EauRouge

Does anyone have pictures of Mark Hein's Speed Star Racing ITR? I'm particularly interested in pix of the cage. Any comments on the reason his cage is so different is also welcomed (for those who know what I mean).

Also, what's with his PCV/oil separator setup?

Here are some pix I grabbed from someone off this board:
http://www.ee.ucla.edu/~davekim/PIR/

Thanx.

johng

I was going to post the pictures I took from PIR, but it looks like you already have them.
You're welcome.

Andrew Sites

I am in the process of purchasing a front splitter from him.

RR98ITR

It's different because it's from England (one of them was from Holland though, I think).

I was very surprised by the lack of a main hoop diagonal and a harness bar on these cars. I can't help but feel that if you were T-Boned in them you'd be at a relative disadvantage. I admit that the diagonals to the tunnel would be of some (possibly sufficient) assistance - but....

Mark said he thinks his cars cages provide more structural rigidity than those in the RTR cars, and that he believes his cars suffer rather than benefit from the relatively greater torsional rigidity. This is an unusual theory, but not unheard of. Such an idea has come up in old stock car chassis literature from Steve Smith, and in Motocross in response to Honda's aluminum frames, and upsidedown forks that have been in use since the early 80's. I personally reject the idea that you can have excessive structural and torsional rigidity in the chassis, but I'm pretty unsophisticated.

Scott, who needs a cage.....for his car.....

356racing

I looked those cars over pretty close after one was totaled at Laguna. They are very well built, and I'd kill for the airjacks, but I can't think of one safety reason to copy the cage. Here's the way I look at it: Think of the top speeds of the other cars that will be in your run group on the tracks you run, say around 150mph. Next imagine worst case scenario, you lose it, stick the wall, and are t-boned drivers side at over 100mph. Do you want x bars or Nascar door bars? Do you want your harness bar to go B pillar to B pillar or to the hop support? Just my thoughts...

Andrew Sites

Before completely slamming a cage design, I would further research their design. When I will looking to build my cage, I read a lot about the difference between European cage design theory and the US cage designs. If you look at BTCC cages, they are more like Hein's in design.

Here is a link to cage info.
http://www.e30m3performance.com/tech..._symposium.htm


[Modified by Andrew, 8:59 PM 9/19/2001]

RR98ITR

Andy,

You're right - we shouldn't dump on these designs. Unless we've evaluated them using a decent FEA program and found them lacking. And that I haven't. I found that site some time ago too - it's interesting. An ME friend of mine who runs an AS Mustang added a diagonal across the windshield after running his cage in an FEA program, so seeing that Trans Am car with an effort made to stiffen the windshield prism is fun. I think that typically one runs operational design loads thru such a program - is it possible to model in such a program a kinetic scenario with a 150 mph T-Bone by a 2800 lb car? Some of you engineer types have experience with this?

Scott, who don't know much more than some questions to ask about this....


[Modified by RR98ITR, 9:43 PM 9/19/2001]

356racing

You are correct, his cage is consistent with European cage design, and as I stated above they are very nice cars. Unfortunetly US track design is not consistent with European track design so we are more prone to side impact. In Europe most tracks have huge runoff and tire walls, in the US we have concrete walls along the side of the race track so you are more likely to be in the race line after an incident and get hit. How many guys have you seen in the main straight wall at Buttonwillow Andrew? I'm sure close to 1 for every event you have done there. I'm sure Cal Club racer, David Fisher, did not plan on going sideways into concrete when his life was taken in Phoenix earlier this year. I'm not speculating that David's life would have been saved by Nascar door bars, I'm just stating that a car can never be too safe!

356racing

One last interesting observation of Mark's car is that he is the first driver I have seen to opt for the new SCCA rule provision for FIA approved seats not requiring a seat back brace. His seat is mounted on sliders without a seat back brace. Just an observation.

Gansan

Taz Harvey was not using a seat back brace in his Integra either. So I guess that's two guys.

EauRouge

Some good pics of the PTG BMW car's can be found here:
http://www.dtmpower.net/pictures/ptg...iteup_ptg.html




[Modified by 98LSTypeR, 5:31 PM 9/20/2001]

Catch 22

Just one note about that cage design.
I'm nearly 100% positive that both SCCA and NASA mandate a diagonal in the main hoop and a harness bar that runs all the way across.
So... It doesn't really matter whether you like the design or not.

johng

FWIW....Neither was Foo.

Andrew Sites

Personally, I would not want a metal bar and plate up aginst the back of my seat. ESPECIALLY if the seat was not made to have this in place.

MechE00

I can definitely say modeling an impact in a computer can be a major PitA.. and accuracy is not always so great.. that's part of the reason they still crash cars.. for just doing relative comparison of roll cages, though, FEA ought to be quite up to the task. (as long as you don't need to know "will it deflect 3 inches, or 4?")
note: I am not volunteering. I'm out of the FEA group now.. (for now..)