Adding front oil cooler, in series or parallel?
 

Might add an additional cooler to my 930 for next seasons HPDE. It was running slightly hot, when ambient temps were high...

When you add a front cooler, I assume you leave the wheel well cooler in, right?

So, is the front cooler then plumbed off the existing lines in series, or in parallel?

I would think that in series, you increase resistance to flow, so you might decrease flow?

In parallel you decrease resistance, so would that decrease oil pressure?

Also, what adapters are folks using to tee off the original fittings? Seems like most of the pics I found on the net bypass the original cooler, which seems counter productive...

My car also has the strakes in back before the wheel wells... Anyone ever add an additional cooler back there? Seems like it wouldn't be too difficult to tee off the brass oil cooler lines after the thermostat to do that, and it would actually use the strakes for something :) !

Also, lots of places sell oil coolers. The ones for American race cars are pretty reasonable, much cheaper the Sertab/Elephant Racing/etc. Any reason not to use one of those?

My 87 930 had front oil cooler plumbed in series with the factory fender cooler. Never ran hot.

Most run in series. I believe Elephant's coolers have bigger inlets and outlets which help flow. The other benefit is their stuff is engineered specifically for your car, you can buy a kit that includes all fittings and brackets. To some not having to make your own lines and figure out mounting is worth the extra couple bucks.

Series. Elephant products are excellent, as is their customer support. You can get their products from this forum's host.

These guys are right. I don't know about your car per se but after having put a couple oil coolers in different cars I can say if someone makes a complete ready to install kit.. BUY IT. Cooler fitment, routing hoses, attaching ends becomes quite labor intensive when your not following a designed plan. It's well worth a few extra bucks if someone else has already figured out the details.

Running them in parallel makes for a lot more plumbing. You would need to split the supply line with one of these Y-manifolds, then route the hoses to the inlet side of each cooler. Then each cooler outlet hose would have to run back to another Y-manifold that merges the two outlets into a single return hose.

http://www.petersonfluidsys.com/plumb_yman.html

The 911 oil pump is pretty robust, especially your 930 pump, and you should have no problem running the two coolers in series.

Thanks guys, in series it is...

Will look again at the Elephant stuff... Was hoping for a less expensive option...

:)

Here is what I made up for Paul K (krasuskyp on Pelican) for his 87 930.....

http://forums.pelicanparts.com/uploa...1473359912.jpg

http://forums.pelicanparts.com/uploa...1473359928.jpg

Photos were taken during installation. He already purchased a very reasonable priced Setrab cooler with AN fittings and I supplied the M30 hoses with my crimped "Direct-Connect" AN fittings at the cooler. The system is routed in "Series" and has worked well on both street & track.

A factory level system at a reasonable price. Perhaps Paul will chime in on his experience with this.

Len at Autosportengineering dot com

:)

Can you comment on what you used, where you got it, and cost? Do you have a link? Do standard AN fittings work?

When you connect the rubber hose to the fittings, are crimp connectors considered adequate? (Not talking about the screw on hose clamps, rather, permanently crimped connectors)...

I see tons of oil coolers for sale for domestic cars for $150, designed for race applications... Can't speak to quality, but I would think they would be adequate?

I worked with Len to fab up a setup that worked out GREAT.

As he said, I sourced a Setrab 172 on ebay quite reasonably. You are correct, ANY properly sized oil cooler will work fine. Line in / out placement and size are the constraints as fitment is within tight confines.

I purchased Elephant's brackets I believe (Len sourced them for me), and Len made me the requisite lines to plum to my OE fender cooler.

As Len stated, works great - street / track.

Any more Q's, feel free to call 860.490.9808.

Len is *the man* when it comes to these lines, as well as fuel lines. I've got his fuel lines in too, and just perforated another f'ing one yesterday so he's dropping me one off tomorrow - how's that for service!? (I'm fortunate to be somewhat proximate)

Hope that helps...

I'd post pics but some say my pics don't show up here anymore, some see them some don't - no idea wtf's going on w/ my Google+ / Picasa acct...

Len, do you have a link to how to order and cost? Couldn't find on your website...

Bo

:)

As above, please email me: Len at Autosportengineering dot com or click on my Registered User name in upper left corner.

:)

I would imagine that running them in parallel might not work anyway. The oil will take the path of least resistance, meaning the cooler with the highest flow. ...so the second one might do very little to help.

Chris is right on - without a means of restricting/forcing flow through both coolers, friction in the longer piping run would hinder flow to the distant cooler, which would be exacerbated by the increased viscosity of the cooler oil in that piping run, cooler, and return piping.

Thinking way back to physics class and fluid dynamics...

Flow is proportional to resistance, I think. So if the resistance in one oil cooler were twice that of the other, it would get 1/2 the flow...but it would still get flow...

By having 2 coolers in parallel, you are dropping downstream resistance, which might actually increase total flow to the coolers...therefore increasing total cooling.

Sounds like putting them in series is tried and true. But I do wonder if doing it in parallel would work better...

In series, oil that has already been cooled off by one cooler, now goes into the next cooler. The difference in oil temp to ambient temp is lower, so the second cooler "cools" much less...

Most cars have their coolers set up in parallel. Think of a bugatti, with its 8 coolers or what have you. They are not in a row, rather, in parallel. Same with the Ferraris: 2-4 coolers, one to two on each side, in parallel. NOT in series.

Same with radiators in pick up trucks. The water coolers are in parallel, not in series...

I suspect that in the 911's added oil coolers are added in series, because its easier... not necessarily "better."

If you have two equal (or nearly so) coolers, which have equal (or nearly so) air flow, you want to run them parallel. Heat transfer is a function of the temperature delta between the cooling air and the fluid. Having hotter fluid in both coolers means they both have the highest oil temps and thus the largest delta, and are the most efficient. See Carrol Smith on this and other race engineering subjects.

Doesn't Porsche do this with the water cooling radiators, one on each side?

Here is a picture of splitting the flow, and on a modified car it is not hard to do.

http://forums.pelicanparts.com/uploa...1474515223.jpg

But on my stock class SC, with one Mazda cooler mounted in the center of the front valance under the bumper, I just ran them in series, with the better cooler (the Mazda) being the first in line, and the fender mounted Lemke getting the second shot. It is the less efficient cooler anyway, and some guys remove their fender mount cooler when they switch to a front mounted one. But it is easier in many ways just to leave it there. As long as you don't need to shed every ounce of weight it will help some.

Researched the mazda oil coolers, and some folks were concerned that they cause too much back pressure? Which mazda cooler did you use?

Looking on ebay, there are lots of oil cooler from BMW, Land rover, and others, that are 2-3 inches tall and 1-2 feet wide... Seems like many of these could be used?

I understand that a setrab 24inchx4inchx2inch would provide the best cooling, but that thing ain't fitting without some serious body work and fender work...

If one places a cooler in parallel, then the new coolers flow rate is less important as its flow is all "additive" to the original flow. Even if the flow to the new cooler is less than optimal, it stiff provides additional cooling, no?

Just googled... a 20 inch mazda oil cooler, about the same size as a setrab 172... is $100 new!!!

ALUMINUM Oil cooler MAZDA RX2 RX3 RX4 RX5 RX7 S1 S2 oilcooler

Is this the type you were using? I may end up going this route. Cheap enough that its worth trying. The Setrab is $600+ or so...

As the mazda is aluminum, welding on AN fittings should be pretty easy...

Anyone used this model before?

:)

Don't think you need to weld fittings to this Mazda type cooler. They appear to accept a straight threaded fitting (NOT PIPE) with a crush ring, similar in design to the Setrab.

Len

:)

I believe that it is possible to wind up with less cooling in some circumstances when you add a cooler in parallel. If, for instance, the second cooler flows a lot more oil than the first, but does not cool as much (likely in part because the oil isn't in it very long) most of the oil will go through the new cooler. And you would wind up with less cooling.

That is the theoretical reason for Walt's caveats about "two similar coolers", I believe.

Of course, practice can and often does trump theory, so.... You can give it a try and let us know how it works!! :)

--DD