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914World.com _ 914World Garage _ Would a cooler like this work in the front
Posted by: JmuRiz Sep 25 2012, 08:57 AM
I was wondering if an oil cooler like this one would work as a front oil cooler of a 2.7 6 conversion.
What are your thoughts? BTW it's a Behr from an old Mercedes.
Attached image(s)
Posted by: SLITS Sep 25 2012, 09:48 AM
Why not? It's a single pass, fin & tube cooler. The type can still be purchased today.
Posted by: carr914 Sep 25 2012, 10:28 AM
pretty sure that is what rfuerst911 used
Posted by: Elliot Cannon Sep 25 2012, 10:34 AM
Contact bdstone. He knows a little about oil coolers. 
Posted by: Scott S Sep 25 2012, 11:30 AM
What is that cooler out of?
Posted by: Dave_Darling Sep 25 2012, 11:35 AM
Anything will work, frankly. Even bare metal tubes--just ask 911SC owners about that. The question is will it work well enough?
A plate-style cooler will be more efficient and reject more heat per area. Not sure about flow restriction.
Is it what you need? Could be, but that depends on a whole lot of variables. Like the air temps you expect to see, how much cooling the engine needs, the exact ducting of cool air to it and warmed air away from it, and so on.
--DD
Posted by: JmuRiz Sep 25 2012, 11:50 AM
What is that cooler out of?
The one I have is out of a euro-spec Mercedes M110 engine (2.8l DOHC inline 6 with 185HP) but that engine is pending sale along with my car.
I was just outside and thought the dimensions were close to the 914/6 GT coolers and since it helped with a 2.8l inline six.....
I'd have to find another one, but I'm sure they are out there.
Thanks to all you guys for your help. I'll probably run either braided lines or those cool GT-style hardlines to the front (the ones PMB are doing). I've been told a front cooler is best, so what the heck.
If anyone has a line on a good RX7-cooler or of a place to get one, I'd be willing to think about that too.
Posted by: Scott S Sep 25 2012, 11:57 AM
I had the RX-7 cooler - they were so cheap from our local pic a part (like 10.00). However, after researching within this group, it seemed like it would take quite a bit of cutting and rewelding to get the cooler to work (removing the built in t-stat). The cost to have this work done and then have the cooler cleaned was getting close to the cost of other options.
I gave away the ones I had several years ago because of this.
Posted by: JmuRiz Sep 25 2012, 12:16 PM
Bummer, but good information to know. I'll see what ideas people have as well as the local Porsche racers near me (not that my car will be more than a street car).
Posted by: SirAndy Sep 25 2012, 12:20 PM
I used to run the same type (old Mercedes oil coolers) on many of my bugs back in the day.
Mounted under the front bumper ...
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Posted by: SLITS Sep 25 2012, 12:59 PM
I had the RX-7 cooler - they were so cheap from our local pic a part (like 10.00). However, after researching within this group, it seemed like it would take quite a bit of cutting and rewelding to get the cooler to work (removing the built in t-stat). The cost to have this work done and then have the cooler cleaned was getting close to the cost of other options.
I gave away the ones I had several years ago because of this.
I hate this .... the only reason to remove the thermostat from the RX7 cooler is that it takes a little longer for the engine to come up to temperature because of the added 1-2 quarts of oil in the lines.
The stock RX7 thermostat would prevent the oil from flowing thru the cooler until it came up to temperature.
If there is that much wear in the engine created by having to warm up a couple more quarts, then there is something wrong in the metallurgy or design.
Besides, you could remove the thermostat and probably use an expandable freeze plug to achieve the same thing as cutting, replacing the mid plate and re-heliarcing the tank back on an RX7 cooler. ( I haven't tried this as yet, but I'm getting there).
Just my thoughts. I've been running a plate cooler for about 10K miles with no thermostat and my engine is far from wearing out.
Rant over .....
Posted by: Scott S Sep 25 2012, 03:30 PM
Crap. I wish I would have known this Ron. I gave away three of those coolers. After reading various threads, I didn't think they were just plug and play. That stinks.
And you never see RX-7's in our local wrecking yards anymore either.....
Posted by: wndsrfr Sep 25 2012, 04:15 PM
What is that cooler out of?
The one I have is out of a euro-spec Mercedes M110 engine (2.8l DOHC inline 6 with 185HP) but that engine is pending sale along with my car.
I was just outside and thought the dimensions were close to the 914/6 GT coolers and since it helped with a 2.8l inline six.....
I'd have to find another one, but I'm sure they are out there.
Thanks to all you guys for your help. I'll probably run either braided lines or those cool GT-style hardlines to the front (the ones PMB are doing). I've been told a front cooler is best, so what the heck.
If anyone has a line on a good RX7-cooler or of a place to get one, I'd be willing to think about that too.
I have two RX7 coolers for, say $ 30 each. I used one for a while with the thermostat plugged off since I have a mocal in line tstat. They are a great fit for a front mount setup. However, do a search on Rx7 coolers here and you'll find the thread on how to remove the strips from inside the tubes & re-weld the tank on the end......without doing that the cooler is very restrictive when the oil is cold & causes an oil pressure drop when the tstat switches. Let me know if you want one.
Posted by: SLITS Sep 25 2012, 05:41 PM
However, do a search on Rx7 coolers here and you'll find the thread on how to remove the strips from inside the tubes & re-weld the tank on the end......without doing that the cooler is very restrictive when the oil is cold & causes an oil pressure drop when the tstat switches. Let me know if you want one.
Not to start an argument, but:
Since the cooler is on the scavenge side of a six pump and no pressure is measured there, I fail to see how it would effect the oil pressure in the engine. The oil returning to the filter and tank is what is cooled.
A six pump is a flooded suction pump with 8 quarts of oil in the tank feeding the engine oil pump.
Posted by: wndsrfr Sep 25 2012, 07:31 PM
Since the cooler is on the scavenge side of a six pump and no pressure is measured there, I fail to see how it would effect the oil pressure in the engine. The oil returning to the filter and tank is what is cooled.
A six pump is a flooded suction pump with 8 quarts of oil in the tank feeding the engine oil pump.
Ahhh.....yes, right on. I was relating my experience with my Type4 & didn't remember that it's a 6 being worked on. In which case, since the scavenged oil is quickly warmed, the only pressure spike in the system will be on startup with high pressure on the elements of the system upstream of the cooler. Where in the system is the filter located on a sixer? Wix has a racing filter good for like 100psi which is what I'm using....
Posted by: SLITS Sep 25 2012, 08:01 PM
With a stock six tank, the oil filter is on the tank. It filters the oil prior to free dump in the tank.
With an aftermarket tank, it can be on the tank or remote in a line.
Pressure of the system would be such to push the oil thru the filter as it is the only restriction other than elbows, lines and cooler capacity,
I use a standard Bosch filter for the early sixes.
Posted by: rgalla9146 Sep 25 2012, 08:53 PM
I had the RX-7 cooler - they were so cheap from our local pic a part (like 10.00). However, after researching within this group, it seemed like it would take quite a bit of cutting and rewelding to get the cooler to work (removing the built in t-stat). The cost to have this work done and then have the cooler cleaned was getting close to the cost of other options.
I gave away the ones I had several years ago because of this.
I hate this .... the only reason to remove the thermostat from the RX7 cooler is that it takes a little longer for the engine to come up to temperature because of the added 1-2 quarts of oil in the lines.
The stock RX7 thermostat would prevent the oil from flowing thru the cooler until it came up to temperature.
If there is that much wear in the engine created by having to warm up a couple more quarts, then there is something wrong in the metallurgy or design.
Besides, you could remove the thermostat and probably use an expandable
freeze plug to achieve the same thing as cutting, replacing the mid plate and re-heliarcing the tank back on an RX7 cooler. ( I haven't tried this as yet, but I'm getting there).
Just my thoughts. I've been running a plate cooler for about 10K miles with no thermostat and my engine is far from wearing out.
Rant over .....
I agree with slits,
why remove a built in t-stat ? By keeping it you avoid four additional connections and the cost of an additional part. It allows reduced flow until operating temp is reached.
Also, it is designed to prevent explosion caused by excess oil pressure when cold.
The adaptation can be as simple as drilling to enlarge and tapping existing bungs and welding on an additional tapped bung for better position.
Rant over x 2....
Posted by: Scott S Sep 26 2012, 09:16 AM
Wndsrfr -
Do you have a good RX-7 cooler for sale? If so, I am absolutely interested.
(sorry for the hi jack...)
...oh - and once again - THANKS RON!
Posted by: wndsrfr Sep 26 2012, 05:25 PM
Wndsrfr -
Do you have a good RX-7 cooler for sale? If so, I am absolutely interested.
Yep, I've got one more available.......PM me.....
Posted by: ConeDodger Sep 26 2012, 05:30 PM
BDStone - Bruce Stone did a talk on oil coolers at WCR2010 Teeners at Tahoe. He specifically mentioned the Mercedes Benz Behrs... In a good way IIRC. 
Clean it and use it!
Posted by: majkos Sep 28 2012, 01:51 PM
Hey Scott, I have one too.
just brought it home from RRC.
Posted by: larryM Sep 29 2012, 05:54 PM
the front cooler is a LONG WAY from the sixer engine - it may NEVER get warm oil to open that RX7 thermo - since no flow exists to warm it up until the thermo is open
take it out
I hate this .... the only reason to remove the thermostat from the RX7 cooler is that it takes a little longer for the engine to come up to temperature because of the added 1-2 quarts of oil in the lines.
The stock RX7 thermostat would prevent the oil from flowing thru the cooler until it came up to temperature.
Rant over .....
Posted by: SLITS Sep 29 2012, 08:36 PM
Flow to the cooler will occur as it is plumbed into the scavenge line of the six.
At the cooler, cold oil will just make a U-turn and head back to the oil tank.
At the cooler with hot oil, the cooler thermostat will plug the bypass and direct oil thru the cooler body.
Also, on a six, the onboard cooler is by-passed with the on-board thermostat. No oil is cooled until the thermostat opens.
Posted by: JmuRiz Jul 22 2013, 08:41 AM
I saw this picture in the sandbox, looks like someone did some custom work on an LE front valance to install a cooler like the one I posted at the start of this thread.
Doesn't look as low as the RSR cooler, but may be a solution for front oil cooling w/o cutting up the front trunk.
What are your thoughts?
Posted by: SLITS Jul 22 2013, 01:51 PM
I saw this picture in the sandbox, looks like someone did some custom work on an LE front valance to install a cooler like the one I posted at the start of this thread.
Doesn't look as low as the RSR cooler, but may be a solution for front oil cooling w/o cutting up the front trunk.
What are your thoughts?
As long as the nay-sayers don't jump you with lines about hitting curbs or objects in the road, it would work fine.
In the late '70s I worked on a 914/6 race team. The stock front valence was pulled down and out, stretched, braced and the oil cooler was installed behind it ... no cutting of the car. It was only a problem when the driver hit a cone at Holtville and broke the AN fitting ... 13 quarts of Castrol R on the track.
Posted by: JmuRiz Jul 22 2013, 02:27 PM
I figure if it's good enough for a 911 2.7RS & RSR...
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