Member Profile - Yowie's SH Forester XT

[Ric]

Thanks for reading.

Thanks for writing!

[Yowie]

Notes from a dirt-track day.

I took the car to a beginner training day at the dirt track auto club. Notes as follows:


Mechanical

The new engine (approx 3,300km old) used very little oil. The cold-engine dipstick level was more or less the same on the morning before the track day as the following morning. Turns out the Subaru stereotypes might not apply to brand-new engines.

It was a 36+ degrees celsius day. After a few runs on "high boost" (16psi - 215KW peak) I switched to the "low boost" (13psi 180KW peak) tune for the sake of engine safety and to bring overall heat down. There was no loss of fun at all and the practice sessions weren't timed/competitive anyway. For actual competition I'm tempted to use low-boost again, at least on hot days. The straights are relatively short so the benefit of max boost is probably marginal, at least while I'm a rookie.

The K-type thermocouple heat probes in the intercooler are having some kind of reliability issue and cannot be trusted for accuracy sometimes (including when needed on a hot track day as it turns out). I'll email the seller to see if they have any clues and/or research the issue. Perhaps the non-enclosed ends get contaminated by fluid in the charge air stream? Or perhaps K-type thermocouples are a bit twitchy as a general rule?

With the new VF52 (versus the old VF46) there is no longer the instant "go" from the start pad (I'll need to rev it more for that) but for the mid-high revs operating range of the relatively tight "second and third gear" track there was no problem with being outside the boost threshold.

For some idling on the day and a bit since the car is running a bit lean (per AFR gauge and my ears). I'll check all the catch can & breather hoses to see if anything dislodged with all the bumps, and if so, re-attach via stronger methods. Catch can contents (both) was minimal, so either the water vapour in the crank gas does not condense on a very hot day OR a hose has come off.

Marking suspension nuts/bolts (when tight) with a paint pen makes it very easy to detect a loosened nut visually. The car developed a mild suspension clunk. A quick visual check revealed that a front swaybar link nut had backed off. It would have taken 30 minutes spanner-checking everything to find that.



On-track

I had the privilege of some in-car coaching, plus the fastest AWD turbo driver in the club took my car for a spin.

Tips for improvement include:

- Hands at 9 & 3 always (no let-go to let the car straighten from a slide)

- Look further ahead, including through the side window

- Late apex (most/all corners)

- via line selection & late apex, "straighten" the wobbly section before the final turn and drive it harder

- Harder braking closer to corner

- Accelerate & brake through sections where I tended to “cruise”

- the dirt track changes day-by-day and sometimes even run-by-run, so there is no textbook perfect line and set of inputs. The driver needs to feel for where/when the car has grip on each corner each time and exploit that.


Interestingly, for this club, the AWD turbo class post the best times, but the front-wheel-drives (usually cheap/light low-powered cars) generally post the second-best times. Rear-wheel drives come in after that. Must be to do with the front wheels being able to drag a car out of a corner on a slippery surface.

[Stifull]

Sounds like a fun day. By the sounds of it you were at Willowbank, not Lakeside.. WB is a much safer track.

[bigBADbenny]

We’d run and record a dozen thermocouples on pre and post weld heat treatments, thick cro-mo or mild pipe usually if not refactory or gas combustion.

They’re attached using a capacitive welder to the workpiece, but also used the probe type. They’re all unreliable enough that redundant pairs or spares are essential. All that matters is that the resistive wires, a pair that constitutes a thermocouple (usually red and yellow) are shielded, usually with fibreglass sheath, up to the bare tip which is either twisted three times, then applied in contact, or in a stainless probe sheath (like yours?) or resistive welded with a 3mm gap between signal and ground wires on the workpiece or contact plate.

As such your thermocouple probes should be serviceable.

What’s the fault mode?

Are your thermocouple wires from the probe to the gauge in a twisted pair configuration start to finish?

Otherwise there’s compensating cable that you can use to extend TC wires.

You might get a few meters of comp wire from your local heat tech hq, for a six pack

Random link see TC precautions: https://www.omron.com.au/service_suppor ... /index.asp

[Yowie]

STIFULL: Willowbank, not Lakeside..

Correct. The large dirt track with Qld Raceway (paper clip) to the west and the end of the drag strip to the south.

https://www.google.com.au/maps/@-27.693 ... !1e3?hl=en

BEN: (1) They’re all unreliable enough that redundant pairs or spares are essential.
(2) or in a stainless probe sheath (like yours?)
(3) What’s the fault mode?
(4) Are your thermocouple wires from the probe to the gauge in a twisted pair configuration start to finish?

(1) Very interesting.

(2) The "air temp" versions I am using have exposed ends - hence my contamination mini-theory. I have some non-installed sealed units for auto transmission fluid temp sensing. I am perpetually "going to" install those.

(3) Unrealistically low gauge temperatures. When its 36 degrees in the shade and the intercooler is too hot to touch on the "cold side" there is no way that the cold side air temp is in the twenties. Bizarrely, there is a worse version that has occurred a few times when I drive out of the motorsports complex at the end of a dirt track day - 14 degrees C apparent cold side in Ipswich Queensland in the afternoon. Bull F***ing Sh*t.

Bizarrely, for normal driving it will all work properly a large percentage of the time.

(4) No idea. It's a plug & play set from these guys https://thesensorconnection.com/product ... s-products with a fairly well insulated lead from probe-to-gauge. I have not extended any wiring.

[Yowie]

Whiteline pitch-stop mount

A quick update. I experienced some thump on hard gear changes. The engine mounts and gearbox mount have been replaced very recently, so that just leaves the original pitch-stop mount.

I wanted to try an aftermarket option and ended up ordering the Whitleline pitch stop mount because:
- good price
- bushings both ends (some were all metal one or both ends)
- no fancy milling so big flat planes in case I need to drill & tap a small threaded hole or two to mount something on it one day (seems to be ample spare strength)
- Australian company.





The original pitch-stop mount had the steel insert loose within the rubber at the small end. This is almost certainly the source of the clunk sound on gear shift.

Installation is very simple. Remove intercooler, remove the two OEM bolts, apply bushing grease, install new pitch-stop mount, bolts back in, intercooler back in.




(excuse the clutter under my intercooler)

With the harder bell-housing to firewall connection I notice a bit more noise when cranking the starter, but otherwise I can't tell that there is a harder-than-OEM pitch stop mount. I have a medium-volume aftermarket exhaust, so the story may differ in a stock vehicle. EDIT: under certain conditions/harmonics I can hear/feel the harder linkage, but it is rare.

The clunk-on-gearshift has gone away.

Thanks for reading.

[Yowie]

Secondary Air Pump delete and blanking plates

This is a bit of a photo essay on fabricating and installing some Secondary Air Pump blanking plates without flash workshop tools.

As most Subaru owners would know, the secondary air pump runs for about 30 seconds on cold start to feed extra air into the exhaust manifold to get the catalytic converter hot nice and early to burn that fuel-rich cold-start exhaust. The trouble is, the secondary air pump system is prone to malfunction - apparently sometimes causing fires when a solenoid jams open. My tuner permanently deactivated the secondary air pump system as part of their standard service. This meant I could remove some engine bay clutter and blank off the air feeds to the heads.

I had the turbo and dump pipe off anyway for "better alignment" reasons so it was a good opportunity to sort this blanking job.




Forum member TMP243 send me these machine-cut plastic templates for blanking plates. I now have spares so hit me up if you want a pair sent to you. Without the templates, matching (or going larger than) the metal gaskets is fine. The external dimensions are non-critical.




I started by applying permanent marker to some 6mm aluminium billet (bought as offcuts from a local aluminium dealer).

I then clamped the plastic template to the billet, scribed around it and marked the centre of the holes with a transfer punch.



I then drilled-the holes to M6 bolt size and de-burred the holes. The holes come in handy for work-holding as the plate becomes smaller and not-square.




I then cleaned up one end with a hacksaw, files and sandpaper. Always consider work-holding in your order of operations. Here I am taking advantage of the piece still being connected to the billet for some of the fiddly jobs.






A "1-2-3 block" comes in handy for work holding once the plate gets fiddly. If you don't have 1-2-3 blocks, an equivalent piece of box steel or hardwood with a suitable hole should do the trick.



The larger passenger side was a similar process, except the holes are drilled for M8 bolts. The plates are finished with wet & dry sandpaper (with WD40) on a flat surface.


Driver's Side (Australian right-hand-drive vehicle)



On the driver's side, this metal air feed pipe lives on the back of the head behind the dump pipe (which will need to be removed for you to get at all this). Also visible in shot is the end of the silicone turbo inlet pipe. I have left in-place the large solenoid the metal pipe connects to (to hard to remove with manifold in place).

However next time the inlet manifold comes off, the large solenoid can come off with it (but keeping the pressure sensor part of it).




This is the small hole to feed air into the exhaust side of the head on cold start.




Now blanked off. You can use the same bolts on the driver's side. Make sure you use the thin metal gaskets when installing the blanking plates.


Passenger Side



On the passenger side there is this smaller solenoid mounted on a robust/structural air feed pipe held to the head via the two M8 bolts. Also visible in that photo is the soft plastic secondary air crossover pipe and the blue throttle body hose. The soft crossover pipe is removable from the engine without removing the manifold with a bit of sweat & swearing. The solenoid assembly, plastic rocker-cover air supply hose and secondary air pump at the front all come off easily without disassembling much.




Once again, the secondary air feed hole to the head is small.




...and now blanked off. You will need shorter bolts on this side because the blanking plate is thinner than the passenger side assembly.





You can leave the secondary air pump in place for stealth if you like. I chose to remove it. This leaves this robust cast alloy bracket which now only holds an upright to support the wiring loom.






I made this aluminium bracket to replace the wiring loom support. It probably isn't necessary - zip ties or even "no wiring loom support" would probably be fine. This car gets shaken a bit on dirt tracks so I don't want to test my luck.

On youtube I have seen some people thin out their wiring loom to remove the now unnecessary wires. I elected not to do that. The now unneeded power supply plug for the absent secondary air pump is wrapped in electrical tape and "Jetstar handcuffed" (ziptied) to the new bracket.






Finally, before putting the up-pipe back in I ground off this unnecessary bracket. Presumably it relates to OEM heat shields which I do not use (I use blankets). Removing the bracket might save some swearing if I need to get a hand or tools into that area later.