You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
8 second OEM 4 link drag race chassis setup
- Thread starter Alky V6
- Start date
One thing I've been realizing lately, the E boost controller is not as fast reacting as I had hoped, moving from launch control pressure setting to the first stage setting (jumping from 12 to 23 psi CO2 control pressure). When I was forced to go to manual boost control awhile back, I noticed that the boost rise was noticeably quicker under manual boost control, and I think I even noted that, but slowed down when I went back to electronic control. I'm going to raise the regulated level of CO2 control pressure to see if I can get a quicker ramp up of control pressure. Or, I'll figure out a different boost control strategy for the launch so that I'm not dependent on the boost control pressure rise. If you compare the datalogs I've posted in this thread and compare the boost rise of when I had to go to manual boost control to the boost rise under E boost control, you can see the drastic difference in boost rise curves. Compare posts #319-321 to #341. I'd like to see how the car will do with a quicker rise in boost during the initial launching of the car. Especially now that I seem to be making progress with the suspension settings. I want to see if that will translate into being able to use more power through the launch.
Up to this point, I've been using boost control and the torque converter stall rate to control the launch rpm level. The more boost I allow during staging, the more the engine pushes the stall of the torque converter, and the higher the rpm. No aux rev limiter was being used.
It seems I've progressed to a point where what I need to do is control the rpm to about 5850 rpm after final staging with an aux rev limiter, control the boost rise to a higher value than I've been using, and when the transbrake is released, the timing will come back in and the sudden climb in rpm due to the higher built up boost level should spike the stall of the torque converter for a better hit on the tires at the launch.
I can see the value of a 3 step rev limiter control system. Prestage the car. Go WOT and a switch on the foot brake would signal the staging rev limiter. This rev limit would be a lower rpm level to allow creaping into final stage. Once on the staging rev limiter with boost rising, creap into final stage and set the transbrake. The transbrake activation would signal the staged/launch rev limiter. This would be a higher, launch ready rev limit. I can understand why dual rear brake calipers are coming more into fashion.
It seems I've progressed to a point where what I need to do is control the rpm to about 5850 rpm after final staging with an aux rev limiter, control the boost rise to a higher value than I've been using, and when the transbrake is released, the timing will come back in and the sudden climb in rpm due to the higher built up boost level should spike the stall of the torque converter for a better hit on the tires at the launch.
I can see the value of a 3 step rev limiter control system. Prestage the car. Go WOT and a switch on the foot brake would signal the staging rev limiter. This rev limit would be a lower rpm level to allow creaping into final stage. Once on the staging rev limiter with boost rising, creap into final stage and set the transbrake. The transbrake activation would signal the staged/launch rev limiter. This would be a higher, launch ready rev limit. I can understand why dual rear brake calipers are coming more into fashion.
Readjust the new target static offset for the AS%s to 10%. This will increase the static Rt side IC length. This will also lengthen the dynamic IC length which will be shorter than the static length.
Take 2 turns back out on the rear shock comp setting.
The latest target launch rpm and map are 5,550 rpm and 160 kPa map (8.7 psi boost).
The nitrous shut off point has been moved to 5600 rpm or 160 kPa MAP. These are good targets. 160 kPa MAP is reached just before 5600 rpm.
Time from start of nitrous activation to launch ready, 1.58 sec. Need to go WOT as soon as the staged bulb lights to be ready by the last amber.
The latest fuel map changes, richening just before the aux fueling transition and leaning after the aux fueling transition, are resulting in more power from less boost through the launch and boost ramp up. More rpm in relation to boost.
Take 2 turns back out on the rear shock comp setting.
The latest target launch rpm and map are 5,550 rpm and 160 kPa map (8.7 psi boost).
The nitrous shut off point has been moved to 5600 rpm or 160 kPa MAP. These are good targets. 160 kPa MAP is reached just before 5600 rpm.
Time from start of nitrous activation to launch ready, 1.58 sec. Need to go WOT as soon as the staged bulb lights to be ready by the last amber.
The latest fuel map changes, richening just before the aux fueling transition and leaning after the aux fueling transition, are resulting in more power from less boost through the launch and boost ramp up. More rpm in relation to boost.
Latest Complete Chassis Settings
The last complete list of chassis settings were noted in post #313.
The last complete list of chassis settings before that was post #211.
Total vehicle weight: 3290.5 lbs. with suited driver and full fuel cell load (15 gallons).
Percentage of weight on the rear axle: 45.75%
Percentage of weight on the left side: 51.57%
CG height = 21.7"
Present weight distribution, including 1/2 turn ARB preload; (Old distribution figures. New ARB preload is 1/6 turn. Weights not updated)
LF 978.2, RF 806.6
LR 718.5, RR 786.7
Ride heights equal in the front, 1/8" higher at the RR than the LR, with driver, helmet and fuel. (ARB preload changed. Ride heights not updated)
I moved the rear axle forward another 1/8". Static clearance from the rear tire to the front lower edge of the fenderwell lip is 1.25" on both sides with a 29.5" tire.
The new IC and AS numbers are;
IC lenght; IC ht.; AS%
Left side: Old: 41.2"; 10.6"; 128.8%. New: 51.3"; 10.6"; 103.1%.
Right side: Old: 43"; 11.9"; 138.2%. New: 54.4"; 12.5"; 115.2%
Old Lt w/.4" rise: 50.3"; 11.4"; 112.8%. New Lt w/.2" rise: 57.3"; 11.0"; 96%.
Old Rt w/.4" drop: 36.9"; 10.9"; 149.0%. New Rt w/ .2" drop: 49.7"; 11.8"; 119.6%
Old Lt w/.4" rise and 5" front end extension: 51.4"; 13.9"; 119.1%. No new figures.
Old Rt w/.4" drop and 5" front end extension: 37.5"; 12.7"; 151.3%. No new figures.
The .4" and .2" rise and drop simulating normal body roll on takeoff.
Pinion angle is set at 1.5 degrees upward angle from horizontal in anticipation of a 1-1.5 degree axle wrap up.
Front shocks (QA1 SA). The adjustment is at 0 clicks, full soft. Both front shocks using the same settings.
Rear shocks (Afco DA) set the same at 20 clicks comp, 10 rebound.
Both front and rear shocks adjust firmer by turning CW from full CCW position.
Range of the front shocks is 0-24 clicks.
Range of the rear shocks is 0-24 clicks comp, 0-39 rebound. Top knob for comp adjust, bottom for rebound.
Front extension travel limiters set at approximately 2" including bumper compression. On an even rise left to right, the RF leaves the ground (3/4") before the LF.
RB preload is 1/6 turn on the rt side. Static weight on the RR is 786 lbs. (not updated)
Rear tire pressure at 9.5 psi. Front at 35 psi. 9.5 psi in the rear has been confirmed to be the best pressure to use.
New target launch rpm and boost level: 5500-5600 rpm, 160-170 kPa MAP.
The last complete list of chassis settings were noted in post #313.
The last complete list of chassis settings before that was post #211.
Total vehicle weight: 3290.5 lbs. with suited driver and full fuel cell load (15 gallons).
Percentage of weight on the rear axle: 45.75%
Percentage of weight on the left side: 51.57%
CG height = 21.7"
Present weight distribution, including 1/2 turn ARB preload; (Old distribution figures. New ARB preload is 1/6 turn. Weights not updated)
LF 978.2, RF 806.6
LR 718.5, RR 786.7
Ride heights equal in the front, 1/8" higher at the RR than the LR, with driver, helmet and fuel. (ARB preload changed. Ride heights not updated)
I moved the rear axle forward another 1/8". Static clearance from the rear tire to the front lower edge of the fenderwell lip is 1.25" on both sides with a 29.5" tire.
The new IC and AS numbers are;
IC lenght; IC ht.; AS%
Left side: Old: 41.2"; 10.6"; 128.8%. New: 51.3"; 10.6"; 103.1%.
Right side: Old: 43"; 11.9"; 138.2%. New: 54.4"; 12.5"; 115.2%
Old Lt w/.4" rise: 50.3"; 11.4"; 112.8%. New Lt w/.2" rise: 57.3"; 11.0"; 96%.
Old Rt w/.4" drop: 36.9"; 10.9"; 149.0%. New Rt w/ .2" drop: 49.7"; 11.8"; 119.6%
Old Lt w/.4" rise and 5" front end extension: 51.4"; 13.9"; 119.1%. No new figures.
Old Rt w/.4" drop and 5" front end extension: 37.5"; 12.7"; 151.3%. No new figures.
The .4" and .2" rise and drop simulating normal body roll on takeoff.
Pinion angle is set at 1.5 degrees upward angle from horizontal in anticipation of a 1-1.5 degree axle wrap up.
Front shocks (QA1 SA). The adjustment is at 0 clicks, full soft. Both front shocks using the same settings.
Rear shocks (Afco DA) set the same at 20 clicks comp, 10 rebound.
Both front and rear shocks adjust firmer by turning CW from full CCW position.
Range of the front shocks is 0-24 clicks.
Range of the rear shocks is 0-24 clicks comp, 0-39 rebound. Top knob for comp adjust, bottom for rebound.
Front extension travel limiters set at approximately 2" including bumper compression. On an even rise left to right, the RF leaves the ground (3/4") before the LF.
RB preload is 1/6 turn on the rt side. Static weight on the RR is 786 lbs. (not updated)
Rear tire pressure at 9.5 psi. Front at 35 psi. 9.5 psi in the rear has been confirmed to be the best pressure to use.
New target launch rpm and boost level: 5500-5600 rpm, 160-170 kPa MAP.
The latest IC location change puts it at about 10-11" forward of where it was just at, and about 3" back from where it was to begin with before I started playing with the IC location. I was trying to split the difference, but I goofed on measuring the new hole locations. We'll see how this does.
I plugged the old hole locations in Kevin's buckets and made new holes. That way, I was able to retain the shorter UCAs.
The span of the IC lengths with .20" torque roll, is now 49.7-57.3". This puts the IC locations from the rear of my fanny to the front of my fanny, sitting in the driver's seat.
I plugged the old hole locations in Kevin's buckets and made new holes. That way, I was able to retain the shorter UCAs.
The span of the IC lengths with .20" torque roll, is now 49.7-57.3". This puts the IC locations from the rear of my fanny to the front of my fanny, sitting in the driver's seat.
The reason for deciding to make the IC change is, the 60 foot did not seem to improve, or at least stay at the same level as what the last IC setting was providing.
After testing with this latest IC setting, I feel that the car was not pitch rotating enough and was not putting enough transferred weight on the rear tires. It appears my setup needs some body pitch rotation to get a little more transferred weight on the rear tires.
I'm hoping the new IC setting will get some of the vehicle pitch back, but just slightly tamed down from what it was before.
After testing with this latest IC setting, I feel that the car was not pitch rotating enough and was not putting enough transferred weight on the rear tires. It appears my setup needs some body pitch rotation to get a little more transferred weight on the rear tires.
I'm hoping the new IC setting will get some of the vehicle pitch back, but just slightly tamed down from what it was before.
A table of the IC settings I've tried and plan to try.
1. The original IC setting with stock length UCAs.
2. The last setting with Kevin's boxes and shorter UCAs.
3. The next setting to test with shorter UCAs.
4. The last setting to test with shorter UCAs.
IC length; IC ht; AS%
Left side. At rest // +.200" rise // +.400" rise. +/- rise to simulate normal body torque roll on take off.
1. 53.2; 11.4; 106.9 // 57.8; 11.9; 102.9 // 63.2; 12.6; 99.1
2. 41.2; 10.6; 128.8 // 45.3; 11.0; 120.5 // 50.3; 11.4; 112.7
3. 51.3; 10.6; 103.1 // 57.3; 11.0; 96.00 // 64.8; 11.6; 89.2
4. 41.6; 10.6; 127.5 // 45.8; 11.0; 119.3 // 50.9; 11.4; 111.4
Right side. At rest // -.200" rise // -.400" rise. +/- rise to simulate normal body torque roll on take off.
1. 51.0; 11.5; 112.6 // 47.4; 11.0; 116.5 // 44.2; 10.5; 120.5
2. 43.1; 11.9; 137.9 // 39.8; 11.3; 143.2 // 36.9; 10.9; 148.8
3. 54.4; 12.5; 115.2 // 49.7; 11.8; 119.6 // 45.7; 11.2; 124.2
4. 49.3; 12.2; 124.2 // 45.1, 11.6; 129.3 // 41.5; 11.1; 134.7
No immediate plans to change corner weight jacking settings, or drastically change the ARB setting.
1. The original IC setting with stock length UCAs.
2. The last setting with Kevin's boxes and shorter UCAs.
3. The next setting to test with shorter UCAs.
4. The last setting to test with shorter UCAs.
IC length; IC ht; AS%
Left side. At rest // +.200" rise // +.400" rise. +/- rise to simulate normal body torque roll on take off.
1. 53.2; 11.4; 106.9 // 57.8; 11.9; 102.9 // 63.2; 12.6; 99.1
2. 41.2; 10.6; 128.8 // 45.3; 11.0; 120.5 // 50.3; 11.4; 112.7
3. 51.3; 10.6; 103.1 // 57.3; 11.0; 96.00 // 64.8; 11.6; 89.2
4. 41.6; 10.6; 127.5 // 45.8; 11.0; 119.3 // 50.9; 11.4; 111.4
Right side. At rest // -.200" rise // -.400" rise. +/- rise to simulate normal body torque roll on take off.
1. 51.0; 11.5; 112.6 // 47.4; 11.0; 116.5 // 44.2; 10.5; 120.5
2. 43.1; 11.9; 137.9 // 39.8; 11.3; 143.2 // 36.9; 10.9; 148.8
3. 54.4; 12.5; 115.2 // 49.7; 11.8; 119.6 // 45.7; 11.2; 124.2
4. 49.3; 12.2; 124.2 // 45.1, 11.6; 129.3 // 41.5; 11.1; 134.7
No immediate plans to change corner weight jacking settings, or drastically change the ARB setting.
A table of the IC settings I've tried and plan to try.
1. The original IC setting with stock length UCAs.
2. The last setting with Kevin's boxes and his shorter UCAs.
3. The next setting to test with the shorter UCAs.
4. The last setting to test with the shorter UCAs.
IC length; IC ht; AS%
Left side. At rest // +.200" rise // +.400" rise. +/- rise to simulate normal body torque roll on take off.
1. 53.2; 11.4; 106.9 // 57.8; 11.9; 102.9 // 63.2; 12.6; 99.1
2. 41.2; 10.6; 128.8 // 45.3; 11.0; 120.5 // 50.3; 11.4; 112.7
3. 51.3; 10.6; 103.1 // 57.3; 11.0; 96.00 // 64.8; 11.6; 89.2
4. 41.6; 10.6; 127.5 // 45.8; 11.0; 119.3 // 50.9; 11.4; 111.4
Right side. At rest // -.200" rise // -.400" rise. +/- rise to simulate normal body torque roll on take off.
1. 51.0; 11.5; 112.6 // 47.4; 11.0; 116.5 // 44.2; 10.5; 120.5
2. 43.1; 11.9; 137.9 // 39.8; 11.3; 143.2 // 36.9; 10.9; 148.8
3. 54.4; 12.5; 115.2 // 49.7; 11.8; 119.6 // 45.7; 11.2; 124.2
4. 49.3; 12.2; 124.2 // 45.1, 11.6; 129.3 // 41.5; 11.1; 134.7
No immediate plans to change corner weight jacking settings, or drastically change the ARB setting.
1. The original IC setting with stock length UCAs.
2. The last setting with Kevin's boxes and his shorter UCAs.
3. The next setting to test with the shorter UCAs.
4. The last setting to test with the shorter UCAs.
IC length; IC ht; AS%
Left side. At rest // +.200" rise // +.400" rise. +/- rise to simulate normal body torque roll on take off.
1. 53.2; 11.4; 106.9 // 57.8; 11.9; 102.9 // 63.2; 12.6; 99.1
2. 41.2; 10.6; 128.8 // 45.3; 11.0; 120.5 // 50.3; 11.4; 112.7
3. 51.3; 10.6; 103.1 // 57.3; 11.0; 96.00 // 64.8; 11.6; 89.2
4. 41.6; 10.6; 127.5 // 45.8; 11.0; 119.3 // 50.9; 11.4; 111.4
Right side. At rest // -.200" rise // -.400" rise. +/- rise to simulate normal body torque roll on take off.
1. 51.0; 11.5; 112.6 // 47.4; 11.0; 116.5 // 44.2; 10.5; 120.5
2. 43.1; 11.9; 137.9 // 39.8; 11.3; 143.2 // 36.9; 10.9; 148.8
3. 54.4; 12.5; 115.2 // 49.7; 11.8; 119.6 // 45.7; 11.2; 124.2
4. 49.3; 12.2; 124.2 // 45.1, 11.6; 129.3 // 41.5; 11.1; 134.7
No immediate plans to change corner weight jacking settings, or drastically change the ARB setting.
This past weekend we made some test runs with the new IC setting. The car left flat and level. Popped the front tires about 3-4 inches. 60 foots at 1.35 sec.
Power felt down. I've been playing with the ign timing settings a little and I may have too much timing going on. I'm dialing the timing back to the level where the car performed the 1.27 60' earlier last year (2011).
Power felt down. I've been playing with the ign timing settings a little and I may have too much timing going on. I'm dialing the timing back to the level where the car performed the 1.27 60' earlier last year (2011).
A still shot taken by the track photographer shows the car about 1 foot forward of the starting line with the tires popped up about 2-3 inches. The angle is from the rear, off to the right side of the car, about chest high. It's hard to tell from a simple still shot, but the car appears to have zero body roll happening. The gap between the right rear tire and the center top of the fender well lip appears to have the same clearance the car has when at rest. The tire sidewall is about halfway crushed to the track surface. This shot was one of the last runs of the day. A 1.35 60'. A very boring feeling launch. Felt like a stocker leaving the line.
Could I have found the right amount of static/dynamic instant center offset? No separation, no squat, no body roll? The present static/dynamic IC setting is;
Left side. At rest // +.200" rise // +.400" rise. +/- rise to simulate normal body torque roll on take off.
51.3; 10.6; 103.1 // 57.3; 11.0; 96.00 // 64.8; 11.6; 89.2
Right side. At rest // -.200" rise // -.400" rise. +/- rise to simulate normal body torque roll on take off.
54.4; 12.5; 115.2 // 49.7; 11.8; 119.6 // 45.7; 11.2; 124.2
The weight jacking, shock settings and ARB were all set as last noted. 1/6 turn of preload on the ARB.
A little upsetting of the chassis at the top end when getting off the throttle and onto the brakes. Nothing that was unmanagable. Just enough to be noticable. I can live with that if it means having a square launch.
Now I need to find the right WG/BOV settings to get the boost rise more happening at the launch. I'm going to swap out the main, small ID CO2 feed line to the boost control solenoids to a larger ID in hopes of getting the controls to react quicker. I may be getting too much pressure drop with the long and small ID line. Maybe I can get quicker WG/BOV reaction time with the larger ID feed line. I know the boost rise can be quicker, from my experiences with going back to manual boost control last year.
After I'm happy with the boost rise at launch, it will be time to look at changing the method of setting the front end extension travel, and back to playing with shock settings.
Could I have found the right amount of static/dynamic instant center offset? No separation, no squat, no body roll? The present static/dynamic IC setting is;
Left side. At rest // +.200" rise // +.400" rise. +/- rise to simulate normal body torque roll on take off.
51.3; 10.6; 103.1 // 57.3; 11.0; 96.00 // 64.8; 11.6; 89.2
Right side. At rest // -.200" rise // -.400" rise. +/- rise to simulate normal body torque roll on take off.
54.4; 12.5; 115.2 // 49.7; 11.8; 119.6 // 45.7; 11.2; 124.2
The weight jacking, shock settings and ARB were all set as last noted. 1/6 turn of preload on the ARB.
A little upsetting of the chassis at the top end when getting off the throttle and onto the brakes. Nothing that was unmanagable. Just enough to be noticable. I can live with that if it means having a square launch.
Now I need to find the right WG/BOV settings to get the boost rise more happening at the launch. I'm going to swap out the main, small ID CO2 feed line to the boost control solenoids to a larger ID in hopes of getting the controls to react quicker. I may be getting too much pressure drop with the long and small ID line. Maybe I can get quicker WG/BOV reaction time with the larger ID feed line. I know the boost rise can be quicker, from my experiences with going back to manual boost control last year.
After I'm happy with the boost rise at launch, it will be time to look at changing the method of setting the front end extension travel, and back to playing with shock settings.
Kevin's shorter UCAs in the rear have increased the ramping rate of dynamic instant center offsetting as it relates to the degree of body roll. The dynamic IC length and AS% ramping in at a quicker rate with increasing body roll compared to the dynamic IC offset ramping rate with the standard upper control arms. In my case, this seems to have been helpful in eliminating body roll at the launch. It allows a smaller degree of static IC offsetting, and only the tiniest amount of ARB preloading.
I will be shaving off 1/4" of height off the front end extension travel limiters. This should result in about 1/2 inch additional front end travel extension. I will leave the existing travel limit offset in place. The right side reaching its travel limit before the left side on an even front end rise. Front shocks at full loose extension. If this gives me too much front end rise at the launch, then I'll start dialing the front shocks stiffer. I don't expect a large change in front end rise.
I will be shaving off 1/4" of height off the front end extension travel limiters. This should result in about 1/2 inch additional front end travel extension. I will leave the existing travel limit offset in place. The right side reaching its travel limit before the left side on an even front end rise. Front shocks at full loose extension. If this gives me too much front end rise at the launch, then I'll start dialing the front shocks stiffer. I don't expect a large change in front end rise.
What's nice about having the right amount of dynamic instant center offset ramp in rate is, with changing power levels the chassis can dynamically handle the change in body anti-roll needs, instead of having to manually find a new ARB setting to handle the same. The body anti-roll needs dynamically adjust to the changing power level without the need of manual input from a chassis techician.
Heavy stuff.
Heavy stuff.
Measuring the tire to fender well lip at rest and comparing that to the launch still picture, it looks like the right side dropped down about .400 - .600" at the launch. It's hard to tell if that is due to body roll or the whole rearend dropping that amount. Body roll is undetectable in the picture. That is an improvement over past performance. The right side drop, whether from body roll or rearend drop, was larger with past settings.
The 60' turned out to be pretty consistent. The first run, I launched too soon and the car wasn't up on enough boost yet (3-4 psi boost launch). That was a 1.457 60'.
The last 3 runs were;
1.355
1.361
1.351
The 60' turned out to be pretty consistent. The first run, I launched too soon and the car wasn't up on enough boost yet (3-4 psi boost launch). That was a 1.457 60'.
The last 3 runs were;
1.355
1.361
1.351
Similar threads
- Replies
- 3
- Views
- 2K
