1.1g barrier?

[Jdata]

Has anyone been able to reach or surpass 1.1g ? If so, how was it accomplished?


Just curious.

[Hobbes]

I assume without hitting a wall?


I don't think there is much more G-force possible without any changes in the cars aerodynamic

[indianamoon]

Assuming here that the OP means cornering.

I believe that JBL's will exceed that.

Don't believe that there is any correlation between aerodynamics and g-force achievable, correct me if I am wrong

[Jdata]

Originally Posted by indianamoon

Assuming here that the OP means cornering.

I believe that JBL's will exceed that.

Don't believe that there is any correlation between aerodynamics and g-force achievable, correct me if I am wrong

Yes I meant cornering. Lateral G. In this case...mechanical grip

[Bearwolf]

Originally Posted by indianamoon

Assuming here that the OP means cornering.

Don't believe that there is any correlation between aerodynamics and g-force achievable, correct me if I am wrong

The only correlation I'm guessing lateral g-force would have with aerodynamics would be, reducing lift could increase traction and increasing downforce could increase traction, both leading to the possiblity of being able to maintain a higher lateral g load.

[spdbrake]

Jdata,

I'm guessing your referring to the 200 ft skidpad that is the benchmark for testing as in Road and Track etc...
I know manufacturers use the data, but I don't imagine very many if any folks test their cobras in that manner.
Skidpan world record

[Ozzie Goat]

even if the OP meant open track days, who's got a calibrated VBox on board most days ?

[Cobra #3170]

CSX 3170 will pull 1.3 G on just about any surface using Bridgestone RE71 200 UTAG tires 285/30/18 fronts and 305/30/19 rears. On good concrete we have seen over 1.4. These are not spike loads but sustained through a corner. I have not tried it on a skid pad but assume it would be similar. We also get 1.0 to 1.1 in acceleration and 1.2 braking G. We are trying a different brand this weekend will let you know if it is better. BFG Rivals pulled about .1 G less cornering and .1 G more acceleration and braking so we switched to Bridgestone three years ago. Under max G load the car lifts both front and rear inside tires slightly off the pavement like a gokart. There is a picture in my gallery of the car doing that. Cobra cornering power is helped by weight put hurt by track width. These numbers are all in the 40-65 mph range. Aerodynamics will limit high speed cornering loads unless you do what Morris has done and fix the high speed aerodynamics.
After watching that video not sure we could pull those G's on a 200 foot pad, would be fun to find out though.

[Jdata]

Originally Posted by Cobra #3170

CSX 3170 will pull 1.3 G on just about any surface using Bridgestone RE71 200 UTAG tires 285/30/18 fronts and 305/30/19 rears. On good concrete we have seen over 1.4. These are not spike loads but sustained through a corner. I have not tried it on a skid pad but assume it would be similar. We also get 1.0 to 1.1 in acceleration and 1.2 braking G. We are trying a different brand this weekend will let you know if it is better. BFG Rivals pulled about .1 G less cornering and .1 G more acceleration and braking so we switched to Bridgestone three years ago. Under max G load the car lifts both front and rear inside tires slightly off the pavement like a gokart. There is a picture in my gallery of the car doing that. Cobra cornering power is helped by weight put hurt by track width. These numbers are all in the 40-65 mph range. Aerodynamics will limit high speed cornering loads unless you do what Morris has done and fix the high speed aerodynamics.
After watching that video not sure we could pull those G's on a 200 foot pad, would be fun to find out though.

Thanks for the response! I really appreciate it.

[Cobra #3170]

Originally Posted by Jdata

Thanks for the response! I really appreciate it.

About 20 years ago I participated in a test at Tire Rack in Indiana. It was in preparation for an event that a friend was running for max G load. We used a timer and ran on a 200 foot circle. My friend had a winged A mod car. He pulled over 2 G just nosing out my Son's Gokart. We found that both the kart and the A mod car had to be set up with a large percentage of oversteer to do well. They had so much oversteer they would not negotiate a normal course very well at all. An ill handling car might do well on the circle but not so well in real world conditions.
Wasn't the new ZR1 supposed to pull 1.19 G, I think I read that somewhere.

[spdbrake]

You're correct on the ZR1 number.

Top 100 "Grip Kings" - fastest cars around skidpad 2018 - FastestLaps.com

[MKS427]

[quote=Hobbes;1452827]I assume without hitting a wall?


That typically creates some intense G's. LOL

[Grey 65]

Originally Posted by Cobra #3170

CSX 3170 will pull 1.3 G on just about any surface using Bridgestone RE71 200 UTAG tires 285/30/18 fronts and 305/30/19 rears. On good concrete we have seen over 1.4. These are not spike loads but sustained through a corner. I have not tried it on a skid pad but assume it would be similar. We also get 1.0 to 1.1 in acceleration and 1.2 braking G. We are trying a different brand this weekend will let you know if it is better. BFG Rivals pulled about .1 G less cornering and .1 G more acceleration and braking so we switched to Bridgestone three years ago. Under max G load the car lifts both front and rear inside tires slightly off the pavement like a gokart. There is a picture in my gallery of the car doing that. Cobra cornering power is helped by weight put hurt by track width. These numbers are all in the 40-65 mph range. Aerodynamics will limit high speed cornering loads unless you do what Morris has done and fix the high speed aerodynamics.
After watching that video not sure we could pull those G's on a 200 foot pad, would be fun to find out though.

My car pulls about 0.1g less than 3170 does, but still over the threshold you are asking about.

How might you ask? I normally stay in a Holiday Inn Express before racing events. That and my Backdraft has been setup as close as possible to the same setup CSX3170 runs. Bruce is kind of my unofficial crew chief. I have reaped the rewards of the countless hours of research and testing Bruce has done on his car.

[vntgspd]

Originally Posted by Cobra #3170

About 20 years ago I participated in a test at Tire Rack in Indiana. It was in preparation for an event that a friend was running for max G load. We used a timer and ran on a 200 foot circle. My friend had a winged A mod car. He pulled over 2 G just nosing out my Son's Gokart. We found that both the kart and the A mod car had to be set up with a large percentage of oversteer to do well. They had so much oversteer they would not negotiate a normal course very well at all. An ill handling car might do well on the circle but not so well in real world conditions.
Wasn't the new ZR1 supposed to pull 1.19 G, I think I read that somewhere.

I was going to say something very similar...
Many years ago I worked on a small project with BFG and a Japanese Tuner company to prove that the street tire could pull 1g on the skidpad (for an advertisement). Neither the car nor the tire could do it out of the box but after I did about 50 laps continually tweaking the car setup along the way I was successful in hitting the target. However, I would have to periodically run the car around the adjacent racetrack to cool the car off and found the handling to be diabolical with the fast skidpad setup.

All that to say that high skidpad numbers do not necessarily equate to excellent handling or low lap times. I suppose they are more relevant when comparing stock vehicles as equipped from the factory.

[Cobra #3170]

Today we tried (4) ACR Viper front tires on the Cobra. They were 295/25/19 Kuhmo's. We tried multiple spring rates, rake angles and shock settings. The car pulled 1.57 G with Kuhmo's vs Bridgestone's at 1.35. This illustrates why these tires are not legal in Optima or SCCA because they are in no way a 200 TW tire. I looked at some of the data and saw where average G for .4 seconds was over 1.4. These tires are still legal for Goodguys autox so we will run them at the next Pleasanton Autox. I need to bring a gun to the gun fight not a knife so on go the Kuhmo's. I hope they are outlawed next year because it is not fair to others that are on real 200 tw tires,

[Three Peaks]

Bruce,
Have you done any work to stiffen the original thin tube chassis on 3170? I've been curious for a while how a stiffer chassis on these would affect G force grip and handling compared to the originals.

[Cobra #3170]

Yes, I did the only thing I could do that would not impact the original appearance. I had two steel tube prepared that had the same outside diameter as the main frame rail inside diameter. I had a vertical member that was .180" thick rosette welded into both tubes every 4" on both sides the full length, then ground smooth. The tubes gained considerable bending strength from the "I" beam configuration. We cut the caps off the frame in the front and forced the tubes inside the main rails and rosette welded them in place then ground the welds down, welded the front caps back on and painted everything original black.
It added 100 pounds to the car but it was well worth the effort. If the floor is slightly uneven when it is on jack stands there will be a gap between the floor and jack stand at the low spot even if it only .060. The car is approximately 300 % stiffer now. Although that sounds huge it isn't, original cars were terrible. Jack them up and the doors would jam. Adding torsional stiffness really helps with everything especially chassis tuning.
You can actually feel a 25 pound spring change now or a slight change in anti roll bar settings too,

[Three Peaks]

Thanks, that is why I asked. Pretty slick solution to a vexing problem. My car has the original style chassis, but with the .120 wall tubing . It still could use a bit of stiffening for my taste, but is much better than some of the old Cobras and early Corvettes I've ridden in.

[Richard Hudgins]

Originally Posted by indianamoon

Assuming here that the OP means cornering.

I believe that JBL's will exceed that.

The only good data that I still have of skid pad testing was back in 2004.

JBL Comp chassis/302 on 200 ft skidpad at Willow Springs with Michelin Pilots

Best lap = 14.52 seconds = 1.16g.
Average of 5 continuous laps 15.1 seconds = 1.08g. Chassis set for minor understeer with front bar @70% and rear bar @55%.

Same car with Hoosier R DOT slicks.
2nd lap = 13.1 seconds= 1.43g. Chassis set for minor oversteer with front bar @80% and rear bar @85%.

Had to stop Hoosier test as the sump could not control oil and the low oil red light would come on during the lap. Also had problems with the carburetor at these lateral acceleration numbers.

I have somehow lost the data set that we had for a injected 358 ci dry sump car but I am pretty sure that the car was no quicker than the 302 car on the skid pad.

However I remember that this 358 car Hoosier test was interesting in that when doing the 5 lap test the times dropped off severely on the 4th and 5th lap as the rear traction went away so badly that the owner/driver thought he was throwing oil out of the dry sump tank or had a bad pan leak.

It was actually that the car had so much motor that the driver was driving with the throttle and not really achieving solid state loading. This made the rear tyre temperatures exceed 135C and was actually liguifying the compound.

In essence he was drifting the car and that is not the way to drive a skid pad. So the numbers he achieved were pretty meaningless as a comparison.

But he had a lot of fun.

[xlr8tr]

Curious Richard, would the 295 and 355 kuhmo's fit on the JBL? Section widths of 12.1 and 14.2" respectively. One would think with current state of the art tires the numbers would be even better, assuming you could keep oil in the engine