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#21
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Engines and acceleration
On 9/12/13 8:25 AM, Mr. Luddite wrote:
"iBoaterer" wrote in message ... In article , "Mr. Luddite" says... "amdx" wrote in message ... On 9/11/2013 1:53 PM, iBoaterer wrote: In article , says... On 9/10/2013 5:56 PM, Mr. Luddite wrote: Since boats have engines and for a change of pace, I thought I'd share some info I recently received from a car nut. He's talking about a custom built, 500 cubic inch dragster engine based on the Chrysler 426 c.i. hemi design. Here's a short list of it's specs and acceleration capabilities: Produces 8,000 horsepower. That's more than the first 4 rows of cars at NASCAR's Daytona 500. Consumes 11.2 gallons of nitro methane per second at full throttle. Dual magnetos supply 44 amps to each spark plug. Capable of reaching over 300 MPH +... before you have completed reading this sentence. Redlines at 9,500 RPM ... only does 540 revolutions light to light in the quarter mile. I want to quibble with the 540 engine revolutions for 1/4 mile. But, the numbers tell the story. Average drag tire is 30" tall, for a circumference of 94" or 7'10". 1/4 mile is 1320ft. 1320 ft / 7'10" equals 168.5 wheel rev's down the track. Assuming a final ratio of 3 to 1 (motor to wheel) 3 times 168.5 = 505 revolutions per 1/4 mile. (does not include wheel spin. Damn! Mikek Fun Fact. When I was kid my grandmother lived 7 miles from Martin Dragway, On Saturday nights we could hear the dragsters run the 1/4 mile from her house 7 miles away. Yeah, 540 revs is not correct. Could you back that up? I just showed you my numbers, were do you think I went wrong? I didn't think his number was right either, then I did the math. Mikek ---------------------- iBoaterer just wants to argue about a difference of 35 rpms. Could be due to wheel slip, could be that they used slightly different gear ratios ... could be that the driver didn't keep it in perfect alignment ... whatever. The point of the original post was that the engine turns surprisingly few rpms in a quarter mile because of the phenomenal acceleration. At a redline of 9500 RPM's that is 158.3333 per second. 4.5 times that (the time it takes to go a quarter mile) is 712.5. And that is not including wheel spin, which by the way in a top fuel dragster is nearly the whole run, and you could easily double that. --------------------------- Again, you assume the entire quarter mile is run with the engine at red line. Remember when Hertz had those Shelby Mustangs for rent, and guys would rent them out over the weekend and take them out to run on the drag strip? |
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#23
posted to rec.boats
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Engines and acceleration
On 9/12/2013 7:42 PM, BAR wrote:
In article , says... On 9/12/13 8:25 AM, Mr. Luddite wrote: "iBoaterer" wrote in message ... In article , "Mr. Luddite" says... "amdx" wrote in message ... On 9/11/2013 1:53 PM, iBoaterer wrote: In article , says... On 9/10/2013 5:56 PM, Mr. Luddite wrote: Since boats have engines and for a change of pace, I thought I'd share some info I recently received from a car nut. He's talking about a custom built, 500 cubic inch dragster engine based on the Chrysler 426 c.i. hemi design. Here's a short list of it's specs and acceleration capabilities: Produces 8,000 horsepower. That's more than the first 4 rows of cars at NASCAR's Daytona 500. Consumes 11.2 gallons of nitro methane per second at full throttle. Dual magnetos supply 44 amps to each spark plug. Capable of reaching over 300 MPH +... before you have completed reading this sentence. Redlines at 9,500 RPM ... only does 540 revolutions light to light in the quarter mile. I want to quibble with the 540 engine revolutions for 1/4 mile. But, the numbers tell the story. Average drag tire is 30" tall, for a circumference of 94" or 7'10". 1/4 mile is 1320ft. 1320 ft / 7'10" equals 168.5 wheel rev's down the track. Assuming a final ratio of 3 to 1 (motor to wheel) 3 times 168.5 = 505 revolutions per 1/4 mile. (does not include wheel spin. Damn! Mikek Fun Fact. When I was kid my grandmother lived 7 miles from Martin Dragway, On Saturday nights we could hear the dragsters run the 1/4 mile from her house 7 miles away. Yeah, 540 revs is not correct. Could you back that up? I just showed you my numbers, were do you think I went wrong? I didn't think his number was right either, then I did the math. Mikek ---------------------- iBoaterer just wants to argue about a difference of 35 rpms. Could be due to wheel slip, could be that they used slightly different gear ratios ... could be that the driver didn't keep it in perfect alignment ... whatever. The point of the original post was that the engine turns surprisingly few rpms in a quarter mile because of the phenomenal acceleration. At a redline of 9500 RPM's that is 158.3333 per second. 4.5 times that (the time it takes to go a quarter mile) is 712.5. And that is not including wheel spin, which by the way in a top fuel dragster is nearly the whole run, and you could easily double that. --------------------------- Again, you assume the entire quarter mile is run with the engine at red line. Remember when Hertz had those Shelby Mustangs for rent, and guys would rent them out over the weekend and take them out to run on the drag strip? They used to do that here at CT Dragway. Avis caught on and liquidated their fleet. One of the GearHeads in town (just up the street) bought one for his little sister, for her 16 Bday.. It was a beautiful car... There is no such thing as a speed bump in a rental car. |
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