Subie oil coolers

[Bill Waters]

Being new to the Subaru EJ25 engine and its features, I was not aware of the Subaru approach to oil cooling such as featured here: http://www.licmotorsports.com/produc...sti_21311aa051

On the face of it, this is a slick solution and approach to the problem, since it uses engine coolant already cooled and circulating to cool the oil and fits between the oil filter and the bottom of the block. Though I appreciate the efficiency of this, I will admit to being a little skeptical of those systems in which a minor defect in the device could have catastrophic consequences. On my new engine, which is an STi block with Tomei dual-scroll headers, it fits great.

However, I would be interested in the opinions of those with high performance/racing applications of the WRX/STi platform as to the effectiveness of this unit. One of the factors that makes me ask is that I haven't seen one in anyone's posts or build threads.

Thanks

[Doowop]

Bill,

not knowing crap about subies, I have found a bunch of stuff that they make for that engine, and I have a whole list of "race" part that I wonder if it is really needed and a problem on those motors. I was gonna post that sound to get opinions of suby people, and yours was one of them.

[tirod]

First of all, a lot of stock Subarus have them, and nobody has made an issue of them - for decades, it seems. They work on the same principle of a trans cooler in the radiator, or liquid cooled intercoolers for turbo apps, other than getting damaged, they have a good track record.

Note they also help warm the oil early in the cycle, too, which gets it to it's working temp sooner, especially in cold weather. Cold oil has high viscosity and is known to cause bearing failure. The old cliche about not running your motor hard until it warms up or it will break the connecting rod was really based on cold oil not getting to the bearing and it seizing up. Some motors have internal bypass filters that make that happen.

I would worry more about bypass filters on a race motor than the little oil intercooler for that reason. Since a lot of racers do use a sandwich adapter to route oil to a cooler, as a device they are well proven. The issues with the adapter setup in that situation are based on inadequate hose sizing - Fords are known to need 5/8 hose as 1/2 will starve the system in extreme applications.

If there is an issue with the stock Subaru adapter it would be the quality of the hose and clamps used to supply the coolant, and that their existence under the engine does make them subject to damage from debris. Like the oil lines to the sandwich adapter, it's not the device, it's the ancillary equipment that could cause the problem.

For a hot street or track car I would consider removing the cooler just to eliminate some dead weight. Seems people measure grams or fractions of an ounce as improvements on Subarus, but I don't see it mentioned on the numerous lists.

[Bill Waters]

Thanks, guys. I know that the street application of this little cooler is well-vetted and it's reliable. I'm wondering how effective they are in a race situation compared with a sandwich adapter-to-standard oil cooler setup.

[C.Plavan]

I'll probably be going the sandwich plate route (thermo switch model) then maybe mount the cooler near drivers side vent. Unless someone talked me out of it. I'll have to see once the body is on.

[Evan78]

Thanks, guys. I know that the street application of this little cooler is well-vetted and it's reliable. I'm wondering how effective they are in a race situation compared with a sandwich adapter-to-standard oil cooler setup.

You'll probably have to head to a Subaru site to get some feedback on using ONLY an aftermarket cooler without the OEM cooler.

The comparison of OEM vs aftermarket seems irrelevant unless you are really considering running just one or the other. Is that the question? Since most people have the OEM cooler already, they simply add additional capacity if they need to get oil temps lower.

[Bill Waters]

That's what I was thinking I'd do, Chad - unless this stock Ti cooler is really effective.

Evan78 - The operation and reliability of the traditional sandwich adapter/air-to-liquid oil cooler (placed in front of the radiator or elsewhere) is well-established. I'm just asking if anyone has experience with a high-output STi in a racing situation which might use the stock STi apparatus and can comment on the relative effectiveness of it. I am just impressed with the ingenuity of this little cooler, but would be inclined to replace the stock one with the old reliable system if I find or am told that the stock one is not effective for a 10/10ths racing application.

[Evan78]

Nasioc has a motorsports forum. You might find discussion there of when people have needed or not needed auxiliary coolers.

[C.Plavan]

I found this one for Perrin. I like that it uses a Setrab cooler. GREAT coolers. I have those on the other race cars, and they perform flawlessly. I'm guessing the lines are around 3 feet long. I'll try to find out for sure, then see if it can reach the drivers side cutout vent. Rallysportsdirect has them cheaper too.

http://perrinperformance.com/i-18010...r-wrx-sti.html

[icky]

I think you could build a similar one for cheaper and have the correct length hoses.

[Scargo]

Being new to the Subaru EJ25 engine and its features, I was not aware of the Subaru approach to oil cooling such as featured here: http://www.licmotorsports.com/produc...sti_21311aa051.... However, I would be interested in the opinions of those with high performance/racing applications of the WRX/STi platform as to the effectiveness of this unit. One of the factors that makes me ask is that I haven't seen one in anyone's posts or build threads. Thanks

When I went to the link I almost crapped my pants! Almost $300 for a worthless POS. Just think what you could do with that money... Well, you could buy a REAL oil cooler for that. As I told Brando, who has an R, you should spend about $600 and do the oil cooling properly. It is pretty important.
I may get flamed, but the "cooler" as discussed in the OP's link, is a heat exchanger. Once it has heated up the oil it is basically a worthless POS. It is in the Hades of oil cooler locations; surrounded by the exhaust and next to the oil pan, it is not only minuscule for what might be called a cooler, but is "cooled" only by the water in the engine so it's benefits are mitigated by the water temps and not helped by air flow (there is no airflow there).
Oil is as important to cooling as water is so relying on the water cooling to reduce the oil temps is a bit of a joke. This heater is designed for heating the oil and was added to late-model engines, probably to help emissions by helping accelerate the warm-up process on a cold engine.

It often positions the poor little filter where it is closer to aftermarket headers. Move the oil filter to a cool location by adding an adapter block where the filter was and plumb in an oil cooler. If yours is a street car that might get driven in really cool weather then you would need to add a thermostatic valve and/or block off the oil cooler when it's cool. Warm it up more slowly before hammering on it. It's always good practice anyway.
If you or anyone wants specifics for an external oil cooling system, I have posted bits and pieces about it here on the 818 forums, but would be happy to provide links to parts if you PM me. My system has been in use on my 400 WHP STi road racing car for three seasons and is a distillation of what I have learned from others who have wet-sump systems and race. I've never had a bearing failure!
Another consideration is, if you use them and spin a bearing (or worse) you will need a new one. Do not re-use them or try to clean them! This on top of having to chunk or try to clean your real oil cooler.

[icky]

I wish you could give reputation points for posts with real information... Nicely put @Scargo

[Evan78]

If you have to actually purchase the OEM cooler, it seems like a good idea to evaluate whether or not you should replace it with a more effective setup, but if you already have it, you should probably run it and add a traditional setup if needed.

I've never experimented with removing it, but in a thread on nasioc, there was 1 or 2 people that said their oil temps stayed the same without it, but more people that reported temps rising without it. Obviously, its cooling capacity is limited since it is using engine coolant to regulate oil temps, but it is still a system that will pull heat from the oil as long as the coolant is at a lower temperature than the oil, so it does perform oil cooling.

Bill - do you already have an OEM cooler? What turbo are you going to run and how much power do you expect?

[Scargo]

Well thanks. I just want an E for effort. Or simply call me Escargo.
Technically, the part I am dissing is a "heat exchanger". Initially the water circulates through it and accelerates the warming of the oil; then it tries to help cool the oil as temperatures increase. An overheating engine would only make the oil hotter! My oil temps have always run higher than water temps but I have a huge racing radiator and an enhanced system. I think once you start modifying the engine to raise performance and modify the exhaust it is a detriment. I'm not kidding about how headers wrap so closely around it and the oil pan and it becoming the Hell-hole spot for heat.
This is how I handle it. Image shows Full Race headers I am adding double slip joints to. Canton 90°, full rotation, remote oil filter adapter #22-597. Don't use short, tight radius 90° AN fittings. Little or no grinding on the cover is required.
Do not overtighten Canton unit, Treat tightening it much as if it were an oil filter. You can kill the square o-ring with excessive torque (and then it will leak).
Canton adapter compressed.jpg
oil routing low res.jpg

[Bill Waters]

If you have to actually purchase the OEM cooler, it seems like a good idea to evaluate whether or not you should replace it with a more effective setup, but if you already have it, you should probably run it and add a traditional setup if needed.

I've never experimented with removing it, but in a thread on nasioc, there was 1 or 2 people that said their oil temps stayed the same without it, but more people that reported temps rising without it. Obviously, its cooling capacity is limited since it is using engine coolant to regulate oil temps, but it is still a system that will pull heat from the oil as long as the coolant is at a lower temperature than the oil, so it does perform oil cooling.

Bill - do you already have an OEM cooler? What turbo are you going to run and how much power do you expect?

I have an OEM cooler; that's why I ask. My engine is a Cosworth short block with WRX heads with hotter cams, racing valve train, etc. My headers are Tomei which provide pressure to a twin-scroll Blousch turbo. 350-400 rwhp is goal.

I appreciate the thought that has gone into the various analyses offered here.

I am definitely looking to cool the oil, and, as noted above, will likely go with a traditional setup, but was just wondering if anyone has actual race experience with the OEM oil cooler.

It's true that the OEM cooler would also warm the oil after start-up (nothing but positive effects from that), but more correct to say that the little device would offer relatively homeostatic oil temps throughout the range (warmer than without it at start-up, cooler than without it at full heat).

[Slatt]

I am definitely looking to cool the oil, and, as noted above, will likely go with a traditional setup, but was just wondering if anyone has actual race experience with the OEM oil cooler.

Stage 2 WRX, prepared to SCCA ESP, OEM oil cooling, 75-ish second lap times on a sort of mini-Montreal track. After 6 hot laps oil was a little under 240F.

[Scargo]

I have an OEM cooler; that's why I ask. My engine is a Cosworth short block with WRX heads with hotter cams, racing valve train, etc. My headers are Tomei which provide pressure to a twin-scroll Blousch turbo. 350-400 rwhp is goal.

I appreciate the thought that has gone into the various analyses offered here.

I am definitely looking to cool the oil, and, as noted above, will likely go with a traditional setup, but was just wondering if anyone has actual race experience with the OEM oil cooler.

It's true that the OEM cooler would also warm the oil after start-up (nothing but positive effects from that), but more correct to say that the little device would offer relatively homeostatic oil temps throughout the range (warmer than without it at start-up, cooler than without it at full heat).

Which Blouch are you running? My, that's a fifty-cent word you're using!
I and two of my friends run HPDEs together. One has two, fully track prepared cars similar to mine. The other has minor Cobb mods to it and Crawford A/OS, but is essentially a stock '08 STi. We have all been out on the track going flat out, whenever possible. Two of us are at or near 400 WHP.
We have all run the "homeostatic" heat exchanger. I just ditched it so I can't really say what the effect will be. I also blocked off the water lines, plugging them with a 1/4" pipe plug. I have had a remote filter, thermostatic bypass valve and cooler on the car for quite a while and I have no temp issues when out on the track for 30+ minutes at a time.
My buddy with about 40K on his nearly stock-engined STi literally blew his up recently. I think the oil temp management is critical when you start pushing the engine to the max. He was only running 16-17 PSI boost.

[Scargo]

Stage 2 WRX, prepared to SCCA ESP, OEM oil cooling, 75-ish second lap times on a sort of mini-Montreal track. After 6 hot laps oil was a little under 240F.

Yea, but it never gets very hot up there, right? I wonder what your air temps were? How much boost? I run under 240 all the time at 23-24 PSI and 400 WHP.

[Slatt]

Well, since you ask... Anchorage is mild but things change as you move north and inland. The track was Tanacross, with weather similar to Fairbanks where the record high is over 90. I reckon it was 70-ish that day. 16.5 PSI always The event was geared around single lap runs but I got the chance to run more. I stopped at 6 laps because my stock-diameter rotors and stock calipers weren't keeping me on the apex anymore.

[Bill Waters]

Thanks, Scargo & Slatt.

Scargo - A Blouch 1.5 DOM.


I will likely move ahead with a Grimmspeed or similar thermostatically-controlled oil cooler system. I just thought the stock unit was actually kind of clever. After all, everyone wants a little homeostasis in the oil pan....

[Scargo]

Thanks, Scargo & Slatt.

Scargo - A Blouch 1.5 DOM.

I will likely move ahead with a Grimmspeed or similar thermostatically-controlled oil cooler system. I just thought the stock unit was actually kind of clever. After all, everyone wants a little homeostasis in the oil pan....

Bill, Do you have your motor spec'd out anywhere here on the forum?
I started this thread about Subaru EJ Motor Builds For Road Racing.... I copied this over to that engine specific discussion. Perhaps continue this over there?

I just had a conversation with a builder who I have a good opinion of (him having built Subie racing motors of all kinds) who said he had good luck with a combination with some similarities to what you mentioned: turbo size, Cosworth short block with WRX heads with hotter cams, racing valve train...
The WRX heads in particular. He built a motor using a standard 2.5 built short block with WRX heads, STI exhaust cams and WRX intake cams. GTX3071, .63 hot side, turbo. "On a Mustang dyno (known to be conservative) it was 330 WHP and 375 TQ. Had great response and full torque by 3700 rpm.
He said my DAVCS setup is even better for torque in the under 400 WHP range. Cams were a surprise. He said if you go to bigger cams you lose the advantage of the DAVCS as geometric limits for adjustment start to come into play. He likes running a longer duration exhaust cam as it tends to hold torque flatter. This squares with my research of dyno results for stock cam DAVCS engines VS those with 272 cams. (Also verified by last engine build where HP was 467 and torque actually dropped (from the previous build of 395/393 to 467/390!)

He liked the GTX3071 with a .63 hot side for a 380-400 WHP motor with lots of torque.
That's 46 lb/min Max Air Flow Rate compared to your Blouch 1.5 or my 2.5's 49 MAF. Just for fun:

Turbo Comp Ind Comp Exd Turb Ind Turb Exd Flow CHRA Bearings
GTX 3071R 54.10 71.40 60.00 54.90 56.0 Ball Bearing
Dom 1.5 XT-R 53.00 71.00 56.50 51.70 49.0 Ball Bearing
Dom 2.5 XT-R 53.00 71.00 60.00 54.90 49.0 Ball Bearing

[Bill Waters]

No, Scargo; I have my spec sheet at the office and can do so later,though. Glad for you to move this around.

So I'm not prepared for a deeply technical discussion, but my logic matches some of the approach you cite. I intentionally used cams which are hotter than stock, but not too wild, since this is a boosted engine, and since my simple approach to it is that I will benefit more from corner exit torque than I will top-end hp. The same logic applies to the turbo size and that fact that I went with twin-scroll. Hope it will be enough to match the Bosch 1000 cc injectors.

[C.Plavan]

I have those 272 cams in my build. I was also told to go DOM 1.5 from Blouch themselves. AJW told me a Blouch 18g...lol They built my motor, they know it has 272's (or it better have them )

[Scargo]

It is very likely that am not going to use 272 cams in my 818 motor. Not for NASA class racing and a max of 300 WHP...
More to come. I am trying to acquire 2.34 de-stroker parts for a high torque/high RPM engine (which I did).

[Sgt.Gator]

Oil temps are a definite issue with turbo Subarus. My LGT race car had both the oem cooler and a sandwich plate to Mocal cooler. Had is the word because I went off track at 90 mph and ripped the entire oem cooler + sandwich plate right out of the block. Virtually all Subaru race cars have an FMIC, so putting the oil cooler in front of the FMIC is not a good idea. And if you put it behind the FMIC is not going to get very cool air.
Most of the oil coolers I've seen are either placed in the driver front corner and fed from a split brake and oil cooler duct, or where the TMIC used to be. Putting it in place of the TMIC is pretty trick since you already have the duct work, hood scoop, and mounting holes.

As Sacrgo said, the OEM cooler is really more of a heater..so I didn't get another one, I just put on a new sandwich plate and redid my cooler lines to the Mocal mini radiator. My latest mod is a naca duct that feeds the oil cooler, plus I added a fan.
Beware, not all sandwich plates fit all Subaru blocks! Some plates have too much stuff poking out, and some blocks have more stuff up around the oil filter connection area. The only good use for the OEM "cooler" is to get the sandwich plate down low enough that it has clearance for the oil lines. I think all the sandwich plates will work if you use the OEM cooler as a big "spacer" . However that drops the whole package down quite a bit which is why mine tore off when I accidentally turned my road race car into a World Rally Car. I did go a long way off track though, down a ravine, across a berm, and back up the other side of the ravine! The oil cooler system was fine until I crushed the top of the berm.

My LGT also has trans and diff coolers, powered with pumps and fans. We don't have to worry about rear diff temps on the 818, but I will be installing a trans cooler too (with pump and fan) in my 818R. I've had channel alarms go off a couple of times for trans temps on 100 degree days in my LGT.