The first pass on manual boost control and the nitrous on time after transbrake release set at .400 second. This caused an intake backfire at the launch. Thanks to the built in blow off valve, the intake manifold didn't turn to shrapnel and I was actually able to complete the run.
8 second OEM 4 link drag race chassis setup
- Thread starter Alky V6
- Start date
New shock settings for next time out.
Front: 11 rebound (softer by 3)
Rear: 16 comp (same), 10 rebound (softer by 2).
AMS1000 unit being sent back for repair.
GPO control of the nitrous system changed to insure that the system will be shut down at any MAP level greater than 240 kPa.
Front: 11 rebound (softer by 3)
Rear: 16 comp (same), 10 rebound (softer by 2).
AMS1000 unit being sent back for repair.
GPO control of the nitrous system changed to insure that the system will be shut down at any MAP level greater than 240 kPa.
Correction.
Front: 11 rebound (softer by 3)
Rear: 16 comp (same), 8 rebound (softer by 2).
After being asked what boost level I use at the launch, it made me think about it more carefully. The best 60' to date was done with 148 kPa MAP at the launch. Lately, I've been playing around with launch boost levels in the 185-240 kPa MAP range with only a little luck trying to match the cars best 60'. The latest best 60' was done using 188 kPa MAP. I'm going to try working with MAP levels in the 145-190 kPa range and see it I can find some consistent 60 foots in there somewhere. It's going to require me to lower the manifold pressure controlled nitrous shut off point which is presently set at 175 kPa MAP.
The front shock setting is down to 3 clicks now. Next outing I'll be trying 1 click. The wheelie bars will be set a little higher. Trying to make sure I get some good weight on the rear tires.
The launch map and rpm I'm presently working with is 185-190 kPa and around 5800 rpm. I'm reactivating the nitrous at the launch and shutting it back down at 210 kPa MAP. This should require less than .2 second of nitrous on time. The aux fueling trigger point has been moved down from 240 kPa to 220 kPa. The rpm makes a good upward bump when the aux fueling comes in, and I thought I'd try to get the aux fueling to come in sooner so that I could take advantage of that rpm bump up earlier in the run.
One electrical wiring bug showed up during the last outing. I'm using an ECM GPO to control the activation window of the nitrous system. In the past, the GPO was set up to make the nitrous system live when the rpm and map were above 2800 rpm and 84 kPa MAP. A map switch would control the shut off point. With the new strategy of reacivating the nitrous system at the launch and switching the nitrous system shut off point control from map switch during staging spool up to GPO control for launch map level shut down, I had to change the GPO control to create a more exact nitrous activation window. I added another parameter to the GPO. The nitrous system would still become live at a rpm and map level above 2800 rpm and 84 kPa map, but now would have an upper rpm and map level shut down parameter of 5800 rpm and 210 kPa MAP. So now if both above 5800 rpm AND 210 kPa MAP were met, the nitrous system would be shut down. This would allow me to very finely control the exact shut off point of the nitrous system during the launch of the car, and would keep me from winding up with too much boost and the nitrous being on at the same time. 240 kPa MAP with the nitrous on seems to be the limit of the fueling. At this point, anyway.
Well, the electrical bug was, the aux fueling power was controlled by a relay that depended on the nitrous control relay being powered up. In other words, the aux fueling relay was in series with the nitrous relay. If now I was commanding the nitrous to shut down at 210 kPa, that meant that the power to the aux fueling would also be unavailable when it was commanded to come on at 240 kPa MAP. This resulted in a massive leanout. The leanout was so massive with the E injector cut back that no damage was done to the engine, but it took me awhile to figure out what the heck was going on.
The power ciruit to the nitrous control relay and the aux fueling relay are now in parallel, not series. The circuit strategy worked fine in the past where I just left the nitrous system live at any rpm and map level above such and such, but now that I was starting to kill the circuit above a controlled rpm and map level, it created a problem that ended up being simple to correct,... once I realized what the problem was.
The launch map and rpm I'm presently working with is 185-190 kPa and around 5800 rpm. I'm reactivating the nitrous at the launch and shutting it back down at 210 kPa MAP. This should require less than .2 second of nitrous on time. The aux fueling trigger point has been moved down from 240 kPa to 220 kPa. The rpm makes a good upward bump when the aux fueling comes in, and I thought I'd try to get the aux fueling to come in sooner so that I could take advantage of that rpm bump up earlier in the run.
One electrical wiring bug showed up during the last outing. I'm using an ECM GPO to control the activation window of the nitrous system. In the past, the GPO was set up to make the nitrous system live when the rpm and map were above 2800 rpm and 84 kPa MAP. A map switch would control the shut off point. With the new strategy of reacivating the nitrous system at the launch and switching the nitrous system shut off point control from map switch during staging spool up to GPO control for launch map level shut down, I had to change the GPO control to create a more exact nitrous activation window. I added another parameter to the GPO. The nitrous system would still become live at a rpm and map level above 2800 rpm and 84 kPa map, but now would have an upper rpm and map level shut down parameter of 5800 rpm and 210 kPa MAP. So now if both above 5800 rpm AND 210 kPa MAP were met, the nitrous system would be shut down. This would allow me to very finely control the exact shut off point of the nitrous system during the launch of the car, and would keep me from winding up with too much boost and the nitrous being on at the same time. 240 kPa MAP with the nitrous on seems to be the limit of the fueling. At this point, anyway.
Well, the electrical bug was, the aux fueling power was controlled by a relay that depended on the nitrous control relay being powered up. In other words, the aux fueling relay was in series with the nitrous relay. If now I was commanding the nitrous to shut down at 210 kPa, that meant that the power to the aux fueling would also be unavailable when it was commanded to come on at 240 kPa MAP. This resulted in a massive leanout. The leanout was so massive with the E injector cut back that no damage was done to the engine, but it took me awhile to figure out what the heck was going on.
The power ciruit to the nitrous control relay and the aux fueling relay are now in parallel, not series. The circuit strategy worked fine in the past where I just left the nitrous system live at any rpm and map level above such and such, but now that I was starting to kill the circuit above a controlled rpm and map level, it created a problem that ended up being simple to correct,... once I realized what the problem was.
The front shock settings are at 0 clicks for the next test and tune. The staging nitrous shutoff setting is at 150 kPa. The wastegate and BOV settings will be used to target a 160-165 kPa staging MAP level. The nitrous re-activation timer at transbrake release will be fine tuned to give the best 60 foot with the present IC setting.
The roll bar arms have been shortened 1.5" to give a little more roll control and to get the roll bar link and arm geometry correct in relation to the rear axle travel. If the body roll is still too much after this modification, I'll be fabbing up a new larger diameter roll bar and arms to replace the TRZ unit.
The roll bar arms have been shortened 1.5" to give a little more roll control and to get the roll bar link and arm geometry correct in relation to the rear axle travel. If the body roll is still too much after this modification, I'll be fabbing up a new larger diameter roll bar and arms to replace the TRZ unit.
Straightening out the ARB link and arm geometry left the thread engagement of the link rod ends on the edge. The thread on the rod ends are exceptionally long, but I would just feel more comfortable if the rod end was threaded into the adjuster sleeve as much as possible. I'll either be rotating the ARB down a little so that I can shorten the links up while still keeping good ARB to UCA clearance, or I'll be making up some new link sleeves.
Rotating the ARB will involve making new special mounting links that will be a little shorter than the links I had just made a little while back to change the position of the ARB. I think this will be the simplest way to solve this problem. Otherwise, I'd have to purchase a left hand thread tap to make up the link sleeves.
Rotating the ARB will involve making new special mounting links that will be a little shorter than the links I had just made a little while back to change the position of the ARB. I think this will be the simplest way to solve this problem. Otherwise, I'd have to purchase a left hand thread tap to make up the link sleeves.
The roll bar modification is done. I simply modified the links I had made up originally to rotate the roll bar for more clearance between the RB and the UCAs. There was plenty of room, so I just rotated the RB back down a little.
These pics show Kevin's control arm mounting boxes real well.
These pics show Kevin's control arm mounting boxes real well.
Attachments
Went to the track with the modified roll bar and a questimate adjustment of 1/2 turn (3 flats) of RB preload on the RR. On the first launch I noticed the car wanted to do a little twitch to the left. I took a third of a turn (2 flats) of RB preload off the RR tire and the twitch disappeared. That left only one flat (1/6 turn) of RB preload on the RR tire. Perfection!
Finished some TT with the car. I'm working the tuneup back up from an 1/8 mile 6.90 index tuneup. It's back up to a 5650 rpm/190 kPa (13 psi) MAP launch. The shortened RB arms seem to have helped out. I'm detecting less body roll on the launch with no ill side effects from the mod. The car is leaving the line so boringly flat and straight that I'm tempted to put the other UCAs back on just to get the front end in the air again. The front shocks are all the way loose (rebound), the rear shocks are the same last noted settings. Still have not been able to break back into the 1.2s for a 60 foot. It is consistently in the mid 1.3s. The car did maintain traction through a 265 kPa (24 psi boost) MAP 1-2 shift. I don't recall the car doing that in the past. Just a hint of slippage was detected.
Latest performance was 5.87 @ 121 mph, on a flat 24 psi boost throughout the pass.
Latest performance was 5.87 @ 121 mph, on a flat 24 psi boost throughout the pass.
I've been playing with the launch nitrous tune a bit lately. I've got it to where the car is launch ready in 1.6-1.7 seconds. This makes the staging a little easier. I can final stage at an elevated rpm of about 2200 rpm, set the transbrake, floor it, and be at launch rpm and map (5600-5700 rpm/190 kPa map) by about the 2nd amber bulb. I release on the third bulb. A slight bump of tire slippage is detected at the launch with this tuneup.
The next TT is the 22nd. I'll see if I can recruit a cameraman.
I just returned from watching a local fella shake down a brand new BB Ford, 3 stage nitrous Pro Mod Mustang (I know, I know... Another Mustang. Arrrg) at the track today. He was having a problem with the shift into high at the transition portion of the track. I decided to use the opportunity to bring up to one of the track owners, that's a good friend of mine, what I thought about the track and what I thought is needed to fix it. He seemed very receptive. Might get the track redone to all concrete all the way to the finish! Yippee!!!
This next time out with the car, I'll be increasing the comp settings on the rear shocks, 2 clicks at a time to see if any improvement in the 60' can be had.
Current rear shock settings are now 16 comp, 8 rebound. We'll be starting out the testing with 18 comp, 8 rebound.
Top knob is comp. Total ranges are 24 comp, 39 rebound.
Current rear shock settings are now 16 comp, 8 rebound. We'll be starting out the testing with 18 comp, 8 rebound.
Top knob is comp. Total ranges are 24 comp, 39 rebound.
During this last track rental with the testing of the Pro Mod Mustang, I went out onto the track with a track official and one of the track owners to take a close look at the track with them. Just off the concrete launching pad, the track has very deep, lengthwise grooving. Part of it is rubber buildup and part of it is the track itself. You could tell by the dull appearance on the top of the grooves where tire contact was happening, and where it wasn't. The grooving was such that I felt we were lucky if there was 30% contact for the tires. I made this known to the fellas that were looking at the track with me, and I got no argument from them. They know it's a problem.
One tried to argue with me that by the 330' mark, the left lane is better than the right lane. I should use the left lane. BTW, I always try to use the left lane. I argued back, it may well be that the left lane is better than the right, still, that doesn't make either lane right. There are problems with both.
I also brought up that most are shifting into second at around the 60-80 foot mark where the grooving in both lanes is bad.
Another argument they had was that I'm running a small tire. 10.5". I argued back that there are 10.5 cars running in the 7s in the 1/4 mile. They responded that they were aware of that. No further argument from them.
Then, one of them brought up something about me running a V6. I looked at them kinda puzzled, "Well yeah, if I'm having to cut back boost at least 4 pounds to get through the 1-2 shift, how do you think the big power V8s are going to do on a track like this?" Not really sure what his point was with that.
One tried to argue with me that by the 330' mark, the left lane is better than the right lane. I should use the left lane. BTW, I always try to use the left lane. I argued back, it may well be that the left lane is better than the right, still, that doesn't make either lane right. There are problems with both.
I also brought up that most are shifting into second at around the 60-80 foot mark where the grooving in both lanes is bad.
Another argument they had was that I'm running a small tire. 10.5". I argued back that there are 10.5 cars running in the 7s in the 1/4 mile. They responded that they were aware of that. No further argument from them.
Then, one of them brought up something about me running a V6. I looked at them kinda puzzled, "Well yeah, if I'm having to cut back boost at least 4 pounds to get through the 1-2 shift, how do you think the big power V8s are going to do on a track like this?" Not really sure what his point was with that.
Finished some testing today. After spending most of the day chasing the tuneup, I had one good run at the end of the day that gave me some good data.
I noticed in an earlier run in the day that the amount of the little bump of tire spin at the launch seemed to be less than what I had been getting used to seeing lately in earlier test sessions. I assumed that it might be from the stiffer compression setting of the rear shocks. I made another 2 clicks stiffer compression adjustment to the rear shocks. The next run was a fair test of the new shock adjustment. The launch was pretty aggressive. The bump of tire slip was gone. I'll post up some details after I have a chance to study the datalogs a little more.
I noticed in an earlier run in the day that the amount of the little bump of tire spin at the launch seemed to be less than what I had been getting used to seeing lately in earlier test sessions. I assumed that it might be from the stiffer compression setting of the rear shocks. I made another 2 clicks stiffer compression adjustment to the rear shocks. The next run was a fair test of the new shock adjustment. The launch was pretty aggressive. The bump of tire slip was gone. I'll post up some details after I have a chance to study the datalogs a little more.
The rear shock adjustments are now at 20 comp, 8 rebound.
Total range: 24 comp, 39 rebound.
Front shocks are full loose.
Another plus I've noticed, tire chatter during a hard burnout is much less with the stiffer compression setting. Only barely detectable now, where as before the level of chatter made me worry about the drivetrain. I'm going to try one click stiffer on the comp setting. If that works out OK, I'm going to start going looser on the rebound to see what's there. Maybe I can get this thing to stick better through the 1-2 shift.
Best 60' yesterday, 1.31. So close.
Total range: 24 comp, 39 rebound.
Front shocks are full loose.
Another plus I've noticed, tire chatter during a hard burnout is much less with the stiffer compression setting. Only barely detectable now, where as before the level of chatter made me worry about the drivetrain. I'm going to try one click stiffer on the comp setting. If that works out OK, I'm going to start going looser on the rebound to see what's there. Maybe I can get this thing to stick better through the 1-2 shift.
Best 60' yesterday, 1.31. So close.
Bin file 16b.
Launch rpm and map: 5844/190.4 kPa.
Map leveled out at 275 kPa, .4 sec before time for the 1-2 shift. The 1-2 shift started with 275 kPa map. The map was ramped down to 270 kPa by just after the finish of the 1-2 shift. The tires took the shift, but soon after the completion of the 1-2 shift, the tires began to slip. They didn't blow away, just slipped 25% for about .9 sec. Stayed in the throttle through the slipping and the tires took hold on their own.
Using the driveshaft speed trace line in the datalog, I'm starting to be able to identify the wrap up of the tire on initial hit off the line. A small spike in driveshaft speed at the hit.
I'll get a shot of the datalog posted up soon.
Launch rpm and map: 5844/190.4 kPa.
Map leveled out at 275 kPa, .4 sec before time for the 1-2 shift. The 1-2 shift started with 275 kPa map. The map was ramped down to 270 kPa by just after the finish of the 1-2 shift. The tires took the shift, but soon after the completion of the 1-2 shift, the tires began to slip. They didn't blow away, just slipped 25% for about .9 sec. Stayed in the throttle through the slipping and the tires took hold on their own.
Using the driveshaft speed trace line in the datalog, I'm starting to be able to identify the wrap up of the tire on initial hit off the line. A small spike in driveshaft speed at the hit.
I'll get a shot of the datalog posted up soon.
