Sam's build thread

[pogopins]

Partner & I wanted to pick up some stuff at the blue+yellow shop today but got there and found the carpark just about full so just turned around and went back home. About an hour round trip, mostly in slow but moving traffic. It's been cool and rainy here and to stop the windscreen fogging up I turned the AC on after a while. Then noticed that coolant temps were heading back downwards, to about halfway between cold and 90C. Anyone else noticed this? Coolant level seems fine. Turned the AC off and it went back up to normal reasonably quickly.

I guess it decided to turn the rad fan on because it would pull air through the AC heat exchanger? Sam I noticed you mention a few times here the coolant temp gauge showing a heavily damped version of reality; did you notice any change in behaviour after you ripped your AC out?

[sambb]

your temps would have come down because when the AC compressor kicks on, both sets of radiator fans are activated. More airflow for the condenser also equals more air for the radiator inadvertently even if it doesn't really require it (ie requested by its own coolant temp sensor), so your coolant temp drops. Should be normal.
Yeah the stock water temp gauge is super damped. Frm watching temps real time direct from the sensor its apparent that anything from 75 or so degrees up to nearly a hundred all show as one happy position on the car.
Having the AC gear out hasn't really affected street temps but I think it does cool more efficiently on the track now - less pre radiator obstruction. I broke into the high speed relay in the radiator fan control module and wired it to a by pass switch in the cabin so that I can run all fans continuously manually to keep the car coolant temps under control on the line at hillclimbs or to start the cool down asap once the red flag gets waived on a track day session, just to be kind to the car.

[sambb]

Decided it was time to finally add an oil pressure gauge. I wanted something that has minimum pressure presets that trigger a loud audible alarm and flashing face in case the pressure nose dives on the track. I also have a sneaking suspicion that the engine is dying a slow death and I wanted to get a read on that before any funds go its way.
The stock oil pressure switch isnt good enough to be relied upon. You can actually unplug it whilst running and nothing will show and it wont be until your next start up that it'll flash and in the heat of the moment you'd never notice it on the track anyway.



So the pressure sender mount I used was a tee with male and female M10x1.0 threads either end to allow the stock pressure switch to be relocated to the end of the tee, and then with 1/8th NPT ports. Turned out to the right way to go as I now have a spare 1/8th NPT port and the stock pressure switch fit neatly on the end without fouling anything.
So all works fine. White daytime lighting and amber night time and flashes bright red if the pressure falls below the preset. The accompanying audible alarm is very loud (luckily it can be permanently muted) and will be able to be heard with a helmet on for sure. Despite how it may look in the pics the gauges are perfectly visible for my driving position and visibility only gets better when I'm sitting lower in the car in the race seat.

Sooooo....problem is the pressures. When water up to temp and oil at 100 degrees with car thoroughly heatsoaked my running pressures are fine eg 55 psi at 2500rpm which is regulation for the car and parks itself at 60psi above that which is the factory pressure relief in the oil pump. At idle though it'll sit at 14psi. The manual says 20-25psi apparently which I need to confirm.
I am due for an oil change which I did just now so we'll see tomorrow if fresh oil and a jump from 5W-30 to 5W-40 gets the hot idle pressures into the pocket.

[h100vw]

I agree the factory pressure monitoring is a bit hit and mostly miss. Pretty convinced it cost me a bearing, which turned into another engine. I over compensated by fitting a Forge sump.
Sam, I havent quite forgotten about the exhaust. I'll contact you tomorrow.

[sambb]

Hey Gav. In the process of making baffles for my next sump at the moment. Just trying to locate some oil control gates to use. Found someone who supplies the Cosworth style flexible viton flaps but might still go aluminium hinged style if I could find anyone in the world who even sells them.

Gav whats your take on the base oil pressure I'm seeing on the engine. Is 20-25psi the accepted range to your knowledge?

[h100vw]

20 would be a minimum based on the pressure switch installed by VW.

[sambb]

well the 5W-40 took it up to 16-17psi. That puts it in the realm of possibly gauge/sensor error being a factor. I'll get a mechanical gauge onto it to confirm idle pressure. If it is sub 20psi then I really don't know what to do ie whether its worth still throwing the TFSI turbo and exhaust at it and getting a year out of it OR doing the bottom end on the other motor right now.

[Sydneykid]

Is it making any noises? Big end knock or main bearing rumble? Rattling rockers or cam chain? Dash low oil pressure warning light?


Cheers
Gary

[sambb]

Thinking about it, the OE pressure switch must only be looked at by the ECU at start up. It'll always go over 20psi at start up even if your hot idle pressures are low like mine. Thats why mine has never blinked despite the low pressure and why you can unplug it with the car running and it wont bring on the dash light. Pretty sure its only there for start up pressure monitoring. For it not to hit 20psi at start up the engine would have to be well and truly shagged. Mines well off that, but yeah I think a mechanical gauge check is in order. I'm not convinced a coupler of psi below the min 20psi recommendation isnt nearly to be expected on a 150,000km engine.
I'm seeing quite a few stories of people having slightly lower idle oil pressures after fitting oil coolers and sandwich plates. Interweb discussion yes, but guys who reported their lowered pressures and then removed or bypassed their new coolers putting things back to stock and suddenly had their pressures back. Hopefully there's something in that. The cooler itself would have to represent a restriction. When up to temp the thermostat in the sandwich plate is wide open with the majority of the now thin oil having to go through the cooler and a good meter of pipe work. Come to think of it, it is when the oil is over 80 degrees (thats the sandwich plate thermostats cracking point) that the idle pressure gets below 20psi. hmmmm

anyone else seeing lower hot idle pressures after they've fit coolers?

[sambb]

Gary there’s no noises that would indicate an issue.
I spoke to the Mocal Australia dealers today and they said it’s not uncommon for a sandwich plate/cooler to knock a couple of psi off your idle pressures. Watching it last night I definitely have spec pressures till about 80 degrees after which the idle psi drops from above 20psi to roughly 15psi. That could be the oil thinning out but it’s a pretty marked step which makes me think it’s the longer path via the cooler that’s doing it. All other running pressures are fine.
As an aside I read that crankcase vacuum can have a part to play. Eg if your PCV gets its guts blown out of it and then the crankcase goes to a non-flow restricted vacuum it can really affect idle pressures. I have been running a pcv so I’ve disconnected that and will just run straight to the can which will only be drawn on by the turbo inlet now. I’ll see if that has any effect.

[sambb]

Oh and the erWin doesn’t spec a base pressure for the bjx 1.8T 20V. It just says that with the engine between 1.2 and 1.6 bar ( 17.4-23.2psi) that the oil pressure light needs to be off, which mine is. In practice this is only relevant at startup as after that pressures can actually fall below that without triggering the light. My light has never come on.
It then says that at 2000rpm @ 80 degrees that the oil pressure needs to be between 2.7 - 4.5 bar (40-67.5psi). Mine easily qualifies there and is pegged at 60psi from then on. The fact that I have healthy running pressure suggests to me that it can’t be the pick up.
I think it’s healthy so I’ll keep going on the turbo mod.

[Sydneykid]

I had a quick look at the data files last night, trying to find some non dry sump engine data with oil cooler and an OE pump. No joy, but I did find one that's close, my RB30 which has an N1 (competition) RB26 oil pump. It shows a 2 psi drop (that's through the remote filter and oil cooler) from ~28 to ~26 psi at idle, that's with Nulon 10W60 at 95 degC with a 900 rpm idle. It has 2 oil pressure sensors, one in the block (OE position) and the other one at the remote oil filter. Flow looks like;

pump -----> sanga plate ------> remote filter + temp & pressure sensors ------> oil cooler ------> sanga plate -----> engine -----> oil pressure sensor


Cheers
Gary

[sambb]

gotcha. Thanks Gary. The pressure sensor position is post cooler from what I can tell. The plate is stacked between the housing and the filter so I assume
pump ----> plate----> filte/cooler -----> plate -----> pressure sensor switch and pressure sender on housing -----> engine

so being post cooler and filter it will be seeing a drop yeah. I have been running just a Ryco recently because I got sucked in by a 2 for 1 deal a while back. Crappy filters can drop pressure a bit too cant they?

Oh and PCV had nil effect. Checked that the valve was ok and that the restricter was definitely in the line. No excess vacuum happening there and observed no difference so put it back.

[sambb]

Gary which type of one way door have you used on baffled wet sumps.


I'd prefer hinged doors that I can just rivet on. I know the Viton RCM/Cosworth style are popular but not sure about that push fit fitting method into a slot arrangement. I can get the RCM ones for 15 bucks each. The other option I was thinking is to cut louvres into the baffles aligned to aid flow into the pocket but not out. That wouldnt block flow out of the pickup entirely but would definitely slow it down yeah.

[sambb]

You're joking. My elec pressure gauge is crap. out by more than 10psi! This tool pro gauge says all is well. Sorry to waste peoples time with advice etc. Learnt a bit though.

Ok on with an exhaust and turbo!! oh and a refund for the gauge