oil cooler, your thoughts Options

[ArtechnikA]

Just curious what the "conventional wisdom" and "good reasons" are for running them in parallel?

mostly, it has to do with the nonlinear efficiency of a heat exchanger and the temperature differentials.

if a heat exchanger can reduce the temperature of 250F oil to 200F, you've rejected 50F to the airstream. that same exchanger is not going to reduce the temperature of 200F oil to 150F. the greater the temperature differential between the oil and the heat sink (the freestream air) the more efficient it is going to be.

so for most efficiency, you want the oil entering the heat exchanger to be as hot as possible to avoid getting into diminishing returns.

as you've observed, there are places and applications where serial coolers make sense.

[Trekkor]

Nice cooler set-up JP. (IMG:style_emoticons/default/clap56.gif)

[brant]

Rich,

my ignorance shines through...
I should have clarified that my new set up is in parallel (sp)

and not in series...
(however I am using double pass coolers so actually the coolers are in series, but they have a built in parallel component also)

Andy, do you still have those pictures of my front hood and ducting on the black car?

brant

[machina]

my ignorance shines through...

Can someone diagram or describe a parallel arrangement?

Do you need coolers with multiple ports like the ones fluidyne makes? If not, I imagine a couple T's in the lines.

dr

[eeyore]

JP,

I like that set-up. That kink in the tub where the steering rack is looks like a good low pressure area.

You do you leave the steering rack cover / skid plate off?

[maf914]

Can someone diagram or describe a parallel arrangement?

Series versus parallel?

Series is when all of the oil flows first through cooler #1 and then through cooler #2.

Parallel is when the oil flow is split with a part of it flowing through cooler #1 and the remainder flowing through cooler #2.

[ArtechnikA]

I imagine a couple T's in the lines.

yes, inline Tees.

less overall pressure loss too, even without considering the scenario where one cooler gets plugged with something.

since the flow is split, you might be able to take advantage of a reducing Tee and run smaller, cheaper, lighter lines to the separate coolers -- but i'd probably keep it all the same.

if you were determined to run two coolers in a /6, a second or replacement cooler in the pressure circuit can pay off -- the pressure-side oil has been de-aerated and pressure-side coolers are much more efficient. scavenge oil is more like foam, yet another reason the fittings must be on the top...

[J P Stein]

You do you leave the steering rack cover / skid plate off?

The cover is on.

The holes are 3 inch diameter. That would seem to be an inadaquate amount of venting area, but it works. (IMG:style_emoticons/default/confused24.gif)

Maybe the front valence helps build air pressure at the cooler.

[p914]

JP,
How much did that cooler setup end up costing?

[J P Stein]

IIRC

The cooler .....direct from Fulidyne... 300
Troutman thermo ....165....got a deal on that. They're around 200-210.
Fittings & hoses.....about 280 (IIRC)....ya need lots of bent fittings and them suckers aren't cheep...damnit....Summit Racin'.

I've got some -12 hose & straight fittings left over....or was that plan B? (IMG:style_emoticons/default/confused24.gif).....Anyhew, the stuff is F/S cheep.

[SpecialK]

Just curious what the "conventional wisdom" and "good reasons" are for running them in parallel?

mostly, it has to do with the nonlinear efficiency of a heat exchanger and the temperature differentials.

if a heat exchanger can reduce the temperature of 250F oil to 200F, you've rejected 50F to the airstream. that same exchanger is not going to reduce the temperature of 200F oil to 150F. the greater the temperature differential between the oil and the heat sink (the freestream air) the more efficient it is going to be.

so for most efficiency, you want the oil entering the heat exchanger to be as hot as possible to avoid getting into diminishing returns.

as you've observed, there are places and applications where serial coolers make sense.

As you stated, heat exchanger efficiency/transfer is non-linear. Let's assume that the maximum heat transfer one HE can achieve will drop the oil temp 50F. So using your example of a heat exchanger lowering the temp. of the oil from 250F to 200F, a parallel HE system would still have a total outlet temp of 200F (50F differential). So if there's an efficiency drop in the secondary HE of a series system (say 50% for the sake of argument) which only allows for a 25F differential over the inlet/outlet temp (200F to 175F), you would still have a total of a 75F differential from a series system VS a 50F differential from a parallel system. So wouldn't "diminished returns" on a series setup be better than "no returns" (in the form of added heat loss) on a parallel setup? NO disrespect intended with my question, just trying to get the facts straight prior to running all of my oil lines (dual cooler).

Kevin

[ArtechnikA]

Troutman thermo ....165....got a deal on that. They're around 200-210.

NOW i remember why i hate you (IMG:style_emoticons/default/laugh.gif)

no matter what i do to the 911 this winter it's getting a front cooler, the big 911RS-sized FluiDyne one. naturally my '71E had no factory cooler and therefore no factory thermostat, so i'm gonna need to do -something- ... a quick search for Troutman thermostatsturned up nothing but people recommending them or bragging they were using them - no leads on suppliers. are these things even available any more ?

i'll use a factory thermostat console if i have to, the more i hear about the Mocal the less sure i am that's a viable alternative. (the factory thermostat console is expensive, but so's my engine ...)

[phantom914]

Just curious what the "conventional wisdom" and "good reasons" are for running them in parallel?

mostly, it has to do with the nonlinear efficiency of a heat exchanger and the temperature differentials.

if a heat exchanger can reduce the temperature of 250F oil to 200F, you've rejected 50F to the airstream. that same exchanger is not going to reduce the temperature of 200F oil to 150F. the greater the temperature differential between the oil and the heat sink (the freestream air) the more efficient it is going to be.

so for most efficiency, you want the oil entering the heat exchanger to be as hot as possible to avoid getting into diminishing returns.

as you've observed, there are places and applications where serial coolers make sense.

As you stated, heat exchanger efficiency/transfer is non-linear. Let's assume that the maximum heat transfer one HE can achieve will drop the oil temp 50F. So using your example of a heat exchanger lowering the temp. of the oil from 250F to 200F, a parallel HE system would still have a total outlet temp of 200F (50F differential). So if there's an efficiency drop in the secondary HE of a series system (say 50% for the sake of argument) which only allows for a 25F differential over the inlet/outlet temp (200F to 175F), you would still have a total of a 75F differential from a series system VS a 50F differential from a parallel system. So wouldn't "diminished returns" on a series setup be better than "no returns" (in the form of added heat loss) on a parallel setup? NO disrespect intended with my question, just trying to get the facts straight prior to running all of my oil lines (dual cooler).

Kevin

I think that in the parallel system, the temperature drop in each exchanger would be greater than it would be in the first exchanger of the series system since in the parallel system the fluid volume is split and would spend more time in each exchanger. But then again, this is all just theory (WAG).

How about you try it both ways and prove it one way or another with a real world experiment? (IMG:style_emoticons/default/wink.gif) Then we would know.


Andrew

[SpecialK]

Just curious what the "conventional wisdom" and "good reasons" are for running them in parallel?

mostly, it has to do with the nonlinear efficiency of a heat exchanger and the temperature differentials.

if a heat exchanger can reduce the temperature of 250F oil to 200F, you've rejected 50F to the airstream. that same exchanger is not going to reduce the temperature of 200F oil to 150F. the greater the temperature differential between the oil and the heat sink (the freestream air) the more efficient it is going to be.

so for most efficiency, you want the oil entering the heat exchanger to be as hot as possible to avoid getting into diminishing returns.

as you've observed, there are places and applications where serial coolers make sense.

As you stated, heat exchanger efficiency/transfer is non-linear. Let's assume that the maximum heat transfer one HE can achieve will drop the oil temp 50F. So using your example of a heat exchanger lowering the temp. of the oil from 250F to 200F, a parallel HE system would still have a total outlet temp of 200F (50F differential). So if there's an efficiency drop in the secondary HE of a series system (say 50% for the sake of argument) which only allows for a 25F differential over the inlet/outlet temp (200F to 175F), you would still have a total of a 75F differential from a series system VS a 50F differential from a parallel system. So wouldn't "diminished returns" on a series setup be better than "no returns" (in the form of added heat loss) on a parallel setup? NO disrespect intended with my question, just trying to get the facts straight prior to running all of my oil lines (dual cooler).

Kevin

I think that in the parallel system, the temperature drop in each exchanger would be greater than it would be in the first exchanger of the series system since in the parallel system the fluid volume is split and would spend more time in each exchanger. But then again, this is all just theory (WAG).

How about you try it both ways and prove it one way or another with a real world experiment? (IMG:style_emoticons/default/wink.gif) Then we would know.


Andrew

Good point Andrew....okay, same senerio but with equal flow/pressure through both types of systems.

[ArtechnikA]

Carroll Smith (who had access to a lot of real-world data) covered this very succinctly in one of his books (the first, i believe, "Prepare To Win"). i don't recall all the details of the points, but give me a couple of hours and i'll be back home with access to all my reference materials. i'll post what Smith had to say on the subject, and then we can debate -that- (IMG:style_emoticons/default/smile.gif)

[SpecialK]

Carroll Smith (who had access to a lot of real-world data) covered this very succinctly in one of his books (the first, i believe, "Prepare To Win"). i don't recall all the details of the points, but give me a couple of hours and i'll be back home with access to all my reference materials. i'll post what Smith had to say on the subject, and then we can debate -that- (IMG:style_emoticons/default/smile.gif)

Excellent! Should the data show a parallel system is more efficient at dissipating heat than the series system (which it obviously does or you wouldn't be posting) then I'll have to rethink my plumbing for my oil coolers and condenser coils. Now would be a good time find out if I'm F'n up by going with my original "series" setups! (IMG:style_emoticons/default/idea.gif)

[machina]

Carroll Smith (who had access to a lot of real-world data) covered this very succinctly in one of his books (the first, i believe, "Prepare To Win"). i don't recall all the details of the points, but give me a couple of hours and i'll be back home with access to all my reference materials. i'll post what Smith had to say on the subject, and then we can debate -that- (IMG:style_emoticons/default/smile.gif)

I have all his books.

In "Tune to Win", Carroll says to plumb multiple coolers in parallel (pg 98)

Can someone diagram this parallel arrangement for me?? I am too dumb to figure it out. (IMG:style_emoticons/default/wacko.gif)

dr

[TimT]

a quick search for Troutman thermostatsturned up nothing but people recommending them or bragging they were using them - no leads on suppliers. are these things even available any more ?

Troutman still advertises the thermostat in Pano or Excellence

I believe this is Troutmans site

I do have a factory thermostat though if your interested..

[ArtechnikA]

Can someone diagram this parallel arrangement for me??

hot oil from engine
cool oil to engine

[ArtechnikA]

I believe this is Troutmans site

that sure looks like Troutman's site - germanpartsusa.com - i'da never found that one by guessing !

interesting nomenclature on the thermostats tho, i suspect the website was built by someone who doesn't know Porsche oiling systems - lists 10mm, 12mm, and 30mm. that's gotta be AN-10, AN-12, and 30mm ...