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.