Video from MSR Cresson on the 3.1

Video from this past weekend. Best 3 laps of the weekend were all in the same session, within 4 tenths of each other, and within 4 tenths of the theoretical best lap from all laps throughout the weekend.

http://www.vimeo.com/14944357

First proving up of a DIY cool shirt setup - invaluable even with temps in the low 90's.
First weekend with a Spec II+ clutch, lightweight flywheel and pressure plate. Rev matching is much easier (though I still need to work on that), and everything winds up faster under power. (Thanks TDR for the parts and Rogue for the install!)
First weekend after a torsen LSD diff swap. Night and day difference in drive out of the corners with the car under lateral load. Wheel spin is gone but is replaced with some understeer. I think I'm going to have to find some alignment specs to make that go away. (Higher air pressure? Stiffer rear damper settings? Less rear toe? (1/8" toe in currently))
Second weekend on 205 Star Specs. Excellent tire. 32 psi front, 30 psi rear, set it and forget it.

Oh, and video + data is awesome.

Chris

Nice video.

Looks good. Does it display lap times? What did you run?

My best laps of the weekend were in that session - 2,3, and 4 in the video. 2:51:57, 2:51:20, 2:51:43 respectively. They're displayed on the right under the passenger seat but are pretty small unless you're in full screen. Theoretical best lap from all the data I collected was a 2:50:80. The best lap I had was where the GTR passed me (and I lifted) on the straight before Big Bend, so there's more to be had.

No idea on the target time I should be getting down to - can't find any event results from NASA or SCCA where they're on the 3.1. NASA TTE is what I'm prepping the car for, though.

Any hints or pointers (beyond not braking as much)?

Chris

Most groups don't race the 3.1 because of the 1.3 section.
I will take a look at your video tonight.

This is my best from a damp, December event.
http://www.youtube.com/watch?v=HZhpNjF6LKI

The full course usually adds about a minute to your normal 1.7 lap time. Ken's video is right on par with that, as a 1:27 on the 1.7 is still booking right along. I run 1:30's on the 1.7 and am shooting for 2:45's this weekend on the 3.1 since I will driving a different car this time around.

Chris - as for pointers: your lines look good, just need lots of seat time to pick up the time. Target times should be around 1:30's -1:28's in NA Miata - I've seen boosted ones run 1:22's driven by Keith Verges.

Quote:

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Originally Posted by ckearns

Wheel spin is gone but is replaced with some understeer. I think I'm going to have to find some alignment specs to make that go away. (Higher air pressure? Stiffer rear damper settings? Less rear toe? (1/8" toe in currently))

Second weekend on 205 Star Specs. Excellent tire. 32 psi front, 30 psi rear, set it and forget it.

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I'm no Miata expert on suspension tuning yet, but no one has addressed this, so here are some things that some to mind:

• I've run the Star Specs on a BMW 325 and on that car they seem to like 38-40 PSI hot. What hot pressures are you getting? I would expect the Miata to like a few lbs lower, but I could be wrong.
• To tune the understeer using tire pressure, lower fronts and/or raise rear tire pressure.
• Setting toe to zero should help the understeer as well.
• Dampers are a bit fuzzy to me still. It theoretically makes sense in my head that stiffening the rear damper might help understeer on corner exit, but I don't know. I'm assuming changing damper settings isn't that hard on your car. If not, play around with damper settings on day and see what you learn!

If someone says something that contradicts me, chances are they are right. ;)

Some good resources:

• Spec miata setup guide
• Spec miata setup and testing sheet

All good info - but do only change ONE thing at time when testing and tuning. Much easier to find out if change really made a difference or not.

Quote:

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Originally Posted by Electro

All good info - but do only change ONE thing at time when testing and tuning. Much easier to find out if change really made a difference or not.

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Yes, left that out. :thumleft:

Here is my feedback from your video. Remember I am not a professional and this feedback is free.

That water makes T12 and PITA.

Track map: http://www.motorsportranch.com/3.1-road-course.cfm

http://www.motorsportranch.com/image...Layout_3_1.jpg

Enter T13 sooner, stay on the gas longer and hug the inside of T14. Accelerate when you just clear the bottom or can see the pole at :46 on the video.

Swing out, more to the right on T15. You will carry more speed on T16 and can get on the throttle sooner in T15. Line at 6:44 looked good.

In T1 you should be on the gas at 1:11.

Come in tighter on T2. Turn in a little sooner on T2 (1:26) and it will setup a straight shoot through T3. Practice different lines. When you hit the turn in right you will see what I am talking about. Plus you can accelerate for a second.

T4 - T7 look good.

I think you can take a tighter line in T8. I have been playing with different line in T8 to see what works best. I think start track right and make it more of a sweeper.

I don’t think you need to drive that deep into T9. In pinches off the turn and doesn’t really gain any speed on the exit.

Try to take T10 more to the right. It make help it flow better on exit speed. More like you did at 5:42.

I think you can carry more speed through T11. It is usually much faster than you think.

Try a little tighter line on T12 6:15. Turn in a little sooner.

NICE on 7:29 - 7:55 making up distance on that GT-R!

I am editing a few laps from this weekend on the 3.1. Ken- played with a M3 for several laps - gawd those things are fast! Unofficially timed a few 2:40 laps, which seems like I'm jogging compared to your 2:27's. I was leaving alot on the table as being the first time in this car, but what a blast to drive when you have some HP to grunt out of the lower sections. Video to come shortly...

I hate how much youtube compresses our antiquated setups - but it is what it is. Here are a few laps from this weekend. First time on 3.1 and in a new car, so these are not the best lines for sure. But seat time is really all I was after... Cheers! http://www.youtube.com/watch?v=OYHCCZpqJI8

Use vimeo.com...

Awfully low camera placement.

No kidding... ran out of time for making a mount. Ziptied to lower grill. Vid has been taken down until I can edit some things. These cameras seem to be getting worse day by day... Loved 'em when I first got them, and seems quality gets worse every time I use it.

I'll just let it be for the moment... http://www.youtube.com/watch?v=LX6jS5kSC2Q

And for Ken-O - :) http://www.youtube.com/watch?v=jN5zMfdDNbQ

Excellent pointers - thanks for taking the time to review the video.

I think the next big mental hurdles I have to get past are to trust the car on turn in and to let it work throughout the corner. It feels as though I'm dumping too much speed and getting as much of the corner rotation done as I can on entry.

Chris

you know, i had a friend that had a bada$$ C6 Z06 that he would drag race. he came to a porsche club event once, and asked "how do i know how fast i can go in a turn?" i said " you don't, you have to find out......slowly" basically, if you pick a corner and gradually increase your entry speed (usually by braking less) you will get to a point that your using every inch of track on exit (and sometimes a few more, over the curbing) then that's the fastest you can go on that corner. only 10-12 (depending on the track) corners to go!