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Discussion Starter #1
Radial tire racers. I see most radial tire racers roll past the starting line after their burnout, then back up. What is the reason for this. I don't see slick cars doing it, just radials. Recently switched to a 275 pro, so wondering what the reason is.
 

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Personally, I think it because the "Other cool kids" do it. After speaking with M/T guys at Cecil county I went home and redid how my daughter did her burn outs and we did MUCH better. We run a 275 pro also. First burn out of the night she cleans the tire pretty good, after that, soon as it begins to smoke we are in the beams ready to rock. Tires are lasting much longer and car starting hooking 99% of the time. We rarely race on a true Radial prep surface, we do NOT race no prep, but it is some where in between. I always try to avoid a second burnout at all cost, even if we have had to wait at starting line. Every time we have done second burnout, we may as well have gone back to the trailer. Don't know if this answers your question, but it's our/my experience. I'll never run anything else.
 

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Discussion Starter #3 (Edited)
Personally, I think it because the "Other cool kids" do it. After speaking with M/T guys at Cecil county I went home and redid how my daughter did her burn outs and we did MUCH better. We run a 275 pro also. First burn out of the night she cleans the tire pretty good, after that, soon as it begins to smoke we are in the beams ready to rock. Tires are lasting much longer and car starting hooking 99% of the time. We rarely race on a true Radial prep surface, we do NOT race no prep, but it is some where in between. I always try to avoid a second burnout at all cost, even if we have had to wait at starting line. Every time we have done second burnout, we may as well have gone back to the trailer. Don't know if this answers your question, but it's our/my experience. I'll never run anything else.
So short burnout, straight into the beams? Thats pretty much what I'm doing. 5 passes on the radial. Very inconsistent. Two passes it stuck, 1.31-1.32 60'. 3 passes, blew the tire off at the hit. Still making shock adjustments/4 link adjustments. Heading to a rental on Friday. Just trying to eliminate any bad things the driver may be doing.
 

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Good question. I was wondering if they were trying to pick up some "glue" off the prepped surface or if it leaves any rubber on the track when rolling after burnout.
 

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So short burnout, straight into the beams? Thats pretty much what I'm doing. 5 passes on the radial. Very inconsistent. Two passes it stuck, 1.31-1.32 60'. 3 passes, blew the tire off at the hit. Still making shock adjustments/4 link adjustments. Heading to a rental on Friday. Just trying to eliminate any bad things the driver may be doing.
Where does the car break the tires loose?

My experience with my car is it's really not that sensitive to shock settings as it is to power management.
 

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Discussion Starter #6 (Edited)
At the release of the button. Last time out only got 2 passes. Greg sure he got too aggressive with the tune up after pass one, since it left so good. He made some changes, but we never got another pass in. That tune up will be the first hit this time. Plus, we have lowered the upper bar one hole on the chassis side, to slow the rate of separation at the hit. We will still get the same overall separation, but it will be applied slightly slower. We're also going to tie the front down a little tighter as well. This is the pass it stuck. Hmmm its loaded but doesn't show.... strange



 

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At the release of the button. Last time out only got 2 passes. Greg sure he got too aggressive with the tune up after pass one, since it left so good. He made some changes, but we never got another pass in. That tune up will be the first hit this time. Plus, we have lowered the upper bar one hole on the chassis side, to slow the rate of separation at the hit. We will still get the same overall separation, but it will be applied slightly slower. We're also going to tie the front down a little tighter as well. This is the pass it stuck. Hmmm its loaded but doesn't show.... strange

"At the release of the button." You're turbo right?

Power management. The first thing I would do is leave with less boost or retard the timing. Then work on how fast you can bring the boost and/or timing in.
 

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Discussion Starter #8 (Edited)
"At the release of the button." You're turbo right?

Power management. The first thing I would do is leave with less boost or retard the timing. Then work on how fast you can bring the boost and/or timing in.
Greg thinks he has approx 100hp pulled out through timing, that he is ramping back in. Try this. You can see the lf wheel come up about 20' out

https://i.imgur.com/Bblx3qY.mp4
 

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It looks like you aren't getting enough front end rise and rear separation but I can't see real details with that video.

Here's my standard comment:

Videos by someone standing near the starting line are hard to analyse. I recommend to everyone trying to figure out their car to stick a go-pro on the rear quarter so you can see the rear tire and fender plus the front end. One video and you can easily see what the chassis is doing. It's much easier than trying to watch the car's suspension from a distance while it is moving.

I have one of my car and it's easy to see everything happening. The video is on my home computer back in the states otherwise I would post it as an example.
 

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And regarding power management here's a personal experience/observation. A 60ft time is affected very little by how much power you have when you release the button - as long as you plant the tires hard without shocking them. After you release the button, how fast you bring the power in without breaking the tire lose will determine your 60ft.

My "standard" hard leave is 7-8lbs boost, 3800 rpm, then my ECU commands full boost at .01 second so the wastegates get slammed shut and the boost builds as fast as possible. This will give me a 1.22-1.25 short time on a good track. I could do some things to improve this but this helps my OEM planetaries live. On a questionable track I will leave with less boost and build a time/boost ramp that is less aggressive.

Simplified - Don't be aggressive with the power available when you release the TB button, but immediately after you release it be aggressive as possible.

When I drove my car across the country I made no more than 2 passes at each track so I didn't have the luxury of test passes. I had to do a conservative "minimum" burnout so the tires would last until my planned stop to change them. Most tracks I was able to hook pretty much 100%, run a mid 1.3 short time and still run 8 seconds or low 9 seconds without using all of the boost I have available. The times I didn't hook 100% happened approximately 30-60ft downtrack and I was able to recover without aborting the run.

One more note. Driving from track to track I would loosen the extension and rebound on all 4 shocks. A couple of times at tracks I completely forgot to change them back to the "track" setting and the car still hooked and got down the track. I only found out I "forgot" when I went to reset them at the end of the night. My conclusion from this is if your suspension is set up to work well, it's less sensitive to the shock settings.
 

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Discussion Starter #11
Good info. Thanks for all the insight. Hopefully Friday is a good day.
 

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PM sent to OP.
 

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Discussion Starter #14
Any results from Friday?
From my post in Chassis and suspension:

Just an update on this. I gave it one more kick at the can, as Greg was sure we could get the car to work on a radial. We took the car to Lapeer dragway to a private track rental. It was 88* and high humidity. Track prep was average radial at best. So a typical radial plot is about 10 up and 41 out. I can't get enough lower bar angle to get there. So Greg Powrie (he tunes the car for me, and is a super smart radial guy) had me lower the upper 4 link bars one hole on the chassis side. Also, he had me tighten the front down another 5 clicks, to stop the upward movement of the front end. As well, while I was making the bar change, I took a harder look at how I had the rear shocks adjusted. Its a street car first and foremost, so I was running the shocks in the middle point of total travel. I believe I was running out of shock travel, and unloading the rear suspension. So I flipped my shock mounts, and only left 1" of shaft showing at ride height, leaving me 4" of extension travel. We made 6 hits at Lapeer on Friday, with less that stellar prep. Car went down the track every pass, and actually rattled the tires on the 3rd, and 5th passes. 3rd pass was not enough compression in the rear shocks. As the car was hooking, Greg started adding power back in while I was on the trans brake, and we rattled the tires. Added 5 clicks (Afco Big Gun DA's all around) and made the same hit again, and went right down without issue. Greg continued adding power (I had always left on 9.6 psi) and the car kept taking it. I rattled them again on the 5th pass, as I didn't leave on full boost, so we under powered it. My last pass had me leaving on 11 psi, and almost all of the timing retard pulled out of it, and it hooked a booked. I would say we got it figured out. The timimng system had some issues (didn't get a slipon first two passes, and suspect the lights aren't correctly located, and Greg believes the car was 60' much quicker than the slips we did get, showed. We do have one slip that has the car 60' 1.28, which is the quickest its ever 60', slick, or radial. Greg thicks it was more like a 1.25 60'. I asked Greg at the end of the day (I don't know if you know him, but he lives in flip flops) what he thought of the track prep, and his response was, "I didn't lose my flip flops". So he pegged it as average radial prep, at best. Now, if the driver would hit his shift points, that would be great! Thanks again for all the knowledge that many of you guys share. Its much appreciated.
 

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Radial tire racers. I see most radial tire racers roll past the starting line after their burnout, then back up. What is the reason for this. I don't see slick cars doing it, just radials. Recently switched to a 275 pro, so wondering what the reason is.

Should be instant DQ during Eliminations.....
 

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Why? Does it hurt the next guy, or just help that guy

At most tracks I race, bracket style, that is the rule, unless you have a dragster with no front brakes. Obviously they can't stop before the line and have to do a full burn out past the line.

For the guy that has to wait for every John Force type out there that has a car with full front brakes, why do you feel it should be ok? It just delays the proceedings and makes the other guy wait for you, maybe even over heating his engine or his clutch....Tracks want cars to get through the lanes, and get the next class up and through as well. If they let everyone do this, it would take forever...Just DQ the guy that can't figure it out, and we move on.
 

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From my post in Chassis and suspension:

Just an update on this. I gave it one more kick at the can, as Greg was sure we could get the car to work on a radial. We took the car to Lapeer dragway to a private track rental. It was 88* and high humidity. Track prep was average radial at best. So a typical radial plot is about 10 up and 41 out. I can't get enough lower bar angle to get there. So Greg Powrie (he tunes the car for me, and is a super smart radial guy) had me lower the upper 4 link bars one hole on the chassis side. Also, he had me tighten the front down another 5 clicks, to stop the upward movement of the front end. As well, while I was making the bar change, I took a harder look at how I had the rear shocks adjusted. Its a street car first and foremost, so I was running the shocks in the middle point of total travel. I believe I was running out of shock travel, and unloading the rear suspension. So I flipped my shock mounts, and only left 1" of shaft showing at ride height, leaving me 4" of extension travel. We made 6 hits at Lapeer on Friday, with less that stellar prep. Car went down the track every pass, and actually rattled the tires on the 3rd, and 5th passes. 3rd pass was not enough compression in the rear shocks. As the car was hooking, Greg started adding power back in while I was on the trans brake, and we rattled the tires. Added 5 clicks (Afco Big Gun DA's all around) and made the same hit again, and went right down without issue. Greg continued adding power (I had always left on 9.6 psi) and the car kept taking it. I rattled them again on the 5th pass, as I didn't leave on full boost, so we under powered it. My last pass had me leaving on 11 psi, and almost all of the timing retard pulled out of it, and it hooked a booked. I would say we got it figured out. The timimng system had some issues (didn't get a slipon first two passes, and suspect the lights aren't correctly located, and Greg believes the car was 60' much quicker than the slips we did get, showed. We do have one slip that has the car 60' 1.28, which is the quickest its ever 60', slick, or radial. Greg thicks it was more like a 1.25 60'. I asked Greg at the end of the day (I don't know if you know him, but he lives in flip flops) what he thought of the track prep, and his response was, "I didn't lose my flip flops". So he pegged it as average radial prep, at best. Now, if the driver would hit his shift points, that would be great! Thanks again for all the knowledge that many of you guys share. Its much appreciated.
Thanks for the post. Good info in here about your strategy in tuning the chassis at the track. I'm just getting ready to work on my 60' and this gives me at least some idea of where to make changes.
 
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