[Autocross] Points Event #1 with TSCC: April 2024
A successful shakedown to start the autocross season
Notable changes to the car for 2024:
This was the first autocross of the year, and while I did run at VIR a couple months ago, the car was largely untouched since then due to wanting to assess it as-is in an autocross setting as well before making any wild changes:
034 RCO Lower ball joints
034 Lowering springs
Fresh BFI LCA bushings and Superpro forward LCA bushings
S3/R aluminum subframe + 034 subframe alignment kit
Looking back at past Trip Reports, I wish I’d done a better job of documenting changes made to the car, etc. on a per-event basis. I’m going to attempt to start dropping a snip of this spreadsheet w/ each event to keep track of changes.
Current setup as run for the autocross
Changes made since the February VIR event:
Girodisc 340x30 2pc rotors - won’t make any appreciable difference for autocross, but before the next track event there will be a major effort to push as much cooling air through the rotors to see if I can drop rotor temps (currently have registered ~1500F w/ the DS3.12/1.11 combo)
245/40R17 Bridgestone RE71RS - Will be nice to finally be on a competitive autocross compound.
Playing around with some various PCV setups
Non-car changes for 2024:
Trying to get a bit better at autocross again I got a buddy of mine (Logan) codriving with me all year this year. This first event we were a tenth off of each other so I think it’ll be a really solid year for personal development, plus will be great to get some feedback on the car itself as well. He normally drives a pretty ridiculous C5 Corvette with way too much money dumped into it, so it’ll be interesting to get his feedback on the handling since Corvettes are basically just much better Miatas. The two best cars I’ve ever hopped into to autocross were a C5 prepped for CAM-S and a C6 Z06 on Hoosiers. They just do exactly what you want.
So how did the event go?
I’m back doing novice course walks and ride-alongs this year with the Tidewater Sports Car Club. We had a bunch of novices come out, so the day was pretty busy as expected for the first event of the year. Weather was great - not overly hot or cold. I had my son with me so he got to ride along with a few cars and in mine for a couple runs as well (he’s actually in the passenger seat in the head-on shot at the top of this article).
I’m not exactly hyper-competitive when it comes to autocross, and competing on PAX is kind of a losing proposition because the XA (Xtreme Street A) PAX is basically screwed unless you build a Street Mod car on 200TW tires. However, we have a lot of people that run this class locally so that makes it a lot of fun.
TSCC combines all of the “Provisional” classes into one PAX-based category for trophy purposes… so as far as the club results go, we are also competing directly against the CAM classes… which have an insanely easy PAX by comparison. Competing directly within XA while comparing mine and my codrivers’ runs is the primary objective this year.
Here was my fastest run:
And my co-driver Logan’s fastest… he managed to beat me by 0.069 sec (nice). Watching the two runs side by side it appears he had much better time through the slalom and I had a better launch. My only data available currently is Simos Tools for autocross, because the Garmin Catalyst does not work for autocross. Getting something else later this year so that autocross GPS data can also be used is definitely on the radar. It might be time to step up to a fully integrated on-board data system like a RaceCapture unit.
What was learned?
The car definitely seems to do better cutting distance moreso than trying to preserve momentum. With the SwitchPatch Traction Control on the ECU tune, the car accelerates very quickly for being FWD.
VMP has a bumpy lot and you can tell the car is bouncing off the bump stops continuously in the long sweepers. Since this event I’ve trimmed the bump stops a bit more, which feels considerably better on the street - much more compliant and the car bites up front a LOT harder now… but we’ll have to see how that changes on course at the next event in a few weeks.
The car being lower via the 034 springs (going strictly based off of memory) is definitely better under transition (slaloms) than at stock ride height. This is something that isn’t near as easy to test. Admittedly I just wanted the car to look a bit better and at least not make it worse than stock. These shocks are not ideal for lowering springs so that has to be taken into account as well, though they seem to be working far better since after the event when I trimmed the bump stops a bit more.
The 034 ball joints gave no issues just autocrossing. Speeds aren’t high enough, you’re not hitting curbs, etc for any bump steer issues to be noticeable. If you’re not wanting to stay in STH (GTI) or STU (Golf R), then they’re a viable option for adding grip cheaply. These ball joints + the hood vent are the main reasons my car now has to be run in XA instead of STH.
It is worth noting that my original 034 ball joints have already worn out after only 3 days on track and less than 3000 miles of driving, clunking with ~1/8in of play. This may have been accelerated wear due to not running the brake backing plates and heating them up. I purchased another set of them prior to this event and installed new backing plates + covered the ball joints in aluminum heat shielding tape as a secondary precaution. We’ll see if they hold up long-term. I still need to try and dial out at least some of the bump steer to want to use them in May at VIR.
And the PCV Testing…
Basically I’m trying to test as much as possible to see what the limits/ideal operating parameters of the MK8 full retrofit really are. With the Venturi as a supplemental vacuum source, it gives the MK8 PCV a LOT of flexibility with regards to setup optimization. One of the potential problems for bigger turbo cars is pulling “too much” vacuum, which while it hasn’t caused “problems” per se, monitoring the crankcase pressure post-diaphragm indicates that this may be holding the diaphragm shut which shows up as a less smooth/spikey trace. On my IS20 this is not a problem with the BMS TIP (which provides weak vacuum on it’s own) vs say an APR TIP (medium vacuum) or stock (lots of vacuum).
I’ve been running this setup on the street for several weeks. On my IS20, there’s really no “up side” to it as there are some conditions in daily driving where the crankcase can get slightly into the positive (+0.05 to 0.10psi) - primarily stuff like 7th gear, slight up hill just maintaining throttle. This is pretty on par with an OEM PCV valve, so not a massive downside as far as that goes.
The way the above setup works is unlike most VTA (vent to atmosphere) setups: Boost powers the Venturi, which pulls a vacuum on the crankcase. The boost and evacuated crankcase gasses are then blown into the catch can which is vented to atmosphere. A normal VTA setup has no ability to generate any vacuum, and instead the best case scenario is that it won’t be under pressure when at WOT. The turbo inlet pipe itself is plugged w/ a 1in ID rubber cap.
So how did it do? In a nut shell there was zero perceptible oil loss on the dipstick and zero smoking from the tailpipe (note there were 2 other MK7s at the event which DID have this issue). You can watch the PCV and CC values in the autocross run videos above.
The catch can hasn’t caught anything in the past several weeks and ~600mi of normal driving, pulls, hooning around… but over the course of 10 autocross runs it did capture a couple teaspoons of oil.
Since the BMS TIP + IS20 provides a decent vacuum, I’m now running the BMS can like originally designed: with the outlet connected back to the TIP.
I plan on making a video in the future going over ALL the stuff I’ve tested thus far PCV wise… because it hasn’t all been documented just yet. I think this variation may be about the best option for these cars when tracked/autocrossed hard.
Event Results Summary
Logan beat me by less than a tenth so we finished:
1st and 2nd (of 12) in XA
4th and 5th (of 22) in the Provisional Class (PAX based vs all CAM classes and XB as well)
14th and 15th (of 86) in overall PAX
8th and 9th (of 86) in raw time - Also worth noting is this was the fastest wrong wheel drive car of the day.
