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View Full Version : ? for people using the RX-7 oil cooler



TRACKMKIII
January 23rd, 2008, 08:07 AM
I have been searching around for a simple oil cooler upgraded and the one that keeps popping up is using the 2nd gen RX-7 oil cooler. I know it will be tough to mount but I have seen the size of that thing and it seems like it would be very useful? Now my question is this a direct replacement for the stock unit or will I have to fabricate some lines? Also how is the new cooler regulated? Does it have an internal thermostat? I just need information on how the system will work once the RX-7 cooler is install and how it installs. Thanks for any info.

Also if you are selling one or know where I can get one let me know!!

spoolint78
January 23rd, 2008, 10:53 AM
internal thermostat.
you have to get new braided lines, or any other type of high temp/pressure lines.

here is a pic of mine.


http://img297.imageshack.us/img297/4601/picture186kg8.jpg
http://img297.imageshack.us/img297/8029/picture185rn1.jpg
this mofo is huge.
i have to raise it up a little, because i'm scared the fitting might get hit, and cause me to leak out all of my oil.

IJ.
January 23rd, 2008, 11:30 AM
Spool: It would be nice to replace that 90 elbow with a 90 sweep....

The Elbow is = to 10 feet of straight hose in restriction.

TRACKMKIII
January 23rd, 2008, 12:07 PM
Do you just run the lines to the block with the N/A stud and a sandwich plate? What kind and size fittings are those?

spoolint78
January 23rd, 2008, 02:14 PM
the bottom fitting is no longer like that.
i only have 1 90 where it connects to the bottom inlet of the oil cooler.

I'm still trying to position it properly, because as you can tell in the pic it sits kind of low.

i'm also debating on welding the fittings onto the oil cooler, because right now a good tap will spin the fitting.

blackturbona
January 24th, 2008, 12:18 PM
make a stong cover for the fitting?

wiseco7mgt
January 24th, 2008, 01:33 PM
arent you scared your car will catch the dreaded rotoary disease and blow a up?:icon_ques but seriously i know of a guy in a rx7 that had his crack under pressure, i dont like the idea of that as it emptys the sump in the blink of on eye...you have to remember they are getting fairly old and that makes them brittle.

jdub
January 24th, 2008, 01:54 PM
...you have to remember they are getting fairly old and that makes them brittle.



I didn't know the RX-7 cooler was made out of plastic...everyone I've seen was metal :sarcasm:
Last I checked, metal does not get "old and brittle"...the cooler is not even under any structural stress.

IJ.
January 24th, 2008, 02:07 PM
runs in chucks the "Work hardened aluminium" grenade and runs out :D

jdub
January 24th, 2008, 02:26 PM
LOL...true, some grain change is evident at temps as low as 250 deg F. To get significant changes in yield and tensile strength requires temps over 450 deg F...I hope the cooler is not exposed to temps that high! ;)

IJ.
January 24th, 2008, 02:30 PM
"Work hardened" not "Heat affected" ;)

jdub
January 24th, 2008, 02:54 PM
Understand...I should have said "temps over 450 deg F accelerate the hardening effect (followed by cool down)". It would take quite a bit of time for the temps the cooler is exposed to harden it to the point of failure with no structural stress present (other than 50 psi internal pressure).

Point taken though...metal does get hardened over time. Just didn't think it was something to worry about in a piece that *should* be no higher than 100-110 deg C.

buldozr
January 24th, 2008, 03:16 PM
arent you scared your car will catch the dreaded rotoary disease and blow a up?:icon_ques but seriously i know of a guy in a rx7 that had his crack under pressure, i dont like the idea of that as it emptys the sump in the blink of on eye...you have to remember they are getting fairly old and that makes them brittle.

The Rx-7 oil pressure is 90-105psi on full tilt, the oem mazda lines will go before the cooler will(Two 88 rx7's in my short lifetime, I replace the oil cooler lines once a year with oem Mazdas that are prone to bursting on the highway... dont worry about the cooler)

IwantMKIII
January 24th, 2008, 06:27 PM
Last I checked, metal does not get "old and brittle"...the cooler is not even under any structural stress.

No...but it does get fatigued, and it is constantly under structural stress, its just negligible in the scheme of things, most of the time ;)

wiseco7mgt
January 25th, 2008, 01:58 PM
sorry guys ive got some mates that are into rotaries and ive just seen a mazda oil cooler after it had been on the original engine for just over 200,000kms and it was fingered..being alloy it seemed like it had gone brittle and crumbly.I imagined it was constant cycling of heat that caused it, sorry if i was wrong.

IJ.
January 25th, 2008, 02:01 PM
Aluminium will work harden in time (think constant flexing)

Boats have a finite lifespan when built in aluminium and eventually get fatigue cracks.

IwantMKIII
January 25th, 2008, 02:23 PM
Aluminium will work harden in time (think constant flexing)

Boats have a finite lifespan when built in aluminium and eventually get fatigue cracks.


im confused by what you're trying to say here. Constantly flexing past a materials yield stress causes fatigue and results in failure.

IJ.
January 25th, 2008, 02:28 PM
Look up "work hardening"

Nothing to do with flexing past it's yield.

I'm talking very small deflections over long time periods.

IwantMKIII
January 25th, 2008, 03:42 PM
Look up "work hardening"

Nothing to do with flexing past it's yield.

I'm talking very small deflections over long time periods.


oh ok, i was relating the more extreme flexing of the boat example you gave to the constant flexing you mentioned

buldozr
February 7th, 2008, 08:54 PM
sorry to open up a dead thread but does any one know the fitting size on the RX cooler?(NEW PROJECT!)

nvgc8
February 8th, 2008, 10:50 AM
The thread size and pitch of the inlet and outlet are M18 x 1.5

Zumtizzle
July 17th, 2008, 12:13 AM
The thread size and pitch of the inlet and outlet are M18 x 1.5

THANK YOU!

I just got one and was about to PM adjuster but you saved him the bother! ;)