What is the difference between Speed Week and the World Finals?

[Seldom Seen Slim]

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

They sure do.  Ask SteveM or Fireman Jim. 

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

[Stainless1]

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.

[rouse]

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

They sure do.  Ask SteveM or Fireman Jim. 

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

[Seldom Seen Slim]

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.

[Milwaukee Midget]

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.

[Stan Back]

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

[4-barrel Mike]

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

[Interested Observer]

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.

[tortoise]

. . . 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.

[Stan Back]

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.

[turborick]

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

[Milwaukee Midget]

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!   

[Interested Observer]

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.

[Eric_CA]

Not sure if anyone noticed yesterday.  World Finals has been cancelled.
See you guys in 2017.
Thanks for the great info/feedback!

[Seldom Seen Slim]

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.