Ron

Here are a few questions that occurred to me relating to the mounting of additional oil coolers.

With an auxiliary oil cooler mounted in series with the stock one wouldn't the increased pressure created by the oil going through the small tubes in the second cooler create additional stress on the oil pump? That would be sufficient to potential cause oil pump damage?

Wouldn't this be the case no matter how large the fitting are that connect the coolers?

Could this be why the factory turbo S cooler is as small as it is? That is they did not want to increase the workload on the oil pump beyond a certain point.

Ron

Hi Kim,

I ask these questions because I am considering making my own and mounting it in the front, with probably a Mocal cooler. It just seemed logical that these could be issues. Of course the oil pump may be more than strong enough to deal with the increased pressure.

It just seemed odd that Porsche would design the turbo S oil cooler so small.

Glen

Ron, the Turbo S cooler is not sufficient for sustained high RPM operating at higher ambient temps. The stock 993 pump can handle the second cooler no problem(Factory ran it that way with the RSCS and The 993 Cup just 1 stock 964 cooler on each side in series).If You want more flow You can run the 996 GT3RS pump and the flow rate was given in the piggyback cooler thread by Bob Linton. The piggyback cooler is a proven track solution for a 993 that wants a plug and play solution to cooler temps on the street and track but would like to keep the ac. The piggyback does not make your AC work less effectively as an added benefit...

viperbob

Kim,

How much extra oil did you have to dump in when you installed the GT cooler? I've put in an extra two quarts, and it still seems a little low.

Thanks

Greg Fishman

Kim,
Don't get too worked up over this. Not a big deal. You will have lots of other things to worry about when the yellow zonker gets home.

Steve Weiner-Rennsport Systems

Hi Ron:

As we've added front coolers to many 964-993 series cars over the years, I'd like to comment, if I may.

IMHO, you have nothing to worry about using the stock 993 oil pump and twin front coolers. That pump has plenty of capacity to do the job without any oil starvation issues. Over the past 12 years, we have looked at many sets of main and rod bearings in cars that were "tortured" FAR harder than any street/DE car, and the lower end (including the guts of the oil pumps) always looked splendid unless there were other problems.

I will also tell you that I am not real comfortable with Porsche's choice of oil lines used with the Turbo "S" auxiliary cooler. I'm sure they had their reasons, but all of the RSR's used the same diameter lines to and from both front (equal-sized) coolers with excellent results in cooling and oil flow capacity. True, these engines are operating up to 8500 RPM but since that oil plumbing hardware does that job as well as it does, I am not one to deviate from success, given what is at stake.

Porsche oil pumps do vary by capacity and are tailored to the mission, but one of the main differences between different pumps is additional scavenge ports and those features are unnecessary in engines that will not see over 7000 RPM.

The stock 993 oil pump is well up to the task of handling dual front coolers without a problem.

Hope this helps,.........

Ron

Thanks Steve that's what I wanted to hear.

Edward

Steve,

It's been said many times before, but you really are a true enthusiast and gentleman! Thanks for your time and expertise on this board. One day, I hope to bring to you my "red zonker" (al la Kim ) for you to do your stuff...if only to support you and Rennsport for your generosity to all us "virtual" Porsche brethren!
...now if only my finances would cooperate

Edward

Steve Weiner-Rennsport Systems

Hi Edward:

LOL,...Thank you for your kind words. I've just tried to be of assistance here, and offer something constructive when and where I can so people do not make a bad decision or waste money.

Kim's Yellow Zonker is enroute to Monterey as we speak so he'll be able to tell you soon what it does,.....

Now THAT, was a very slippery and steep slope,.....

boostid

I was talking to a P-car friend tonight and mentioned I was thinking of having a piggy-back oil cooler installed like the one that Kary has. Basically an additional factory cooler installed next to the existing factory cooler. We talked about whether or not the coolers should be used in parallel or sequential mode. He thought that running oil sequentially through one cooler then the next wasn't as efficient and didn't produce as much cooling as running them parallel by splitting the oil between the two coolers with a Y fitting. Anybody have any data/info about the best method. Steve?

Steve Weiner-Rennsport Systems

Boostid:

Your P-car friend is a sharp fellow; kudos to him for truly seeing what a cooler actually does,...

Oil coolers, aka heat exchangers, reduce oil temps by transferring heat from one medium, oil to another, air. The degree (no pun) of "exchange" or transfer, is totally dependent on the surface area, airflow rate and temperature of the incoming air. The air that leaves the backside of the cooler will be hotter (obviously) than the incoming air.

Installing twin coolers that permit very hot air to enter the second cooler really reduces both coolers efficiency, and the net results will not cool the engine anything like two independent coolers with fresh air (in and out) to both. On the 993, the airflow is already very very compromised by the mounting location that I would not comfortable in recommending nor installing a second cooler in this fashion.

We see the results of excessive oil temps (mostly track use) in these cars all the time and I look to find and employ the best solutions for problems like these and IMHO, this isn't the best one.

Kim's new Yellow Zonker was a perfect case-in-point about excessive oil temp operations when it arrived here and it showed the wear, stress, and continued high oil temperatures without proper oil temperature control. Its much cheaper to deal with this proactively, rather than after the fact,....

kary993

I agree with all statements about the piggybacking efficiencies. I would add that the solution I have compared to stock definitely runs cooler compared to stock. I also believe that separation of two coolers like RSR's is the ideal setup, but then I am a weekend warrior on a budget. So this looked good and operates well for me and others I know that have this set up.

Maybe someday when I modify the car more I will get to the optimal solution.

Glen

Here is the piggyback cooler info I have. Joe Anselmo of SSF told me about it over two years ago as a plug and play solution to 993 track/street cars that want to keep AC without losing efficiency of the AC. My results were that with a single cooler in Texas heat at driving events I would see 10-10:30 on the gauge. With the Piggyback cooler plumbed parallel I would see 9:30-10 , With the piggyback plumbed in series(best results were to send the oil through the outer cooler first and then the inner) I would see 9-9:30 on the gauge. Now with 2 coolers on each side we see 8:30-9:00 all in the heat at sustained high RPM. The appeal of the piggyback is that it is Plug and Play and does not affect AC or need extra lines. Eric in Chicago will be installing one in series on his cab soon and he can give further feedback to the group from up north. These are the specific results I saw with each different setup.Hope that helps.

Flying Finn

Another mod to my list...

Well, my car is like me, I always tell to my wife, in Alan Jackson's words: "...Just be patient, I'm a work in progress..."