chuckieho

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Fireindc

iTrader: (13)

I like it man. Good work.

doward

Need to get caught up!

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...

Wingman703

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?

doward

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.

doward

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.

emilio700

iTrader: (3)

Sorry if it was implied and I didn't get it, but what tire was the Mid-O TT5 record GR86 on?

doward

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...

doward

RC1v2, 255/40/17 17x10"