Shortcutsleeping

I'll throw out a few more data points here on splitter height.

First, we do not care what the splitter does in a straight line. In fact, if we were straight line racing (I'm looking at you, drag racing, along with your buddies "half-mile", "full-mile" and "bonneville") we'd want only enough downforce to keep directional stability because every ounce beyond that limits speed and straight line is all about speed. Speed FTW!

For those of us in the turning department it has been proven too many times to mention that when we press the car down to the pavement (a little or a lot) we increase cornering speeds resulting in the reduction in top speed (eh) as well as a reduction in lap times (now we're talkin!).

Having the benefit of setting up or advising on setups in a tunnel many times to max df and perfect balance, not one single car has come out of the tunnel balanced in 'real life' (skid pad or high speed corner). Not even close. Each one has required a big change to balance it 'in the real world'.

Why? Lots of reasons...

The 'real world' has lean as well as direction of travel (DOT) angling the wind component. Where air 'stacked up' in a straight line, when we alter the DOT that area is washed laterally. When you're at max grip in a 90mph corner how much did the inboard edge of the splitter rise and how much did the outboard edge drop? Take a snap in action and check it out.

Now introduce heat. Heat dramatically changes the properties of the air with respect to plume expansion/contraction as well as general levitation. While the air under/over the splitter will be ambient, in a turn the inboard tire/wheel/brake is exposed and that air is typically hotter than ambient. It drives odd behavior on the edge of the splitter, changing both velocity and vector.

We won't even get into waterfall hoods and rear wing....

Back to the topic, of course a splitter helps, but please test. We tested at T2/T3 cota as well as the carousel. When legal, we ended up with a hell of a lot more splitter than 3" and it was faster when we went bigger. Of course, we didn't measure mythical numbers in a straight line since we only care about the corners. <loller>

Aero is complex. F1 teams spend kazillions in CFD and a bazillion hours in a real tunnel. And yet....they all show up to the first test and some/many are crap. Most/All of them have big revisions of wings and aero devices to optimize in the 'real world' and lap times drop. One of the things I love in RacecarEngineering magazine is the little illustrations they do to show aero changes/generations to a single car over the course of a test/races/season as they worked to improve performance.

I'm not here to rain on the data, I just want to bring a dose of reality into the conversation. Like F1, use simulations to give you a starting point, but be ready to test a lot of changes to optimize.

"Trust, but verify" ~Reagan

Costas
cars and such...

romandian

surely the optimal height must depend on speed?

also, what about the angle from horizontal?

STANG KILLA SS

First race of the '24 season. at Cresson
an eventful, uneventful event
one of the 1100 lb Rush SR prototypes in my class. didnt have any chance against him on this 1.7 mile track. he was some 3 seconds faster a lap.
so needless to say i only saw him on the first lap starts.
however we fought electrical gremlins.
just before the loading for the race at home, i realized the alternator and battery were both done. so put in a new alternator and battery. all fixed right?
wrong. Race 1 we smoke the brand new alternator, and the new battery just wasnt keeping up cranking the 7L.
so searched around located a new alternator, bought a new proper battery while there, and it seemed to fix everything. had to miss race #2 to get it fixed.
other that that pretty uneventful. but a good time with the fam.







despite loosing 1/2 a second to the CMC cars, this was somehow still my fastest lap of the weekend.
we were on 15 heat cycle R7s. 20 by the end of the weekend.

lobsterroboto

you should really consider detuning to 2 or 3 , we need to increase car counts.

STANG KILLA SS

working on that.
i agree. kinda boring doing solo laps.
likely gonna bulid a ST4 car though. seems to have the highest car count in texas region.

STANG KILLA SS

back to back race weekends and without a doubt my biggest race of the year.
season opener at Super Lap Battle, the GLTC race at Circuit of the Americas!
unfortunately with the new rules we were 90 lbs heavier and on old tires with 15 heat cycles, that were 20mm too narrow. so just not competitive all weekend.



car was a bit over steery and had alot of body roll, so we added some front sway bar, and rear wing. really helped. gained about a second on lap time and made the car much more confident to drive.



overall a great weekend though. fought an issue were the car would randomly only take 10% throttle, but a quick power cycle would fix it instantly. never seemed to bother me in the races. always happening on the outlap or cool down lap.





near the end of Race 3, i was coming down into T2 and grabed 4th a little to hard and lost all forward drive. after getting towed back we discovered a broken axle. thought our weekend was done.
luckily my crew was able to track down a spare axle from another racer in the pits, and the tools we needed to change it (mostly a 32mm axle nut socket and an impact more powerful than mine. as well as some reverse torx E sockets for the axle bolts) in about an hour the new axle was in and good to go to make the final race!





couldnt have done it without my family and crew!


despite the under prepared car, i was able to go 1.1 seconds faster than last year. sadly the rest of the field all got 2 seconds faster than last year. i felt like i drove well just didnt have the car or tires to mix it up with them.

my fastest lap of the weekend.

96GS#007

Congrats on getting the axle solved and back on track! I always appreciate your videos!

One sincere suggestion.....helmet shield down or at least nearly so. I know it gets hot and many of us have a habit of leaving it up, but as you're aware when racing....particularly in traffic....**** happens.

TrackAire

My one piece of advice is if you care about your placement, then you're first priority has to be fresh tires of the correct size. Why spend so much money to go racing but not spend the money on new tires? That one second per lap could have easily be made up with stickier rubber.....which the fastest guys probably had.

STANG KILLA SS

your 100% right.
what i didnt mention in the write up, is since the beginning the plan was so sell this car right after the race. (literally held onto it for 8 months just for this one race or it would have already been sold.)
i just didnt want to spend $1600 for a set of tires just to sell it. but i knew that going in. profit wise it just didnt make sense.
but as you pointed out, just goes to show how tires are the #1 most important part of a build. i would have had a hell of alot more fun and been more competitive had i spent the money.
but i had the end long goal on my mind.

lobsterroboto

how much you want for it?

Captain Buddha

Why you leave your visor down (among other reasons)...this is Mark's helmet (from AMT):

STANG KILLA SS

gonna start at 39k but i think the market has fallen a bit since i made that decision.

smitty2919

Less helmet cam footage, more roll cage footage. I'm all kinds of dizzy now

STANG KILLA SS

i also have a B pillar cam. but i always prefer the helmet cam when i watch both. also helps me when i go back to study brake points etc next year.

SocalC5Z

Couldn't agree more. Don't understand the attraction to head movement footage.