VIR Notes

FT · #1 (**permalink**) 03-07-2006, 12:33 AM

As it is relatively long, I posted them at http://www.renntech.org/forums/blog/fts. I welcome criticisms, feedback, questions, etc.

Cheers,

Devo · #2 (**permalink**) 03-07-2006, 01:09 AM

Nice write up! Any surprises during the track time? How did you fare against other models?

Paul

**K-Man S** · #3 (**permalink**) 03-07-2006, 01:14 AM

FT,

You know you can cut and paste into this editor... here is your blog transferred here for easy reading:
<div class="postcolor">Back from VIR, getting a rest now after a truly awesome weekend. Learned a lot, got familiar with the car and can’t wait to go out again

Saturday was generally a slow day for everyone. The Grand East (http://www.tarheelbmwcca.org/GrandEastMap.pdf) course of VIR is long (4.2 mi.) and takes time to learn. After few laps you get the hang of the turns and flow, but on 50-60% of the corners there are different lines that can be taken and learning different lines and the tricks will take many more visits.

As a reference, on Saturday my lap times were between 4:09 to 4:15, depending on traffic (~ 40 cars in my group out of 167 total in all groups). Traffic was not too bad on Saturday, considering everyone was warming up to the track and the length of the track; after couple of laps and passing first-timers, you could find the open track. But 4 mins + is quite slow for the track no doubt. I also got passed a lot as was not yet comfortable with the car of myself. The best part for me was that there is literally no getting bored on this track; each session being 30-35 mins (Sunday sessions were 20-25 mins) we are able to do between 8 to 10 laps. However, I got an instructors on Saturday that was not giving any feedback or trying to teach me different/new techniques, so it mostly felt like a fast cruise; not terribly exciting.

On Sunday morning, I requested that they change my instructor and I got Alan. He was totally superb, pushing all the right buttons in me. He immediately picked up on my poor breaking and we kept working on it all day. My lap times dropped to between 3:47 to 3:56 depending on traffic (that stop watch is nifty ). In comparison, A group students (advanced group, I was in the D – novice group) were lapping an average of 3:25 to 3:40. Traffic was much more as everyone picked up speed, but I did not get passed as my confidence increased and improved my breaking noticeably.

Now about the Cayman:

Engine and Drivetrain:
Very smooth power delivery; however, once you reach just above 5K RPM, the car transforms itself and rockets out. Below that RPM, the car is somewhat slow (for track speeds) in building RPMs. Obviously the gear ratios are to blame for that. At the Oak Tree corner (12), which is a 110-115 deg. right-hander because of the approach angle at about 35 mph, in 3rd gear even E36 325s would pull away, but in 2nd gear it was quite a different story. Unfortunately, because the shifter is relatively long and a little rubbery for my taste, shifting from 4th to 3rd then to 2nd within 6-7 secs between corner 11 and 12 was not possible for me. I should have keep in 4th through corner 11 and then downshifted to 2nd at 12; oh well…next time.
I ran the whole course with 2nd, 3rd and 4th gear with 2nd gear used minimally. At the front straight I got to about 120-125 mph and at back straight to about 110-115 mph. Those gears proved sufficient. Obviously for serious trackers/racers, lower ratios will prove to be more efficient as the car was very comfortable staying between 5K and 7K RPMs.

On Sunday air temp was high 60s and with hard running the noisy and huge radiators fans worked and paid their dues. But, oh boy, are they loud

Steering
I cannot add much more than what the magazine have said. Very communicative, stable and sharp. You get so much information out of it that you may not know what to do with that information. You know what the tires are going through, how the road surface is and what the front suspension is doing. No play in the middle, makes you feel completely in control.

Chassis and Handling:
I have been a professional suspension tuner and consider myself knowledgeable about chassis setup; however, at this time, I cannot tell you exactly how to improve what comes out of the factory for people that drive their cars daily and do track days or amateur competition. It is absolutely fantastically balanced. One thing I would recommend would be not to lower this car any further, but sometimes that is done for aesthetic reasons, so its individual owners’ preference of course.

The springs chosen out of the factory, obviously, matches the shock travel length and pressures at various shock speed fantastically. The body lean is noticeable quite a bit, especially in high-g off camber turns; however, you want that, you do not want a car that is completely flat without using r-comp tires and several other items to stiffen the chassis. The chassis seems very stiff already as reported by everyone already, there is no flex that I could pick up while driving. Of course this is with street tires; things may be a little different with slick r-comps.

I have no doubts that PASM in normal mode is noticeably under-dampened for this chassis and springs. Of course this gives a smooth ride on the roads that most people feel comfortable. In sport mode it is *just right*. No floatiness, no skipping off the ground; totally plants the tires to the ground. The transitions, especially rapid ones like through the Sess in the map between turns 6a and 8 in the infield. That section is a blind approach to sharp down-hill Sess, and I vouch first-hand this car transitions while smiling as if it is saying “that’s all you got!?!?”. Amazing balance, thanks to the PASM sport setting valving.

One criticism I can possibly have is that – I am no aero expert at all, but… -- this car may need more downforce front and back. At the front straight there is a smooth kink followed by imperceptible-to-the-eye bumps. At 120 mph that kink becomes a corner and the bumps are quite unnerving. You can feel the front washing out at steady steering angle, all the while you are accelerating towards turn 1. A front spilter should settle the front end and make the job easier. Of course, I imagine, then you would have to compensate the rear with a larger spoiler too, and that should also help under high-speed braking, but more on that later.

Tires’ conditions are very good indicators of how well the suspension is working. I started out, on Saturday, with 40 psi rear and 34 psi front pressures (Bridgestone RE050s, 18” setup). I kept measuring pressure gains after each run; consistently the fronts gained 5.5 psi and the rear 7.5 psi. This is actually an interesting topic in itself, but I won’t go too deep at this time. I had understeer with those pressures than I like, so on the next day I decreased the front pressures by 0.5 psi each session; on the third session at 32.5 psi the fronts felt very good and wear came down to the markers.

On Sunday, even though I was running harder, the fronts’ gain remained at 5.5 through each session, but rears’ gain was 8 psi. The wear on the rears were at the markers, so I got lucky catching a good starting pressure that allowed to fine-tune the fronts rather than dealing with both.

Seats:
Well, these “sport” seats handle the driver as well as it can be expected given that they are leather, which is mediocre at best. I kept sliding side ways and back and forth, but at an acceptable amount. Their comfort proved awesome even when returning home during the 5-hour trip back after a 11-hour track day. That should say all there is about their comfort. I am lucky though, the whole interior setup, including the seats, seems to be made for average-height drivers, like myself, so things worked great. However, I would really like to have GT3 seats and steering wheel, especially the 997 one, I do not know how much comfort I would be compromising though.

Brakes:
Porsche Reds! Obviously they are very good, there wasn’t a doubt in my mind. However, like any manufacturer does, they did put street pads. I changed them prior to going to track pads (Porterfield R4) and used a brake fluid that I know will be sufficient (Motul 600).

The best part of the brakes is how it seems Porsche has dwelled on fine tuning the booster. With many cars nowadays, to make it easy on regular drivers, they use strong brake boosters, which at the touch of the brakes you can feel their power. The downside is they provide very little paddle travel, hence modulating the brakes becomes quite difficult; well at least that is my theory. With Cayman, the paddle travel is just the right amount to be able to modulate the brakes easily and to do heel-and-toe. Everything clicked quite easily in this regard.

Also, you can feel the rear brakes are working as hard as the front in this car. The front to rear balance seems near perfect, may be a touch too much towards the rear. At the end of the front straight, the right-hander is probably a 55-65 mph turn and the back straight ends with a 35-45 mph right-hander. Coming down from high-speeds braking hard to either of those turns, the rear-end would twitch just a little initially, but enough to feel. This might be due to the brakes, or might be that a little more down force to help the matter may be needed; I do not know the answer, but it wasn’t something that bothered me.

Exhaust:
We are being ripped off this sound inside the car. Several people commented that as I passed them with full-throttle, the exhaust sound was so loud, in a nice was, that it drew their attention. You can obviously hear some of it inside as well, but not like they do. And with the windows open and the engine being behind your ear, we do not seem to get the full effect of the exhaust.

Overall:
While waiting for the car to arrive after ordering, I was terribly excited. It was just another car that I know I will enjoy driving and owning, but nothing so special that I need to count the days until its arrival. After this first track event, my feelings completely changed, I am truly in love with this car. It was so easy to drive, so easy to get connected and so satisfying that I just cannot imagine toping this car that serves as a daily driver and tracker. The package is as complete as it can be. Granted few minor modifications would not hurt; such seats, steering wheel, wheels/tires, MP3 player, but overall the package is of tremendous value to me, even at $71K cost.
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FT · #4 (**permalink**) 03-07-2006, 01:33 AM

Thank you K-manS.

Devo - it is hard to compare to other car in a DE setting. As we are not racing, it is 100% dependent on the driver. However, during my last session onSunday, I was behind a E36 328i (I believe) who was really fast, I mean the driver, and him and I were passing many cars, I kept a 2-3 cars length to him as I really did not want to pass him and practically get pushed from behind as I might then make a major mistake. We were doing fine, he was giving me the opportunity to observe his lines and learn from a different perspective. Because I had horsepower advantage and most likely a better handling and braking car, I was sometimes closing on him too fast.

Any how, two laps before the checkered flag, as we went into the in-fieled, I closed on him and came inches from his bumper during the first of the down-hilss Sess (turns 4 & 5 after the back straight). I think he got nervous and nailed the gas on the short straight labeled as '6a'for the next down-hills S; I gave him some room, may be 1.5 car lengths, but he went in too fast and lost it, going off the track. He was definetly a good driver though: he controlled the first back snap and the second, then went straight off the track in a controlled manner, probably saving car from flipping. My instructor said that he saw him looking at us in his rear view mirror as he was in the middle of the first left-hand turn of the S.

Other than that I passed M3s, M5s, etc. even on the straights; but that was not the car, I am sure this was those drivers' first event ever. It is an intimidating track, the speeds, the turns, elevations changes, etc. It is a track that is quite difficult actually to build up speed.

There was one more Cayman in the A group, a silver one on Saturday. unfortunately, I never got to meet the person as he was parking outside of the paddock area and our session/class times were conflicting, so I could not locate him. Then I did not see him or the car on Sunday at all.

There was a beautiful GT3, C4S, 930s, 964, 997 C2S, several 944 Turbos, etc. May be 14-16 Porsches all together. It was an awesome event, the BMW CCA Tarheel Chapter did a fantastic job. They even used actual in-car videos during classroom time, which made it easier for us to relate to the tips they were giving us.

Edited by - FT on 03/06/2006 7:41:32 PM

djb_rh · #5 (**permalink**) 03-10-2006, 02:13 AM

Good report, and about what I would have expected. I've never run Grand, but I have a lot of laps on full. For a second I forgot you were on grand while reading though and was like 'only 115 on the back straight? I get close to 110 in my 1.6L MIATA!' Then I remember you gotta turn a bit earlier off that straight on grand than on full, and the turn is a *lot* tighter.

Dyno'ed my car and it hit 256HP at the rear wheels. Man, you talk about loud...that's loud. But no curves to show because we didn't realize until after we got there that there was no way to get a tach signal to the dyno (it needs a plug wire). You gotta remove interior bits to do it, and we didn't have the time there. We now know how and will go back.

As for handling, on Hoosier A3S05's in 275/35/18 front and 295/30/18 rears on high grip concrete, we got a *lot* of inside rear wheelspin (PASM in sport, PSM off). Same thing when we switched to 245/35/18 fronts and 285/30/18 rears (looking for a little better gearing). Incidentally, OEM tires will go 75MPH in second, the 295 rears were 72MHP, and the 285's were 70MPH.

Need a bigger front swaybar for stock class, badly. Nothing seems to exist yet, though.

I also felt that the balance of the car was really good. In fact, we had to dial some toe-in at the rear to tame the rear down a bit, which was unexpected (stock cars usually understeer badly on R-compounds in this setting). That's good, though, because a bigger front bar will likely cause the rear end to tighten up, but we can take that toe back out to normal, hopefully, and achieve good balance again. But right now we're just not able to put power down coming out of corners in high grip situations. That e-diff seems non-existant in this situation.

Did you ever notice any wheelspin coming out of Oak Tree? I could get wheelspin there back in the old days when my Spec Miata didn't have LSD in it, but even then I was on R-compound tires. Oh, and yes, you will want to learn to go 4-3-2 for those turns. In the SM on full course we are going 5-3-2 there with no trouble. And the thing might be a toy, but it's one toy that will handle.

Oh, and did you have PSM on or off for your adventures?

--Donnie

**RussK** · #6 (**permalink**) 03-10-2006, 04:03 AM

That is good to know about the exhaust. I must let someone drive my car so I can hear what it sounds like.

Russ

FT · #7 (**permalink**) 03-10-2006, 11:12 AM

Thanks for the feedback Donnie, nice to have some comparitive data, even it is to the SM.

No wheel spin at the Oak Tree, because I stayed on 3rd gear; I suspect if I had shifted to 2nd, I might have gotten some. I did not turn off the PSM, it stayed in Sport mode and I did not get any intrusion from it. Of course that is probably an indication of two things: 1- you really have to get to 7 or more deg. yaw to have it kicked in, which I barely got may be 0.5 to 1 deg (my data logger is not yet working; otherwise I would have recorded it [img]/fckeditor/editor/images/smiley/MWPX/angry_smile.gif[/img]), 2- I was slow nevertheless.

I can comfortably say that I drove, especially last two session in the second day, about 7/10th of my abilities. I suspect that barely touched 4/10th of the car's abilities. One thing is quite clear though to me, this car really likes smooth inputs and rewards drivers that know how to look ahead 300-400 yards. Autocross thought us that and trained us well; however, I am used to looking ahead may be 100 yards depending on the course. At VIR I struggled with the distances that I need to look, its huge.

I believe Sportec now has 24 mm front bar, I do not know if they sell it seperately or as a package with the rear one. I have not driven the car in autocross environment like you have; however, my track experience was that we get slight understeer mid-corner and then slight oversteer at power exit. If this is in-line with your experience, softing the rear bar might be a better way to go; otherwise you will increasemid-corner understeer, which will be worse I think. Of course ideally, since there is significant body roll at high lateral gs, upgrading both the front and rear with rear upgrade staying a little softer would be the best choice; but need to do some testing to really figure it out. Of course none of this helps you in Super Stock, but might be a setup consider as I think the car may be competitive in ASP in few events depending on attendance.

How were your lap times btw in the Full Course with the SM? We prepared an SM this winter and will be running it in some events, hope at VIR as well.

Russ - you gotta find a way to listen to the exhaust at full throttle (partial does not as well) above 5K rpm, it is intoxicating [img]/fckeditor/editor/images/smiley/MWPX/wink_smile.gif[/img]

Cheers,

Edited by - FT on 03/10/2006 05:20:47 AM

**K-Man S** · #8 (**permalink**) 03-10-2006, 11:49 AM

I noticed yesterday after I passed about 1500 miles on the car the exhaust seemed louder to me... could be my imagination after reading this thread, but seems that way to me...