linderpat

Hey there! Yes, I was watching you kick butt in that car - very distinctive with the French style yellow lenses. Congrats to you moving up to C

My Carrera 3's are 10's on the rears. These are very good track wheels. I do not use them for daily on the 911, but in fact, swap out the rubber and use them as dailys on my 928. They are a bit too big for the 928 though. I normally run 19's on the 997. I do know my tires are finally shot. They lasted a good 3 seasons, so they owe me nothing (about 2/3 sessions per year). I'll have new tires for the next one, which for me will be October with the Club, unless I do an Auto Interests between now and then.

lazyfatdog

Just spent another weekend at Carolina Motorsports Park and wanted to report out on the oil cooling and pressure issues. Weather was much hotter this weekend than back in March, as daytime highs were in the mid-90s (as opposed to mid-60s in March). That said, the car ran MUCH cooler. Didn't touch 250 oil temp, even during the 30 minute sessions. I added the 3rd radiator, low temp t-stat, 2QT deep sump and XP9 oil between the March and September events. Also took the advice from this thread and didn't run it up to redline much, if at all. I may have seen around 240 degrees towards the end of some sessions, but otherwise was in the 225 degree range most of the time. The bad news is that Hella-Buggin' is absolutely right about the pressure drop in the right hand sweepers. Even with the LNE 2Qt deep sump (which has a windage tray), the pressure was dropping in right hand turns. I'll even see pressure drop on the street, like in a highway cloverleaf, where the pressure will drop to 3 bar or lower. Anything else I can do to avoid this (besides backing off or buying a GT3)?

I didn't upgrade the pads before the weekend, but will do so next time. Stock pads started to fade towards the end of the longer sessions and didn't have the bite I'd prefer. Ferodo DS2500 will be on order soon.

Hella-Buggin'

It's my understanding that the scavenger pumps in the heads are the issue. There is only one pump per side and they are located on the rear of the head on the passenger side and the front of the head on the driver's side. So what happens in a right sweeper is that the oil pools in the back of the driver's side head and can't escape. That paired with the oil in the pan sloshing up the sidewall results in air being sucked. I've read that some people have had some success with installing the X51 Tandem Scavenger pumps which puts pumps on both front and back of both heads. You could also run an Accusump, but that is really just going to giver you an additional amount of oil injected into the system to help bridge a gap in pressure. What worked best for me was knowing the issue and short shifting these corners and just admitting that it's a limitation of the car and that if I wanted to play hard that this was a necessary compromise for limiting the stress on the engine.

cwheeler

After I installed the LN sump, i dont see much pressure drop. I've read somewhere that there is an "acceptable" range... I believe it's 3 on the gauge.

Either way, I know CMP has a couple longer corners to the right, but nothing neat as long or fast as NCCAR. And I've done many man laps around there without consequence....

Food for thought.

Cw

lazyfatdog

In this 996 thread, Jake Raby says that controlling the temp should be the focus: https://rennlist.com/forums/996-foru...p-996-mk2.html

Would this apply equally to the M97?

cwheeler

Yes.

roadie13

Here is another current long thread on this topic from 996-land:

https://rennlist.com/forums/996-foru...stability.html

The good news is that there might soon be a bespoke deep sump with modified oil pickup that resolves this issues completely...fingers crossed.

lazyfatdog

Just started to dig into that thread and am already very depressed.

cwheeler

Starting to read through the thread as well. Love this stuff.

BUT we could be losing sight of the forest. Perhaps the resolution of the data is too great and that these quick drops in pressure don't matter? Perhaps this is why the dash gauge is buffered?

BUT we also know that the M97 has many flaws and perhaps these were compromises made to hit a profit margin...

Cw

Hella-Buggin'

Keeping temps down is important because cooler oil is thicker. Once you get hot enough for the shearing to be a factor it's like water.
I guess I look at it like this. You may be fine this corner and that corner today and tomorrow. But you are increasing wear on parts whenever the pressure drops.
That increased wear comes at a cost. Either you accept that there are design limitations and sacrifice speed, or you carry on pushing knowing that eventually something
will let go and cost money to replace. Or you pre-emptively mitigate the design shortcomings with mods that will extend the life under these conditions or you build an engine that will
stand up to the task.

linderpat

all true, of course. As you progress in DE and run hotter, faster and more extreme, then the mods start to make sense. Look at race cars for example - there is a reason why race teams tear down and rebuild motors so frequently, and why it is rare to find a classic hot rod style car (old 911 that ran lots of races, or a Shelby Mustang or Cobra) with the original engine. It can be a use item. I would not worry about it for a couple of DE's a year, and running in the slower groups.

Dk27

Well there may be a solution to the oil drops. Skip, who created the ultimate AOS, is creating a solution for this oil aeration/pressure drop issue. Check out this thread. Looks promising and it's already in testing https://rennlist.com/forums/996-foru...ds-v2-2-a.html

lazyfatdog

Fingers crossed that the UIDS will be the answer to these issues. Excited to see how Zbomb's eventual testing on the track plays out.

lazyfatdog

Just got back from a great weekend at VIR with PCA Carolina's Region. This was my second time at VIR, but the first time with the 997. Damn I love this car.

Weather was significantly cooler than my other times at the track (didn't get above 55 degrees all weekend), so oil temps were a non-issue. I don't think I hit 225 degrees once. Didn't notice any pressure drops either, but VIR doesn't have the big right hand carousel like CMP has. It was the first HPDE with the new DSC controller, which is awesome and really confidence inspiring. Also used DS2500 pads for the first time. No oil temp concerns, no brake fade issues, it was really nice to not stress about anything mechanical and instead focus on driving, learning the line and meeting new people. Got bumped to blue group at the end of the weekend too, so all around felt it was a really successful weekend. Now I just have to deal with the long winter wait until the next event.

mikes70

Good thread read.