Relegate

Exactly. I guess it's more of an extractor. I will order that up, it's $159.00. I don't know if I need the radiator bracket from the GT2 (I recall a post where the guy was doing it, ordered a TON of parts, didn't end up needing them all.)

I will definitely replace the pump and T_stat and I know there are a few coolant lines at the back that are on their last months so I'll get those out of the way as well. When we pull it apart (I may let the shop do this project) I'll ask them to inspect the impeller.

There is always a chance that its not hooked up right, but I'm pretty sure it's proper since the shop is very reputable and has no C-level techs that they might ask to do a job like that.

I do DD the car (weekends, cars and coffee, it's not a dedicated track car but approaching that direction) so I'd keep the AC for now. We like to take it out to dinner.

Holes in the under tray- I think the need a cowling TBQH. I have a GT2 lip/diffuser, but I could see air being turbulent enough to interfere with air coming through the front and trying to find that little hole. Fun Fact- I had an 09 WRX with an FMIC but didn't do the non-turbo hood so it still had the top mount hole. At Thunderhill the front felt horrible (AST coilovers, alignment, etc etc). I ended up taping over the scoop (had a rock grille) and, boom, no more negative pressure zone straight over the front.

I am not tracking the car again this year that I know of because of life schedules so I will have time to get into this a bit deeper.

+1 for not swapping my brand new plugs

Brad Penn oil was recommended for heavy tracking as well by my PCA guy.

This is the VARSITY TEAM of responses!! I always appreciate it!!

Note Temp Gauge in video overlay- Its cropped a little from the YouTube image stabilization but you can see it right there at the red.

Relegate

Sneaky, that's why they cut the vents I guess. Basically I bought the GT3 kit but upgraded to the CSF radiator instead of the stock one. I think the GT2 kit (based on research last night) might have different brackets to tilt the rad forward? I haven't pulled the bumper to look.

Daily driving temps are "normal". The 8 in 180 or maybe the 0. A different shop I brought the car to replaced a tranny output shaft seal and agreed that with a 160 and functioning system it should be much cooler as well. I might bring it back there. Both shops have 4.5+ star review locally here in the Philly area.

5CHN3LL

The underdrive pulley is a crank pulley that underdrives all of the accessories. I ran a UD pulley on my 986 and for the first couple of years I had my 996 and had no issues with cooling. M96 lore is that the UD pulley is better for the water pump on tracked cars because it theoretically reduces the chance of cavitation when the car is near/at redline; I don't know if there's any fact behind that particular UD pulley claim.

The ONLY issue I ever had with the u/d pulley was a very occasional low voltage situations when sitting in traffic evidenced by the PSM/ABS warning light combo (I am aware that there are other potential causes for that issue, but I have not had a recurrence since reverting to the stock crank pulley).

steved0x

A friend of mine with a 986 Boxster (same up front as your 996) put on a GT2 style aftermarket bumper and suffered overheating even after several attempts of opening vents and cutting holes. After he got too hot and burped out some coolant onto his back tire and had a big spin, he went back to stock and it is solved for him now. I hated it for him because the bumper looked sooooo good.

ZuffenZeus

He probably just changed the bumper and left the OEM duct work that matched the previous bumper which could be a problem when tracking the car obviously.

ZuffenZeus

Super! Let us know how it turns out. Pictures would also be most appreciated!

chsu74

You can always do the fan mod and hard wire to go on high speed.

fpb111

For what it is worth the Turbo center rad vents down.

Ahmet

^Indeed. The GT3 center radiator (and if you have a center radiator fitted on any street 996 aside from GT3 RS and GT2) all vent down. That said, the venting up is supposed to be beneficial for a few reasons, chiefly downforce. You’ll need to tilt the radiator to do this.

Anyway, Porsche claims to have achieved superior cooling with the MK2 cars, by changing just the front bumper shape. You can see how the ducts channel/force more air into the side radiators. I would suspect the problem in your case may have to do with the air ducts to the side radiators, are they nicely sealed against the radiators AND the bumper? Remember your car has different radiators than the ones that came on the turbo/GT2... The radiator fans should not have an effect once the car is moving. There many people running 996s without radiator fans. The GT3s only came with one fan for example. I’ve tracked an early 996 into triple digit heat, on very hot days even running the A/C without over heating issues on track.

ZuffenZeus

Notice the wind tunnel tests and you'll see the GT2's ability to funnel air through the center vents.

himself

I removed the plastic housing in the back of the side radiators that forces air downwards. It was essentially a log jam for air flow. And, when I pulled them, I put in GT3 brake cooling ducts. On my 996, it made a difference in air flow, which improved temps as well.

-td

Relegate

Heres a pic of the car... Don't even mention the drag from the intercooler inlets that go to, well, the inside of the fenders. =)

Relegate

I spoke with one of the 2 shops today here outside of Philly. He feels like when we pull the water pump we will likely find impeller issues. Either way, it's beyond time to replace that and I'm getting a new LN thermostat as well.

He also recommended using an IR gauge thing to get actual temps of the radiators, heads and expansion tank to make sure the temp gauge is correct. (And the temp gauge and OBD2 would be feeding off of the same data/sensor, so the only thing I can verify is the gauge and the OBD2 are reading the same - so the gauge isn't broken).

The downside of all of this: I won't be able to get the car back on track anytime soon to test it because of my schedule...

Relegate

Where do the GT3 brake ducts pick up air? I have the plastic GT3 ones that snap on the LCA, did you get those or something more legitimate?

himself

They are more legit. The ducts pass air that comes through the radiators/condensers. And (as I mentioned) the air has much better flow without the downward fender inserts.

Here's an old thread from my build on this point.
https://rennlist.com/forums/996-foru...-mod-pics.html

-td