Otto Mechanic

Please don't misunderstand; I didn't say we weren't the folks to make the rules. I said "We're in no position to make rules". That comes from a background of making rules myself. I suppose you could say I have rules about making rules and I'd expect a laugh when I said it.

My background is in measurement and reliability theory; risk management is another application of the same thing. How does one objectively assess risk? What are the things a person needs to know? How do you do it without just expressing your opinion (which is admittedly something that's done regardless of objectivity)?

What data do we need? To start we need exposure time; no assessment of safety or reliability of any system, part, procedure, practice, etc. makes any sense in the absence of an exposure time measure; we must first know how much exposure the subject has to any risk we're studying. It's a fundamental measure and without it nothing else works. In this model, we assume incident frequency is a function of exposure time. It's important to remember that assumption since there's no solid evidence to support it. It's typically binary; we know that if you don't do something, it likely can't hurt you, but we don't really know if the function is linear, non-linear, stochastic, or maybe something else entirely. In truth, we know nothing about the shape of risk.

Following that we need a full understanding of the device, method, etc. used to mitigate the risk. We need to know how much exposure time that "thing" has also. Then we need a measure of incident frequency; how often does the thing we're trying to mitigate occur? From there we can start developing some basic statistics that might eventually tell us how effective that method is in mitigating the risk. Given enough exposure time, and enough testing time, we may arrive at objective reasons to either require or discard a particular method.

This really isn't the place to discuss these things in depth, but that's why I say that, at present, we really aren't in a position to make rules.

We can make recommendations, relay anecdotes, tell stories, etc. But we're not in a position to make rules. Not meaningful rules that have any objective support.

The ground truth is we're all test pilots, and test pilots have no real use for rules.

ace37

Otto Mechanic

Thank you. You're right saying it isn't in line of the OP and we should restrain ourselves from further debate off topic.

But the topic comes up frequently on this forum and Luigi is right to say "we make the rules", so perhaps another thread, carefully moderated, designed and intended to discuss the issue in a civil and respectful fashion, as has occurred here, is in order? Maybe a forum moderator such as Mr. Vampa might take it on himself to host such a debate?

Regards,

LuigiVampa

This is what I mean about how you never know who you are "talking" to on the internet. You are correct Ace, everyone here has a background that causes them to look at it from their own perspective. When you come out of law school all you see is risk and bad actors everywhere.

On another note, I am shocked shocked that a Rennlist thread has been derailed into a different topic!

Civil and respectful discussion? I'm not sure I am the man for the job.

Olemiss540

Agreed! The op's thread title:

Besides a full out race car what is the safest way to DE

So, can we leave the "Everyone needs a full out racecar or else they are silly to consider driving in an HPDE" out temporarily and make some more ACTUAL suggestions that reply to the OP?

OP,
Considering you want to street drive your track car (which is an awesome way to enjoy the ownership experience), the question is do you HAVE to maintain rear seat access? A bolt in half cage with fixed back seats and 6 point harnesses (along with a HANS device) is a great middle ground. GT3 buckets or even better having a Sparco Ergo with removable halos.

Keep stock seat belts in place as they should be used when street driving due to their functionality with no HNR in place and airbags.

Otto Mechanic

I'm wrestling with this one. My car is an '89 944 S2 and it does have front airbags. I'm not clear on whether they're an effective HNR replacement using a 6 pt. harness. Does anyone know? I'd rather not keep unnecessary belts on the car if I can avoid it.

Olemiss540

No way. If you are fixed in your seats with 6 points, you HAVE to be wearing your HNR. If you are street driving (and thus not wearing your helmet), you really should wear the 3 points or other ASM rated seat belts as they allow slack in your shoulders to accommodate movement into the airbag so your neck/skull doesnt take the entire whiplash.

ajcjr

As much as i would like to keep rear seat access, my 14 yr old is growing by the day (which he is happy about because he is a big hockey player) so the rear seat is not necessary for me.

Again my purpose for this post was basically not having a car and money sit in my garage when i can only use it at De days.

LuigiVampa

Finally, we can agreed 100% on something!

I have both a 6 point harness and OEM 3 point in my 944. When I drive on the street I never use the harness.

Olemiss540

I think we would agree on a lot of things (and have in the past) excepting how to respond to:

Besides a full out race car what is the safest way to DE

LuigiVampa

I think the question begs inclusion of the starting point which is a race car. It's like the given in a math formula - everything is based off of it.

Otto Mechanic

FWIW, I've personally experienced a head on collision in a 1981 931 at a combined speed of about 100 mph using only a 3 pt. stock belt and no airbags. I did suffer a non-contact concussion (my head didn't hit anything) and that knocked me out, I came to in the ambulance about 45 minutes after the accident. Not sure how much slack or resistance is in those 3 pt. harnesses.

What I'm looking for is test data on harnesses with airbags. I'm not sure anyone has ever done them, but it seems reasonable some folks on this forum may have experienced it.

Olemiss540

Are your harnessses DOT rated? Otherwise, regardless of test data, it is illegal.

Otto Mechanic

Not exactly what I was looking for in the way of experience

ace37

Not a direct answer, so it's worth what you're paying for it. The way I would approach this is to determine if you could move far enough forward for your head to meaningfully impact the airbag when strapped in with full harnesses. If it would take a load of 100g+ for your head to touch the airbag OR if your torso would remain very close to the seat and your head would touch the airbag (which sounds intuitive to me), the answer is clear - you'd need a HNR. You may be able to review videos to see how far people move forward and use this line of thinking in your decision. If the head motion is 5x the torso motion or more, you may want a HNR regardless of the airbag simply because the torso-head distance is concerning.