carbondan

Greetings all,
I'm starting the process of tracking down a 991 Cup car to use exclusively for trackday purposes, no racing whatsoever (just doesn't interest me).
I'm making the move up to a full blown race car primarily due to the added safety features, and I've settled on a 991 Cup vs other options like a GT4 CS or 997 cup because, as silly as it may sound, it's a car that I can really 'love' and a car that I look forward to devoting extreme amounts of time and energy into learning deeply in every facet imaginable, in terms of driving dynamics/optimization, driver development, and understanding the car's mechanical and electrical engineering and support.
Will be used for around 45 track hours per season at the current rate, or more if possible.

As I research options, and look at some of the cars available, there is a huge swing in pricing, largely driven by the number of hours on the gearbox and engine.
I hate to ask because I've read countless threads on this topic but still haven't found a definitive answer - to beat this dead horse just a little bit further:

- What should I expect to pay for a typical 30/60 hour gearbox rebuild, and 50/100 hour engine rebuild from PMNA?
I do know for DE purposes, I can likely stretch those intervals out by quite a bit, but I'll want to plan and budget for those from the start at any rate.

- Are there any third party shops that can handle those jobs for a lower price? (With the understanding that if it's not PMNA sealed it might cause resale problems down the road)
If yes, what kind of rate would we be looking at there and what shops specifically?

- Side note, for DE purposes, what tires do you find provide the greatest number of usable heatcycles, assuming typical 20 minute sessions?
I am glad to sacrifice overall laptime performance, even relatively dramatically, if it means getting more usable heatcycles (to keep costs down, within reason).
The Hankook F200s seem quite attractive to me...

I'm not terribly price sensitive, but at the same rate, I'd rather spend less than more!

- Additional side note, does anyone know how much total Downforce the .1 and .2 991 Cup cars produce in typical race trim at varying speed levels, or even just at ~150 MPH?

Thanks for anyone who takes the time to respond, greatly appreciated!

hollmatt

i bought a 2016 991.1 Cup last year and so far no looking back after 20hrs on track, all DE so far. I noticed in your sig you have a street 991.2 GT3, i do as well and toyed with the idea of putting a cage in it and tracking it but i'm glad i didn't. The Cup car has all the safety equipment built in and its much more fun! In terms of maintenance its about pro-active maintenance and carrying spares and having a good shop and ideally one who also goes to the track with you. I do generally support myself but my fuel pump failed at Sebring this winter. I had a spare and the shop had it swapped in 90mins. They do say that the cheapest expense with a Cup is the purchase price..i actually think that's the case with any dedicated track car which sees a lot of action. I put well over $100k into my 996 GT3 with an engine refresh/2 x trans refresh/MCS and reg maintenance so go in with the idea that you will spend money maintaining it but for the fun you get its worth it

Trans - i've just had mine refreshed at 50hrs, i could have ran longer but it was a good time point before the north east season gets going - it was mainly bearings and some diff refreshing, i had Rader do it and i think the invoice is going to be approx. $13k. You can use Copans too. With these guys the quality of work is so good i don't think its worth using PMNA

Engine - its a Mezger so very robust and and if looked after with regular fluid changes i've heard of some going to nearly 200hrs - i do blackstone oil samples every change and do a leakdown annually on all my track cars to check for wear and so far so good on the Cup but i'll likely pro-actively do an engine refresh at 150hrs. When i do i will likely weigh up a PMNA one to help resale but i think an Autometrics build also carrys such a good reputation so that will be one i will check out.

Other parts - again pro-active replacement of the rear axles and then keep old ones as spares (they're expensive from PMNA though, $2.5k each so looking forward to Ed from Demonspeed getting these on his inventory), I also pro-actively replaced the lower arms front and rear as Sebring can be tough on cars. I bought a spare set of shocks too which came in handy as the rears started leaking. Brakes are excellent and last well (should be good for a season) and are relatively cheap from PMNA, cheaper than my 996 GT3 previous track car

Tires - mine came with Yokohama Advan's and i've been really pleased with them - plenty of grip and i usually get 20 HC from them. I have flat spotted a few while learning the car - i may install ABS this season

DM me with any specific questions as happy to help.

carbondan

Wow incredible! All exactly what I was hoping to hear!
20 Heatcycles out of a set of yokos is more than I could ask for.
I've also independently come to the same conclusion about pricing - after a few years, the car's price itself will be the cheapest expense. That's almost reflected by the current pricing where 991.1s can get down around $100k these days, 997 $80-90k, 996 $60k, all largely driven by where that particular car is at in terms of maintenance. Same deal with the ferrari and lambo race cars that I've considered too.

Two quick questions:
- Where do you buy the parts from? I've been poking around trying to find a parts catalogue that shows list pricing and if possible real-time inventory, just so I can get a feel for what some of these items cost and if anything has gone on to indenfinite backorder.
I read through the ~300 page technical manual yesterday just to start getting a feel for official maintenence intervals and what all is involved with some of the jobs.
I will be self supporting it at the track but having a local shop (probably Cantrell) do all the service off track.

- Does the PIWIS need to be involved for any function at all? Or is the singular datalink the Cosworth datacable connected to any generic laptop? Is there any annual service fee for updates or Cosworth software access?

- Do you have a very general idea of what a run of the mill engine refresh costs at both PMNA and third party, with the understanding that if something is broken all bets are off?
And actually, on that note, what would a full OEM brand new replacement motor cost, approximately?

Thanks again for the tremendously helpful response, I would certainly PM you with some more questions I am going to inevitably have as I find a car and get closer to pulling the trigger.

tcsracing1

Orbit build cup motors

C4SGRPDK

At 60hrs my shop opened up my 991.2 cup transmission and it was like new see pictures attached. We simply closed it up and it went back in the cup.





now it's at 127.5 hrs and the dogs of 4th and 6th are starting to show some wear. Still drivable but needs special tooling to change them. Parts are ordered, but will do a couple more track days until the parts and tools arrive at my shop.

gearbox oil and engine oil was done after each track events, cheap insurance and seems to have worked good so far.

These gearbox are way better then the ones in the 997's

The clutch pack lasts about a summer (30-35 track days) so for me it's a once a year change while the gearbox get's inspected

As for tires I go through rears twice as fast as the fronts. so 20 HC on yoko or pirelli is out of the question. after 5 or 6 20-30 min sessions they are done and corded

amso3

Autometrics for a rebuild of the engine or trans, for sure!

carbondan

That's a thing of beauty!
I haven't looked into the details closely yet, but is the .2 gearbox the same as the 2015+ .1 box internally?
I do recall they increased the stated rebuild interval from 30 hours to 60 hours, but wasn't sure if that was due to hardware changes or simply the benefit of time/experience of looking at pristine boxes at 30 hours and deciding that was too conservative.

carbondan

Couple more quck questions:

- Does the .2 offer any substantial safety improvements over the .1? I know the netting was added at some point, but I imagine that's a straightforward retrofit to a .1, if needed.

- Sorry for the extremely morbid nature of the question, but given that the primary goal in doing all of this is to increase my on-track safety, have there been any reported fatalities or severe injuries in a 991 Cup car?
Seeing some of the violent rolls these cars have experienced, as well as the giant pile up at the Glen in 2017 gives me about as much confidence in the car as I can imagine. The risk will never be zero and I accept that, but do so while also actively working towards pushing that risk down as close to zero as possible.

Thanks again for all the input, you guys are a wonderful resource! Which also frankly makes these cars more valuable as having this community support and feedback goes a long way towards demystifying the research and ownership experience.

coryf

Appreciate all the recommendations for Autometrics. As stated above we do both engines and transmissions. The transmissions are basically the same between the .1 and .2 with the primary difference being the bell housing to match up to the newer style engine case. It is an incredible gearbox. Rebuilds typically end up being focused on the ring/pinion, cross shaft and differential housing and internal plates. The gears, dogs, sliders ect.. are normally in great shape.

The .1 and .2 are the same as far as safety. If the budget allows I would get the .2. The engine has a lot more torque which makes the car a lot of fun to drive. The best value though is still a .1.

Ed@Demonspeed

Good morning.

+1 (at least 1) on Autometrics. They would be my go to right now if I was going to have a cup motor rebuilt. Also the go to for the Bosch M5 ABS, which I consider a must for these cars. Especially at the club or DE level. Makes the cars much safer with cold tires. Of course, you can get warm tires with our Demon Speed tire warmers (blatant plug)

We, at Demon Speed, are working to add more and more 991 cup parts into our stores. We have tried to be the PMNA alternative for the 996 and 997 cups both with our parts manufacturing and our parts sourcing. With the 996 and now the 997, Demon Speed is manufacturing parts to fill the gaps of PMNA as they are making the parts no longer available. Our intent is to keep with that tradition on the 991 cup cars as well.

If you need any help on parts sourcing, let us know. We will help. Even if we arnt the best to sell it to you, we probably know who is and will send you to them.

See this post for the new development parts we are working on.

List of current projects at Demon Speed and looking for suggestions for more - Rennlist - Porsche Discussion Forums

Thanks

Ed

carbondan

Fantastic! Another big plus for this community - where else do you get responses from an authoratative source like this? Definitely cementing my decision to go with a Cup and have Autometrics do the big rebuilds.

I've read through lots of your posts, including the project post, and checked out your site. I definitely appreciate what you're doing at Demon Speed!
Nothing is worse than having parts on indefinite backorder or cancelled production, a problem I've experienced first hand with both my 04 murcielago and 04 challenge stradale. Tons of critical components are not to be produced anymore.
Hell, even my 2017 Viper ACR, which is under factory warranty already has parts permanently out of production!! The carbon diffuser had a major factory defect in it, it's covered under warranty, and I've been waiting for the part for a year - dodge said they won't be making any more and tough luck!

I've had a bit of an idea to stretch out the useful life of these slicks for DE purposes, care to comment on if this is sound or delusional?

Would it make any sense to basically run a DE session (20 mins), pull straight into my pit, air up jacks, and then immediately put the tire warmers on until the next session. Repeat all day for the 7 track sessions, thereby essentially running a 'single heatcycle' for that particular track day? Stretching out the tire's useful life by decreasing the heating/cooling cycles that happen rapidly during 20 minutes on, 40 minutes off DE sessions? (Assuming tread remains).

I'm definitely doing ABS from the start, figure it'll pay for itself in short order in tires not flatspotted!

Ed@Demonspeed

On the ABS, that is how we justify it too.

On the ACR, we make wheel washers and lock pots for those centerlock systems too. I am not sure all of them are centerlock, but I know some are. We had a customer ask us to make some and had a quantity that made it worth while doing. I have a stub bolt example sitting on my desk to reverse engineer for them as well.

For the tire warmers, Of all the reasons I give, the extension of the heat cycles is the hardest one to definitively say one way or the other that it provides benefit. I would rather sell tire warmers on the virtue of the increased safety and track time, since those are more quantitative than the heat cycles.

Thanks

Ed

93 FireHawk 968

I cannot imagine getting anywhere near 20 heat cycles with any tire mfg. I find 10+ and your giving up significant grip which truly alters the way these cars need to be driven.

sl951

+1 for Bill Rader for transmissions
+1 for Xtreme-Di for Bosch Motorsport things (ABS, programing, etc).