of the magazine article and can send you better photos.

At the speeds you (and others) are turning, there is some "low hanging fruit" to be had @Aerodynamics. Lower the drag coefficient and the mph WILL jump up. Remember, hp vs mph is not a linear curve!

Conrad

Conrad
 
I do actually have a copy of that book. You're correct. It is a fantastic book.
After I get the launch tune nailed down better I will be looking into aero projects for the car. The grill is already blocked off and the next area to modify will be the front air dam. After that, either a rear wing or a ground effects deal.
I have an interesting idea for ground effects. Something that can enhance safety too.

Speaking of safety, my next immediate project for the car is to install hoods pins before the Pinks event.
 
Hood Pins

Don, your posts are always very informative reading. Please do a write-up on your hood pin install.
 
If I know Donnie he'll fabricate them himself and they'll look fantastic as well as work better than anyone elses.:biggrin: LOL
 
charlief1 said:
If I know Donnie he'll fabricate them himself and they'll look fantastic as well as work better than anyone elses.:biggrin: LOL
Click to expand...
I was actually thinking of machining some up, but decided on buying them. I went with the Hotchkis design.
 
DonWG said:
I was actually thinking of machining some up, but decided on buying them. I went with the Hotchkis design.
Click to expand...

You getting lazy on us Don?:eek: I understand. Sometimes it is the easy way to use someone elses parts and it costs less in the end.:cool:
 
You must log in or register to reply here.

Similar threads

8
looking for proper fuel pressure setting for the carbed turbo setup
Replies
3
Views
596
81LimitedT
8
J
Showing some love to the GN - Time for updates - Looking for Advice
Replies
19
Views
2K
JadeMonkeyStang
J
R
What is needed to put a 153 (on center) engine into a TR?
Replies
13
Views
2K
Mr.Spool
M
M
more anti-squat.....relocate upper or lower arms
Replies
10
Views
1K
mommasGN
M
ttypewhite
Precision 8285 DBB turbo for sale
Replies
5
Views
1K
ttypewhite
ttypewhite
Top