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Post by Crossbones Dennis on Jan 4, 2011 10:56:05 GMT -6
There is an article in the back of National Dragster with the same title. It says never do a burnout against the rev limiter. Engines that have been ran that way show excessive wear. Here's the article northwestvets.com/blog2/ |
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Post by 358t on Jan 28, 2011 19:47:30 GMT -6
My experience with this... In 2007 we used a rev limitor (set at 7k) in the burnout. My burnouts are typically 3-5 seconds long. At the end of the year when we took the engine apart for inspection it didn't have any more wear than all of the other years that we didn't use a rev limiter.
I do totally agree about lifting before tire shake sets in though... had my bell rung a few times. Not to mention it will destroy parts in a hurry.
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Post by W333 on Jan 28, 2011 20:36:10 GMT -6
Scott, you say we used a rev limiter. You don't use one now? Mine is set at 7000 and seems to work fine. I will also agree about tire shake. If you have to stop and think to yourself, " have I ever had tire shake", then no you haven't experienced it. You will know!!
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Post by 358t on Jan 28, 2011 23:59:08 GMT -6
Scott, you say we used a rev limiter. You don't use one now? No, just a high side limiter (8k). 2007 was the year we put our engine in Dan Boones Spitzer dragster. It had a 3-step in it so we used it. I liked it and actually think that I got more consistent burnouts with it. I've just been too lazy to put it on our current car. With the 7k burnout chip it was never close to tire shake. Without the 3-step it is easier to get into tire shake if your right foot doesn't control the rpms good enough. |
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Post by sg3526 on Jan 29, 2011 7:03:41 GMT -6
Scott, you say we used a rev limiter. You don't use one now? Mine is set at 7000 and seems to work fine. I will also agree about tire shake. If you have to stop and think to yourself, " have I ever had tire shake", then no you haven't experienced it. You will know!! I agree!! When I had my first dragster it was pull into the water mat the pedal let the car shift on its own and hang on. Used to rattle the tires so hard that it would vibrate the header gaskets out, not to mention rolling over 4 sprags in the converter. Put a 3 step in the Roadster with a 5000 chip on the burnout side and it's much better. So when I built the Dragster last year we put a 3 step on it and start the burn out in second gear and go to 6000 much smoother on the car and me... |
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Post by W333 on Jan 29, 2011 7:16:28 GMT -6
Another good point. I always start my burnouts in 2nd gear. Hold the three step button and floor it. Smooooooooth.  |
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Post by 358t on Jan 29, 2011 8:12:24 GMT -6
I shift manually in the burnout wether I'm using a 3-step or not. When not useing a 3-step I find it easier to get the rpms and tire speed up fast and then control the rpms once the burnout is started. It isn't in first gear very long... basically I shift within the first second of the burnout. When using a 3-step it wasn't about controlling the rpms but about getting up on the tire quickly. This was especially important in the hot summer months when they don't put down much water.
2007 was the only year I used a 3-step. When I first got the dragster 10+ years ago I learned how to do a burnout without one so I'm used to not having one. My torque converter flash stalls 6k and has a fallback stall of 6300 so I try to keep the rpms around 7k in the burnout. Which brings me to my point... If a person is using a 3-step and chips it at stall or very close to stall it will be a tire shaking, sprag breaking, inconsistent racecar. The rpms must be well above stall to ensure consistent tire speed and less chance of hurting things. In my opinion it is the biggest mistake I see many make... chipping too low in the burnout. I was helping a customer of KilleRONS last year who has a dragster and was having inconsistent elasped times. We had been through everything fuel related. On a whim I asked what rpm he was doing his burnout at. He said 6k which is right around his stall (he had switched to spragless years ago because of sprag problems). Anyway, had him move it to 7k and his problems went away, he picked up performance and won a race the second time out after the change. Basic rule I like to use is fallback stall +600 or more rpms.
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Post by W333 on Jan 29, 2011 9:58:13 GMT -6
Great post Scott. I agree with your views on tire speed vs converter stall. Your customer proved that making one change to his program changed his on track performance. Sometimes I get accused of over thinking things at the track, but goes to show you the devil is in the details.
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Post by sg3526 on Jan 29, 2011 12:27:55 GMT -6
I shift manually in the burnout wether I'm using a 3-step or not. When not useing a 3-step I find it easier to get the rpms and tire speed up fast and then control the rpms once the burnout is started. It isn't in first gear very long... basically I shift within the first second of the burnout. When using a 3-step it wasn't about controlling the rpms but about getting up on the tire quickly. This was especially important in the hot summer months when they don't put down much water. 2007 was the only year I used a 3-step. When I first got the dragster 10+ years ago I learned how to do a burnout without one so I'm used to not having one. My torque converter flash stalls 6k and has a fallback stall of 6300 so I try to keep the rpms around 7k in the burnout. Which brings me to my point... If a person is using a 3-step and chips it at stall or very close to stall it will be a tire shaking, sprag breaking, inconsistent racecar. The rpms must be well above stall to ensure consistent tire speed and less chance of hurting things. In my opinion it is the biggest mistake I see many make... chipping too low in the burnout. I was helping a customer of KilleRONS last year who has a dragster and was having inconsistent elasped times. We had been through everything fuel related. On a whim I asked what rpm he was doing his burnout at. He said 6k which is right around his stall (he had switched to spragless years ago because of sprag problems). Anyway, had him move it to 7k and his problems went away, he picked up performance and won a race the second time out after the change. Basic rule I like to use is fallback stall +600 or more rpms. Something I may need to look at. Car has the same motor, trans, converter, carb and weighs less than my old Dragster did but still doesn't run the number the old Dragster did. I went to a spragless in my first Dragster and also run one in the Roadster. When doing the burnout in the Roadster we usually sit in the water with the line lock set and I shift it. Once it starts to bite a little I let go of the line lock and the RPM's go to around 7500 and we come on out and usually lift before it bites real hard. Wuth the Dragster I keep that button down the whole time and only release it when I'm hit the by-pass to back the car up. Converter flashes to 6200 so there may be something to what Scott is saying. Guess we'll give it a shot in the spring time and see what happens |
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