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10-19-2016, 10:46 AM | #11 | |
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Re: Launch RPM
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Permitted Manual Transmissions: 1. Tremec T5 2. Tremec T45 3. Tremec T56 4. Tremec TR3550 5. Tremec TR3650 6. Tremec TKO 7. Tremec TKO-II 8. Tremec TKO500 9. Tremec TKO600 10. Ford Getrag Last edited by weedburner; 10-19-2016 at 10:49 AM. |
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10-19-2016, 11:17 AM | #12 | |
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Re: Launch RPM
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1- less aggressive disc 2- smaller diameter disc or reduce the effective diameter of the disc you have 3- reduce clamp pressure by either swapping to a weaker PP/spring or shimming your existing PP away from the flywheel 4- temporarily hold back some clamp pressure with your foot, basically ride the clutch out for 5-10 feet. Adding an adjustable spring loaded pedal stop can make it easier to consistently find the sweet spot in the pedal travel 5- temporarily hold back some clamp pressure with a timed mechanical device |
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10-19-2016, 11:44 AM | #13 | |
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Re: Launch RPM
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Stephen Johnson #2162 Horace Johnson #2167 SS/D 427 Ford Fairlane NHRA-IHRA |
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10-19-2016, 11:57 AM | #14 | |
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Re: Launch RPM
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• G-Force –G101A, GF4A – 2.933, 1.867, 1.333, 1.000 3.000, 1.870, 1.340, 1.000 3.173, 1.960, 1.346, 1.000 3.252, 2.009, 1.380, 1.000 3.300, 2.100, 1.406, 1.000 • Jerico –DR4 - • Liberty -LCS 5000 4-Speed** • Andrews Transmission –A431 H-Pattern 4-speed** **Contact NMRA Tech Department for permitted gear ratios |
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10-19-2016, 12:35 PM | #15 | |
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Re: Launch RPM
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On my car I keep the rpm drop to around 2000 and the clutch lockup on launch no more than 0.9 seconds. .9 seconds is too loose, and is based on the input shaft moving till the engine and input shaft rpm are the same. A general rule has been .3 to .8 on lockup. If you start getting to .3 the clutch may drag the engine down way too much and then the engine struggles to recover. This is where data acquisition is money well spent and can help you maintain clutch maintenance and performance. Sean
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Sean Marconette 84 Mustang 5060 SS/N |
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10-19-2016, 01:56 PM | #16 | |
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Re: Launch RPM
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I'm dead hooking with radials, so the clutch does all the work. It seems the longer i let the clutch slip the faster it goes, for me around 1 sec is a good compromise. I shoot for zero rpm drop but when a 500 drop is spread over a second or so, it makes little difference. Grant |
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10-19-2016, 03:32 PM | #17 |
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Re: Launch RPM
What's the ideal launch RPM? As much as your engine, chassis and tires will handle. In my case, the 2 step is set at 8400 but the one time that it failed and I left at well over 10,000 netted me the best 60' that I've ever had. Not brave enough to repeat that but you don't see Comp cars or Pro Stockers leaving at anything less than kill.
I am in agreement with most of the other comments here. Without a good slipper clutch and some form of data logger, you're pretty much twisting in the wind. The days of 40 pound flywheels and 3500 pound dead lock up clutches are gone unless you want to go slow and break parts. My flywheel and clutch assy weighs well under 20 pounds total. There are huge performance advantages in reducing flywheel & clutch diameters and weight. Jim Caughlin SS 6019 |
10-19-2016, 11:52 PM | #18 |
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Re: Launch RPM
I am not sure where you think I guessed on my information? My results are from paying attention to how my clutch performs. My tires are not slipping otherwise I would see it with the data. 60' and ET are best for my combination at the info I posted. If my clutch does not lockup before .9 it shows on the time slip.
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Sean Marconette 84 Mustang 5060 SS/N |
10-20-2016, 05:49 AM | #19 | |
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Re: Launch RPM
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James Schaechter 3163 STK |
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10-20-2016, 01:59 PM | #20 | |
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Re: Launch RPM
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When i saw .3 to lockup, that usually means the tires are getting knocked loose unless there's a ton of SLR involved. If my car locked up at .3 from 1st movement and the tires were stuck, it would suck the engine all the way down to around 1800 rpm if it didn't break something first. |
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