mark kibort

Anyone got any data logging of vehicle speeds through turn 8 at Thunderhill?
We had a race school last weekend and a few of the open cars with street tires were posting some pretty impressive speeds. some, looked like they could defy the laws of physics. I know how fast I run through turn 8 on DOTs and a sub 2:00 car, but I wonder what anyone here that knows has seen.
Thanks,

Mark

Tom W

IIRC, my MoTeC says ~105 mph and ~1.5 g. If I get a chance, I'll post some example data later tonight. I think there are another 2 mph that could be seen there too, if I simply had the ***** for it.

My car is 2350 lbs (with me), has good but not great down force and I use Goodyear R430 compound bias-ply slicks. My best time is a 1:56 (over the top).

What were they running in the school?

quickxotica

All sorts of confusion is about to be unleashed unless you define what you are looking for:

Minimum speed? Apex speed? Average speed over the segment (this would probably be best, but impossible to gather since we all have different segments defined).

Also, when you say you "know how fast [you] run" in T8... does that mean you using data aq or are *trying* to glance at the speedo at some consistent location? The velocity vs distance plot looks like a "V" here (assuming we are talking about cars powerful enough to need a tap on the brakes) so just glancing at a constantly-moving speedo isn't going to be very accurate.

Lastly, assuming we could all agree to apply a standard criteria for this requested reference speed, what value, exactly, is a list of different cars/setups/weights/classes and their respective momentary speeds going to be? I fail to see.... but please do enlighten me.

mark kibort

Thanks Tom! thats what I was looking for. my best is still in the 1:58-9s and thats on DOTs. I think the fastest ive seen has been a tick over 100mph. I always look at the same spot, not as accurae as Motec, but years and years of glancing in the same spot, and the correlating it to lap time has worked for my curiousity.
I was going nose to tail with Jordan a few years ago, and he had motec At the time, he was a little faster, with a boat load more power, and his apex speed was 102mph.

The school was the Art of Racing. it turned out great, with a huge turn out. most of the cars were low powered miatas, BMW e30s, and a few 928s.
It was the day after the HOD open track day. the rain made things interesting, especially for coaching "out" of the car (lead follow, drills, exercizes, etc). But, in the end, I think everyone got a lot out of it.

mark kibort

Sure, its a rough estimate. yes, ive been using video freeze frame, glances at the same specific spot, and generally, just looking for maximum speed at the apex or slightly after. Its not as great of a speed range as you might think. I do have to do a quick tap of the brakes, to set the nose for turn in, and then its a hang on for your life exit. 120, down to 100/102 is where my best lap times happen. I found if i have ever hit this in the right range of indicated speeds, my lap times fall in a narrow range. It proved to me that 8 was near the most important corner, similar to turn 6 at laguna. (same requirement, i need to be 80-83mph at the exit for best lap times).

I would just love to take the guess work out of it by having Motec for a day . Im very envious of those who can get a theoretical lap, match it with video and then have a better shot at putting it all together for improvement. Having raced at these tracks for so long, Its probably taken me a little longer to get where I am now with cave man tools, than the folks with Motec.

as far as what this is for, there was some talk at the school of students hitting 105mph with street cars (low powered) on street tires, with a feeling that they could hit 115mph if they had the guts. physics would guide them to a different range of speeds I would think, especially since 1.5g is what slicks usually see and that speed for2400lb cars is around 105. I think Ive only seen 1g as a max, reasonably sustained for a true street tire, but I have no idea. Only feel from what Ive raced on in the past. (WC used to use 280tread wear T1S toyos in the early 2000s, and they were like ice skates.)

justaguy

95-100 for me at the apex. 100 puts me over the paint over the rumble strips right to the very edge of the track at track out. I just can gather it up before I run out of the extra pavement. I would have to grow an extra set to try it any faster and I think the out come would not be worth the extra 2-3 MPH

quickxotica

Regardless of speed, I will say this: T8 is one of those corners where an ounce of subtlety with the lift/braking is rewarded by a pound of laptime reduction. You gotta be gentle with the longitudinal weight-transfer. I agree it's a very important corner too.

Tom W

A very good point about the speeds (where/what). My number is the minimum corner speed, definitely not apex or exit.

Minimum corner speed is something that's easy to get with MoTeC or a Traqmate and I find it a very good measure of how consistent I am. I don't believe that trying to work on maximizing corner speed is worth a damn until you are consistent.

I agree that there is much, much more to be gained by maximizing T8 and T1 than you will ever see from worrying about corner speed in T11 or T5.

IcemanG17

it seems to get much past say 105mph minimum speed in the corner you need real slicks and serious downforce.....

Bill L Seifert

I was suppose to go to that school but had to pass because of other commitments. I really wish I could have gone. That darn corner can be taken a lot faster than you think, and I don't think I have ever gotten it right. I have no data collection in my car except a speedometer, and I sure don't have time to look at that.

Bill

Virtual Surgeon

I was at that course, which was a blast. I was in a spec Miata, and on the mock race dropped two tires on turn 8. Fortunately, I was able to recover without any real issues, but I have a greater respect for that corner now. OBTW, I was no where close to 100 MPH.

IcemanG17

In Spec Miata's you floor it BEFORE the apex of 6...and hold FLAT all the way through 8 until the brake zone in 9...its just freaky....but rewarding when you get it right.....I do turn in a smidge early in the miata's since the bump at apex tends to make the front wash a bit towards the track out.... I can almost take it flat in my 928 Estate...just haven't had the stones to try it yet.....

Bill L Seifert

"In Spec Miatas you floor it before the apex of 6...and hold FLAT all the way through 8"

WOW, I have gotten to where I lift a little just prior to entering 8, but that was the best I could do. I race a 99 Civic SI which is in SSC, so I obviously am in the slowest class in SCCA, but I still can't go through FLAT, and I am several seconds off our "Hot Shoe" in SSC. Our next race is the middle of March, and I will try it flat, "gulp". I'm sure I lose a lot of time through that corner, and IMO that is the most important turn on the track.

By the way did you drop those wheels on the inside or outside of that turn?

Bill

IcemanG17

I can do it just barely kissing the apex berm and running a little onto the rumbles at track out.... Once you get used to in in Spec miata's it becomes kinda normal....I have found even spec miata's with worn tires can still do it....a well setup ITA or PTE Miata on hoosiers can do it with EASE..you can even be a bit late and still make it flat!!!! I drove Evil Genius Racing best ITA Miata on Kumho V710's with JRZ shocks and it understeered a bit (setup that way for endurance racing), but took the corner with zero drama....

In my 928 I lift briefly..turn in...and roll throttle to flat about apex....on R comps....I think it could hold the corner dead flat....but I still need to try it on a higher traction day!!!

dp35

Spec Miata - around 95 and (barely) accelerating at WOT through T8. This corner is easy flat in a decent SM.

Ariel Atom - my best was 105 on Hoosier A6's, but not very consistent, with most fast laps between 100-105. Lift required in this car.