Interesting that water temps dropped 10 degrees after installing the OEM dual coolers. If anything, that's a testament to just how poor the FD single oil cooler setup really is. I know Rx-8's with single oil coolers (mostly automatics I think) have a tough time with cooling. I also noticed on my FC that oil temps were much lower during highway cruising than any other kind of driving.

I never bothered to measure it but a quick search in the 2nd gen section says the FC oil cooler has these dimensions:

Length (including endtanks) 22.5"
Length (core only) 19.75"
Height 4.5"
Width 2"

multiplying the bottom 3 dimensions gives a volume of 177.75 cubic inches excluding the endtanks. That's about the size of many FMIC's for turbo Hondas I wonder what the combined volume of the OEM FD dual oil coolers works out to be? Of course, there's more to a heat exchanger than its total volume.

FYI, the factory 2nd gen oil cooler has a dual-pass design with a 150F thermostat. They have rubber mounts and a bracket on the car. It's held on by four studs.

 

Thank you for this thread. FD's really should have come from the factory with twin oil cooler...ALL of them!

This is 100% on my to-do-list this winter.

 

When building my new motor I also went with dual oil coolers. However I bought brand new from Mazda. Fortunately I get a significant discount. The money was well spent. I too agree don't know why Mazda did not do this on all FD's.

 

I have an fd touring with a single oil cooler and have been planning to upgrade the oil cooling. I am aware of the size and availability of the FC oil cooler and was thinking about maybe using one rather then blowing money on dual oil coolers. I was wondering if anybody has done this and knows of the benefits?

 

I don't know if anybody has done it on an actual FD. FC owners with REW swaps have adapted the FC oil cooler to the FD engine though. If you can find a good place to put it (proper airflow etc) the FC cooler will be a vast improvement over the single factory FD cooler, and probably perform at least as well as the OEM dual oil coolers if not better. 2nd gen owners rarely upgrade the OEM oil coolers, although some people have actually done dual FC oil coolers. Here is a diagram of the FC oil system:



The fittings on the cooler itself are M16 (M16x1.50 ?), so you will need metric to AN adapters. You will want 10AN hose and probably some 90 degree fittings. Here is a writeup from somebody who did custom oil lines on an FC block (factory FC hoses eventually fail): https://www.rx7club.com/2nd-gen-archive-72/custom-oil-cooler-line-partlist-270545/

I believe the FC block has M16 on the front cover and M18 on the rear iron. I'm not sure what the sizes are on the REW block. They might all be M18. Here are pics (credit to Corksport) of the factory mounting points (10mm nuts) on the FC cooler:



I'd budget at least $150 for the oil lines. All the hose and fittings won't be cheap. If you could fab some brackets yourself you could probably do the whole project for under $250. I think the oil coolers (turbo and non turbo are the same) go for about $50 used on this forum, so you wouldn't be out a whole lot of money if you bought one and at least tried to mock it up see whether it would be feasible or not.

 

I see a 10 degrees drop in Celsius for coolant on my PFC commander.

In 90F temp with a single cooler, I used to see 106+C on the coolant temp (running Evans NPG+).

In 90F temp with dual OEM coolers, I never see higher than 95C.

 

Also, unless you are experienced at making your own braided fittings, best to try the local hydraulic shops. I blew out the Aeroquip oil lines (the push on type) TWICE! I think it had to do with the 90psi oil pressure. The cost of these Aeroquip lines was around $130.00 that ended up in the trash can. I kept the fittings but I don't trust them.

In San Jose, I went to one that makes fittings for the small engine airplane crowd and for the construction industry. Two lines for $150 as long as you give them exact dimensions and size of the fittings. They will crimp that sucker down so that it would take 1500 psi of oil pressure.

 

Yep, here's one.

LINK

 

Question mike,

Have you tracked your FD in hotter (90degree +) weather with the duals? If so how were the temps?

I ask because Ive been to the track many times when weather even passed 100 and without monitoring my oil temps I have no idea what temps I was hitting. Coolant was in check tho. I hope the stock duals can hold up Cali heat.

 

Last time I was out was on Memorial Day weekend, May 29 @ Cal Speedway. According to the weather record AT THIS LINK it was about 89*F max... from about 2-6 PM that day. My run sessions later in the day as it heat up did not indicate hotter oil..

However I think in 100+* heat you would need more cooling, depending on how hard you drive and the track itself. A track like CA Speedway is very hard on your motor because of the high speeds, a good chunk of that track is pure straightaway.

Towards the end of the day my water temps were more of a problem. Hit about 230*F @ the thermostat housing and decided to back off for the last 5 minutes or so. Oil never went past 240*F measured at the pan, so the oil going into the motor would be cooler than that, not sure by how much. My guess is that the cooled oil was around 200*F. I'll talk to a heat transfer person/engineer and it shouldn't be hard to calculate a ballpark figure for the cooled oil. On my next setup I'm thinking of installing an additional oil temp gauge after the coolers to measure the effectiveness of the coolers. How about that, dual oil coolers and dual oil temp gauges

I think it's a really good idea for a tracked car to get a oil temp gauge. My oil temps would change a lot faster than water, I could tell when my water would heat up because the oil would go up first, and conversely for cooling too.

Here's a couple of notes on engine oil and temperatures:

Here's a good read from a Porsche vendor/racer on oil temp vs. engine life, etc.

Racing Beat says oil temperature in rotary shouldn't go above 250*F w/o severe engine damage & synthetic oil drops oil temps 5-10*F

Racing Beat says oil going into motor should be < 205*F

I can't seem to find it anywhere, but on the old Mazdaspeed site, they recommended that oil for an N/A rotary on the track should never exceed 260*F (it may have been 265, don't rememeber exactly) @ the pan...

 

engine oil less than 205F is simply asking too much.

 

yea at temps above 100f I think its best to at least have a cool down lap every 10-15min max. At least with the stock dual coolers. I personally stopped going to the track during the summer, especially streets of willow which is in the desert because its just too nasty when its hot.

I sweat like a dog, get sweat in my eyes while driving, tires melt, brakes fade earlier, engine runs hotter... Its a headache and not too enjoyable. Couple times I went by myself and didnt bring a cooler or a canopy...I had quite the farmers tan when I got home.

 

Great read, im about to undertake this project myself, it was good to have a visual on what exactly im getting myself into

 

this may be a stupid question but........ would it be possible to make a v mount with a rad ic and oil cooler? kinda like...

 

^ The question is, what will you have to do to make it fit and will it actually be efficient (proper airflow etc)? You will most likely have to answer those questions yourself.

 

^^ That's not a stupid question at all. Only thing tho is that for a generally stockish plumbed setup, you have a large area directly in front of the car dedicated to IC/rad air, and two more areas on the sides specifically for oil coolers. From a plumbing/mounting/airflow/simplicity perspective, I would stick with that setup... but that's just me I think it also heavily depends on your bumper openings/airflow to the coolers. But anything is possible... just have to justify it, measure it, try it, and report your results. Then you can say it was worthwhile. My $0.02

 

Does anyone have any pics of the install especially the famous "missing line" from the passenger cooler.

 

^^ Got ur PM, I will reply later this week or weekend. Here's a pic of the line:



Also, if you look in the parts manual there are pics of it there too... show you every part you need.

 

mdpalmer thanks for the pics and the diagram.

I have included a few pics of all the lines I received from the seller and question if one line is the one from the passenger cooler or the one I already have on the car.

If anyone can give me a positive answer, I would appreciate it. I am trying to have everything in order before I start the job.

Line in Question


All lines including the one to the oil pedestal, which I know that I already have on the car.

 

is there any specific proceedure on how to fill the system with oil ? or simply turn the key and start the car?
when you install an engine after a rebuild and these new oil coolers , the system is completely dry.
is it ok for the engine to start?

 

Wow, those pics are shitty bro. The line that goes from the oil filter to the d/s cooler does not change, already on the car. The line in question is the one that goes from front cover to dual oil line to p/s cooler. Just make sure you have crush washers for the line as you should replace them. I re-used my clips, even tho manual says to replace them (they are just a retainer, if they still have stiffness, no need to replace). Should take a 23 mm wrench to remove the banjo bolt on the front cover.

When the engine is assembled, builders typically use oil and/or assembly lube to help assemble the parts and provide some protection on 1st startup. I've heard of some guys using "pre-lubers" to fill oil passages with oil before starting the engine up, but I don't see any benefit to doing that unless you plan on firing up the engine right away... the oil will probably gravity drain back to the pan if you let it sit for a bit.

I let my FD sit for 2 months one time w/o starting it up, I would imagine oil coating/thickness/protection on internal parts like bearings, etc. would be similar to a fresh built engine. It took a few seconds for oil pressure to come up, when normally (I normally drive it 3 times a week) it would be almost instantaneous after cranking it over.

Talk to your engine builder. From reading internet posts, sounds like a lot of chevy v8 guys just fire the engine up and let it build pressure, should be w/in seconds.

 

Fill the motor with oil... pull the FP fuse, crank it over a few times. This should help to prime the empty lines. It may not fill everything, but it will prime it enought that when you fire it up you wont be starving the engine/turbos etc.

 

Since this thread was bumped I thought I would share the information that I posted on another OEM dual cooler thread. If anyone needs pictures or parts placement, then just ask.

This will completely replace all OEM lines with SS line & AN fittings using the OEM oil coolers. No fitment issues with A/C. Be sure to cover the SS lines with plastic loom at possible rub points.

http://www.batinc.net/

QTY....OIL COOLER FITTINGS…………………………………..........................PAR T#............PRICE

4.... Male 22 MM X1.5 MM metric concave seat -10 AN aluminum...AM22AN10...............12.95--- 51.80
13 ft -10 aeroquip line.............................................. .................FC3-10.....................6.50---84.50
2.... 45 degree alu -10 hose end............................................... ....T45-10..................18.75---37.50
2.... straight alu -10 hose end............................................... ........TS-10......................8.95---17.90
1.... male 18 MM X 1.5 Metric concave seat to -10 AN steel...........AM18AN10.................9.85
2.... 90 degree alum -10 hose end............................................... .T90-10...................37.50
1.... "Metric Banjo -AN Male"............................................. .............BJ1810M...............30.15
1.... banjo bolt.............................................. .................................BJBM18........... ....11.90
2.... seals............................................. ..........................................DS-M18................0.80--- 1.60

$282.70

 

has anyone done testing to compare the cooling of dual r1 coolers vs. a single 19-row cooler?

 

Good idea. Another thing you may consider is putting fire proof sleeve over the lines. For -10 line looks like you can use these in 7/8 ID:

http://www.pegasusautoracing.com/pro...p?Product=3299

The sleeve is kinda ugly however.. it has a nasty orange color to it. From what I gather this hose is very durable. I covered my stainless steel clutch lines with this stuff.