Mid Div TT development thread
 

So a little back story. I purchased this '13 FRS last year in April. Previous to my ownership a '15 engine/trans was swapped in after the original one let go of valve spring material. There was a good chunk of mods already done to it, but I've removed or swapped some parts more to my liking.


I ran mostly autocross with it, but started doing a few track days when possible last year. My first on track experience was at a Hallett High Speed Touring day. It was awesome. I've been back quite a few times at this point, and so far have wiggled my CCW time to 1:32.15 and CCW to 1:34.84. I've got more time to make up either direction, but the CCW were my first two times out with heavy traffic so it has the most to gain. This track is so hard on brakes plus a pretty rough surface. Still a fun place though, and not too far from home.



I also got a quick trip over to MSR Cresson late last year with a poor alignment and wet/cold weather. Either way it was a blast. I did clock a 2:45.16 after 2 sessions, with TONS of time left on the table. What a great track. I'd like to get back there in some better weather and try again.



Last month I ran North to Heartland at an SCCA TNiA to check it out. What a great facility and well laid out track. Smooth as butter compared to Hallett. With traffic all 3 sessions I managed to get a 1:59.74 running the Motorcycle GP circuit. This has a slower kink at turns 8/9. I am going back on the 30th of this month as a private day, so I should be able to have some clean space to run.



Anyway, I've decided to do some TT next year. HPDE days are fun, but I want to step into something with some competition. Looking at lap times for both Heartland and Hallett within the Mid Div or NASA Central region, I think it's plausible to podium at either facility.



Current weight with driver, no safety equipment and 1/2 a tank of 91 :


2912 lbs.


https://live.staticflickr.com/65535/...a04861e0_b.jpgUntitled by hatchethairy, on Flickr


I noticed my rear passenger sway link was broken when we started corner balance, so called it quits until my new Racer X ones show up.


I'm also planning a purchase of RR Racing Stage 1 front and Sport rear BBK. I'm going with Stage 1 due to wheel fitment with my street and track wheels. I think it will be enough thermal capacity added to help over the stock system. It's mainly for Hallett and to reduce consumables.



With my current weight and assumed wheel HP I'll be in Production C with either power to gain or weight to lose running with Mid Div. I don't really have any power to gain since I'm already running e85 and an ACE header. As for weight, I'd like to keep the car civil, so I doubt there's much in the way of low hanging fruit.


For NASA I could potentially be classed in TT5 if I ditch the rear spoiler. If not I'll probably end up in TT4. If I lose any weight for Mid Div, it effects my classing in NASA. Some head scratching left to do for sure.




Current mod list:


Engine:


ACE a350
e85/91 flex tune via ECUTEK

1320 dual resonated front pipe
Kraftwerks oil cooler with Derale thermostatic switch



Suspension/wheels:


Enkei Nt03+M 18x9.5 +40
245 40 18 Re71r

Eibach sways with Racer X endlinks

RCE Tarmac 2 with 500 pounders
Whiteline roll correction/bump steer kit

Raceseng Cascam plates
Whiteline toe arms
SPC control arms
Whiteline rack and pinion mounts

Perrin rack lock


Brakes:


Carbotech xp10 fr/rr
DBA t3 fr/rr
Goodridge stainless lines
Grimspeed MC brace
Motul RBF 600



Interior:


Beastronix auto pedal dance/TPMS

Velox throttle spacer kit
Cusco sports accelerator pedal
Scarco Champion wheel
NRG gen2 quick release
NRG short hub


Body:


Carsmo Duckbill spoiler
I've got some Bayson Motorsport STI style skirts to cover a dent on the passenger side, but not really wanting to install them. I also have a Downforce carbon fiber front lip. I pulled into a curb too quick popping the fasteners. Just been too lazy to put it back.



https://live.staticflickr.com/65535/...ba755d20_b.jpgIMG_5038 by hatchethairy, on Flickr


https://live.staticflickr.com/65535/...8e5634e7_b.jpgDSCF2938-(ZF-9848-96915-1-004) by hatchethairy, on Flickr


If anyone has any tips or tricks for a novice like myself that would be great.

Question for you aero folks:


I know this can be subjective based on driving style, parts installed, tire pressure, suspension settings, etc. but based on my above list would there be much gain/loss with re-installing my Downforce carbon lip and STI skirts with rear spats?


My main reason for install is to cover the unsightly passenger side dent, but if there's actual aero benefit I'd be persuaded to make it happen. Otherwise it will be taken to a body shop to remedy properly.



Also I imagine the duckbill spoiler isn't really doing too much. So small wing with splitter? If splitter, then ditch carbon lip? Wing or splitter recommendations?

Unless I'm missing something, with your mods (especially street tires) you can run TT5 easily with Aero.

You'll violate tire template with 9.5s, so step down to 17x9s and you can run R7s too.

Anyways, If you're going to take points for a duckbill - should most likely be running a dedicated rear wing. Same goes to splitter, your current lip isn't doing much.

I currently run Verus Front Splitter w/Race Upgrade and their new UCW Rear Wing offering. I've been happy so far with it, the rear wing has enough AOA adjustments and gradual adjustments where I'm not totally zero'd out trying to trim the car and can't dial any wing in it due to increased drag. Last week at NCM I was running 5 Degrees and set a sub 2:20 time on 15 Heat Cycle R7s in TT5 Trim (which would have been lap record if it was an official NASA event).

Good to know on aero. I think the issue may be dyno power and weight. I haven't had mine ran on a dyno, but was assuming a little over 200hp with e85 and ACE header to the rear wheel. I haven't dug into finding a chart with similar mods ran on a Dynojet with their specific corrections though. With a splitter added in and weight at 2925 that's right at 200hp. I'm sure if I drop the e85 that's an easy target. If I run r7s that's down to 192 hp, so I'm not sure how that would work. Maybe I'm way overestimating power or using the calculator wrong?



As for tire template, I tested it last night with the 266 limit and it had loads of room. With the 245 40 18 I thought I might be too close. Granted the wheel was still mounted to the car with weight on it. I also may be misunderstanding how the measurement works.


Also I should clarify the spoiler is only a points hit with the Mid Div rules. Technically if I leave ditch the spoiler I can get the points back for BTM aero with NASA though.

You’re thinking of peak HP, not average HP which is what NASA uses.

FWIW - my car at 186 Peak averages to about ~177 AVG HP. If you’re making 200 average you have a seriously stout car lol.

So, at MidOhio on Yokohamas from no Aero to Aero I dropped close to 1.5 seconds.

At NCM street tires to takeoff R7s I dropped 3 seconds.

So, IMO if you’re planning on NASA competition, it behooves you to run aero and Hoosiers. Obviously that’s not your primary goal, so build as you see fit


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That could make a big difference in what I had assumed was peak. I could have sworn I have seen an ACE a350 dyno with e85 at 206 or so peak though. Unfortunately NASA is not as prevalent in my area, so my plan is to mostly focus on the Mid Div and hopefully make a couple NASA events. Better to plan for both than chuck the kitchen sink at just one. BUT it sounds like I can run TT5 no problem with that knowledge.



Mid Div rules sound like peak numbers, so I just assumed NASA ran the same. This is Mid Div description:


A.3 Dyno runs must be produced on a Dyno-Jet chassis dynamometer. All readings will be corrected to SAE J1349 Rev JUN90 (29.23 in/hg, 77F, zero humidity) and the dyno’s smoothing function must be set to 5.

B.Dyno sheets must be from the current engine configuration and not more than 12 months old

C.If a Dyno-Jet brand dynamometer is not available in your area, sheets from other brands may be evaluated on a case by case basis.

Yup. Build for what you want to run and if it works in TT5 send it.

Just for information/reference.

https://uploads.tapatalk-cdn.com/202...451093a83d.jpg


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That helps explain it better.



What brakes are you running? I'm considering skipping the aero for now to pursue a better wheel/brake package. RR Racing is being flakey, and they seem to be the only kit that fits my street and track wheels. If not I really need to figure out a better setup for Hallett, and I think the stock brakes may be inadequate for the lap times I need to run.

I run AP Racing Sprint BBK Setup w/rear stock and DS1.11s all around.

Have had no complaints running 20-30 min sessions without any fade overheating.

We've had good experience on our own cars with the Sprint and Endurance AP kits. Also the newer Stoptech kit.

- Andrew

I also have a set of Cobalt Friction XR2 pads for OEM calipers at home I'd let go for a deal if you want to try stock calipers. :)

- Andrew

I'm not too familiar with those, but PM me price and maybe it's something I can consider.

So messing with the classing calculator for Mid Div I can squeeze into Production B if I do the following:




BBK with 4 or less pistons(no 2 piece rotors)

Simple rear spoiler, fixed wing(any suggestions?), side skirts, splitter/air dam

200tw tires
2923 lb minimum
186 hp


If I run 91 I think I should be okay HP wise, but since the car has never been on a dyno I have no clue what real world numbers I'd have with e85/ACE/catless front pipe.


Also I noticed that I'll have to go back to the stock steering wheel. Rules say interior piece removal is unrestricted providing it doesn't impact safety equipment. Pretty sure an airbag falls within range of that.

why waste money and points on brakes? It's TT, you're only going to get two flying laps out of the tires anyway, chuck some track pads+fluid at the stock calipers, take a lighter overall weight depending on where your dyno comes out and send it.

I think you are right. The only benefit I'll get from the BBK is lower consumable cost. That consumable cost goes way up when I have to buy two sets of wheels to clear the BBK. That seems silly, so I'm not going down that road at the moment. The XP10s I have right now are good for 6 or 7 laps at Hallett, and I think a better fluid could help that too. The RBF600 is good, but from some reading I think there are better options out there.

I spent a couple hours tinkering last night. I raised the car up to 13.75" from hub center to fender all the way around, which is an inch higher than my previous setup.

Installed new front bump stops since mine were crumbling away.

Rolled both front fenders for a little more tire clearance, but mainly driver side since that was the only side causing most of the issue.

Installed new Racer X end links. I'm pretty sure the Whitelines I had in the rear were binding and not short enough, probably causing the one to snap. The new ones I could set loose and tighten under load without issue. I feel like that was never possible with the Whitelines.
Carbotechs still have a ton of life left in them, so I'll probably keep running them into next season. I bought the Cobalt XR2 pads from Andrew, so I may throw those on with a new set of rotors for Hallett days or ones with heavy brake usage.



I scheduled an appointment with my tire shop to flip the Re71s and fresh alignment for tomorrow. I was hoping to have enough time messing with the scales for corner balance, but just wasn't in the cards.




Private track day is planned for Heartland this coming Sunday, so hopefully I can pick up some time compared to my last trip.

Car is back in my possession with the alignment and tire flipping. Basically looks like there was a lift kit installed compared to my last ride height setting, BUT it seems to soak up bumps better? It feels a little darty from what I think is tramlining while rolling down the highway. Not sure if that's from the tire wear or the tires themselves. I haven't really driven it much for the past month, so it was re-learn mode and questioning if there is something wrong with the alignment. I have a bumpsteer/roll center correction kit that was originally designed for lowering the car, but I think I'm above that level now. It may be time to go back to stock ball joints and tie rods? Could it be bumpsteer I'm getting? (edit: bump steer kit is okay for anything lower than 20mm from stock from some light reading, and I'm below that.)


https://live.staticflickr.com/65535/...af8ce875_b.jpgUntitled by hatchethairy, on Flickr

https://live.staticflickr.com/65535/...e1990fbd_b.jpgUntitled by hatchethairy, on Flickr

https://live.staticflickr.com/65535/...433dc84f_b.jpgUntitled by hatchethairy, on Flickr

A new track build to follow! Looking good.

My only suggestion is 17" wheels for lower tire cost. I have the bump steer kit as well. I am consistently considering ditching it, but I don't any data to prove it is hurting the performance. Unfortunately I changed other things when I installed it so I don't know how much it helped.

I really want to switch to 17s, but both my street and track wheels exist in 18s already. If things go well next season I'll track down a set of 17s, or at least when it's time to buy a new set of tires.

I started tracking on 18s no biggie. Its funny how much a mod list/priorities change once the track bug bites. I look forward to your progress.

It soaks up better because you have more travel in the shocks and aren't slamming off the bumpstops, presumably.

You'll need an event on the tires to re-scrub in the bevel.

0 Toe up front will still net you some tramlining regardless. Can be better/worse depending on what tire you have.

I bought the car with the nt03m wheels, and just have dealt with it. Every time I went to buy tires it was just cheaper to stick with the 18s since I have to buy a set of rims to reduce size. It probably would have paid for itself by now if I just got them the first time. Oh well.

So I spent a half day at Heartland Motorsports Park with quite a bit of seat time. I managed to sneak in times better than my previous trip with a best of 1:58.49 which is over a second quicker than before. Lots of different 1:58s and 1:59s peppered in there. I seem to do better chasing someone faster than me than out on my own for some reason. I had a time that clearly would have been a 1:56-57 but I shifted early and let a car by before I ran through the finish. It was excruciating to watch my timer tick away as I waited. Should have just ran into turn 1 before letting him by, I assumed he was closer to me. It's not a race though, so not that big of a deal.



Anyway, I had an issue with my Beastronix box causing a CEL and cutting power. The OBD connection must have been slightly knocked or loosened, as I couldn't get it to work again until I unplugged it completely and then re-seated the plug. VERY annoying, but it's working again for now. Manual pedal dance is for the birds, I've been spoiled for far too long. I see there's a new option available to replace this one, but not ready to throw money at it yet.



Suspension. I love how the car feels now. I should have raised the car up sooner.


I didn't bring enough e85 with me, so topping off with 91 was all I could manage later in the day. e85 and 91 I can feel the difference in power, but was still pretty close to my faster times with a lighter tank. The temp obviously rose later in the day as well, so it may not be enough difference to bother with e85? I guess if I want to be competitive just run the corn juice and bring more fuel with me. Tire trailer should help that as well.


Pretty sure my clutch is close to the end, or the pressure plate is struggling. I can feel my up shift being a little clanky. It's been like this for a little while, but I think it's time to address it before getting stuck somewhere.




Tires. I don't have much life left in the Re71s. People say they go all the way down to the cords, but I've never really ran tires below the wear bars before. I need to research how much I really have left, but they only have 4 track days and 1 autocross. I'm contemplating R7s for longevity throughout next season. I can run takeoffs cheaply or a new set to run the whole season which will probably be way cheaper than multiple sets of the Stones. If I run the R7s I'll be bumping up a class, but from the times I see from previous weekends I think I can still be competitive. Any thoughts from others on tire choice for being competitive and still somewhat easy on my wallet are welcomed.


Thinking on tires a bit, I am now wondering if my lack of camber before my latest alignment may have lost some tread early on in the Re71s. I was running 3 degrees because my Falken Rt615ks seemed to like that, but the Stones wanted 3.5. I wish I knew how much it could have made a difference.

Check this out for help with your fuel capacity issue

https://www.amazon.com/dp/B000MT94QA...v_ov_lig_dp_it

That's awesome. I'm going to put that on the "Christmas List" for the wife.

Stones probably want more than 3.5, FWIW. The 615s wear like iron so they're happy at any camber.

I have been able to score 1 HC R7s for $300/set. So I have 2 sets sitting in my basement right now that gauged at 99% life. For me, it's a no brainer to run a tire that is better suited for the track that'll last longer, for cheaper.

RE71Rs you're good for 1 magic lap and you're done. Everything after that is just tire wear

Where are you getting your r7s? How many days are you getting out of a set?

Via a friend hookup. Nice to get to know people ;)

JB Racing Tires is a good spot to check out though.

My current set has 21 HCs on them. Just ran 6 sessions (20 minute stint hot laps) on them at NCM last event and they're starting to fall off now. Pace wise they're about a Yokohama Pace

If you replace RE71R when wear gets to the indicators, you're getting less than half the useful life out of them. I would also be at the indicators after 4 track days, but when I kept running them on the BRZ while Porsche was in the shop last year, I got 6 more track days out of them and didn't reach the cords or lose much if anything in terms of grip due to heat cycles.

I'll snap some pics later, but my rear tread is almost gone. The fronts have a fraction more, so if I swapped to the rear I have maybe another half day on them. UNLESS you can run them with zero tread depth left.

I've had a couple friends order autocross compounds through JB and seemed to be pleased. I'll ask around to see if there's any that pop up. I know I can get some 255 40 17 Gforce 1s for cheap, but not sure those are worth snatching up over spending a little more for the r7s.

I'd say this is the replacement mark;
https://lh3.googleusercontent.com/3x...-no?authuser=0

We've run them down to this;

https://lh3.googleusercontent.com/Tq...-no?authuser=0


They get edgier, much harder to get 10/10ths out of them, but they still feel like they have grip to my butt dyno.

My rears are right about the same as yours above except my shoulders are even. Fronts have a smidge more depth, but I'll double check this evening.

You can run them with zero tread depth left...

If you were autoxing I'd say another event day or two depending on conditions via swapping, but assuming your TT offers HPDE levels of seat time (1-2 hours per day) fresh tires are relatively cheap.

You need more camber!
You probably should have flipped them before it came to this...

On my BRZ with -3.3 front -2.6 rear camber I never flipped them, just rotated every event. I ran them as "slicks" for at least 3 track days. Never showed cord.

Has anyone run the Falken rt660 yet?

I'm not honestly sure where I was at for that set of tires, I'm on -4.3°F and -2.3°R right now, will probably bump the rear up a bit and reduce the front a touch since I'm getting some inner camber wear along and I'll try a bit of toe out.

:cheers:

Interestingly I ran my rear tires like that at my last track day but with inner camber wear instead of outer. The tires (RS3's) felt the exact opposite. Loose but easy to catch in corners. Never felt like they had any real grip especially on throttle.

Different rubbers and construction, not surprising they act different as they age.

I hear BFG's for example feel exactly the same, they just have less grip.