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01-08-2019, 11:13 PM | #1 |
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Re: Super gas/comp/Street forums?
Okay, I'll start. I like to run a lower cruise RPM for a shorter time. The thinking is I can get into high gear sooner for longer and make more MPH. Saw a couple of MPH.
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01-09-2019, 08:41 AM | #2 | |
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Re: Super gas/comp/Street forums?
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But will it effect consistency or 60 ft? Just a 1st rd Duck looking for a win. Cal SST 1177 |
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01-09-2019, 04:09 PM | #3 | |
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Re: Super gas/comp/Street forums?
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No, we go on cruise at the same time, just at a lower RPM. Because we run a lower RPM we don't have to be on the stop as long. Like anything else it depends on what the car likes. We've run it on 540 and 565 engines. I'm not sure it would work well on a small block. |
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01-09-2019, 04:57 PM | #4 |
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Re: Super gas/comp/Street forums?
I wonder about this also. If we have a car that runs SG, 9.90 @ 160ish. If the stop stall is
4200 for 3.5 seconds. How fast is the car at 4200 for the 3.5 seconds? Lets just say it's 130 mph and then gets to 160 at the finish. If the same car is 4000 rpm for 2.5 seconds. Is that car now running 125 mph. Does it get to 165? The car is at a slower speed and has more time to accelerate, but can it over come the lower rpm while on the stop to run faster at the stripe? Or, is it better to be at a faster mph on the stop and not have as much mph to gain? I have heard many discussions about this but I'm still not sure which one is better? Dan SC4698
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01-09-2019, 06:34 PM | #5 | |
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Re: Super gas/comp/Street forums?
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01-09-2019, 08:27 PM | #6 |
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Re: Super gas/comp/Street forums?
That had me confused as well. I don't remember exactly, but I believe my datalogger showed MPH on the stop at just over 60mph. And my cruise RPM is on the high side.
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01-10-2019, 09:28 AM | #7 |
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Re: Super gas/comp/Street forums?
my car with a 4.88 and 32 inch tire shows about82 mph at 4200. drop to a 4.30 would be about 93 doing the basic rpm tire diameter gear ratio calculations. ofcourse thats with no convertor slippage so its actually less
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01-10-2019, 01:49 PM | #8 | |
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Re: Super gas/comp/Street forums?
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Dan
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Dan Foley SC 4698 |
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01-10-2019, 02:16 PM | #9 | |
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Re: Super gas/comp/Street forums?
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My dragster is mechanically injected, so I go on the stop at 0.100 and shut it down to a dead idle. My cruising speed is almost a stop. I also come off the stop in Low gear. I've never run this combination wide open to the 1/4 but I only lose 2-3 MPH at the 1/8 mile when running 8.90 on the stop as compared to a wide open pass. 6.19 @ 145.86 compared to 4.69 @ 148.14. I would hazard a guess that cars running a more traditional cruise RPM and coming off the stop in High gear are down 10+ MPH at the 1/8 compared to a WOT run.
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01-09-2019, 06:31 PM | #10 | |
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Re: Super gas/comp/Street forums?
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If two identical cars go on the stop at the exact same time, the one with the lower cruise RPM should have more top end MPH. My personal guidelines are: 1. The 'stop on' time should be just high enough for the car to cut a light. 2. The cruise RPM should be set so that the car can at least clear the 60' beam while on the stop every pass in any weather conditions. There will be other things to consider in each case. Some cars may need to be WOT a little longer at the start to work the chassis properly. Some cars may come off the stop cleaner with a little higher 'stop on' RPM than absolutely necessary. I run oddball combinations in both of my cars, so I can't always use these principles but I use one of them in each car.
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