993tt

As the topic says. What's best, to connect it in series with the existing oilcooler or parallell?

Any suggestions?

/Erik

Greg Fishman

Most of the time they are in series. The 993GT2 race car was in parallel, IIRC.

993tt

I was told by one Porsche tuner that if I don't put them parallell the pressure can drop. Anyway, it does make sense, to me anyway, to put them parallell. As far as I can figure this out. If in parallell the oil will get the same cooling time but the force needed to press it through the coolers will be half as much. Correct!?

Just wanted your thoughts on this before I decide.

/Erik

JohnJL

An uneducated opinion, admittedly, but let me try...

You basically would have a tradeoff to balance, I think...you want greatest overall delta in temp, and you want lowest possible resistance.'

If in series, I believe you'd get the lower temp output, but you might experience more resistance, either resulting in more strain, or less overall throughput.

If in parallel, you would experience lower resistance, but the output temps might not change (maybe even get worse if the second cooler is of a lower capacity than the primary).

I'm not familiar with how the oil pressure is generated (I believe the term 'dry sump' is relevant, but I need an education here) so I'm not sure if resistance is all that critical a consideration.

993tt

1. Delta t is directly related to the time the oils stays in the cooler, right?

2. Adding a extra oilcooler in parallell, everything else equal, would mean that the oil would spend twice the time in the cooler(s).

Example - I pour 1 bucket of oil into 1 cooler and get it back in one second. I can pour 2 buckets trough 2 coolers in the same time. Wouldn't this mean that the oil could spend twice the time in the cooler(s) with the same flow/pressure?

/Erik

Jeff 993TT

Seems like getting the proper air flow would probably be more important than if the coolers were in parallel or serial.

Greg Fishman

Eric,
Maybe I have my terms wrong (series and parallel) but here is how I understand it, please correct me if I am wrong.

In the 993 GT2 race car the oil running to the front would have a split right before the front fender. One line would go to the left cooler, one to the right and then return. I called this parallel.

My car, and all the other street 993's (that I have seen) with dual coolers. The line goes into the first cooler and then out and over to the second cooler and then back to the tank or where ever. I called this in series.

993tt

I agree with you but since there aren't too many place to put those things, I guess choosing how to link them up could make a noticable difference.

Btw. I found out that Porsche motorsport is selling a kit which contains a oilcooler (exactly the same as the stock) with hoses and mounting brackets for around $1000. Sounds like a bargin compared to the small turbo S aux cooler. Anybody who installed this?

/Erik

993tt

Not quite sure what you mean. "In parallell" would mean that the first cooler is connected exactly as stock but from those two connections there should be two hoses that goes to the next cooler. Right side hose to right side on the next cooler, left side to left side. Think of a step ladder where the steps are the coolers and the sides (what the steps connects to) are the hoses. Was this what you meant?

Yes, this is "in series"

Stuttgart

The 993 cup cars Oil coolers are in series

Greg Fishman

"Not quite sure what you mean. "In parallell" would mean that the first cooler is connected exactly as stock but from those two connections there should be two hoses that goes to the next cooler. Right side hose to right side on the next cooler, left side to left side. Think of a step ladder where the steps are the coolers and the sides (what the steps connects to) are the hoses. Was this what you meant?"

I see what you are saying and I have not seen a cooler set up like that. I got mine from PMNA and it is in series as I described above. BTW it requires you to remove the AC condensor.

The 993GT2 race car I was referring to had half of the oil going to one cooler, and half to the other. Then it returns. The oil does not travel from cooler to cooler directly.

Not sure what the ramifications would be as you describe it with the "step ladder effect" but be aware that these coolers have a definte inlet and out let. I would be afraid the oil as you described would not circlulate as well as the other methods since the hot oil might not spend enough time in the cooler while to cool oil never leaves the cooler. I am not an engineer but I would suggest to stay with the factory kit and directions. Rarely are they wrong about these things.

kary993

Or are you talking about the piggy back oil cooler solution on the same side as the existing one?

I agree with Greg, the separate oil coolers are in series not parallel (how ever you define that) and the piggy back cooler concept is also in series.

993tt

This should be parallell.

Hmmm... why would they bother to connect it in parallell in the 993 GT2 but not in the cup car? Sound strange since there should be a difference between the two ways. One have to be better. I can't see why one way would be better in one car and the other in an other...

Whether you connect it in parallell or in series the oil have to go trough the coolers. As far as I can tell, there's no possibilities that "the hot oil might not spend enough time in the cooler while to cool oil never leaves the cooler"
The oil has to circulate. Otherwise there must be some problems with the pump.

993tt

Nope. The cooler I'm thinking about are on the A/C side. Don't know yet if I have to remove the condenser but will know next week.

The whole concept of "piggy back" is parallell connection though this might not be the case with the "piggy back cooler"

/Erik

Greg Fishman

My take is the GT2 needs more cooling as it is a mega hp air/oil cooled turbo engine. So this set up must be better. And they did lots of long distance races and might need to change one or both coolers out very quickly. Next time I am at my mechanics shop I will ask him about the difference. He has a lot of experience with these cars.

The 993 Cup is no where near as stressed of an engine and very close in hp to what some hopped up street 993's could see.


I think the answer to our other question would be better discussed over a beer and with some paper and pencil to draw some diagrams. I have a feeling that what I am thinking is much different than what you are.