NASA TT - Lets talk about spending points!

[phastafrican]

Interesting data. While I won't discount rolling resistance, 235 zII and 225 r6 should not vary by the amounts seen here. The width of the tires are extremely close, resulting in similar drag. I'm more inclined to think the setup is not allowing you to effectively put the power down.

A 4mph corner exit speed difference should be HUGE at the end of a straight. Typically, 1 mph difference on a medium-long straight is ~ 3mph difference, so there's something weird there as well. Without seeing other variables such as steering angle and throttle pedal position, it does appear that your hypothesis is worth investigating.

I'd need a few more laps to confirm this, but it also looks like you are braking at about the same point, for relatively the same amount of distance, sometimes even sooner.
I know I occasionally struggle to remember sometimes that I have added grip with a different compound and can go deeper into the braking zone. Even if the 225 R6 is a lot of tire for your current power levels, the red graph should be a shifted a tad more to the right since the lap starts of with a heavy braking zone... which is typical of a graph line comparing a faster lap with more grip.
You get bogged down on the front straight for some reason, and into T4, and T7. The acceleration should be linear just like on the ZII. If you didn't over-brake on the zII at T5, those lap times would be likely be equal.

Here's Marc's lap on 225A6. Notable speed deltas are:
T1-2: 124/48,
T4: 99/79,
T5-6: 108,45,
T7-9: 108,83
You're right there with him. Just need more acceleration, torque, and 1 second in T5
[ame="https://www.youtube.com/watch?v=R279Lb9SFdg"]https://www.youtube.com/watch?v=R279Lb9SFdg[/ame]

[phastafrican]

Originally Posted by JustDoItMikey

What are you guys using to record this data? Im thinking this needs to be the first "mod" I invest in so I can track what makes a difference and what doesnt.

Also from reading all of this, and a better understanding of what points I was misapplying it looks like there is no way around just slapping mods on the car and going out there and doing well. For instance to put a well sorted RCE T2's on the car will cost 10 points, but if you spend the time thru trial and error and get a custom spring rate custom valved non adjustable coilover you can do it for 4 points. So to me it looks like trail and error will in most cases be the only way to tell what works best for the track and your driving style while costing the least points.

There are lots of data acquisition choices. The AIM Solo and SOLO DL are the more popular ones in TT, and Traqmate in racing.

RCE T2s are 5 pts. Not sure where the 10 is from.

[celica73]

Was that tire comparison done on the same weekend? Just wondering if it was hot and the engine was pulling timing with the Hoosier runs.

[phastafrican]

Originally Posted by ja1217

To be fair, the R6's were on their 20th heat cycle which I'm sure didn't help braking distances. Rolling resistance and acceleration still applies though.

Originally Posted by celica73

I figured there was a simple answer. With that many heat cycles, I'm surprised they had that much more grip in the turns.

Well that explains a good bit as well. I'd say don't make a decision based on worn out tires unless you plan on running worn out tires all the time.

[phastafrican]

Originally Posted by phastafrican

Interesting data. While I won't discount rolling resistance, 235 zII and 225 r6 should not vary by the amounts seen here. The width of the tires are extremely close, resulting in similar drag. I'm more inclined to think the setup is not allowing you to effectively put the power down.

A 4mph corner exit speed difference should be HUGE at the end of a straight. Typically, 1 mph difference on a medium-long straight is ~ 3mph difference, so there's something weird there as well. Without seeing other variables such as steering angle and throttle pedal position, it does appear that your hypothesis is worth investigating.

I'd need a few more laps to confirm this, but it also looks like you are braking at about the same point, for relatively the same amount of distance, sometimes even sooner.
I know I occasionally struggle to remember sometimes that I have added grip with a different compound and can go deeper into the braking zone. Even if the 225 R6 is a lot of tire for your current power levels, the red graph should be a shifted a tad more to the right since the lap starts of with a heavy braking zone... which is typical of a graph line comparing a faster lap with more grip.
You get bogged down on the front straight for some reason, and into T4, and T7. The acceleration should be linear just like on the ZII. If you didn't over-brake on the zII at T5, those lap times would be likely be equal.

Here's Marc's lap on 225A6. Notable speed deltas are:
T1-2: 124/48,
T4: 99/79,
T5-6: 108,45,
T7-9: 108,83
You're right there with him. Just need more acceleration, torque, and 1 second in T5

Another point, if you have a DL, load up Vehicle speed and wheel speeds as well. There are lots of trees at summit, so it could just be a plotting issue.

[ja1217]

Originally Posted by phastafrican

Another point, if you have a DL, load up Vehicle speed and wheel speeds as well. There are lots of trees at summit, so it could just be a plotting issue.

Here's the data, if you want to look at it:

https://drive.google.com/file/d/0Bz6...it?usp=sharing
https://drive.google.com/file/d/0Bz6...it?usp=sharing

According to the vehicle speed/wheel speed, the straight line difference is even higher (up to 6mph) although the corner speed on the hoosiers isn't as high as in the GPS data. Looking at the wheel speeds is also what is leading me towards getting an LSD as through turn 9 my rear inside wheel was spinning up to 9mph faster and just wasting power. And, the LSD is just a +1 so it will bring my to a nice, even 19 points in TTD with the 225 RC-1s and +5 exhaust.

Back to the street tire vs hoosier discussion, it is completely possible that I was over-driving the hoosiers and was more smooth on the street tires. I was trying desperately to get into the 1:25's, but was stuck at 1:26.1 for the weekend. I'll have a fresh set of R6's on when I go to VIR in October. So far my best time on the Z2's there is a 2:18.1 and 2:15.5 on the Hoosier's, although I was not having the best weekend when I was there with the Hoosier's. I was getting CEL's and ended up having to get my DI seals replaced after that event. I'll probably do another comparison with the street tires since I doubt I'll be in competition for winning any tires that weekend, being up against both Marc Cantor and Jon Kozlow.

[ja1217]

Originally Posted by celica73

Was that tire comparison done on the same weekend? Just wondering if it was hot and the engine was pulling timing with the Hoosier runs.

Same weekend, different days similar conditions each day though. Engine shouldn't have been pulling timing as it was probably the coolest it had ever been on track. That was my first weekend with the oil cooler installed. No more ~280f oil temps at the track

[ja1217]

Originally Posted by phastafrican

Interesting data. While I won't discount rolling resistance, 235 zII and 225 r6 should not vary by the amounts seen here. The width of the tires are extremely close, resulting in similar drag. I'm more inclined to think the setup is not allowing you to effectively put the power down.

A 4mph corner exit speed difference should be HUGE at the end of a straight. Typically, 1 mph difference on a medium-long straight is ~ 3mph difference, so there's something weird there as well. Without seeing other variables such as steering angle and throttle pedal position, it does appear that your hypothesis is worth investigating.

I'd need a few more laps to confirm this, but it also looks like you are braking at about the same point, for relatively the same amount of distance, sometimes even sooner.
I know I occasionally struggle to remember sometimes that I have added grip with a different compound and can go deeper into the braking zone. Even if the 225 R6 is a lot of tire for your current power levels, the red graph should be a shifted a tad more to the right since the lap starts of with a heavy braking zone... which is typical of a graph line comparing a faster lap with more grip.
You get bogged down on the front straight for some reason, and into T4, and T7. The acceleration should be linear just like on the ZII. If you didn't over-brake on the zII at T5, those lap times would be likely be equal.

Here's Marc's lap on 225A6. Notable speed deltas are:
T1-2: 124/48,
T4: 99/79,
T5-6: 108,45,
T7-9: 108,83
You're right there with him. Just need more acceleration, torque, and 1 second in T5

Marc was kind enough to send me his data for his fastest run. I've been over it a fair amount and its mostly down to lack of torque, but there are definitely places I can improve my driving.


Blue line is Marc, Red line is me.

[JustDoItMikey]

Originally Posted by celica73

I'm not seeing that for the RCE T2. They should be 5 points. They are only double adjustable with no remote reservoirs. They are not inverted, or have large shafts. That puts them in E3 and E5 for a total of 5 points. It's no different than running off the shelf Koni's and lowering springs.

Sorry I got confused by one of the previous posts and read it as confirming that the T2's were an E1 item. I thought the rules said "two or more adjustments" and then read the reply as confirming that. I reread the posts again figured it out.

To clarify for anyone reading through these posts; NASA TT rules will asses 5 points (E3 & E5) for coilovers with two or less damper adjustments (assuming no external dampers or large diameter shaft).

Im confusing things more than helping things I feel.

[phastafrican]

Originally Posted by JustDoItMikey

Sorry I got confused by one of the previous posts and read it as confirming that the T2's were an E1 item. I thought the rules said "two or more adjustments" and then read the reply as confirming that. I reread the posts again figured it out.

To clarify for anyone reading through these posts; NASA TT rules will asses 5 points (E3 & E5) for coilovers with two or less damper adjustments (assuming no external dampers or large diameter shaft).

Im confusing things more than helping things I feel.

Haha, ask away. I'm horrible on the internet before lunch... much confused unless I've had a healthy breakfast. There are no penalties here for getting something wrong, which I usually am anyway.
Sway bar endlinks are +2... that's one of the few rules that suck. Make sure whatever suspension works with the flimsy stock endlinks.

[THEmailman]

Originally Posted by phastafrican

Haha, ask away. I'm horrible on the internet before lunch... much confused unless I've had a healthy breakfast. There are no penalties here for getting something wrong, which I usually am anyway.
Sway bar endlinks are +2... that's one of the few rules that suck. Make sure whatever suspension works with the flimsy stock endlinks.

I dont know where this weak endlink tging com3s from but it took me about 10-15 minutes to cut one in half with a power metal hack saw hahaha

[phastafrican]

Originally Posted by ja1217

Marc was kind enough to send me his data for his fastest run. I've been over it a fair amount and its mostly down to lack of torque, but there are definitely places I can improve my driving.


Blue line is Marc, Red line is me.

Sticker R6s, better acceleration curve with a bit more power, and a smoother transitions at T3 and T5 should put you right on his heels. You've got him covered with most of the corner speeds. Just need to be able to get to the power a tad sooner. Just focus on that for the next event at Summit and see the results.
If I were your engineer looking at this, there are a few things to do.
There'll be some benefit in an LSD for sure, but I can't make that assumption given the state of the tires.
I'm seeing the loss happen after gear shifts. It looks like you're blipping the throttle on down shifts, but the RPMs are dropping too fast for an advantage in the heavy braking zones. Blip a little later, or transition onto the the throttle pedal 50ft earlier. Flat foot shifting might make a difference after all with the lack of torque. (think of go-karts).
That's a lot to focus on, assuming that a 1:24 is the ultimate lap. Anyway, I think we've gone quite

[phastafrican]

Originally Posted by THEmailman

I dont know where this weak endlink tging com3s from but it took me about 10-15 minutes to cut one in half with a power metal hack saw hahaha

I'm not saying I expect them to break or crack.... but they are subject to bending. If a car is set up to go nuts on cornering speeds, which I think I'll be trying to focus on, then I'm concerned there's some flexing with a lowered car at >-3camber and >1.5g in the turn. My floor jack bends it when I test loading the suspension with the wheel off. I could be absolutely wrong as well, but wish I could have something beefier.

[dradernh]

Originally Posted by phastafrican

I'd say don't make a decision based on worn out tires unless you plan on running worn out tires all the time.

So true.

It can be very instructive when you find your laptimes dropping off after the number of heat cycles has gone past the limit for you and your car, you come in and put on a fresh set of tires, and then go right back out and find that you have quite a different car under you. The first couple of times you do this are sort of magical.