Dual oil coolers for serious track duty

[tadams72]

Well I've crunched the numbers and it looks like adding a second 25 row cooler will be quite a bit cheaper than trying to go bigger like X25 did. Now the next problem is those damn brake cooling ducts. Seems the fog lights are not very efficient due to lower pressure and turbulence in this area. I think I am going to see how close to center I can put the coolers and then fit brake ducting outside of those if possible.

Orange, what kind of oil pressures were you seeing (hot and cold) running the dual setup. Improved Racing estimate a 6 psi drop across two coolers. I think I can live with that running a ported Melling 10296.

[X25]

Originally Posted by Orange Crush 1LE

Awesome, keep us posted!

I suppose I should post it here, too

From my build thread:

Originally Posted by X25

The oil cooler update:

Here is my older oil cooler. Some of the issues: The ports are at the side, it is install high up (missing the better flow down low).


The new cooler core is narrower, but much taller, and now spans the whole opening!


It actually goes down lower than the condenser!


I tried to do my best to make it as parallel to the condenser as possible.


Finished!


It actually looks a lot like a radiator : )



Now the numbers
I conducted my usual stress test with the new oil cooler. I basically drive on the highway, varying the engine speed between 4500 - 5500 RPM at whatever gear the speed limits dictate. With my older set-up, this creeps the oil temps to about 260 degrees F. With the new set-up, I could not exceed 233 degrees F! The coolant temps also stayed at or below 200 degrees. It would be an understatement to say that I'm excited. Obviously, I'll need to go to track and try it out to make sure I finally have a car that will not overheat

There's no one right answer here. Two cores might work better since it's easier to channel air into smaller cores. But then you run the risk of too much drop in oil pressure. Besides cores (and small cores cause more pressure drop already, not to mention having two), you'll also have a lot more fittings and lines causing additional back-pressure; pick your poison If I were to ever do that, I'd use 12-AN lines like I do now, and would investigate if I could install them in parallel, not in series, which should reduce the core-induced back pressure by half, instead of doubling it. The fear is obviously not having enough flow for efficient cooling (which I doubt would be an issue).

As I've explained in my build thread, if I were to do it again, I'd keep the OEM cooler intact, let it do 80% of the job, and supplement it with a modest external oil cooler through a sandwich adapter (with no thermostat). I'd then check if coolant thermostat is effective enough to regulate oil temps as well through the OEM cooler/warmer, and add an oil thermostat only if it lets it over- cool at the street.

[tadams72]

Well that might have been worth looking into with the hybrid system but I sold the stock cooler and lines so no going back now.

Hoping to see what ORANGECRUSH had for pressure drop on his setup. He was duals with a -8 which would probably be more drop I would think.

[Orange Crush 1LE]

Hi guys,

Oil pressure was a huge concern after grenading my previous motor and not really knowing why. I spoke with several that thought that my stock 1LE oil pump would be up to the task.

Taking no chances, I had an oil pressure sensor, oil temp sensor, and Aim data acquisition system installed which continuously monitors both. A data acquisition system will even capture momentary dips, as it outputs a plot of your entire session. Momentary dips may be hard to catch on just an oil pressure gage.

Keep in mind that not only did I install the oil coolers, but also an Improved Racing Oil Pan Baffle. As I run a big wing set at 9 degrees (tons of downforce) and 315 Hoosiers, the car is at risk of oil starvation.

Although I can't quote numbers on oil pressure because I sold the car, two things I observed which put my fears to rest:

1. No oil pressure starvation at all. The Aim plot for pressure confirmed that even in long sustained high-g sweepers like Riverside at Buttonwillow Raceway, no pressure starvation at all. Very relieved!

2. Oil pressure was fine at all temperatures and RPM. Never dipped low at all. Sorry I can't remember the numbers but they were way out of the danger zone. This was true with both 15W-50 and 5W-50.

So although I agree with you guys that oil pressure drop should be of concern, I'm happy to report that I had no issues with this.

[hcsi99]

Do you know if your coolers were ran in sequence or parallel?

[Orange Crush 1LE]

Originally Posted by hcsi99

Do you know if your coolers were ran in sequence or parallel?

I hate to admit being a dummy about my own car, but it was installed by 7s Only and I didn't get a chance to look at all of the details. I am pretty sure they were run in sequence, but you could call 7s Only in Buttonwillow to confirm.

[tadams72]

Some good info from Mocal on cooler placement, series vs parallel, cooling system efficiencies, etc. Encourage everyone to read it. Seems we are seeing a lot of bad info getting put out there on the forums.

http://www.mocal.co.uk/FAQ.html

[X25]

Originally Posted by tadams72

Some good info from Mocal on cooler placement, series vs parallel, cooling system efficiencies, etc. Encourage everyone to read it. Seems we are seeing a lot of bad info getting put out there on the forums.

http://www.mocal.co.uk/FAQ.html

Thanks for the link; it was a great read

What bad info have you been seeing? We should address them, and make sure they are corrected (to avoid getting them spread further).

[tadams72]

Originally Posted by X25

Thanks for the link; it was a great read

What bad info have you been seeing? We should address them, and make sure they are corrected (to avoid getting them spread further).

Much is addressed in the article but I've seen confusion regarding the placement of the coolers (closer to the radiator or closer to the fascia), impact of the oil cooler on radiator efficiency, etc.

One thing I found interesting was the discussion on possible problems running coolers in parallel and problems with flow. Also the recommendation to mount larger coolers in a cradle vice using the mounting brackets. This might drive me to change my mounting solution.

[Woodsman44]

hcsi99 - his were done in sequence. I called 7's before ordering my parts for the dual setup. I'll be hopefully knocking out the install this weekend if all the parts are in.

[hcsi99]

Thanks! I hope be done with my new set up this weekend as well. I have a track day next Friday. I will post details of my set up after that (if it works). Good luck!

[Woodsman44]

Well, I had all intentions of installing the dual oil cooler setup this weekend but decided to pull the plug after the bumper was off. It would have been a pain to install the duals since they barely fit between the bumper supports and would have had to have been on a sloping angle for clearance. It just didn't seem worth it considering I was losing a good spot for brake ducts as well. After the article tadams72 posted along with some further research I've decided to go with X25's setup instead. The 5-15 degree increase in air temps reaching the radiator will not be ideal but when I'm on the track going an average of about 80-90 MPH, I don't think it will be an issue at all considering I'm freeing up the radiator from cooling the oil. It will be a month or so before a track day but I'll keep you all posted.

[Orange Crush 1LE]

Originally Posted by Woodsman44

Well, I had all intentions of installing the dual oil cooler setup this weekend but decided to pull the plug after the bumper was off. It would have been a pain to install the duals since they barely fit between the bumper supports and would have had to have been on a sloping angle for clearance. It just didn't seem worth it considering I was losing a good spot for brake ducts as well. After the article tadams72 posted along with some further research I've decided to go with X25's setup instead. The 5-15 degree increase in air temps reaching the radiator will not be ideal but when I'm on the track going an average of about 80-90 MPH, I don't think it will be an issue at all considering I'm freeing up the radiator from cooling the oil. It will be a month or so before a track day but I'll keep you all posted.

I think that both are good solutions, just comes down to what works for you. If someone is running a big brake kit such as the CTS-V / ZL-1 6-pistons up front like my car, running cooling ducts to the fog lights should be more than enough. I think its worth it to use the high pressure area like I did to cool the dual oil coolers.

However if you're sticking with the stock 4-piston brakes, they really need effective cooling if you're pushing it hard at brake-intensive tracks like Laguna Seca. So in that case, running the brake ducts to the high pressure area in the grille may be the better choice.

Looking forward to seeing how the single big cooler set up works for you guys that chose that route.

[X25]

Just did a track day with the bigger oil cooler. From my build thread:

Long story short, the oil temps stabilized for the first time, and I did not need cool down laps, but it might still be a bit too high for some. I'm sure it can be improved even further by using a non-thermostatic oil cooler adapter (and just putting a high flow thermostat installed on the hoses), but I think this will be sufficient for me.

Originally Posted by X25

Finally got to try my new oil cooler at Oregon Raceway Park today (yesterday)! Ironically, the ambient temp was 88 degrees F, which is what GM suggested they test their products at for track duty.

I started the track event late (at 11 AM) spent the first session testing out the oil cooler, temps, and tire pressures, and did not care for lap times. This turned out to be a big mistake since it was the only session I had where ambient temps were at or below 80 degrees F. During that session, the flaggers clocked me at 1:56.xx! Unfortunately, I did not take the lap times during that first session. The following (afternoon) sessions had ambient temps climbing within every hour (up to 90 degrees F), and I could not do that time again. Blame it on me (heat exhaustion), engine, or the tires overheating; I'm not sure which.

Here is the 1:57.1 lap I made at 87 degrees F:


I've also met a fellow Camaro Forum member, Tom. He does have a ZL1, and we even played in one of the sessions, driving lead-follow back and forth. I do have a footage of chasing him within safe distance, but I forgot to ask his permission to post, so I'll have to ask first

Temps:

• Oil:
  • Long story short, with the new oil cooler, the oil temp stabilized in 270s! It has never stabilized before (I used to start cool down before seeing 300s).
  • Yes, it would be better if it stabilized around 250s, but if I will see 280 max regardless of how much I push the car even at 90 degrees F, I'm OK with that!
  • I should also note that Tom stated he did not see oil temps above 250 degrees F at the same track. He is usually up-shifting much earlier than redline, though, and it seems to make a huge impact on temps.
• Coolant:
  • This is a bit bizarre. I checked out my logs, and I realized that at every session without exception, at either lap 3 or lap 4, I hit 228 degrees F. After that lap, the coolant backs down, and never gets past ~221 again.
  • What's happening at 228 degrees F? Does it start using reservoir? Does the engine management change the engine map? If you guys log the coolant temps, it would be nice if you check and see if you see such a behavior, too.
  • Anyhow, besides that odd lap, it never gets past 221s, so I think it looks pretty good.

Tires:

• I've read in multiple places, and even heard of it in a car magazine video (where they mention GM recommends 28 PSI cold, 32-34 PSI HOT target for Trofeo Rs on Z/28s), but this did not work for me.
• First off, how can you guys get the tires to only have 4-6 PSI increase? Of all the cars I've driven at the track, except the 2500 lbs Miata, none of them had an increase of <7 PSI.
• No wonder, I quickly hit 35 PSI during the sessions, and it crept up to 37 PSI(!).
• I eventually dropped the pressures to 26 PSI cold (by just bleeding another 2 PSI from whatever pressure I read from tires at the paddock), and it seemed to help.
• When you check out Pirelli's track prep docs for Trofeo R, you'll see that Pirelli recommends only 2 bar operating pressure, which translates to about 29 PSI HOT. This would mean 22-24 PSI cold, which would be dangerously low for a heavy car like ours. GM recommends minimum 26 PSI for our cars with whatever tire, so I did not go below 26 PSI, but I think it's fair to say that 26 PSI should work better per Pirelli's recommendations, too, even though it's not low enough, either.
• This was my second track day with these tires, and they are so far holding up fine (I still see the grooves :P). We'll see how much longer they can last.