FredR

I have no idea how Nick concluded what he did but the intent of my post was to assure him that the implied conclusion he wrote about could not be correct.

Your post is somewhat intriguing in that it is difficult to understand how you make the conclusion you have noted. The dual pass cooler may well be flow limited given it notionally has half the hydraulic cross sectional area to flow through but in this case one does not know the size of the cooler Nick is using to even begin to make such determination.

928S MN

Smaller fan assisted oil coolers are used on Motorcycles all the time. Could something like this be considered for a remote mounting?

https://www.revzilla.com/motorcycle/...2016?rrec=true

docmirror

Sure, however if I note from the pics, the manifold size is rather small, so it could not be used in series as it wouldn't provide enough flow. It could be adapted to run in parallel with the bottom fan, and some of the oil would traverse this unit. Doesn't give any specs on flow, or thermal transfer.

worf928

It seems to me that the main thing that's wrong with the 90+ oil cooler is that it has no fans. Surely there's a way to remedy this.

SwayBar

From the factory, my air-cooled 993 has thermostatically-controlled fans mounted behind the oil-coolers, which are mounted in the front below the headlights and in front of the tires.

Some claim the 993 is cooled more by the oil versus the forced-air thru/around the cylinders and heads.

So a fan mounted on a 928 oil-cooler should provide the same functionality as on the 993. And it will also isolate and remove the heat-load from the water cooling system thus improving the overall cooling efficiency.

docmirror

Some of the DFW crew were discussing this as well. I voted to use a extractor plenum, into a 4" round duct, use some vent hose to an in-line bilge blower, and drive the blower from a relay that taps the main cooling fans. If the cooling fans run (for whatever reason), relay will pick, power to the blower, and suction through the duct, and plenum. Mount the bilge blower in the fender well.

Speedtoys

Doc: Is the cooling system an option with -a- [small] volume of oil in a tube oil cooler in the lower rad hose?

That would achieve the same result I would think with less engineering.

docmirror

Again, recall that we are trying to add new, not yet used cooling paths and methods. This seems like once again it would simply transfer heat load from the air to the water jacket, and then to the rad, without adding any area.

It's very difficult to add surface area to the whole engine cooling system on any car, including definitely the 928. The only place I can think to add either a cooler and lines, or a blower setup is the fender well, where Greg has stashed his AC setup I think(haven't seen it in person).

Thom

Did you not notice that Nick's comment was an indirect reply to mine, regarding the stock cooler and not whichever cooler he may be using? Nevermind.

V2Rocket

use some brackets to lower the rad fan assembly 2-3".

this would leave the top inches of the radiator uncovered by fan shroud but would then cover the oil cooler...

Carl Fausett

Just an FYI:, I found that when I mounted coolers in front of my radiator I was always disappointed at the results. Radiator temps increased each time as it was no longer in fresh, cool air. That's why we ended up moving the oil coolers into the fenders so they could have their own air, as could the radiator. See pic I posted in Post # 22 above.

drnick

Carl Fausett

Higher pressure in the cooling system will not result in lower temps.

It will, however, make it less likely that you will boil your coolant in the heads at the back of the exhaust valve seats. This is the hottest area the water is tasked to cool in the engine. Steam is incredibly powerful, and if the coolant is allowed to boil in the heads and make steam - well, there are a lot of blown head gaskets that are blamed on everything else that actually might have been prevented by raising the boiling point of the coolant. Many a weekend warrior has found "blown head gaskets" the day after a DE day, and I believe this is the second most common cause (the first being going lean). We run 20 psi in our cooling system in the race car (1020 HP) just for this reason, and our radiators are designed and rated for 20 psi too.

However, we do not have plastic end tanks in that car! Recommend no more than the stock radiator cap pressures if using the stock radiator. Those plastic end tanks are 30 years old and have no sense of humor...

A 16-lb. radiator cap will raise the boiling point 48 degrees higher than the normal 212 degree F boiling point at sea level to a 260 deg boiling point. A 20 pound cap adds another 12 degrees to the boiling point, for 272 deg F.

FredR

Nick,

I presume from the tenor of your post that you are deducing a cooler run temperature based on the dash panel indication given your refer cooler water temps or do you have independent sensors? Either way what were the before and after numbers assuming that the last white line on the display represents 100C.

The pressure in the cooling system is for the most part controlled by the cold coolant level in the header tank- as the water heats up it expands more than the volume of system it resides in and hence the term expansion tank and why it is important to have the correct level within a narrow range. The pressure has no impact on the amount of cooling performance that takes place give or take a smidgen but it does give a bit more safety margin to the boil point that under normal circumstances is not needed given the coolant typically leaves the engine at about 97C.

Bottom line - a certain amount of heat has to be removed from the motor either in the coolant or the oil, take more out in the oil and less heat needs to come from the coolant. If the coolant return temperature drops the thermostat nips in to reduce the flow to the radiator so I am a little puzzled as to what may be going on. My motor seems to be happy when the coolant return temperature is about 90C.

The other point I noted from one of your pics was that is looked as though when the pic was taken you did not have an a/c condenser fitted- is that still the case?

Rgds

Fred

Bigfoot928

did anyone ever buy and install one of these setrab coolers? It's not really a custom 928 part as it has bosses to mount it from the top and bottom that isn't needed on the 928.