this thread is a continuation from my intercooler thread

I'm trying to lower my oil temps. With original intercooler being only 6" tall, I had the oil cooler sitting above it- not in direct flow. In this location oil temp would hit 270f with countless boosted runs, under cruise it would stay around 250f. Now I've got a 12" tall intercooler occupying that space, so the oil cooler was moved to what I thought would be a good location- under the bumper support with an air exit to the mouth. Temps went up- showing 280f at cruise and near 300f after lots of boosting. I added a scoop which dropped the temps but only by 20f - not enough. And it hampered the flow to the rad.

The cooler setup is a Hayden sandwich block with internal 180f tstat, 3/8" ports, to -10 line, 2x3x10 true cool oil cooler with 1/2" npt ports.

So I'm trying to locate the oil cooler in a good spot to lower temps. I'm considering the following or a combination of:

• Enlargement to the lower mouth area with larger oil cooler placed under the intercooler in front of the rad
• Enlargement to the lower mouth area with existing oil cooler in front of rad (difficult because the ports are on the top of the cooler)
• Existing oil cooler in wheel well with air feed from spoiler duct
• Install factory water based oil cooler (or none) to see if there's a problem with the current setup (causing high temps)

Diagram below shows the proposed lower position. The 2nd gen rx7 oil cooler is about 3 times the volume of the current cooler- and it's a double pass with the inlet and outlet on the same ends. My thinking is that the change in the lower section of the mouth piece would compensate for the blockage of the rad face due to increased flow.

Open to any other brilliant ideas. - rob

 

Granted the proof is in the pudding of actual water/oil temps, but since flow across the rad is mostly pressure differential based, it probably will reduce radiator flow, but may not make a big enough difference (1-5 degrees) to matter.

I know that you already have the oil cooler, but just an FYI that even though FM does not sell the twin cooler for the 90-97 anymore, doesn't mean that it can not be found elsewhere. Pricey yes, but a nice clean solution.

 

I could do the same with my existing setup since my rad is narrrow to allow passage of the cold side IC pipe. So the Rx7 oil cooler might work (or something similar) in that vertical space at the price of a "around the rad" cold side pipe. Good suggestion.
Here's the space:

 

Instead of blocking what little radiator surface area you still have exposed, what about oil cooler under intake manifold, facing down, with fresh air supply via duct from undertray? Or oil cooler wherever it fits under the hood, with 12v fans providing airflow?

 

I'm opposed to the fan on the oil cooler thing... tho I don't know why. It's similar to having a pump running for an air:water IC I suppose. IF I stuck the cooler in the wheel well and fed a spoiler duct to it, I'd probably consider the fan for traffic driving. Sticking the oil cooler under the hood makes me think that it's only contribute to the massive amount of heat under hood already.

 

is your car a daily driver?

if not you could put it in the headlight area with a duct leading to it, or the front of one of the wheel wells. FM put a tranny cooler in the back bumper, got the air in it as it came up and over the rear of the car.

 

Yeah- more or less. Want to try to keep it from being too much of a race car.

 

Doesn't look like there's enough space to get a decent size oil cooler in the fender well and feed air from the spoiler duct. It might work if I put a hole in the bumper cover- but that's beyond what I want to inflict on the body. The reality is the NB just has a more square nose than the NA and that makes the difference (along with a driving light hole) to making that work. Here's the site that shows the NB install.

Based on the input at this point, I think I'm down to two options.

• Put a larger cooler parallel to the ground, in front of the steer rack and feed the spoiler ducts to it - and a fan on the back side.
• Put a new cooler in the spot where my current cold side IC pipe passes, next to the rad.

Feeding the spoiler ducts will increase the underhood pressure, but I'm definitely putting holes in the hood so it should make that big of difference. The duct feed might be overkill - I could just put a smallish scoop at the base of the cooler to catch air under the car- though I don't know exactly what the flow is like. I still don't have the under tray on since the swap is going to require some alterations to it to get it installed. Don't know how that would play in to the equation either... probably an asset for flow, especially if introducing air post rad.

Mounting the oil cooler next the rad requires fab'ing a new IC pipe setup (pita because of the bov and tb hose). There's no way to get a fan on the back either (funky size - 14x4x2) unless I fab up a rear shroud and place the fan further back which might even be space limited.

Underside shot- this definitely looks like the easier job. Essentially the price of another larger oil cooler ($50), some hose shortening, connectors and duct hose. (no hydraulics used in creating this photo )


Area where coldside pipe passes

 

I removed the entire oil cooler arrangement and installed just mazda oil filter. Went out and thrashed the car. After numerous 1st-4th and 4th low to high rpm runs at full throttle the temp peaked at 290f and didn't go any higher. That's VERY similar to what I was seeing with the oil cooler- and the oil capacity was reduced by about 3/4 qt.

I've got a mercedes oe cooler that will fit next to the rad. It's about 2.5x the capacity but a tube design. Need to weld on some AN fittings and maybe brackets, shorten hoses, add fittings to install.

 

Maybe it was a combination of way too small cooler and no airflow?

 

Is there a fluid flow path that should be followed from the sandwich plate? In other words, inlet and outlet at the plate and inlet and outlet at the oil cooler?

I've been watching the developments with your oil cooler optimization...I'm in the process of doing the same with mine, though mainly due to borderline-uncomfortable oil pressures. Without getting into my rationale, methinks I need 1) a thermostatic sandwich plate, 2) shorter lines, and 3) 90-deg full-port hose ends to route shorter lines.

Just verified I can use 90-deg hose ends today (my cooler is mounted behind the mouth on the passenger side, most of the cooler is exposed to rushing air), so depending on bracketry, I might be flipping the cooler upside down to run my non-straight-end hoses. Hard to explain without a pic...and I certainly wish I had an oil temp gauge. :\

 

Do it Bosozuka-style ON the front bumper!




j/k.

I like the parallel/ in front of rack idea. Many OEMs use that location for PS coolers. My SRT4's PS cooler is in that spot and has a simple 1"x (Length of cooler) piece of plastic to catch some air.

 

beer- I hope you're right. We'll see soon- the new IC will sit right next to the rad in direct flow of oncoming air.

Cooler doesn't care where the oil comes in/out... or at least mine doesn't.

I'm considering an upgrade to the mocal Tstat because it has the larger 1/2" npt ports, whereas my hayden has 3/8" and no room for overbore and rethread.

koto - - that first pic is too appropriate - my d-side headlight is missing (lowpro lights) so it would work. Or I could get some of those flares and mount a cooler in one with a duct?

 

when the t-stat is closed, what happens to the oil? does it simply bypass the path to the cooler and flow to the pan? if so, is there a possibility your t stat simply failed to open?

 

The tstat opens. When my oil temp gauge got near 200f, I pulled over and the lines were hot. It doesn't make a whole lot of sense to me. And it's easier for me to just change a bunch of **** rather than going thru one piece at a time, just because I don't have a lot of time to do the pinpoint troubleshooting.

The merc cooler was $35, plus the mocal tstat sandwhich plate $90 and whatever I spend on fittings. I could drive on the street all day like this (apparently) but IF (when) I track this car, I don't want to have to look at the oil temp gauge all the time. Most turbo'd street miatas are fine (even in the SE heat) but put them on the track and that all changes.

I'm probably being overly cautious. For example - CSR did his DIY extractor hood because of water temps - he doesn't have an oil temp gauge. I think he's tracked his 95 for five years now, turbocharged at 12psi.

 

Just wondering how your project is coming along ?
I have the Mocal sandwich plate, 1/2" lines and a small-ish 7 row cooler.
My cooler is mounted off the steering rack, between the ARB and the crank pulley, then ducted from the undertray. Cruise temps are 195F, track temps get up to 230F max. It works pretty well, but i always worry about it on the track, its kind of exposed being on the bottom of the engine should i take a trip into a gravel trap....or worse, the scenery.

 

I am sure you know what you are doing (and I am a newbie on the forum but...

I have a kit from Moss, with the filter on the firewall and the cooler in the driver side wheel well (my car is a -99, so far without boost). The thermostat in my kit (and I assume in other kits) is always a little bit open, to make sure the cooler stays filled with oil and no air gaps are created in the system. When it “opens”, it actually just opens more, flowing more of the oil thru the cooler. Therefore, my oil cooler and oil lines actually gets hot before the thermostat is open, just from the slow base flow thru it.

 

torkel, you may have a point. I know there's a gap behind the tstate blade- you can see it when the fitting is off the car. It looks fine, but it's not too complex either being the cheapie flat coil type vs. the true mocal type tstat. That said, the coiled blade works, has worked forever, which is why it's still used.

My merc cooler now as -10 bungs on it, just need to install it. Haven't had ANY free time, and when I do get some I've got to do the tbelt on the RX300.

lloydie- you could build a shroud/housing around the cooler and run some ducts from the front (spoiler vents). That would protect it and channel some direct air. That's what I'm planning to do.

 

Man, i like this guys setup. Might just have to copy the oil cooler portion. Found this on someone's cardomain as you can tell.

 

yeah, I've got that marked. Perfect for an NB, but no room on an NA w/o sticking some stoooopid holes in the bumper skin.

I've seen those coolers come up on ebay as trans coolers (still have 1/2" npt fittings) for cheap. No mention of oil cooler, so it might be a way to pick up one cheap. AND ebay is a good place to find all kinds of hose and AN fittings - second hand nascar stuff if you don't mind washing it out.