Traction vs. salt?

[Blue]

Sorry if this has been discussed before;

What is the range of traction at Elmo (typical dry lake) compared to the range of traction at Bonneville?

I realize that conditions vary widely, please state as much data as you can and all of the conditions that you can:

recent rain, wet salt, dry salt, chewed-up salt, course wear, etc.
recent rain, soft lake, hard lake, dry-powdery lake, course wear, etc.

I have been told that the range of traction coefficients (combination of friction coefficient and surface displacement condition:  i.e. what we actually FEEL as friction) on salt is between .50 and .40 with typical values of .41 to .45 during speed week on a prepared course.  Conditions naturally deteriorate with time on a given course due to the wheel spin that comes with everyone putting all that HP into the surface.

Many of you know me; I am completely open on this to any data, observation, opinion, or combination.

[desotoman]

Blue,

Here is a link that is very helpful. Read all the way to the bottom.

Tom G.

http://www.saltflats.com/traction.html

[bvillercr]

Just remember the section where he says unproven theory about tires.  That's just it unproven.

[jl222]

Blue... there are 6 records over 300mph at El Mirage indicating better traction as it is only a mile and one third course,
 if the traction was equal the bville speeds at the 21/4 mile would be much higher. This is assuming both courses are good.
 Of course Bville has been better than El Mirage since drought conditions.

  Hear is a run at EL mirage in the 222 camaro where the start was good with the cracks melted together for 1/3-1/2 the course

All times are after a 3-4 sec push with 10'' wide tires.

1st gear 116 mph--- 4.45 sec--- 51% throttle position

2nd 153 mph---10.05 sec--- 51% TPS

3rd--189.2---14.9 sec---59% TPS  came to marbles on track and broke loose


  Bonneville run [spin]

 1st gear--103.6 mph---7.3 sec--47% tps

 2nd--167.5 mph--- 13.2 sec---got loose when increasing throttle from 52% to 56% in .3 sec spun out and hit 1/2 mile
marker.

  Bville 268mph at the 21/4----285 mph in 1st timed mile when blower tube connector came off with 2 sec [on video] before end of 1st timed mile.

 1st gear--- 75.3 mph---8.1 sec---42% tps

 2nd--- 141.9--- mph---19.5 sec 47% tps

 3rd---217.1 mph---35.7 sec---56% tps

 4th---311.6 mph---56.9 sec---100% tps

 The bville runs were in 09 and it was a smooth good and hard course from what I remember


                         JL222
  
 

[Blue]

jl, thank you.  Do you remember the specific surface conditions before and during the Elmo and Bonneville runs?

[Dean Los Angeles]

El Mirage is a super fine dust cemented into the lake bed. It is fine enough to go through just about everything. If the lake bed gets ANY moisture it turns into really slippery mud. When it is dry you can take a hammer to it and do less damage than the same hit on concrete. A hard hammer hit barely leaves a dent. The surface condition is generally smooth to cracked and crumbly. The condition month-to-month and year to year depends on the amount and spacing of the rain. Anybody with horsepower spins the tires and during the day the surface deteriorates from all the pounding.

I don't think the salt at Bonneville is ever dry. It is obviously wet when there is surface water. When there is no surface water you don't have to dig very far to hit water. I believe the racing surface is somewhat plastic and deforms from the vehicle weight and traction.

[jl222]

jl, thank you.  Do you remember the specific surface conditions before and during the Elmo and Bonneville runs?

  At El Mirage the start was fairly good [ no cracks or a lot of dust] were Troy could accelerate pretty good with no wheelspin
 but we knew there could be problems once we hit the loose stuff down track.
  At Bville the course was smooth with a few black tire marks at the start. I did here something about wet conditions from an underground stream were I lost it, but the tires did leave black marks were I spun from scrubing sideways.
  I once drove thru a soft spot on the course, that got my attention Conditions can change during the day with the sun bringing
up moisture at times.
 
                        JL222

[fredvance]

Thats why I try and do early morning runs, preferably from impound. Have left the bike inline, overnight several times so I can get in an early run.

  Fred

[desotoman]

Blue,

One thing to remember if you are trying to compare the two venues is how people run their cars. Some run a different tuneup for El Mirage, than Bonneville. Some tuneups at El Mirage would never make the 3 mile at Bonneville. 

Tom G.