V2Rocket

i made such a harness for my fan, it uses the Porsche high-speed fan plug as a relay trigger (using a 70A fan relay off a Ford Contour), then a big 12?-awg wire from the battery to the relay/fan motor and ground at the frame rail.

my fan sucks down 30 or 40 amps at startup so the big dedicated wire is needed.

George D

Thanks for the kind offer. I just thought I posted a long response, and it's went to oblivion!!

Cliff Notes from Ron Davis:

The biggest reason our cars have varying degrees of cooling ability is because of gaps in the shroud to radiator. The gaps are from heat warpage, age, etc. The factory fans are far more reliable than even the Spal fans, and this is why they stopped offering fans with the 951/968 radiators. He doesn't know the exact CFM of the factory fans, but they felt the factory fans and properly sealed shroud was the better route.

He recommended I close all gaps using adhesive window tape. Even a 1/8th gap will cause far less air being pulled through the radiator than if sealed. He's seen builders spend thousands on customer cars building custom shrouds, when this could have been remedied sealing the gaps, especially with the better engineered manufacturers.

It was recommended I move the condenser as far away from the radiator as possible, not really an option for me, so he recommended I drive it in similar conditions without running the AC to see how much heat is being produced from the condenser, and if this makes much difference.

He also no longer recommends distilled water with a water wetter. With racing applications, demineralized water and alumaseal only. Endurance offroad racing, Evans coolant, and street/track cars only run the newer OAT coolant in premixed bottles. They recommend Prestone as it uses demineralized water in their premixed OAT coolant. This with a bottle of alumaseal.

Once I drain the radiator, he recommends I flush with Prestone radiator flush using their flush kit that hooks up to the heater hose. The citric acid solution recommended by Mercedes they don't recommend in their radiators. Hot dipping is better, but you have to know who's doing the work, and the Prestone flush is almost as good, and has a 10% citric acid in it's content, but is much easier to flush out.

I was wrong about this being a CFM issue, hopefully I have some gaps in the shroud to radiator I'll seal, then flush, then add their recommended coolant.

Thanks to all of you who've posted/helped me get closer to a solution.

I'll let you know how things turn out.

rlm328

Good info, thanks

George D

Got gaps? That's a YES. This pic shows the gap on the passenger side up top, same deal on the driver's side. Once I pull the belly pan, likely same.

Drove the car to work early with AC on without my laptop/TEC in the loop to verify exact H20 temps. Got to 3/4 of way to the second white line on the dash gauge. Left around 5pm with over 100 degree temps without AC on and barely left the first white mark. Turned on the AC, and once stopped for a minute approached the second white mark. Turned it off, rolled down the windows, and the temps quickly dropped close to the first white mark. The newer condensers, as shared by Davis, expel close to 350 degrees just prior to the radiator. No wonder it works so well! I'm now draining the coolant, doing a flush, cleaning the oil around the shroud to radiator gaps, then sealing.

With the AC on and sucking hot engine bay heat then blowing on the motor without much of the radiator doing it's job is likely the issue.

We'll find out.

V2Rocket

go to home depot/lowes and get some of the sticky-back foam weatherstrip for garage doors etc and line the edges of your fan shroud (on the inside) with it...

George D

Funny, went to Lowes, but have a large position in HD 29.58 24.46 22.88 49.88 35.65 29.77 12.61 annual returns since 2009. YTD 12.61 with an annual yield of more then the ten year treasury. The chart looks like Duke's HP curve!

Done with the flush. I'll drive it tomorrow. Used the foam strip where easily applied. My mechanic will loosen the shroud, apply the adhesive foam tape, and tighten till there are no visible leaks.

Hoping this solves the issue.

George D

You're in LA, some fun 951 guys there. Jeff Dicicco is one, and still owns one of my old 951's. It's still embarrassing modern exotics there. 3.0 24 psi killer ride.

These guys have a 951 lemons race car I've donated a few parts towards wheel time.

G

reno808

I have a too much cooling issue with my car. i had to put a piece of cardboard in order to raise temps for the oil and water. factory fans and factory rad.

mahoney944

That's new, stuck open thermostat or are you running no thermostat?

333pg333

George, I'd be interested to know why he only recommends Evans for offroad endurance racing and not track racing? We got to a point of running the Evans on our currant motor but were still having overheating issues. I've not heard of Alumaseal so I'll look it up.

George D

Hey Patrick,

For one, it's not legal to run here at most tracks, slippery as KY. He was talking about offroad endurance racing, with plenty of Evans in case something breaks. You can't add water to Evans, but he says you can run the snot out of the cars knowing the motor won't be used again after without a complete teardown.

George D

Do you have a thermostat in place? If your temps were truly too cold to even turn on the low speed fan relay, can't think any other explanation other than very cool weather and an open thermostat housing.

I have an attachable shield that came with my Duramax to be used in extreme cold temps, but I've never used it, even in -10 temps.

A few 951 guys years back with large builds used to delete the thermostat. Most of us didn't go that route, and in the winter it took a long time for the motors to come up to operating temps. Don't know of anyone doing this today.

George D

Ran the car in stop and go traffic to a lunch appointment about 6 miles from my office. It's 102 degrees now and the factory H20 gauge stayed between the 1st and 2nd lines. The radiator flush was clean, just a little rust, likely from the idle heater core. I forget to cycle it during the offseason.

I closed the gaps on top of the shroud, but not anywhere else. That will be done by my mechanic. Looks like Ron Davis was right, those 1/8" openings really suck in air. I could feel it last night when running the car, draining, a few times. Interesting how far modern coolants have come. For Davis to recommend them today, when just five years ago they didn't for any track duty. The demineralized content of Prestone is why they recommend that product. He shared demineralized quality water is fairly hard to find, but is what's in the high end premixed Prestone. I was able to get at Walmart.

Good Article sent:

Pure water is probably the best fluid for holding and transferring heat, but it has three problems. It freezes at 32º F which causes it to become solid and expand, thus cracking the engine, it boils at 212º F turning into vapor at too low a temperature considering those generated by the internal combustion engine, and pure water running through the cooling system would promote internal galvanic corrosion.

So, science came to the rescue. By adding a chemical product known as Ethylene Glycol (C2H6O2) to pure water, it changes the freezing and boiling points of the new fluid, now known as antifreeze or coolant.

Adding Ethylene Glycol obtained the needed anti-freezing qualities, but the coolant still boiled at too low a temperature. So again, science to the rescue. By pressurizing the system to a safe pressure of 14.7 psi the boiling temperature of the coolant is now raised another 45º F (25º C) so the coolant can withstand the higher temperatures without boiling.





Coolant or antifreeze, has four (4) basic functions it must provide:


1.- It must carry heat from the engine to the radiators where it will be dissipated


2.- It must not freeze in the winter and must not boil in high temp environments


3.- It must lubricate the system’s moving parts such as the water pump, and


4.- It must protect the cooling system against corrosion





There are 3 basic types of coolants based on the different types of additives used:


Inorganic Additive Technology (IAT), Organic Additive Technology (OAT) and Hybrid Organic Additive Technology (HOAT). Although, technically each one of these would work on any automotive cooling system, each one was developed to meet specific manufacturer’s needs.





IAT has been around since the first water cooled engines. It contains silicates and or phosphates that form a protective barrier on everything in the cooling system, even on the hoses. IAT coolant is generally recommended for iron-block and heavy-duty engines.





OAT coolants work differently. Aluminum and ferrous metals form a surface-layer of corrosion in the presence of moisture. OAT coolants anneal (transform by the engine’s heating and cooling cycles) this metal-oxide layer into a thin surface coating that protects against further corrosion. OAT coolant is what’s in our engines because most of the components are aluminum.





HOAT are hybrid coolants that use both silicate and organic acid corrosion inhibitors, generally recommended for engines that have iron-blocks and aluminum heads.





The recommended antifreeze for our Porsche vehicles is the OAT type.

Many of the famous, over-the-counter brands offer OAT coolant with an aluminum-protecting inhibitor package and contain no silicates, borates or phosphates and will be stated as such on their labels. Generally these are called “Extended Life Antifreeze Coolant”.
These coolants can be put on top of the existing Porsche coolant, if needed for a top off, even if it’s a different color, and although Porsche sells it’s coolant as a lifetime product, whenever there’s a need to service any cooling system component, such as a radiator, a cooling line, the thermostat or the water pump, for which the system must be drained, fresh coolant mix should be used to ensure that the additives are there in the necessary quantities to protect the newly installed surfaces.

George D

Holy S***

I didn't pay even close to this much money for three gallons of premixed Prestone Dex Cool. Only Dex Cool premixed contains 50% demineralized water and it's about 12 bucks a gallon!

Copy Paste:

Demineralized Water - 5 and 55 Gallons
Demineralized Water
Demineralized Water - 5 Gallons
Our Price: $99.99
Sale Price: $89.99
Savings: $10.00
Availability: Usually Ships in 3 to 5 Business Days
Product Code: CW-DEMIN

George D

I'm only talking about Prestone, likely other brands stepping up their coolant ingredients.