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Its April and the car has already done three days on track, two back to back weekends and all I did was add oil and PUMP gas! What an awesome change of pace from the last couple years.
The first of which was a Sunday only HPDE with AutoInterests at Mid Ohio. The first "public" day on the new pavement. WRL was here a week before, but thats an endurance racing org.
I ran 2 sessions on 245/40/15 Falken RT660 on 9.5" as Gridlife GLTC and general 200tw street tire practice. I've havent driven a Miata on track on street tires since "Taxi" on BFG Rival S for SuperLapBattle 2018?
Then 2 sessions on my old-DOT-but-only-1year-since-first-heat-cycle 225/45/15 Hoosier R7 on 9.5"
Then ended the day back on the RT660s.
I was super rusty, was only a handful of tenths faster on the R7s, basically a seat time/re-acclimation day, no real testing work done.
In prep for NASA I did find that both right side lower control arms had slipped, which could/does explain some of my handling complaints and lack of pace at the DE day.
The K24 is also still messing with me mentally. I've been struggling to wrap it out over 7400rpm after so many years(a decade?) of racing BP4Ws that I'm just hardwired to shift before 7800rpm. The balance shaft delete vibrations are so not-normal to me. I also did my first two events, last august ST4 and two weeks ago HPDE on the Hoosier R7 detune. I got so used to that ~185 peak/178avg power level that switching maps and gaining ~15whp was not even noticeable.
I tried a max power map, no splitter, small tire credit(226mm tire while over 2400lbs), 1.6 category(Toyo RR) credit, 2450lb build this month. Went slower than I did in august, even with a repave and a new class record being set ahead of me on the podium. Toyo RR are no bueno. These are 225/45/15 RR on 15x9 +35 Rota Grids
I did bring home two 3rds out of a contingency paying "full" class of 5 and a 2nd in the new Time Trial Target class(most consistent two laps of of your two fastest sessions). Moral victories...
So the plan is to slap my new 4.77 OsGiken in, cut my restrictor plates and get back on a dyno for an attempt at a ~180 average whp flat tune.
That will let me run 245/40/15 Maxxis Rc1v2(which is the fastest of the 1.6 category tires. The same map will let me run pretty light for GLTC in June.
I also have an AIM MXM and a SmartyCam here, ready to install. I hope that big bright display telling me im short shifting will help me not short shift...
Teases several posts with hotboi bumper
Doesn't run hotboi bumper
k
Is it really just going to be a very specific GLTC spec thing, or did you abandon it in favor of the ugly but functional airdam?
TEEHEE!
It is very specifically illegal in 5.
It is legal, but penalized in 4 due to the "canards"
It is legal, but penalized in GLTC for the same reason, but GLTC is a class for much bigger/heavier cars on 255-305mm 18" tires and has a written rule about cars that look cool get more stream time, so...
So, it WILL make an appearance in GLTC in June(alongside a bbk and maybe some V8R FLCAs) which means it might just stay on the car for ST4/TT4 in August.
So, the ruleset has moved on from Hoosier. NASA has iterated into the required maths to properly hinder/disincentive their "requirement" to be competitive. In ST5/TT5 it really has become possible to win and set records on something other than Hoosier R7s. Hoosiers are right there, and arguably still the preference for an ST_ car due to long race heat soak, but the Maxxis RC1v2 seems to be the hot ticket for cars with enough power to take the big 1.6 tire category credit. Aero still wins, splitters seem to be very much 'worth' the penalty still.
The car that reset the Mid O Pro record that was set during the 2019 Championships was a 2nd gen GR86.
255/40/17 RC1
17x10
OsGiken lsd
SPL FLCA (The arm is allowed for free with last year's power creep rules adjutsment, but the SPL part in question is all spherical, so Jimmy takes the extra .2 penalty. He gains some cheeky roll center correction too though)
A-arm
Splitter, diy plywood
Zebulon wing
longtube 4-2-1 header, e85, detune for flat power.
I ran last weekend on a "missile" build. I removed my splitter, removed my Hoosiers, went to a 1.6 category Toyo RR, AND downsized them (225/45/15 when I am allowed 245/40/15)to take the "small tire credit" at the lightest possible weight breakpoint for that credit. All in order to remove my 60% TPS detune and run my full power map, gaining over 20whp.
I think the sheer quantity of compromises was too much for the power to cover, as even my AIM theoretical best lap possible would have been over a second off the new record, and only matching my previous PBs set on Hoosier R7s. Terminal velocities were only up a mph or 2. 128 vs 126 on the 205/50/15 and 146whp GLTC setup. I have done another 36.9 on 225/45/15 hoosiers in nasa TT detune spec but that was only a 125mph terminal. Top speeds all in different conditions, one with a tow, etc. Miatas hit a brick wall up top and their speed comes from lateral grip. Building a missile miata is stupid. Dont do what i did.
I drove a 1:38.001 according to transponder/timing and scoring.
I drove a 138.124 according to AIM
I rolled a 1:37.640
Theoretical best of a 1:36.8, which would have only~tied what i did in August last year, and in GLTC in 2021.
If I replicated the big rc1 + splitter formula that jimmy ran by adding weight and only doing a slight detune for flat power, It would look like:
- 245/40/15 RC1 on 15x10 (~$1900)
- 4" splitter
- add another ~130lbs of ballast
- go spend a couple more hours on a dyno.
1. Status Quo. 2450lbs, 187avgwhp 225 RR, no splitter (how I ran it last)
2. Record replica 2567lbs, 186avgwhp 245 RC1, + splitter + ballast
3. Add only aero. 2530lbs, 186avgwhp, 225 RR, + splitter + ballast to cover.
4. Add only tires. 2493lbs, 186avgwhp, 245 RC1, no splitter + ballast
The extra .1 ratio comp weight chart credit from 2450lbs to 2550lbs is worth 8.5whp when combined with the 100lbs of ballast from 2450 to 2550lbs.
This all gets cloudier when I know I would rather drive a zero-ballast car with a splitter on hooisers. Thats an ST4 car, which gets a free BBK and allows my Garage Vary bumper. That makes it much easier to slot into GLTC 1-2x/year with just a tire change and some ballast...
I also cut up the old alumalite splitter that got ripped off the car to act as a mockup undertray. This will now template my rear edge shape, mounting hole locations and tire clearance for a fresh alumalite splitter or undertray to be cut to follow either the inner lip of the GV bumper, or 3" exposed if I drop the mounts down an inch to act as a splitter.
Having the undertray slotted inside the lip of the bumper also helps support the weight of the bumper and reduce the headlight gap.
Also pumped to get a 4.78 geared OSGiken diff back in the car. I had one way back in the PTE days and loved how it transformed the car. Sold it for Supermiata S2 prep(4.3 Torsen that is still in the car today)
Welp, lets get this back up to date!
The NASA ST5 no-splitter trashcan bumper *might* have seen its last usage. However, i crafted a new radiator duct and did NOT repurpose the one that fits this flat-front airdam and oem bumper half. So here is one more shot of that setup that has surfaced since the events prior...
First step was to slap the bumper on so I could gaze at the combined hotboi of the ModeloDrive "GarageVary-ish" bumper and the Rota Grid "Teehee37s"
Then, off came the Toyos. I hope I never have to drive on them again. For sale, lightly used, super low miles, only driven on weekends...
In went the 4.77 OSG:
...and then splitter fabrication could begin.
First step was to square off/level the bottom of this bumper:
Then my alumalite mockup undertray was transferred to plywood, the mounts lowered an inch and the too-large-for-now splitter temporarily installed for the first of eleven times on and off the car.
I very breifly considered following these bump outs on the sides, but decided that having a splitter molded into the bumper, plus the canards PLUS an additional 3" of 'real' splitter might be too far into the grey area foe me. So I stuck to a constant radius for the leading edge.
The sides of the splitter were cut flush, this is a w2w racecar after all and also not a bleeding edge competitive one in either class at this point, so the 2.5" of surface area were sacrificed for keeping everything inside the track width.
Radiator blockoff panels mocked and trimmed.
new duct was arts-and-crafted:
Splitter got some rustoleum:
Also pictured is my previous Supermiata Crossflow. I sent a 12" sawzall blade through the core while trimming out more of the front core support to make this new rad inlet duct more of a square... Luckily SPM had them in stock and I caught Ed before Fedex overnight pickup deadline. This was Tuesday night:
New radiator installed on wednesday, and everything could go back on for the final time!
extra little airdam thing to cover that front bumper curl shape.
Proof of legality, GLTC is a 3" maximum exposed blade.
Then it was again time to stare at it like a showcar.
New stickers.
loaded up. It is pretty weird going to the track with no 'rain tires' and no "B" tires or scrubs. 200tw racing is wild.
Delivered. Also, peep the new Supermiata hood art. (it didnt stay on very well, this carbon texture vinyl is tough stuff and the hood sees way more airflow than the doors do)
The other project I didnt quite finish was the AIM MXM dash and AIM SmartyCam HD.
Both got installed, but I didnt get the dash communicating properly to the ECU, so I was flying blind again. Much like the first race weekend on the kswap last fall before I got the factory cluster working...
shitty potato cam photo. i'll get a better one out in the sunlight some day.
Nice updates! How's the freedom express tow rig been treating you so far?
Its great. We've put ~6k miles on it in about 18 months. Lots of learning about RV maintenance and im glad the 36k mile 6.0L drivetrain is the last thing we have to worry about. Lots of fresh water lines, fittings, a sink faucet, water pump, generator rebuild/tuneup, etc...
I still want an enclosed trailer to go along with it and have lined up first rights of refusal on a buddies.
This event was just to enjoy being racing again. I knew i;d be midpack, and I was. Qualified right at the A group/B group split and started Race 1 on the front row. Went backwards every race due to the car pulling timing due to air in the rear outlet from my radiator swap wednesday night. Oh well. Still had a blast.
I'm also feeling more and more confident in the swap. Dont want to jinx it though.
Next event currently planned in NASA Mid Ohio in late August for my annual birthday race. I would like to find a test day or HPDE between now and then though.
P2, front row for Race 1B.
245/40/15 RT660s are big.
Cool side shot of the Signal Auto splash.
Corvettes and BMWs and Hondas, OH MY!
Probably the best lit shot of the front aero, where you can actually see the block off panels, grill and ducting.
Super awesome stuff all around! Would love to see some driving footage if you have any, and also your thoughts on the MXM once you get more experience with it. That front bumper looks pretty cool.
04-26-2024, 10:25 PM
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