Sam's build thread

[Sydneykid]

with a water to air intercooler sitting beside the engine where the battery/airbox used to be.

Now you're talking .............. for hillclimbs (and time attack) I wouldn't use anything but a water to air intercooler. An esky full of ice and water should last you all day.

Just spent the Easter weekend at Bathurst playing Technical (enforcer) for the 6 Hour, the BMW M3 and M4 use a water to air intercooler.

Note how small it is for ~450 bhp. And how short it enables the inlet system to be.

Cheers
Gary

[sambb]

yeah I'd been looking at old Subaru and Toyota GT4 ones but they pale compared to this baby. It'd be hard to go past that. They look pricey! Coupled with the M4 GTS direct water injection system I'd be a happy boy.

[sambb]

Spent some time looking at temps of the SEAT ic while commuting around the place. The positives of it are that provided it's not heatsoaked and you are able to keep up speeds above 40kmh it'll keep temps very close to ambient. Eg today in 26 degree weather it barely got above IAT's of 32 degrees even with a few boots here and there. And even with a couple of back to back 3rd gear pulls the temp rise doesn't really exceed 10 degrees. However if it does heatsoak (I glanced down once and it was showing 66 degrees! In stop start traffic in 27 degrees ambiant) unless you can really get the car moving and for a while it'll stay very hot. In the above case I drove for about 4 Kay's thru suburban streets at civil speeds and it never got below 50 degree IAT's again and when I stopped in the driveway they went straight up to 60 again. I even let it get hot a few times, gave it a few squirts with the intercooler water spray I rigged up and put on the aircon to force both fans to run and get some air moving through it, and the temps continued to climb. So I think that at speed it is very good provided it doesn't start out hot, but it'll start to heatsoak very quickly at rest. The intercooler is light for how big it is. The treadstone replicad of the SEAT are built heavier sochace more thermal mass and may not suffer as quickly on heatsoak situations. So this is bad news for giving it a hiding after lots of idling/1st and 2ng gear traffic, and Hillclimb start lines. I think that would be timing pull central. I did do some 3rd gear logs and noticed this. I pulled over idling, set up the log I wanted to run and did 3 pulls. The first one after I'd been idling had cross the board timing pull which I could actually feel. Each pull after that got better and the last run had barely any timing pulled. So I think it'll be a good IC for the track but is turd for hillclimbs. I think even for track days ( when I was at Wakefield one of our sessions was only 7 laps) there's a lot of heatsoak time between your calls and I think you'd be starting the IC very hot. I think as a do everything car I'm sold on water to air intercooling now that I've seen this and that will be the long term plan.

[sambb]

So while I had things apart I looked at if the Xr6 turbo ic would fit. Short answer is yes but it may end up spaced out off the condenser or radiator too far ( which can cause pressure drops behind the core and in front of the radiator = bad for radiator flow) because the end tanks aren't offset like the SEAT's. I'll post some pics so you can see what I mean. Despite being smaller it is actually heavier so has a bit of thermal mass and being black might not suffer as badly with heatsoak as the SEAT at rest. So because of it needing to be spaced up to 25-30mm off the condenser I decided not to waste time making brackets and didn't fit it.
I found some nice restrictions that I want to deal with before I write off the SEAT too. All the piping that is fitted to it is tiny. The IC's end tank pipes are52mm I.D which is fine but the aluminium pipe bends are 46mm! The I.D of the standard plastic hard pipe that comes thru at sump height is 42.5mm!!!!!!' So before I can say the SEAT is restrictive I think the pipework needs to be brought out to a consistent 2in ID which will need to happen before any future turbo swaps anyway cos 46mm pipes and 42mm in one spot is just turd. Maybe Meters and Meters of tiny pipework is why it's felt a bit weak compared to the stock side mount for peak power.
Having seen how badly the SEAT can heatsoak I also repositioned my water spray and that's working great now and nearly blankets the whole core face with a water mist which should help on start lines.
Also the boost drop across the core is not greater than 0.12 bar so isn't drastic I don't think.

[sambb]

nasty heatsoak. Hate to see what it'd be like on a legitimately hot day.
offset in/out let pipes get the core right against the condenser core.


XR6T BA/BF core laid over the seat. 8 bars versus 27. Its fins are 12mm thick versus 7mm on the SEAT. It has a beautifully profiled inlet end tanks compared to the stilted offset path that the SEAT in/outlets take so I reckon it would flow great but they get in the way of the air con pies. Without the A/C I think it could be fitted quite flush with the radiator. The top parallel hose basically sits in behind the crash bar and could be run over or under the crash bar support on the drivers side. Wish I could have tried it but while the hose all looked like they'd line up fine, mounting it was going to take a bit of thought re brackets etc. and kids school pick up was looming. Another time maybe.


IC water spray nozzle and viewed from above shooting into the gap between crash bar and IC. It coats the bottom 2/3rds of the core face and predominately the area where the hot inlet is. It runs off the rear window wiper pipe (no water goes rearward anymore) and so pushing the stalk forward gives the core a good cool down when you're in the start queue or heading down the straight at Wakefield. I had a base temp enabled/boost activated water spray on the SMIC but I don't think that's needed on this IC because its ok with lots of airflow. It'll only really need the water to prevent heatsoak before heading out onto the track so the wiper stalk will be fine for what I need.

[sambb]

Am thinking i'll block this air feed above the radiator. It goes nowhere unlike the one on the passenger side which is the air intake. All it'll do is allow air pressure off the front of the radiator/cores and into the engine bay where it can hurt cooling yeah? Seal it?

[Sydneykid]

The Seat intercooler is what we call a tube and fin, whilst the XR6 is bar and plate. For circuit racing we prefer tube and fin as they work better with a constant airflow, plus they don't "disturb" the airflow as much to the radiator behind. Drag racers tend to prefer bar and plate as they take longer to heat up, due to having more mass (as you noted). For hillclimb use I suspect the bar and plate maybe better. The downside is once they heat up they take longer to cool, the water spray will help there. Bit of metho in the water helps.

Yep, block off any holes that allow to airflow to go anywhere other than the through the radiator. What does that vent usually flow into/over/around? It's unusual for a car manufacturer to leave a gap like that without there being a reason for it.


Cheers
Gary

[sambb]

The vent feeds nothing. I suspect that maybe that radiator surround is used in 6N's as well as 9N's and maybe one of the models has a drivers side intake for one of the little atmo engines or a diesel? and its just a common part? not sure. I blanked it off already because any way I looked at it it was wrong

[sambb]

Christ. Ran some fuel logs last night in VCDS and found some lean spots. Luckily I never push the timing to ever get more than 3 degree pull. I do worry what it was doing at Bathurst in 35 degrees with heatsoak IC. Crunched some numbers tonight to work out my injector duty cycles.
I used this IDC calculator: Stealth 316 - Injector Duty Cycle Calculation
I'd only ever been checking peak load IDC which are ok at sub 80%, but the breathing mods I've done are obviously working (intake, ported mani, wastegate ported turbo wastegate actuator) and the top end is stronger and above 4800 rpm I'm into 90% IDC territory!! I had suspected I was getting up there so had fitted an uprated 265Lph pump (thanks Louis!!) and just got the injectors flowed and reinstalled yesterday. So I've put in another 3 bar FPR and vacuum line from the old engine and will retest in case that was it but I'm now looking at an ECS adjustable FPR to get me out of trouble ($$$$$) for the couple of events I have coming up. If I cant get my hands on one of them it may even have to be a 4 bar FPR from an S3?? Anyone used the ECS adjustable FPR?

[sambb]

Tested again with the spare 3 bar FPR and its the same story so it wasn't a dud FPR causing it. Next test will be to go back to the 10psi wastegate actuator spring. I only went away from it because I thought it was the spring causing top end timing pull and now I realise it was a fuelling problem. The boost still wanders around with the close to stock 7psi spring which I still think is too soft for the better breathing turbo. If boost is varying in the same spot, its reasonable to assume that it would be varying fuel pressure with it too (since that's boost actuated) yeah? Maybe fuel pressure is varying affecting mixtures because boost still isn't stable.
. I'll log boost against fuelling and see if there's a story there. If that looks to be the problem then I'll do the same again after a swap to the 10psi spring tonight which will hopefully get the fuelling stable (although it will still be lean). Once its stable then hopefully an adjustable FPR will do the trick and push more fuel through until I can get it sorted properly.