Anyone know why this happened? Third rad is standard for 2011 onwards 997.2 pdk cars but disappeared again on the 991.

 

It's a different engine and different car...

 

More efficient cooling system plus it has twin fans in the back.

 

991 is actually oil/air-cooled much like the pre-996 engines. No need for the radiator.

As they said, different car/model.

 

is it really a different car? engine design seems same even the pdk design is the same with some software updates and lightned materials. some said the raidators were bigger…just for our knowledge...

 

If its an all air/oil cooled engine then no water cooling and no radiators would be needed at all. Is that the case?

 

I'm sure it was a joke as the 991 is not air/oil cooled. It's liquid cooled like all modern automotive engines. My Ducati is air / oil cooled and it had a radiator for the oil...

Matt

 

Yes, it's really a different car...

Matt

 

It's clear that the 991 is a different car that leverages/enhances the designs that came before it. So we can understand that it has different cooling needs that are met by its twin radiators. Perhaps the 991 radiators are larger, thicker or have more surface area, so a third radiator is not necessary.

However the OP had another part to his question: why was a 3rd radiator introduced in 2011 on the 997? Was the existing standard twin radiator design deemed insufficient? If so, should we all run out and install the 3rd radiator kit? Or was it an end-of-model-life-cycle marketing decision to keep the car fresh and help improve sales with cost-efficient off-the shelf components? Hummm...

 

Exactly, it took a psporsche to understand what i meant...
Was there really a cooling system upgrade for the 991, bigger rads, new water pump with bigger impeller, bigger intercooler? Sometimes understanding the future model design will allow us to see what porsche discovered and had to improve on the past model design.
Was the third rad, as psporsche wrote, a marketing thing to keep the product fresh for the last year?

 

That's a great observation. Often you see the last year car in many sports car makes get extra goodies to help it sell, otherwise everyone would just wait for the new car and the manufacturer's sales of the last-year car would radically drop. Corvettes are always a good example of that.

As PSPorsche also states, you also have to wonder if Porsche had a lot of the center radiators made in the prior years but not many people optioned to buy them, so they found they had quite a few on hand and rather than waste them they included them as standard. I know in the aftermarket the OEM center radiators seem surprising cheap, almost as if Porsche was just trying to get rid of them.

 

As Matt observed, it was a joke. For reference, even the oil cooled ones needed a radiator. It was an oil radiator. Porsche initially coiled brass piping thinking it was enough to cool the oil. Ultimately, they replaced the coiled piping with actual radiators. I had to install the factory one in the fender.

Back to water cooling: IMO Porsche probably subsequently realized that a third radiator is needed thus they made it standard in later years. There's no way that they'll just install these bcoz of extra inventory. Heck, the metal snaps that I could buy for $3.00 for my 1983 tonneau cover still costs $20.00 each from Porsche. Waiting for a Porsche giveaway or a sale is like waiting for an Oakley sunglasses sale---it just never happens.

I just had a bad flashback: when I had my Z, it would actually go into limp mode bcoz of high oil temp. Z-owners ultimately had to install oil coolers and the limp mode went away. We subsequently found out that some Non-US models came standard with oil cooling. Nissan never admitted to the possible weak engineering design.

 

cab83_750, I meant they used an optional feature and made it standard to "freshen" the model, instead of spending $ to design and manufacture something new. I imagine Porsche would do this to create sales interest in the model, giving it something interesting and appealing for the model year. (I didn't mean to imply they had these things sitting on the shelves and needed to get rid of them).

So it is possible that the extra radiator would not have been an engineering requirement. If it were, shouldn't there be a service bulletin to retrofit it into the pre-2011 cars if they were experiencing extra high temps?

 

I thought that production/inventory was mostly real time these days - such that you do not need to carry and store whole lot of parts inventory. If that is true why would there be "extra" rads sitting around? At the start, PDK, being brand new technology, maybe on paper two rads were fine but once real use data was available the engineers decided two were marginally fine but three had a bigger cooling cushion. So, "marginally fine" would probably preclude a TSB. (Moving forward, with more and more cars in production, The cost of a third rad is probably a lot less than the warranty cost of repairing something related to insufficient cooling.). Note that the 991 does seem to have addressed this issue so it must have been something on Engineering's mind. Of course this is just a guess and I'm probably wrong.

 

Hey cab i was able to buy my oakleys on sale!