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You can do it with a relatively small compressor: I've got a portable 1 HP, 6 gallon Craftsman "hot dog" compressor (2.4 SCFM @ 90 PSI) and it's been more than adequate to do the job on any car.
The Airlift vacuum tool I use requires 4.2 SCFM @ 90 PSI, but that's for continuous service. With a smaller compressor you just close off the cooling system now and again and let the compressor catch up. Just close the valve to the expansion tank (the system will hold vacuum), disconnect the air line, wait for the compressor to repressurize, and go again. With my small compressor, two cycles is enough to get the Cayman down to required vacuum.
If you're willing to repeat this more times I bet you could do it even with one of those little pancake compressors.
We will likely add another cooler this summer and remove the A/C condensers as the car is track only now.
For a track-only car, I would absolutely remove the A/C condensers and probably add thicker CSF or other radiators to take advantage of the space made by the condensers being gone.
Having said, that, if the car isn't raced and is only used for HPDE or track days, just removing the condensers would provide additional air flow and you could avoid the cost of the aftermarket thicker radiators.
Yeh, im competing in TTs or practicing for TTs and try to be consistent so I pretty much always wring it out. I short shift on the warmup laps and drop into regular Sport on the cooldowns. If temps get high I short shift, but I think 260F is about the highest I see and from what I gather that's fine. Running Driven DI40 oil.
I always ran Driven DT40 until DI40 became available and switched to DI40. I consulted with Lake Speed about the switch to DI from DT and he advised DI was preferred for how I was using the car.
FWIW, the Suncoast kit includes the ducts needed for your specific car to ensure the side ducts and center duct are dedicated air ducts for the three respective radiators. Suncoast goes by the VIN of your car to put the kit together.
And yes, absolutely buy the Airlift kit for refilling the coolant. It's the fastest way to get all air out of the system and all the coolant back in. It's also the same way the techs do it at the dealership. The Airlift tool kit is available on Amazon for around $75, IIRC.
I installed my center CSF aluminum radiator in 2019 and participated in the Planet9 thread under the signature "981cayman*s" on post #27. And as I mentioned on a previous post above there was an issue in getting the correct part number for the duct that connects to and snaps into the bumper cover and into the the new radiator. In 2019, according to the linked thread, the Suncoast kit did not show the duct in their picture and they did not include the duct and said it was not necessary. The current Suncoast picture still does not show the duct that IMHO is important in forcing air through the radiator. That duct is expensive and is over $300 and the two side ducts are over $40 each. Maybe Suncoast has updated their kit and now includes the center and two side ducts based on the VIN number, but I would call them and verify as the duct not only makes a functional but a cosmetic difference. If you have time I would read through the entire thread as it has a lot of good information including part numbers.
Jim
I installed my center CSF aluminum radiator in 2019 and participated in the Planet9 thread under the signature "981cayman*s" on post #27. And as I mentioned on a previous post above there was an issue in getting the correct part number for the duct that connects to and snaps into the bumper cover and into the the new radiator. In 2019, according to the linked thread, the Suncoast kit did not show the duct in their picture and they did not include the duct and said it was not necessary. The current Suncoast picture still does not show the duct that IMHO is important in forcing air through the radiator. That duct is expensive and is over $300 and the two side ducts are over $40 each. Maybe Suncoast has updated their kit and now includes the center and two side ducts based on the VIN number, but I would call them and verify as the duct not only makes a functional but a cosmetic difference. If you have time I would read through the entire thread as it has a lot of good information including part numbers.
Jim
Good info, thanks. One should absolutely ask quetions before ordering anything. That's what I did. I should fill in all the details for my 3rd radiator kit purchase. I purchased my 3rd radiator kit from Rennline on 30 October, 2017. Rennline told me when I bought it they go directly to Suncoast and order a kit and have it drop-shipped. The Rennline kit I ordered was Rennline part number SC-PK981RADIATOR with the description shown on the invoice as "SunCoast Third Radiator Kit". I paid Rennline $795. The reason I went to Rennline is they were cheaper at the time compared to SunCoast. The kit arrived from SunCoast and it had 100% of all parts needed down to the o-rings for the radiator hose connections, the slippery Porsche goo Porsche recommends for the o-rings, and the center duct adapter for my bumper including the duct that attaches to the bumper cover and 3rd radiator. I didn't have to purchase a single additional part. I have all my original parts and when I remove the 3rd radiator here in the next few weeks, I'll be converting back to the 100% original configuration.
Last edited by okie981; 01-24-2022 at 02:44 PM.
Reason: spelling
Good info, thanks. One should absolutely ask quetions before ordering anything. That's what I did. I should fill in all the details for my 3rd radiator kit purchase. I purchased my 3rd radiator kit from Rennline on 30 October, 2017. Rennline told me when I bought it they go directly to Suncoast and order a kit and have it drop-shipped. The Rennline kit I ordered was Rennline part number SC-PK981RADIATOR with the description shown on the invoice as "SunCoast Third Radiator Kit". I paid Rennline $795. The reason I went to Rennline is they were cheaper at the time compared to SunCoast. The kit arrived from SunCoast and it had 100% of all parts needed down to the o-rings for the radiator hose connections, the slippery Porsche goo Porsche recommends for the o-rings, and the center duct adapter for my bumper including the duct that attaches to the bumper cover and 3rd radiator. I didn't have to purchase a single additional part. I have all my original parts and when I remove the 3rd radiator here in the next few weeks, I'll be converting back to the 100% original configuration.
To add to the confusion, Suncoast uses the same picture for the Boxster and Cayman 981 third radiator kit with the Boxster at $785 and the Cayman 981 kit at $1095. Neither photo shows the bumper to radiator connector duct.
If you go through the Planet9 link, it previously was an issue getting the proper center duct but hopefully that has changed or maybe I created a problem for myself buying the separate parts to use the CSF aluminum radiator.
Jim
To add to the confusion, Suncoast uses the same picture for the Boxster and Cayman 981 third radiator kit with the Boxster at $785 and the Cayman 981 kit at $1095. Neither photo shows the bumper to radiator connector duct.
If you go through the Planet9 link, it previously was an issue getting the proper center duct but hopefully that has changed or maybe I created a problem for myself buying the separate parts to use the CSF aluminum radiator.
Jim
Yep, I read the Planet 9 thread. All I can say is my experience went well but I did ask plenty of questions before I purchased. I went with the OEM 3rd radiator just so I could have confidence everything would fit together with minimal hassle and because I wanted the car to remain in an OEM-like state. If I had been building a dedicated track-only car, I would have investigated other options like the CSF.
These guys provided a nice write-up of their 981 3rd radiator install with pictures. I can try and dig up the parts list for when we did ours as well if needed. The center plastic shroud/duct was 6 weeks from Germany when I needed it back in May, so plan ahead to make sure all the parts are available before diving in. We ended up making our own shroud for this. I will say if I was to do it again, I would look into a larger center radiator as the GTS size replacement is pretty small (15"x7"). The GT4 bumper with top vent seems to be a better design as well and utilizes a larger center radiator (21"x7"). These things run hot, anything you can do to cool the fluids/oils will help with longevity.
Part 1: blog.schnellautosports.com/2015/02/installing-center-radiator-on-your-981.html
Part 2: blog.schnellautosports.com/2015/02/installing-center-radiator-on-your-981_24.html
Read the comments at the bottom of the install... I added one that is critical... The pics of the radiator mounted show the radiator installed backward. The radiator has a rim edge around it that goes to the front. The ducting snaps onto the rim on the front of the radiator. The bottom of the radiator pulls forward to latch onto the bushings. The top pushes in.
One thing I did was to reduce spillage as much as possible by clamping off the radiator hoses and also pre-filling the center radiator before fully seating it. Connect the hoses to both sides of the center radiator and one of the hoses to one of the side radiators. Tilt the radiator up and fill through the open hose. Fill all the way up. It should self-burp. I think after this was done, I had only lost maybe a couple cups of coolant. I didn't have to vacuum fill. I just topped off a bit the next day.
One thing I did was to reduce spillage as much as possible by clamping off the radiator hoses and also pre-filling the center radiator before fully seating it. Connect the hoses to both sides of the center radiator and one of the hoses to one of the side radiators. Tilt the radiator up and fill through the open hose. Fill all the way up. It should self-burp. I think after this was done, I had only lost maybe a couple cups of coolant. I didn't have to vacuum fill. I just topped off a bit the next day.
Good tip for those who want to keep using their existing coolant mix. I wanted to refresh my coolant when I did mine, so I drained as much as I could from everywhere, kept track of how much I drained, and refilled with new 50/50 mix (coolant/distilled water).
Has anyone attempted to install the larger center radiator from the GT4/GT3?
Seems like center radiators from the GTS use up a pretty small amount of the real estate available.
Not sure it's really going to do much. Once I installed the center radiator I've never seen high coolant temps on the track, even with ambient temps over 100F. There is plenty of cooling capacity. I think what's really needed is a larger oil cooler.
I'd be curious to see behind the radiator on a GT4. I don't think you're going to get proper airflow through the radiator on a standard 981.
Not sure it's really going to do much. Once I installed the center radiator I've never seen high coolant temps on the track, even with ambient temps over 100F. There is plenty of cooling capacity. I think what's really needed is a larger oil cooler.
I'd be curious to see behind the radiator on a GT4. I don't think you're going to get proper airflow through the radiator on a standard 981.
Yes I doubt it would ultimately make an enormous difference. For me if its more of a matter that if I'm going to take the effort to add a third radiator, why not fit the biggest one I can?
I know the air running through the center radiator vents upwards on a GT4/GT3. But I believe the 911 turbo uses the same center radiator part but vents the air downwards like in a standard 981. So I think its a matter of finding the right support brackets to position the radiator appropriately and whether it'll fit.
01-22-2022, 05:42 PM
