froggy47

I saw an ad recently from a major Vette tuner for their external EOC, the ad stating that the built in ones restrict flow & lower pressures.

It was a generalization, and I got to thinking, why would a cooler in a radiator restrict more or less than a cooler not in a radiator?

Is that just sales hype on the part of the vendor or is there some inherent difference in the oil flow?

Seems to me it depends more on the size/length of the oil lines and the size/design of the cooler itself or am I missing something?

Also how good the oil pump is doing, as it's originally not spec'd to push oil thru a cooler plus it's regular duties.

trackboss

It's probably related to a built in cooler that is in a direct replacement radiator. With that there is limited space in the tank. I have several stock car type radiators with built in coolers from ron davis and the area of the tank is way bigger than the rest in order to fit the cooler which tells me the cooler is quite large. The fittings are 3/4" NPT if I remember correctly. Not to mention the cooler is pretty heavy.
Below is a photo of the dewitts cooler that I cut out of my old direct fit C5 radiator. It's very small in my opinion and really didn't cool enough. I'm sure it's all related to packaging.

froggy47

Thanks, I see what you mean, that's not much of a cooler.

Would the FLOW be a RESTRICTION though or would it more be an issue of simply not cooling the oil much.

It would depend on the plumbing (which I am not really familiar with).

I guess whatever oil flows thru an add on eoc is taking "something" away from pressure elsewhere. Yes? Whether in or outside of a bigger radiator (coolant radiator).

V4kerker

http://www.setrabusa.com/oilcoolers_engine.html

http://www.setrabusa.com/pdf/Applica...ons_112610.pdf

Froggy47 and Trackboss here's some links to Setrab EOC's with some spec's for there different size EOC. Looks like the pressure drop is more with longer and fewer rows and a less of a pressure drop with shorter and more rows on the EOC's.

That cooler in the picture looks to be about a 5 psig drop being only 7 rows. I'd like to know if the coolant flows at 90 degrees across the rows or flows along the rows. Across is better. I think Mocal makes EOC's that are external and use the coolant system on the car. The only good thing I see with a EOC in a Radiator is the heating up of oil in the winter.

0Tom@Dewitt

For the record, we use a 7 plate oil cooler and the stock GM unit was a 3 plate. So our cooler is more than twice as big as what GM used. Now, regarding pressure drop....both internal or external oil coolers were not designed to handle the total oil pump flow. GM installed a 7 psi bypass in the factory adpater to limit the flow to the coolers as flow varies with rpm. With this system, oil cooling is the same at low and high rpm because the oil flow is the same. When people started using aftermarket oil adpaters without the bypass, that's when pressure drop becomes a problem because now all the flow produced needs to go through the cooler. The smaller internal type are not designed handle this flow and the pressure drops are huge. The externals are not as bad because there is no limit to the size one can use.

froggy47

Being new to the eoc scene I had not seen those charts, thank you.

naschmitz

Thanks for the technical info. The A05E is still working very well in my 2006 C6 LS2.

victorf

froggy47 - thanks for another stimulating question.

froggy47

So this is good info, bottom line either internal or external needs an adapter WITH a bypass to limit flow & thus limit pressure drop.

The adapters sold by the major aftermarket radiator companies, are they all equipped with bypass/flow restrictors?

V4kerker

Naschmitz what temps are you seeing on the track? I have a2007 base coupe with no EOC. If I keep this car I need to get a EOC the HPDE's are killing my engine slowly.

V4kerker

Tom is that bypass to supply at least 7 psig oil to the engine no matter what or to supply only 7 psig to the cooler? Is this GM bypass adapter like a thermostat adapter? Also do you have a BTU rating for your EOC's?

Thanks for the info v4kerker

fatbillybob

A large pressure drop would imply starvation to the engine. with the stock location of pressure gauge is the reading on the dash the reading for the engine? All of us socal racers in T1 have used no thought to this at all. ingorantly we have placed adapter block with no known bypass or restrictions to External EOC made by whoever and whatever fit back to the adapter block. Engines don't blow up is our ownly datapoint.

Should we be doing something else?

naschmitz

90-deg day, all the temps are logged, VIR South Course very tough on engines and brakes, never cracks 280, even after a 40min session. On the VIR Full course I normally see 260-270.

Before installing the DeWitts radiator, I would always see oil temps of 300-F and once the DIC alarmed at 320.

davidfarmer

I think that a cooler that is good a COOLING is going to have some restriction regardless. A flat-plate cooler will cooler better than a tubular (think auto trans cooler) cooler with simple fins, BUT the change in cross-area is going to hurt pressure a bit more.

However, a quality cooler should not effect the pressure of a healthy engine enough to matter.

In my experience, generally speaking, stand alone coolers are more effective!

trackboss

I've tried all sorts of coolers on a variety of cars and am now a big fan of laminova coolers. IMO, they thave the most efficient design and least restriction.
In the case of smaller coolers I think the bypass makes sense. Hot oil is preferred over no oil. Personally, I would not use a bypass and do what it takes to run a cooler with little restriction although I understand how that is not an option for everyone.

0Randy@DRM

[QUOTE=davidfarmer;1584109063]
However, a quality cooler should not effect the pressure of a healthy engine enough to matter.
[QUOTE]

It is a very true statement!!! Healthy engine = no problems. Loose tolerances/worn out = pressure problems with any sort of additional strain on the system.

We even have cars running happily with dual coolers, one internal and one external. Strong oil pressure and good bearings after tear downs. End of the day loose lifter bores/side clearance/or thrust cause more pressure drop then any cooler will.

Randy

Plano76vette

So the external coolers are the way to go? I live in houston and Do HPDE's around Houston.

With these EOC costing $700+ i thought why not just buy a plug and play all in one Dewitts or Ron Davis and call it done for $1000.

What do you guys think?

Isn't there a temp that would be too low?

0Tom@Dewitt

I can see how many would conclude that externals are better but it's really an apples and orange comparision. The true conclusion is that externals are simlpy bigger and therefore are not as limited on flow than would be a smaller cooler that has to fit inside the radiators end tank.

As testified above, the internal cooler is capable of knocking off 30-40 degrees and it works quite well. Can the external remove more, sure, because it's bigger, and it uses air temperature and not coolant temperature. The question is, do you NEED more than and internal?
And yes, the external can cool too much if the ambient temperature get too low, requiring some more expense in a thermo bypass.

Last but not least, our most expensive radiator, with two plate coolers is only $745, not $1000

Plano76vette

I guess this is the first time I realized the cooler is a liquid to liquid lol.

Okay let me word my question to be a lil more specific.

I have a 2006 C6 C51 car with the tran and oil cooler in the end tanks of the stock radiator. What type of HPDE track day temp should I expect from a Dewitt's compared to stock?

I completely understand that the external oil cooler cools more.

Can you buy a radiator with only the tran cooler built in?

I live in Houston. All I have is exhaust and intake but I want heads and cam soon and I don't want temp issues.

Oh your setup for my car is $750?

C5ZEE06

I'm in Houston too.
For DE's - get an external..a big one.