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Author Topic: What is the difference between Speed Week and the World Finals?  (Read 5605 times)
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Seldom Seen Slim
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Nancy -- 201.913 mph record on a production ZX15!


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« Reply #15 on: September 22, 2016, 08:05:30 AM »

Johnnie said:  "...Blown motors change the whole ball game."

They sure do.  Ask SteveM or Fireman Jim.  evil

Oh - you didn't mean "blown", you meant "blown".  Now I got it.  Sorry, Johnnie -- it must've your brogue.

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Jon E. Wennerberg
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Stainless1
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« Reply #16 on: September 22, 2016, 08:06:46 AM »

Well I would have to say if you maintain the same A/F ratio that you would go faster in denser air with your NA engine.  Midget, do you have AFR to go with your chart?  
Our experience with the lakester, Pork Pie driving, was 199.6 in the high Density Altitude of speedweek at 13:1 and 205 at the same AFR with 3500 feet lower DA.  More air means you can burn more fuel and get more power.
As always your mileage may vary, but we always do better with NA engines in October.
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Stainless
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MSA Bockscar Lakester #1000 my fastest mile 245 and change, 84 ci turbobusa motor... but Corey's 233 MPH H/BFL record is still 3MPH faster than mine.
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« Reply #17 on: September 22, 2016, 08:59:44 AM »

Johnnie said:  "...Blown motors change the whole ball game."

They sure do.  Ask SteveM or Fireman Jim.  evil

Oh - you didn't mean "blown", you meant "blown".  Now I got it.  Sorry, Johnnie -- it must've your brogue.



Jon, AKA SSS,

Sounds to me like your anxious for the first cold front to hit your area.

Rouse
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Seldom Seen Slim
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« Reply #18 on: September 22, 2016, 09:09:23 AM »

Johnnie, I could read that wrong and say "NAH - Nancy wears warm sweaters" in response, but somehow I don't think that's the line of thought you were following. rolleyes
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Jon E. Wennerberg
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« Reply #19 on: September 22, 2016, 09:12:27 AM »

Well I would have to say if you maintain the same A/F ratio that you would go faster in denser air with your NA engine.  Midget, do you have AFR to go with your chart?  
Our experience with the lakester, Pork Pie driving, was 199.6 in the high Density Altitude of speedweek at 13:1 and 205 at the same AFR with 3500 feet lower DA.  More air means you can burn more fuel and get more power.
As always your mileage may vary, but we always do better with NA engines in October.

As slick as the Boxcar is, that doesn't surprise.  

Bob, I think in your case, the lines between aero drag and power output with respect to air density cross at a somewhat higher point on the Graf . . . er, ehh, graph.

We were running a DCOE Weber, and my oxygen sensor gauge was nothing more than a flashing disco light, with readings I did not trust and will not quote.  Plugs read clean, despite 3 jet changes during the runs.
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« Reply #20 on: September 22, 2016, 12:42:46 PM »

I don't even know how you get in that itty-bitty thing -- let alone change jets during the runs.
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« Reply #21 on: September 22, 2016, 01:57:13 PM »

I don't even know how you get in that itty-bitty thing -- let alone change jets during the runs.

He has a tiny riding mechanic?



Mike
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Mike Kelly - PROUD owner of the V4F that powered the #1931 VGC to a 82.803 mph record in 2008!
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« Reply #22 on: September 22, 2016, 04:20:51 PM »

Well, I may have to take issue with Chris’ graph in reply #9.  As presented it seems to show an uncanny correlation between the speed and density altitude.  However, when you look at the numbers and make a more valid graphical comparison, the correlation seems much less emphatic (see worksheet below).  Plus, there were apparently jet changes involved, morning/afternoon changes in the salt surface, wind, etc. etc.  And, does anybody know just how the density altitude printed on the time slips is arrived at?  Does SCTA calculate that on their own as a site specific value, and if so how do they do it.  Or do they just repeat a value obtained on-line, like Wendover airport or Weather bureau numbers.  Some of the simpler calculation methods (incorrectly) do not include the effect of humidity e.g. Weather Bureau. 
So, with only about a 3% variation in velocity for a 20% variation in an ill-defined DA, and a number of other unsubstantiated variables, concluding that there is a speed/DA correlation of some sort would seem to be unjustified on the basis of this data set or any other such loosely supported numbers.

* DA.XLS (30.77 KB - downloaded 49 times.)
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« Reply #23 on: September 22, 2016, 04:29:11 PM »

. . . concluding that there is a speed/DA correlation of some sort would seem to be unjustified on the basis of this data set or any other such loosely supported numbers.

What he said. Furthermore, the other unaddressed issue is gearing. Unless you regear the vehicle, or use a CVT, either the high density or low density situation will be geared more suitably.
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« Reply #24 on: September 22, 2016, 05:27:47 PM »

Ya know, the correlation might depend a whole lot on the configuration of the vehicle.  What's shown on a brick would not apply to Costella.  That alone could be the most relative factor.

Get the slide rules out -- or just change pills.
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« Reply #25 on: September 22, 2016, 06:32:13 PM »

Ya know, the correlation might depend a whole lot on the configuration of the vehicle.  What's shown on a brick would not apply to Costella.  That alone could be the most relative factor.

Get the slide rules out -- or just change pills.

I agree Stan
On nebulous theorem 2 with a turbo we would always go faster when the DA was high. Record return runs were always slower unless I tuned it up
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« Reply #26 on: September 22, 2016, 06:40:02 PM »

Well, I may have to take issue with Chris’ graph in reply #9.  As presented it seems to show an uncanny correlation between the speed and density altitude.  However, when you look at the numbers and make a more valid graphical comparison, the correlation seems much less emphatic (see worksheet below).  Plus, there were apparently jet changes involved, morning/afternoon changes in the salt surface, wind, etc. etc.  And, does anybody know just how the density altitude printed on the time slips is arrived at?  Does SCTA calculate that on their own as a site specific value, and if so how do they do it.  Or do they just repeat a value obtained on-line, like Wendover airport or Weather bureau numbers.  Some of the simpler calculation methods (incorrectly) do not include the effect of humidity e.g. Weather Bureau. 
So, with only about a 3% variation in velocity for a 20% variation in an ill-defined DA, and a number of other unsubstantiated variables, concluding that there is a speed/DA correlation of some sort would seem to be unjustified on the basis of this data set or any other such loosely supported numbers.


A fair and valid critique.  My understanding is that the DA is calculated at the timing shack in real time - likely 3 1/2 miles from the end of the run, and collected at the time the run was made.  I'm also assuming it's accurate - it may not be.

Track conditions, wind speed, driver error, engine temp, jet sizes, tire pressure - none of this is taken into consideration.

I'm thinking I'd like to check out some other timing slips from multiple runs of naturally aspirated, aerodynamically challenged cars.  If we compare only the speed to DA in a larger pool of data, we may well spot a trend or a coincidence, and STILL walk away not completely sure!   

 
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"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  rolleyes

We are NOT rebuilding . . . We are reloading.

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« Reply #27 on: September 22, 2016, 10:23:03 PM »

Quote
If we compare only the speed to DA in a larger pool of data, we may well spot a trend or a coincidence, and STILL walk away not completely sure!   

Yep.
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« Reply #28 on: September 23, 2016, 07:01:43 AM »

Not sure if anyone noticed yesterday.  World Finals has been cancelled.
See you guys in 2017.
Thanks for the great info/feedback!
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Seldom Seen Slim
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Nancy -- 201.913 mph record on a production ZX15!


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« Reply #29 on: September 23, 2016, 07:25:03 AM »

Eric, with all due respect - you're not experienced in the way the land speed racers hang together -- yeah, we noticed that WF had been cancelled.

I got emails and phone calls from all over the country in a 15-30 minute period yesterday telling me/asking me about the cancellation.  People on the road got calls, people in Wendover sent emails and photos, and so on.

I suppose other forms of fun have their inner networks -- but boyoboy, the LSR folks sure do.

Yep, we noticed that the event had been cancelled.  Thanks for your interest and questions and please hang around here.  Thanks.
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Jon E. Wennerberg
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