^^^ this + the smaller radiator + the lack of undertray + maybe even the vents in the hood. I’ve experienced vented hoods that actually make the engine run hotter as the airflow over them prevents hot air from escaping.

Yes, this is entirely possible. In a phone call with Mike Lindsay he was not an advocate of front mounted intercooler (in front of the rad) and also said I better have really a good air dam. He said he knew of a very fast track 911 vehicle with a slanted rad, but mentioned air will fight to go the path of least resistance. Which makes sense.... My intention was to improve aerodynamics of the car, similar to GT350 series cars but never fully saw the project through. In theory if the batwing style engine pan goes on then it (hopefully) will increase flow through the rad.

pictures of your 45 deg radiator setup?

if you have very good ducting to the rad AND a powerful fan setup the rad angle shouldn't matter.
off road trucks, Rx7, and i think corvettes? run rads at various angles. some show trucks run their rads fully horizontal without issue, just need a place for air bubbles to go thats mounted higher.

the stock size 951 radiator should be plenty for your car. even the 944 rad should be sufficient if you have an external oil cooler.

IMHO....the coolant is being allowed to boil. Man invented the pressure cooker to make mashed potatoes and the factory uses a higher psi cap to manage the heat.

any chance the fans are blowing/sucking the wrong way.

Thomas,
At one point I checked with a plastic grocery bag in front of bumper & it sucked it out of my hand onto the rad, but at another point (possibly later) the wiring needed repair, so that's a good idea to check.
Thank you everyone for your brainstorming, this exactly what I needed!
My plan is to add a supplemental rad or failing that, get a custom rad built.

There are two ways to bleed off heat. First is the water, as outlined above, and the second is through the oil. If you get an S2 oil filter housing, it has two ports for an oil cooler. It normally fits into the right front fender area..If you want to use the OEM hoses, that would be OK, depending on the shape of the hoses. That should be a bolt on. If you decide to go with AN hoses, and mount the cooler in the front of the lower valence, you'll have to convert the fittings on the oil cooler to AN, and run longer hoses. This will also eliminate the oil/water radiator arrangement on the side of the block...and presumably, make for a milkshakeless and happier engine. You'll also have to make a new mount for the oil cooler if you want to go that way..

At least that's the old school way..Ask any Jag owner how many quarts of oil it takes to change in an XK engine. Varies between 12-16 quarts..At least that's how the Brits used to do it..just sayin.

radiator airflow
 

Seems that almost everyone has problems with the bleeding of air in these systems. Doesn't a vacuum pump set on low pressure, say 5-6 psi negative pressure help any? Just wondering Noah, try tuft testing on your hood louvers. Make certain that at road speed the air is flowing the way you think it should. Also, be certain to make sure that the spaces around the radiator on all sides is filled with a pliable foam to insure that ALL the air coming in from the front of the car has to go through the radiator. Just a note or two from captain obvious here..LOL and good luck!

Never understood the issues with bleeding.

Raise front of car, open bleeder, open heater, fill tank with coolant and massage the upper rad hose to pump air out... repeat until it accepts no more coolant.

Start car and allow to warm up, continue squeezing hose as long as possible... when it gets hot coolant will steam out the vent, continue adding coolant until a steady stream of liquid comes out the vent, close vent.

Is it true that S2 oil filter housing with the two ports connect by hose with AN fittings to an external oil cooler eliminates the oil/water cooler on the side of the block??????????

the 968 lacks the heat exchanger in the housing....but it does take longer to heat up the oil and the housing still leaks coolant when the seal goes bad.

the early 70s 911 owners manuals had plots of bearing wear vs engine oil temp. the spiffy ones had an oil temp gauge for the three or so gallons of oil.

Yes. Filter housing on a car with stock external oil cooler does not have the integrated oil/water cooler as part of the housing hanging off the block.

I just ordered a 996 Porsche middle radiator, so will be running this in series or parallel with the n/a rad, depending on how I can fit it in the 944.

@T&T racing: If I remember correctly, all the OEM connections are metric.and threaded..You will have to convert the oil radiator to AN by TIG. and adapters. The side plate can be changed out to AN by screw in fittings. I used Aeroquip for all my stuff in this dept. When you change out the side plate on the block you will need the appropriate OPRV tool for your engine year. Hope this helps some.