Heat problems on track: TECH. Read before adding an oil cooler!

[DerHase]

Edit #2:
Renaming this thread so I don't have to start a new one. This is to bring some resolution to this Golf R averaging crazy high temps. Has all the "right" stuff that everyone throws at these cars on track: APR IC, CSF radiator, and a 19 row oil cooler. Here's a quick summary of the entire thread, and you can go through the posts for the full story:

1. Car runs hot on track IAT-wise, pulls timing like crazy losing tons of power and is just a mess.

2. Other cars running the same radiator/IC don't have this problem.

3. It has crazy high IATs even on the street vs most other testing. This lead us to believe it was airflow related.

4. We initially thought it may be airflow related. We tried yarn tuft testing the Seibon hood. Seemed MAYBE a tiny bit better with the vents BLOCKED instead of open, but within margin of error realistically.

5. We eliminated the hood as a variable by running my newly vented hood with a 24x14in racelouvers vent. Imperceptible changes. So we think it's either airflow IN being restricted (or rather air going AROUND the cores) OR the oil cooler itself is heating up the intercooler.

6. Tested by blocking the oil cooler and confirmed 100% that is actually the problem.

Edit #3:
7. Testing was completed with moving oil cooler position, + experimented with ducting. Jump to the first of the summary posts here:
https://golfmk7.com/forums/index.ph...-over-ambient-with-apr-ic.426885/post-7983057

Edit #4:
8. Street testing CONCLUSION/SUMMARY HERE:
https://golfmk7.com/forums/index.ph...-over-ambient-with-apr-ic.426885/post-7989154

We figured out the oil cooler location + heat coming off of it and right into the IC was to blame. After moving the oil cooler from pass side to center, and adding a duct that takes all the hot oil cooler air through the bottom of the bumper, we saw a ~60% drop in IATs on his car. Assuming this number translates to on track... that will put his IATs right in line with where almost every other car is, rather than more than 2x higher than the rest of the data samples.

Track-testing/validation will be happening at the end of August at Palmer Motorsports Park to put all this theory to the test that matters.

Feel free to continue reading to see the entire process from beginning to end.


Edit #5:
9. Track testing SUMMARY AND RESULTS HERE:
https://golfmk7.com/forums/index.ph...fore-adding-an-oil-cooler.426885/post-7994425

With the final oil cooler duct installed, @Redslaya went to Palmer Motorsports Park where we finally got some solid data to prove the IAT issue is fixed.


At some point I'm going to come back and clean up this ridiculous mess of a first post.
>>>>>>>>>>>>>>>>>>>


Edit: This hood does NOT seem to be the root cause of these problems. We think the oil cooler and/or placement (passenger side of grille).
Jump to post here: https://golfmk7.com/forums/index.ph...od-actually-hurts-cooling.426885/post-7978698
This also means the Seibon hood vents open/closed will need to be re-tested when complete. They won't flow any more if there's no air getting to them on the underside.

>>>>>>>>>>>>>>>>>>>

ORIGINAL POST:

(It's a long video, and I'm not going to put any huge effort into editing it for hours. The latter half of it has better views where stuff is a bit easier to see.)

If you've been following my Track Temp data thread here:
https://www.golfmk7.com/forums/inde...mbo-data-collection-spreadsheet-added.425356/

Then you've seen there is one vehicle that sticks out like a sore thumb when it comes to IATs. This is a 2018 Golf R that is averaging 55F OVER ambient temps on average on track. Most other cars in the logs I've collected have been in the 20-25F range for reference. This is with an APR IC, CSF radiators (all 3), an iAbed oil cooler, and a Seibon vented carbon hood on an APR Stage 1 car.

We just got another data sample from Kyle Gurney (Golf R, CSF rad, and APR IC as well, though no oil cooler and a different hood vent) and his car maintains 20F over ambient under similar/worse conditions which was what led me and redslaya to the tuft testing. We got together this evening to evaluate what's going on with it. We're not aerodynamicists or anything... but it seems that the forward holes in the hood are too far forward (directly above the cooling fan/radiator, not slightly behind which is ideal) and may actually be allowing air to push under the hood instead of vent from it as intended.







Note how far forward the front ducts are - above the radiator. For reference Race Louvers recommends the front of louver openings be installed 2-4in BEHIND the radiator.



As always more testing needs done, I think we will be trying to put the little yarn strings into the centers of the openings of the hood vents so they will be directly in the airstream to see what's going on next. Should be a more visually definitive indicator of direction of flow in or out of the hood.

Any input is welcome.

 

[AzteCypher]

Block the most forward facing vents and see if the tuft testing shows better results?

 

[DerHase]

Block the most forward facing vents and see if the tuft testing shows better results?

That is another thing we will try for sure

 

[ironicbadger]

https://amp.formula1.com/en/latest/...edley-on-flow-vis.7nU2VePGlVrhIGa8wgCoLE.html

You boys need some flow-vis!

 

[gboticus]

That is another thing we will try for sure

You can also defeat the vents entirely by putting the rain cover on if you wish to try that

 

[yakboyslim]

This is all arm chair engineering. I can throw some credentials at it -I have an MS in aerospace, a rudimentary ability with CFD, and my car doesn't overheat is all I got though. I haven't CFD'd or tunneled the Seibon hood and TBH I barely watched the video. Anyway, heres some thoughts:

• I have not tufted my car, but I have the Verus hood vents and have good results. The driver's side vent is clearly far less effective though. The passenger side vent is always hotter after running, and the dry spot on the hood is more pronounced on the passenger side when driving in the rain.
  • Based on that I would say that is likely a byproduct of the under hood arrangment, so it isn't surprising that the driver's side on the Seibon looks worse.
• Placement further front means a likely lower pressure zone on top of the vent (from CFD) but the effect under hood is not really known, and way beyond my abilities to CFD.
• I did some CFD for the Verus vents before purchasing, and I was looking at engine bay air pressure and downforce. Due to the limits of my CFD I knew that flow would be wildly inaccurate, so I was just looking at differences in those other variables. The vents were a definite improvement in CFD (which is why I bought them) and that has pretty much been confirmed through my track results. However, I won't ever quote any numbers, because the single biggest factor in the hood vent performance was the radiator. I was modeling the radiator as a pressure drop, and setting that pressure drop higher or lower DRASTICALLY changed the impact of the hood vents. At the high end of "reasonable" pressure drop figures the hood vents had nearly no impact because so little air was going into the bay that engine bay air pressure was too low to have the air "sucked out" through the vents, so it almost didn't matter if the vents were there.
  • Based on the honestly very poor results of folks with the CSF radiator I suspect the flow through it is probably the big issue here.
• The vents on the Seibon are flowy and pretty, but they shouldnt be.
  • The "lip" of the bump in front of each vent is radiused. This means that flow stays attached longer. You can see this in the tufts in front of the first vents, they bend over the lip instead of standing up. A wicker (or gurney flap) normally seen on a lot of vents is purposely ugly, and sharp, promoting flow separation. This creates a low pressure area to "suck" air out the vents. Also it prevents the flow from reimpacting the next bump or louver, which could cause a high pressure area leading to circulation inside the "bubble" of flow leaving the hood vent.
  • The vents are slanted aggressively rear ward. This looks cool, and looks race car. But on race cars the vents are this way because the flow of air is managed. The air is usually forced through a radiator, then channeled to the vent in such a way that it is flowing out, smoothly rejoining the flow.
    • In a street car with slapped on vents (and even with sealing the radiator flow) this is not the case. We are cramming air through a radiator (that needs to be big enough for city traffic), slowing it to a near halt as it runs into the engine, etc, then yanking it out of the bay with a vent. Because of this when you look at how big the vents are you need to look at them from above ( not at an angle) and the rearward slant of these Seibon vents means they aren't even that big then.

Excited to see what you figure out, and you got my discord if you want to bounce any ideas. I would try making some simple wickers to go in front of the vents and see if that helps, but I suspect even if you get the flow through the vents better, they just aren't big enough and (harder for me to justify my hunch) the CSF is not the solution.

 

[gboticus]

This whole conversation is making me wonder if I can ask HPA to do some testing on their rolling road simulator which can simulate air flow up to 300kph or so.

 

[yakboyslim]

This whole conversation is making me wonder if I can ask HPA to do some testing on their rolling road simulator which can simulate air flow up to 300kph or so.

That would be super cool to see. Unfortunately, I think one of the biggest variables look at (the radiator) does not really lend itself to back to back efficient testing. But it would be cool to have a hood with holes cut for the center and side vents, and then swap them out with covers to see what works best.

I just think there is a good chance that what works with stock rad does not work the same with CSF (or even certain IC options)

 

[DerHase]

That would be super cool to see. Unfortunately, I think one of the biggest variables look at (the radiator) does not really lend itself to back to back efficient testing. But it would be cool to have a hood with holes cut for the center and side vents, and then swap them out with covers to see what works best.

I just think there is a good chance that what works with stock rad does not work the same with CSF (or even certain IC options)

This is kind of my inclination. I suspect that adding more radiator buys you time (because more coolant to heatsoak), but without enough airflow it's not long-term sustainable. Good enough for a 20 min session? In most cases probably. But big high speed track + fast driver + hot day it'll probably see the coolant temp creep up.

I'm working on more spreadsheets to plug data into more visuals to be able to able to hopefully look at stuff like 6MT vs DSG, Stock vs [not stock] intercoolers, Stock vs [not stock] radiators, etc. Goal is to be able to add a card to the PBI report, update spreadsheet and general overview/drill downs automatically update in PBI (and eventually get published at the beginning of the overall PDF exported report).

 

[Redslaya]

Retufted and retested the hood today. Results are uploading and they're not good!

Here are the videos: https://drive.google.com/drive/folders/1jB6R6rA_VCahl3iqvmzGX8-nuD7Jre9B?usp=sharing

you can see the tufts right by the vent exits, especially the front one, are all over the place.

 

[DerHase]

@Redslaya did more yarn tuft testing this evening on his own as he posted above. He sent me these logs since I loaned him my spare ST dongle to review in the meantime. Don't have time to look at the videos in-depth myself tonight.

This is just VERY simple testing with some changes he tried today with highway driving over the course of an hour or two for all of these samples to be taken. I am just pulling some quick snapshots from Megalogviewer with observations. I THINK this is in the order that he did the testing in, if not hopefully he can correct me or confirm and I'll edit this post order.

Stuff to note for this baseline setup that we'll be evaluating overall:
2018 Golf R
APR Stage 1 tune
APR Intercooler
APR CF Cold Air Intake
CSF Radiator
Seibon vented hood

Baseline cruising temps (looking specifically at IATs though) with Seibon hood vents OPEN (as he's been running it on track for the last year):

Then a WOT pull... notice the IATs only dropped a whopping 4 degrees the entire time (!):

What is interesting to note is that the temps eventually dropped... another 4F about 2.5 seconds after the pull was over:

So now let's look at if there are any notable changes with the hood vents CLOSED on the highway:

Hmm. Ok. Maybe marginally better? What about with a pull?

And again it drops a tiny bit more after the pull just so it is noted:

So results of the hood with this very crude and not terribly stressful and likely flawed testing is at best inconclusive, at worst perhaps the vents closed is just *marginally* better?

BUT WAIT! There's more!!


....

 

[DerHase]

So @Redslaya swapped his OEM airbox back in because this shit needs to be figured out definitively and that is one last piece that is a non-constant from other cars that have the same radiator and/or intercooler.

So let's look at this setup:
2018 Golf R
APR Stage 1 tune
APR Intercooler
OEM air intake
CSF Radiator
Seibon vented hood (vents CLOSED for these logs)

Seems marginally but quantifiably better. What about a pull?

Edit: One thing I just noticed in this log vs the other two is that (modeled) oil temp is a bit lower overall. I'm not sure what the dash was saying since it reads actual in the pan, but it might be worth taking on a long drive again to get fully heat soaked and repeating this test just to confirm. Based on the log times, it was about 30 minutes between the last of the APR intake logs to the first OEM intake log for reference.

Edit #2: I checked with @Redslaya and per him the intake swap was a 10 minute process, and then ~20 minutes of highway driving passed before taking the final logs. It is important to note that oil temperature logged is just MODELED. Per his dash, the oil temp always remained between 180F-190F for all of the above logs from beginning to end. Because he has the iAbed oil cooler and radiator, the modeled oil temp is wildly inaccurate and dash value should always be used. I just can't log that value on his car since it's not flashed via Simos Tools with the 3E HSL patch like mine.

Definitely seems a tad bit better overall. Will be super interested to see how it performs on track with the intake changed back to stock and be able to do a more accurate/definitive test of the Seibon vents open vs closed.

 

[swcrow]

this is actually fascinating

 

[yakboyslim]

Very interesting with the OEM airbox. Especially since the APR isn't really a "hot air intake" like people traditionally worry about.

I have an open intake and have no IAT issues, but I actually did notice in a very un-scientific study that my IATs might actually be lower with my "rain guard" (just a piece of ABS to cover the top of my filter from most of the rain).

I would be interested in trying to correlate IAT improvements with oil/water temp improvements though. Totally underestand that IAT is the easy one to track that shows more immediate results, but I don't know how much that will transfer over to oil temps etc.

 

[Redslaya]

on my car I no longer have oil temp issues. with the Iabed cooler they stay solidly in the 250°f range. The issue now is high IATs pulling all timing leading to power loss and potential damage.