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-   -   Power Needed for Sub-2min Thunderhill Lap? (https://www.miataturbo.net/meet-greet-40/power-needed-sub-2min-thunderhill-lap-63573/)

Rennkafer 02-17-2012 03:41 PM

[QUOTE=Builder;836272]Thought it might be a few more pounds than that. All adds up and every little bit helps. What does your car weigh?QUOTE]

My car with my 200lb ass in it was 2522 with half tank of fuel on the corner weight scales... this is a full interior, no lightening done '97 with 15x9 6UL's w/225/45's, Harddog roll bar, FM frame rails, and more stereo gear than stock.

I think since I have a nice Audi for a DD now, it's time to "add lightness".

Builder 02-17-2012 04:07 PM


Originally Posted by Rennkafer (Post 836581)

My car with my 200lb ass in it was 2522 with half tank of fuel on the corner weight scales... this is a full interior, no lightening done '97 with 15x9 6UL's w/225/45's, Harddog roll bar, FM frame rails, and more stereo gear than stock.

I think since I have a nice Audi for a DD now, it's time to "add lightness".

That's about the same...mine is 2585 with full fuel, spare & jack, 8x15, two UltraShield RallySport seats, etc. No lightness added yet. I do take the spare and jack out at the track.

Gonna be a blast to have more power and lighter weight!

Builder 02-17-2012 05:57 PM

Thunderhill Video
 
The
was the best of the afternoon. I had passengers in all three PM sessions. In the second morning session, I turned a 2:14.97 in the damp, but the GPS hadn't arrived yet, so no data overlay on that (
).

emilio700 02-17-2012 08:37 PM


Originally Posted by Builder (Post 836623)
The last lap of the last session[/url] was the best of the afternoon. I had passengers in all three PM sessions. In the second morning session, I turned a 2:14.97 in the damp, but the GPS hadn't arrived yet, so no data overlay on that .

T1
In one video you downshift to what sounds like 3rd. Faster and smoother in 4th.

T2
You sorta late apex but you don't need to. Fastest line there is shortest distance. From extreme right edge coming down hill, angle in towards inside if T2 then brake and brake late. Carry a tiny bit of braking into beginning of turn. You carried very little speed into the turn and released the brakes too soon. If you can release the brakes in T2 that early, you're not carrying enough speed going in.

T3
When you exited T2 you unwound too early and just went straight down the center of the track. You want to keep turning left as you hit the exit kerbing of T2 so you shoot across to the left a little bit. From there you angle back in to the middle of the track and then brake. You were braking while still pointed away from inside of T3 instead of towards it.

Once you begin braking you want to end up on the inside of T3 sooner. You never hit the apex but should be right on top of it for at least half the length of the kerbing. It's way off camber so the less time spent in the turn the better.

T4
You didn't use all the track on exit but you need to. Also you lifted after you made the right left transition. That can upset the car. Better to lift when you first making the steering input to change directions, getting weight on the nose, then back to WOT as you finish the direction change. As you carry more speed off T3 your mis-timed lift will get the rear end to step out in a big way. The other detail is the length of the lift. Make that transition hard, max right to max left abruptly with a very quick lift. That's just time spent coasting :)

T5
Good line but the lift could have been much shorter.

T6-7-8
Good

T9
You brake too much and didn't nearly use all the room on the track out. You should struggle to stay on the track at exit there if you want any speed down the straight. You also don't need to traverse all the way to the left side of the straight. Sticking on the right side save about 50' distance

T10-13
Good

T14
Braking too early and not hard enough. You then hang on the brakes too long and over slow for the turn. Too wide there too. Try just straddling the rumble strips mid turn so the car is loaded harder as you track out of T15.

Other notes:

-Your shifts are kinda slow. Most were a full second, one was over 1s. The slow ones should be 500ms. If you have a light flywheel, you should be able to routinely snap off 300ms shifts.

-You're not braking very hard anywhere. Miatas make a lot of time up under braking. If you are after a sub 2:00 there with just enough hardware to get the job done, you're going to have to learn to threshold brake everywhere. The first time you do T1 right is a bit spooky. You go in deeper and just dab them briefly but very hard. Roll off gradually to set the nose and slip angle then right back to power. It's not a long smooth braking zone.

- You spend a lot of time with your hand camped on the shifter. Stop that. The right hand should only come off the wheel to flick the shifter and reach for a beer.

- I might suggest changing the camera angle to capture the forward view and your hands on the steering wheel. Very helpful to see steering and pedal inputs.

Camera angle I like in my cars http://youtu.be/CXWqcvYBhug

Best guess is that car will go ~2s faster as it sits.

Builder 02-17-2012 10:44 PM


Originally Posted by emilio700 (Post 836689)
T1
In one video you downshift to what sounds like 3rd. Faster and smoother in 4th.

Agreed. With the previous setup, my apex speed was a full 5mph slower and required third. Discovered lat in the day that I have more grip and 4th would be much faster.


Originally Posted by emilio700 (Post 836689)
T2
You sorta late apex but you don't need to. Fastest line there is shortest distance. From extreme right edge coming down hill, angle in towards inside if T2 then brake and brake late. Carry a tiny bit of braking into beginning of turn. You carried very little speed into the turn and released the brakes too soon. If you can release the brakes in T2 that early, you're not carrying enough speed going in.

Makes sense. I'll give that a try.


Originally Posted by emilio700 (Post 836689)
T3
When you exited T2 you unwound too early and just went straight down the center of the track. You want to keep turning left as you hit the exit kerbing of T2 so you shoot across to the left a little bit. From there you angle back in to the middle of the track and then brake. You were braking while still pointed away from inside of T3 instead of towards it.

Once you begin braking you want to end up on the inside of T3 sooner. You never hit the apex but should be right on top of it for at least half the length of the kerbing. It's way off camber so the less time spent in the turn the better.

Interesting. Never had the grip to get back left on T2 track-out. I'll check it out. Yes, I should have been tighter to T3 and for longer.


Originally Posted by emilio700 (Post 836689)
T4
You didn't use all the track on exit but you need to. Also you lifted after you made the right left transition. That can upset the car. Better to lift when you first making the steering input to change directions, getting weight on the nose, then back to WOT as you finish the direction change. As you carry more speed off T3 your mis-timed lift will get the rear end to step out in a big way. The other detail is the length of the lift. Make that transition hard, max right to max left abruptly with a very quick lift. That's just time spent coasting :)

Agree I need to go wider on T4 track-out. That worked better earlier in the day. Best result I had was to start the cross-over angle before the drop, then short-shift at the drop, which settles the nose well on the other side. That allows WOT and further turn-in on compression. This was my first day with the bypass and I was trying different things...including not tracking out of 4 and different launch points over the drop. I caught some big air there once and almost weeded left of T5.


Originally Posted by emilio700 (Post 836689)
T5
Good line but the lift could have been much shorter.

Maybe. Looks like I should actually wait another tenth or two after the short shift. I grabbed throttle too early and had to breath throttle before entry. Better to have waited on downhill.


Originally Posted by emilio700 (Post 836689)
T6-7-8
Good

I should go in earlier on 7.


Originally Posted by emilio700 (Post 836689)
T9
You brake too much and didn't nearly use all the room on the track out. You should struggle to stay on the track at exit there if you want any speed down the straight. You also don't need to traverse all the way to the left side of the straight. Sticking on the right side save about 50' distance

Agreed. I've been taking it really easy on the brakes, but will be using them a lot heavier next time out. Much more grip now and I can go much deeper without worrying about flat-spotting tires. Not hitting my marks well for T9.


Originally Posted by emilio700 (Post 836689)
T10-13
Good

Love T10. Could go deeper on all entries, though.


Originally Posted by emilio700 (Post 836689)
T14
Braking too early and not hard enough. You then hang on the brakes too long and over slow for the turn. Too wide there too. Try just straddling the rumble strips mid turn so the car is loaded harder as you track out of T15.

Yup, braking heavier on all corners next time. That was wider than normal. Trying to preserve as much speed as possible onto the front.


Originally Posted by emilio700 (Post 836689)
Other notes:

-Your shifts are kinda slow. Most were a full second, one was over 1s. The slow ones should be 500ms. If you have a light flywheel, you should be able to routinely snap off 300ms shifts.

Yes, I can easily shift much faster, but am taking it easy on the trans.


Originally Posted by emilio700 (Post 836689)
-You're not braking very hard anywhere. Miatas make a lot of time up under braking. If you are after a sub 2:00 there with just enough hardware to get the job done, you're going to have to learn to threshold brake everywhere. The first time you do T1 right is a bit spooky. You go in deeper and just dab them briefly but very hard. Roll off gradually to set the nose and slip angle then right back to power. It's not a long smooth braking zone.

Yup, I am pretty safe going into T1, especially with a pax aboard. As stated above, more focus on braking next time.


Originally Posted by emilio700 (Post 836689)
- You spend a lot of time with your hand camped on the shifter. Stop that. The right hand should only come off the wheel to flick the shifter and reach for a beer.

Haha. You think it's the shifter, but it is actually a beer. I probably won't break that habit until I need more effort to turn. Ain't power steering wonderful?


Originally Posted by emilio700 (Post 836689)
- I might suggest changing the camera angle to capture the forward view and your hands on the steering wheel. Very helpful to see steering and pedal inputs.

For some reason, the mount wouldn't stay on the rear glass that day. I think the suction cups were compressed in the box. It's usually pointing over my right shoulder to show shifts and steering input.


Originally Posted by emilio700 (Post 836689)
Best guess is that car will go ~2s faster as it sits.

Yup, I figured 1.5.

Thanks for the nit-picking, I mean, detailed critique. I appreciate you taking the time to do a thorough dissection. It's great to have this kind of analysis with suggestions that can be put to immediate use. Can't wait to get back there and try some line adjustments, challenge the brakes a little more.


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