The day of this testing, I was also entering an arm drop competition, so I had to use my transbrake creep feature (which still needs a lot of dialing in) that naturally wants to deep stage the car. Hard to get a best 60 foot with a deep stage and not enough time to get on the turbo. Mid 1.30s is very average for the car, even with a proper staging, so I'm sure a better 60 foot is waiting in the wings.Saweet! Glad you like how it feels.
I hope the rest of the tuning can better or equal your previous 60's, I think it should.
I'd still like to see what a shorter IC would do but obviously you're limited by the tire clearance. Don't pay attention to that Dave Morgan recommendation. The last time I spoke with him he had no clue what I was talking about with that program when I asked about that box.
From what I can conclude that "box" is better for a true 4link car that's really low with 14/32's, tube chassis, etc. It seems the higher the car (stock ride height) the farther back the IC works, but naturally you're doing the best thing: TESTING!
ks
8 second OEM 4 link drag race chassis setup
- Thread starter Alky V6
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It seems the higher the car (stock ride height) the farther back the IC works, but naturally you're doing the best thing: TESTING!
ks
Hijacking for a second Donnie.:biggrin: Thanks.:smile:
Would you mind explaing this statement a little better Kevin. My chasis is being modified for a better IC by lowering the UCA mount location 1" on the frame. It will probibly be close to stock ride height and the LCA location on the axle will most likely be moved up on the axle as well.
If you use the Performance Trends software the "recommended" IC length is shown as an option. But from experience I've had better luck moving the IC back farther compared to the recommendation. This software is pretty old so my guess is that the recommendation is for tube chassis cars where the CG is lower and the cars are lighter. This is my own observation from using this program but it should give an idea of where to start and others could have different results than I get depending on how they set up their car.
KS
Kevin is right. The IC suggestions given in the Performance Trends 4 link software are starting point suggestions that have been taken out of Dave Morgan's book, "Door Slammers: The Chassis Book".
As stated in Dave's book, they are in no way suggestions for a final configuration, but are only meant to be a baseline, based on the weight and performance potential of the car, to start your IC location testing. As Kevin and Dave in his book have eluded to, no two cars are going to react the same, and TESTING with your car is the only way of finding out what your particular car is going to like for an IC location.
After I work with the shocks a little, I may still go back to the IC and move it back more to see what improvement, or not, there might be. With Kevin's buckets, it will be a breeze to remove them, plug the mounting holes and drill new ones to change the IC location.
I really want to get some video so that I can see what the tires are doing relative to the body during the launch.
I checked out the track photographer's site for any pictures of the car from the last testing and there were a few that caught the car launching. The car looked pretty flat, very little roll, if any, and the front tires were off the ground an inch or so. This pretty much follows how the launch felt from inside the car. It really felt like the tires didn't lift at all, but the pictures do show some air. For a Pro Stock car, I would imagine it would be a perfect launch attitude. For mine, not so sure.
I'm not sure if I should have more lift in the front. What do you think Kevin? Would a car of my performance level and weight usually need a little more front end lift?
As stated in Dave's book, they are in no way suggestions for a final configuration, but are only meant to be a baseline, based on the weight and performance potential of the car, to start your IC location testing. As Kevin and Dave in his book have eluded to, no two cars are going to react the same, and TESTING with your car is the only way of finding out what your particular car is going to like for an IC location.
After I work with the shocks a little, I may still go back to the IC and move it back more to see what improvement, or not, there might be. With Kevin's buckets, it will be a breeze to remove them, plug the mounting holes and drill new ones to change the IC location.
I really want to get some video so that I can see what the tires are doing relative to the body during the launch.
I checked out the track photographer's site for any pictures of the car from the last testing and there were a few that caught the car launching. The car looked pretty flat, very little roll, if any, and the front tires were off the ground an inch or so. This pretty much follows how the launch felt from inside the car. It really felt like the tires didn't lift at all, but the pictures do show some air. For a Pro Stock car, I would imagine it would be a perfect launch attitude. For mine, not so sure.
I'm not sure if I should have more lift in the front. What do you think Kevin? Would a car of my performance level and weight usually need a little more front end lift?
Moving the IC back has made a very noticable difference in how much the front end is lifting at the launch. The front end feels heavier.
If by loosening the front shocks the front end still has a hard time lifting, I would have to think that moving the IC back further than it is now would not be the thing to do. I know testing is the only thing that will show what needs to happen, but is my 'if this, then' logic correct on this, Kevin?
If by loosening the front shocks the front end still has a hard time lifting, I would have to think that moving the IC back further than it is now would not be the thing to do. I know testing is the only thing that will show what needs to happen, but is my 'if this, then' logic correct on this, Kevin?
The longer the IC the more leverage the suspension has to lift the nose of the car but the less the rear tires are loaded. The less the rear tires are loaded the more they may spin so you may have to de-tune the power during the launch. Remember, you need to load the tires first in order to get the weight transfer started. If the rear tires are not loaded then they spin. So the more you load them the more power you can apply and still get traction, this is a big simplification so don't take this literally. Once the car gets traction then the weight transfter starts and the lose lifts up. This is why it would be interesting to see what a shorter IC would allow you to do, possibly launching it harder.
More travel will allow more weight over the rear tires once the front end stops rising but if you can get the car to accelerate hard enough then minimizing the lift should get the car to move forward sooner. For cars that have the frontend tied down with little rise the LCA's point down in the front a little to help lift the nose but it all depends on how hard you can get it to leave within the first 6"-18" of the launch.
If the frontend is lifting off the ground then I would try to apply power to carry the tires as far and low as possible..being careful of course.
ks
I'm going to start some testing in the shop today with the nitrous system to improve the power through the 60 foot.
The plan is to have the system controlled by the present manifold pressure switch while staged and on the transbrake, then come back on full time at transbrake release with the manifold pressure switch control bypassed, and have the system finally time out through a delay timer. That should provide a fair test of the suspension, I think.
In the past, the nitrous system would be shut down by the manifold pressure switch (175 kPa MAP) during staging, and was not used at all through the launch and the 60 foot. This should be interesting.
The plan is to have the system controlled by the present manifold pressure switch while staged and on the transbrake, then come back on full time at transbrake release with the manifold pressure switch control bypassed, and have the system finally time out through a delay timer. That should provide a fair test of the suspension, I think.
In the past, the nitrous system would be shut down by the manifold pressure switch (175 kPa MAP) during staging, and was not used at all through the launch and the 60 foot. This should be interesting.
An interesting point about the IC length. According to Dave's suggestions on IC length relative to the cars weight and performance potential, it is suggested that the lighter the car and lower the performance potential, you will see suggested a shorter IC length. As the weight of the car goes up and the performance potential of the car increases, the suggested IC length is longer to lessen the leverage advantage and save from overloading the tires. A true balancing act.
The shorter IC length gives some leverage help in planting the rear tires in cases where there is a lack of static weight and/or axle housing torque to do the proper job of planting the tires and keeping them from spinning. So vehicle weight and engine power input are important factors when searching for the right IC length. So many variables.
The shorter IC length gives some leverage help in planting the rear tires in cases where there is a lack of static weight and/or axle housing torque to do the proper job of planting the tires and keeping them from spinning. So vehicle weight and engine power input are important factors when searching for the right IC length. So many variables.
The line lock circuit has been wired into the transbrake circuit. A diode is being used so that the line lock button cannot activate the transbrake, but the transbrake button will activate both the line lock and the transbrake. The line lock will deactivate upon release of the transbrake button. The transbrake will also deactivate upon release of the transbrake button, unless time has been entered into the delay box for the transbrake release.
Having the line lock engage with the transbrake is an effort to smooth the transbrake creep feature. Now when the transbrake enters creep function there will be some front wheel braking to slow and hopefully smooth out the creep of the car into final staging. There will need to be some balancing and dialing in of the TB creep pulse width setting and the delay relay time setting.
For the next testing session I lowered the pw setting a tad and raised the delay relay time setting from .25 sec. to .35 sec. We'll see what that does and adjust from there.
The amount of brake pressure that will be used will be the amount needed to hold the car still at an idle. In the future it may be necessary to install a brake pressure gauge so that different brake pressures can be experimented with.
Having the line lock engage with the transbrake is an effort to smooth the transbrake creep feature. Now when the transbrake enters creep function there will be some front wheel braking to slow and hopefully smooth out the creep of the car into final staging. There will need to be some balancing and dialing in of the TB creep pulse width setting and the delay relay time setting.
For the next testing session I lowered the pw setting a tad and raised the delay relay time setting from .25 sec. to .35 sec. We'll see what that does and adjust from there.
The amount of brake pressure that will be used will be the amount needed to hold the car still at an idle. In the future it may be necessary to install a brake pressure gauge so that different brake pressures can be experimented with.
I've decided to not wait and go ahead and install a brake pressure gauge and another roll control solenoid for the rear brakes. Both the new rear roll control solenoid and the present front brakes line lock solenoid will be energized with the transbrake switch to help control transbrake creep function.
Took her to the track last night. VERY INTERESTING! Yippee!!!
Details coming up after I can digest the datalogs a little.
The nitrous activation after transbrake release was moved from .6 sec of on time to .500 sec of on time. Half a second on time is just about right. .6 sec presented a traction issue. :biggrin:
Using the brakes to tame down the transbrake creep worked beautifully. By the last run, I got the parameters dialed in closer and I was impressed with how the car gently bumped into final staging. When I saw the second staging bulb come on solid and the car didn't deep stage on me, I had to sit there for a second and just admire it. Very cool.
Details coming up after I can digest the datalogs a little.
The nitrous activation after transbrake release was moved from .6 sec of on time to .500 sec of on time. Half a second on time is just about right. .6 sec presented a traction issue. :biggrin:
Using the brakes to tame down the transbrake creep worked beautifully. By the last run, I got the parameters dialed in closer and I was impressed with how the car gently bumped into final staging. When I saw the second staging bulb come on solid and the car didn't deep stage on me, I had to sit there for a second and just admire it. Very cool.
The time delay relay setting was pushed back to .25 sec from the .35 that I wanted to try. .35 sec was just too long and it deep staged the car.
The .25 sec time along with using roll control with both the front and rear brakes worked real well to smooth out the creep into final staging and took care of the rocking of the car once the car had finished staging. That was accomplished with using a reading of around 300 psi on the brake pressure gauge. I can't remember an exact brake pressure number. I know I recalled making sure that I used more brake pressure on this run compared to the last attempts. I can't wait to get to the track and play with it more. I'm going to try .2 or .225 sec on the delay timer next time to see if I can get a shallower stage and improve the 60' time.
The best 60' time of the night happened at around 10:00 pm with a cool track temperature. It was cold enough that dew was collecting on the cars. The 60' was 1.34.
I'll be loosening the front shock rebound setting more, the next time out. The rear shock rebound was at full soft for this last tuning session. I have no video, but the car launch seemed very tame. She just pulled straight out. No drama. Straight as an arrow. I got more comments about how well it seemed the car was setup lately. I did get the sense that the front tires lifted, but it wasn't much. Just a straight and flat pull out. Definitely a different style of launch for me. Got to get some video.
The details on the engine power through the launch to come up next with pics of datalog details. WOW is all I can say.
The boost controller settings were left the same as the last time out with the car when I was trying to dial the car in for a 6.00 index race event. I was doing 6.03-6.08 with that setting. I did tame down the aux launch setting (BOV control) on the boost controller by 1.2 psi to lower the boost level at the point where the nitrous initially turns off while being staged and waiting to release the transbrake. With some fuel table changes the previous BOV setting was giving me a launch rpm and boost level of over 6200 rpm and over 220 kPa MAP. A little bit too high for both. Impressive, but not the best setting for a good launch. Backing the BOV setting even more may be in the near future. Anyway, with that past tuneup, and only the latest changes to the launch strategy, the car performed a 5.87 ET on a cold track. Max boost setting for the pass was 265 kPa MAP (about 24.5 psi boost).
The .25 sec time along with using roll control with both the front and rear brakes worked real well to smooth out the creep into final staging and took care of the rocking of the car once the car had finished staging. That was accomplished with using a reading of around 300 psi on the brake pressure gauge. I can't remember an exact brake pressure number. I know I recalled making sure that I used more brake pressure on this run compared to the last attempts. I can't wait to get to the track and play with it more. I'm going to try .2 or .225 sec on the delay timer next time to see if I can get a shallower stage and improve the 60' time.
The best 60' time of the night happened at around 10:00 pm with a cool track temperature. It was cold enough that dew was collecting on the cars. The 60' was 1.34.
I'll be loosening the front shock rebound setting more, the next time out. The rear shock rebound was at full soft for this last tuning session. I have no video, but the car launch seemed very tame. She just pulled straight out. No drama. Straight as an arrow. I got more comments about how well it seemed the car was setup lately. I did get the sense that the front tires lifted, but it wasn't much. Just a straight and flat pull out. Definitely a different style of launch for me. Got to get some video.
The details on the engine power through the launch to come up next with pics of datalog details. WOW is all I can say.
The boost controller settings were left the same as the last time out with the car when I was trying to dial the car in for a 6.00 index race event. I was doing 6.03-6.08 with that setting. I did tame down the aux launch setting (BOV control) on the boost controller by 1.2 psi to lower the boost level at the point where the nitrous initially turns off while being staged and waiting to release the transbrake. With some fuel table changes the previous BOV setting was giving me a launch rpm and boost level of over 6200 rpm and over 220 kPa MAP. A little bit too high for both. Impressive, but not the best setting for a good launch. Backing the BOV setting even more may be in the near future. Anyway, with that past tuneup, and only the latest changes to the launch strategy, the car performed a 5.87 ET on a cold track. Max boost setting for the pass was 265 kPa MAP (about 24.5 psi boost).
This was the first run with the nitrous timer set at .600 sec after transbrake release. The nitrous would turn on at the release of the transbrake, and would turn off after .600 of a second.
We now have a situation where there is more than enough power on tap to blow the tires away at the launch. A first for this engine/turbo combination.
We now have a situation where there is more than enough power on tap to blow the tires away at the launch. A first for this engine/turbo combination.
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This was the next run with the nitrous timer changed to turn the nitrous off .500 of a second after transbrake release. The tire slip was much more manageable on this run.
It may be time to take some gear out of the car to tame down the torque getting to the ground at the launch.
There are also starting to be signs that the torque converter can stand to be tightened up without adversely affecting the launch.
It may be time to take some gear out of the car to tame down the torque getting to the ground at the launch.
There are also starting to be signs that the torque converter can stand to be tightened up without adversely affecting the launch.
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It's interesting to see how the engine rpm reacts when the nitrous is shut off and the timing is ramped back in. Controlling timing retard while on the nitrous is very effective at controlling the power level. Engine rpm, anyway. Timing retard while on the nitrous does nothing to control the MAP. MAP will continue to climb even though increasing amounts of timing retard will control the rpm rise.
Looking at the first datalog, during the second activation of the nitrous at the launch, you can see how the rpm ramps up at first, and then with increasing timing retard, the engine rpm noses over and begins to actually fall. All the while, the MAP maintains a very steep climb, until the nitrous is shut down and the timing begins to ramp back in. The engine rpm then sharply rises to a level where it stabilizes for the rest of first gear. It turns out that the timing retard was coming in at about the right time to do a very effective job of controlling wheel spin that was developing at the beginning of the launch. This was all accidental. I am presently not using any form of traction control with the timing. It was only a function of my base timing table where the timing is lessened as the MAP rises. The amount of nitrous retard is a static amount used whenever the nitrous is activated.
Looking at the first datalog, during the second activation of the nitrous at the launch, you can see how the rpm ramps up at first, and then with increasing timing retard, the engine rpm noses over and begins to actually fall. All the while, the MAP maintains a very steep climb, until the nitrous is shut down and the timing begins to ramp back in. The engine rpm then sharply rises to a level where it stabilizes for the rest of first gear. It turns out that the timing retard was coming in at about the right time to do a very effective job of controlling wheel spin that was developing at the beginning of the launch. This was all accidental. I am presently not using any form of traction control with the timing. It was only a function of my base timing table where the timing is lessened as the MAP rises. The amount of nitrous retard is a static amount used whenever the nitrous is activated.
After studying the 2nd datalog, I may lessen the delay timer just a tad more to smooth out the rpm climb at the launch. I'd like to eliminate the point where the rpm begins to drop just before the nitrous is deactivated. Attempt to keep the rpm on a rise with no dropping. Lessening the time while on the nitrous during the launch will also help control the peak level of the boost spike that is very closely tied to the nitrous activation time duration.
