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I know there is no set formula and conditions very, However I was wonder what the pro's on here had for rough numbers as to 20 HP gain on an asphalt sled = 0.10 of a second gain????. (Example only)

Or a 200 HP sled should be maybe mid 9 second and 250 HP should be 8.80????

Anyone have any rough calculations???

Thanks in Advance
 

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Only from what I have run or friends run:
Times from good traction tracks as well.
PS800 214hp - ran 9.1's at 625lbs w/1.28 60ft
PS1000 245hp - 8.7's at 650lbs w/1.24 60ft
PS1000 280hp - 8.2's at 650lbs w/1.14 60ft

200hp will get you in the mid 9's with decent 60fts and sled dialed in decent but so many scenarios hard to say based off hp.
 

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Only from what I have run or friends run:
Times from good traction tracks as well.
PS800 214hp - ran 9.1's at 625lbs w/1.28 60ft
PS1000 245hp - 8.7's at 650lbs w/1.24 60ft
PS1000 280hp - 8.2's at 650lbs w/1.14 60ft

200hp will get you in the mid 9's with decent 60fts and sled dialed in decent but so many scenarios hard to say based off hp.
that is one hell of a 60 footer on the ps1000 whose sled was that paul austins? not many have been there

you also have to add weight as a factor to determining et which in your case you used as an example

ptm
 

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I have two sleds, both weight 680 lbs. with rider, both have the old 15" wide 121" tracks, and both have cheap "home made" rear skids. One is a 800 twin @ 145 HP and runs in the 11.10 range and the other is a 809 tripple @ 171 HP that runs in the 10.80's.

Just by looking at my sleds and one bad 800s post, a 10 HP gain is Maybe/almost a 0.10 second gain???.
(Of course there is a other factors and I'm sure 10 Hp on a 280 HP motor running low 8's won't pick up a tenth)

I'm hard pressed to cut a 1.4 second 60', Also at my local track the finish line is almost 9 feet higher in elevation than the start line.
 

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that is one hell of a 60 footer on the ps1000 whose sled was that paul austins? not many have been there

you also have to add weight as a factor to determining et which in your case you used as an example

ptm
Stan, my guess would be Louie Wirbels sled. It ran 8.289 @153 mph at martin speedway last year, I saw it myself.
 

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Those calculators work fairly well but you have to remember to use total weight (sled + rider) and some rendition of TRACK horsepower. The change in horsepower (you have to use the same reduction factor as track horsepower) will give you an idea of what your ET and MPH will change. For instance, a 20 HP change at the engine may only be 12 HP at the track.
 

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I tried the calculator and its not even close I know the track hp and the sled weights for all my sleds and I even tried motor hp? Not sure.
 

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I tried the calculator and its not even close I know the track hp and the sled weights for all my sleds and I even tried motor hp? Not sure.
I have treid many calculators and used my own sled as well and agree cant get it close. Stone seems to have a formula he uses which appears to be close but he would have to post it not sure he will. Most calculators are car based so not sure if that makes a difference.

ptm
 

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I tried the calculator and its not even close I know the track hp and the sled weights for all my sleds and I even tried motor hp? Not sure.
You noticed I said rendition of track horsepower. The track dynos have issues for determining actual horsepower. Using the equations, the horsepower from a track dyno tells you a sled could never run the ETs or MPHs that are calculated. The Mach Z 1000 SDI will run around 10.0 and speeds of 127 to 128 MPH. The sleds weigh 700 to 730 pounds with a rider. A track dyno usually says a good running Mach Z puts out around 90 HP at the track. If you do a little reverse calculations, the equation will tell you a Mach Z must be getting 130 -135 HP to the ground to get those ETs and MPHs.

Here are my thoughts on what is going on. Do you think a motorcycle weighing 700+ pounds with rider and only 90 HP at the rear wheel could ever run 10.0 flat at 127-128 MPH????? No way. Years ago, 520 pound motorcycles with 130-140 HP at the rear wheel were running 10 flat times and a few more MPH. Gee that is about the same horsepower that the equations spit out. This tells me that the Mach Z must be getting more than 90 horsepower to the ground and much closer to the 130 - 140 HP that is derived in the equations.

Doesn't anyone question where all of the lost horsepower goes that the track dyno alludes too??????? Lets take the Mach Z 1000 SDI. They have been shown to have 170 HP at the crankshaft and roughly 90 HP on a track dyno. That is an 80 HP loss. Where does most of this loss go?????? Turning the track and lugs???? Turning the drive belt???? Turning the clutch sheaves?????? Oh what about heat? Let's just say that half of the loss goes to heat. That would be 40 HP or about 30 kilowatts. 30 kilowatts is a lot of heat. A burner on an electric range is only 1.5 to 2.0 kilowatts. My guess would be there is not anywhere near 40 HP being lost to heat.

Don't get me wrong. A track dyno is an excellent tuning device and does have repeatable results but the output is very questionable.
 

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Like already mentioned that formula is more for cars, My personal feeling is that the calculator gives a higher MPH number because cars have a different transmission.... At our local track the bikes always have faster MPH times than the sleds that run similar E.T.

It's still good to see links like that one.

Good work.
 

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Kind of gives you an idea of how much gets to the ground. Clutching , chassis & skid losses.
I personally dont think you can use a calculator because of all the different factors that effect a run. I was starting to believe it and think you can generalzie based on the time one has spent at a track but because of so many loses to the track from the engine how can it be accurate especially as technology advances.

For fun I used the other calculator you posted and when putting in the factors there it said the sled was 175 hp so I am getting better hahahaha now all i need is one to get my sled down to a 8.5 or something hahahaha

ptm
 

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Like already mentioned that formula is more for cars, My personal feeling is that the calculator gives a higher MPH number because cars have a different transmission.... At our local track the bikes always have faster MPH times than the sleds that run similar E.T.

It's still good to see links like that one.

Good work.
The bikes usually have more horsepower but less traction, hence the similar ETs but higher MPH.

TGR

Amazing!
 

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I personally dont think you cna use a calculator to many different factors. i was starting to believe it but I used the other calculator you posted and when putting in the factors there it said the sled was 175 hp. I fully understand lots is beign lost to the ground but I still dont think there is a calculator one can use for a sled and be accurate.

ptm
Agreed.
 
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