All ideas on table. OEM side scoops are heated as they are over the headers and part of the engine bay heat problem. And the diameter allowing air flow appears minimal. Several ideas are good. Few are good looking, maintain rear view, and pleasing to the eye.

I will entertain all ideas.

 

Did you ever happen to test the upper control arms or rear lower arms?

 

Z06 arms? Nay. I have monoballs in all those positions so I just bought the front lowers.

 

I think the upper control arms are the same. It's hard to do a scientific test (since the rubber is not exposed outside of bushing housing), but the UCAs looked identical on Z51 vs Z06. LCAs looked different (and Mark mentioned not all bushings are different on those, either).

I had a crazy weekend!




First of all, this happened 30 mins to the hotel. I pulled over to a narrow shoulder by US97, and thankfully had all the tools necessary to do the job since I had tools for the track. It was not too safe, but the traffic was also very light. The blown up tire also blew my removable fender off.

Someone pulled over 5 mins later. I was going to thank them and say I don't need help, but it turns out a driver driving a lifted HD truck hit my fender, and (lightly damaged her truck). She was very upset and shouting at me right as I was trying to change the tire. I told her it's just money, and we'll figure it out, no worries, and she took it as I am trying to negotiate. In the end, I had to say "Please calm down". She replied "I am calm!"; and then she calmed down : P

Anyway, this was very stressful! I thought these were high end tires (that come with Futura trailers), but it turns out it's just cheap Chinese tires. I always change tires on my trailers with better quality ones to avoid this, but this time I trusted the manufacturer, and had a completely blown up tire for the first time in my life! I will get all 5 tires (including spare) replaced with Hankook Vantra tires...


This is how the tire disintegrated. FYI, all tires were at 60 PSI when I left home (65 PSI max on these), and I was well below their speed limit (75 MPH), driving in 60-65 MPH range..


The upset driver brought my fender back, too; not sure if it's usable, though. I filed a request with Futura on a replacement part.



Track day
For context (Area 27): In this wonderful track, my personal best is 2:12.63 with C7 Z06 with room to improve:


On less ideal conditions, I often got to hit 2:15-2:18 range with the Z06.

The sessions are 25 minute long, and I had no cool-down laps during the sessions to stress things out.

• Session 1
  • Temp: 68 degrees F - The coolest session of the day, the time to make best laps of the day.
  • Tire: R7 315/30/18, 345/30/19 - My fast tires, in hopes of making good lap times.
  • Coilovers: Set them to MCS's recommended initial settings of 6/8 (Compression, rebound)
  • Avg coolant temp: 209 degrees F.
  • Remarks: I could only do 2:30s during this session. I had very slow turn-in (understeer), and I could see other cars having much better handling than me, seeing them 'waiting' for me to finish my turn : P This was not good.
• Session 2
  • Temp: ~75 degrees F - Temps are starting to pick up
  • Tire: R7 315/30/18, 345/30/19 - Dropped pressures a little bit
  • Coilovers: The car was not confidence-inspiring in previous session, so decided to substantially increase settings; set them to 10/12 (Compression, rebound).
  • Avg coolant temp: 219 degrees F.
  • Remarks: The car felt much better with the stiffer settings, and the laptime dropped to 2:27s. This is still far cry from what I should it (2:20s).
• Session 3
  • Temp: ~85 degrees F - It started feeling pretty hot!
  • Tire: R7 315/30/18, 345/30/19 - Checking on tire surfaces, they still look good.
  • Coilovers: Since I got results from stiffening, jumped to 14/14 (Compression/Rebound) to see if it makes a difference, or if it's just too far.
  • Avg coolant temp: 219 degrees F. 10 degrees F increase in ambient temps did not move the average coolant temps; nice!
  • Remarks: The car actually felt good, but it was just too hot, and I lost time, and got back to 2:30s.
• Session 4
  • Temp: ~88-90 degrees F - It was pretty hot!
  • Tire: Nankang CR-S 200tw tires at 315/30/18, 335/30/18 - Decided to install my spare tires to see if it makes a difference. These are supposedly my 'slow' practice tires. The short rear tire also messes up rake of the car a bit. I've later found 325/30/19 CR-S tires, so in future, diameter issue will be fixed.
  • Coilovers: I kept settings at 14/14 (Compression/Rebound), leaving tires as the only change.
  • Avg coolant temp: 225 degrees F. The averages are climbing a bit, but it was still fairly stable. I had no cool-down during the 25 min sessions.
  • Remarks: The frontend immediately felt much better, as soon as second or third turn into the session! I had more grip on rearend as well, and my confidence translated into better lap times, despite hitting about 90 degrees F ambient, and I hit 2:26s!

Here is the video from the last session:


Remarks

• Despite being the hottest session of the day, I was able to drop times by 4 seconds with stiffer coilover settings + switching to my supposedly slower CR-S tires.
• Oil temps: They stayed below coolant temps most of the time, or about same as coolant as the ambient temps got very hot. I've never had a Corvette that keeps oil temps this low. I also like the fact that much lower coolant temps with the additional cooling will help extend the life of engine, as well as transmission.
• I don't have all the answers yet, and I don't want to deliberate just yet, but this was a good testing day for both temps and suspension settings.
• Here are some of the leading questions:
  • Perhaps R7s were already heat cycled out? They still seem to have thread left. With C7 Z06, I am used to destroying tires before they can heat cycle out, and this might be one of the reasons for poor laps.
  • Stiffening the coilover has helped a lot in getting good results. I wonder with the last settings and Nankangs, could I hit low to flat 2:20s in the morning session? Or with fresh R7s, could I do even better?
  • I have kept the rake at stock, but per my discussion with my brother, I should definitely try more rake to fight the understeer (and slow turn in) issues I've been having. I definitely want to try it at some point, but one note here is that Nankangs had much reduced rake due to rear tire diameter. This might mean rake doesn't matter as much, or might mean they could do even better with more rake(!). Once I stop finding lap time from tinkering, I definitely want to drop fronts by 10mm and see what happens.

Overall, it was a good day to test things out, both on suspension and cooling.

 

The upper control arms have the same part number along all the lines, Z06, Z51, and standard.
Lower control arms have a different P/N for the Z06, the Z51 and standard have the same P/N.

 

@X25 Sorry to see what happened with the trailer but glad you and all the hardware are ok. I had to change a fuel pump (1980 Corvette!) on the side of the interstate but at least I had an extra couple feet of shoulder!

I'm disappointed to hear about the tires Futura is using. They're on my short-list for an aluminum trailer and for what they cost, one would think they'd have decent tires.

 

Wait she was yelling at you about someone else hitting damaging her stuff?

 

The blown tire has also blown away the removable fender, which became a road debris. She then drove on it, and damaged her truck (minor) a few minutes after I passed through there..

 

V09 install yesterday. Everything is straightforward except disconnecting the stock coolant hose, pack your patience on that one. I don't know how the OP posted those pictures but there is not that much room to work with.LOL

 

same parts list? Did you insert a thermostat?

 

Actually my stock fake radiator had the baffle so I didn’t need that. Only needed clamps, hose and the radiator. I already installed the center z06 radiator a while ago. I actually had to put a cover on the v09 radiator because my engine oil temp would hover around 150-160 normal driving in 90 degree heat

 

You should still get the V09 shroud ($13 IIRC; I forgot) in my opinion. it comes with a baffle to split air going to the intake and radiator, and blocks the blowback from radiator.

With the thermostat, it'd not impact anything when coolant is below 180 degrees F, which is nice : )

 

I have a 2020 z51, it has that baffle on the fake radiator. Probably the later model years did not have it. It's simple to check before you order it, just look in the side pod.

 

I may take that liner off and add the stat.

 

I've been busy this week with good stuff on suspension tuning for both car and the truck, and safety upgrades...



Installed Roadmaster Active Suspension (RAS; 3611-Y) on my truck. With spare tires in the bed and car on the trailer (with about 500 lb of tongue weight), I do have about 2.5-3" of sag max. The truck never felt unsafe or unstable, but I've been getting quite a bit of flashes, so my headlights are definitely not looking at the right place. I've been researching air bags, but unlike what I could easily do inside the rear coil of RAM, there's no airbag option that doesn't mess with ride quality for a truck with leaf springs. They all change the bump stop, and it makes it drive rough whenever it's not loaded. Enter RAS. This solution is supposed to not hinder right quality, reduce axle wrap and improve driving dynamics (tightens suspension, reducing float), and reduce sag. I bought the non-HD version, but installed at higher (40% spring rate help) setting. I was confused on how to install the spacer on bump stop, but the rest was easy : )

I am looking forward to trying it next time I tow my car!
My truck's rear heights:
Tools/tires + trailer with car: ~37.75"
Tools/tires (trailer removed): ~39.3"
Empty: ~40.125"
After RAS installed: ~41.25"

Yes, RAS increases rear height about 1.125" (which will create a head start as well with sag). It's supposed to increase it only 0.5" at 25% help setting. I checked front height only after install, and it's at 37". I test drove the car when empty, and it felt good. There's a section of a road on my commute where this truck feels floaty, and I'm also looking forward to driving over there next week to see how it feels with the tighter rear end.


Got all 5 trailer tires (including spare) replaced with Hankook Vantra tires; yay!! These tires are rated up to 87.5 MPH, providing more headroom (over my usual cruise speed of 60-66 MPH), and should not explode like Road King mambo jumbo brand.



Of course, Futura trailers thought about this, and realized they could annoy the owners by moving the spare tire mount sooo close to the pulleys, it would be impossible to mount a tire if it's even a tiny bit taller than the original skinny (185 mm) tires. Thankfully, the mount is adjustable, and I moved it about 25mm to clear the cables under the trailer.


Here's the (GPS) speed graph of C7 Z06 vs. C8 Z51 (bold color) acceleration at Area27. As you can see, the acceleration seems to be pretty similar until about 70-75 MPH, at which point Z06 starts pulling away. That said, the shift costs valuable time, and gives C8 Z51 chance to stick around for another 15-20 MPH, after which Z06 just keeps pulling away. I thought this was a good demonstration of how DCT helps us keep up, especially in lower speeds. I should also point out that C7 Z06's ambient temp was 75 degrees F, while C8 Z51 was running at 88 degrees F ambient. I think this also shows that I should STOP worrying about intake temps : )


EDIT: I found a lap from C7 Z06 at 84 degrees F ambient (vs C8 Z51 at 88 degrees F ambient). The shift deletes the speed advantage, but of course it only catches up in speed, but Z06 always maintains a bit of a delta in speed in everywhere but during the shift.

Suspension settings:
I also went out for a test drive today with my brother visiting. We've immediately felt that the drive was very bumpy, and the car was bouncing around. Now that I know a bit more about how I should've tuned, I realized compression was too high (at 14/14 Compression/Rebound). I dropped the compression only to 12, but it did not help much. Then I dropped it to 8, while reducing rebound a bit to 12, and it felt much better! Considering how bouncy the ride was, I was probably losing gobs of time. Anyway, my new baseline is 8/12, and now that I know that I shouldn't need much more compression than 8, if any, I think I can somewhat focus on rebound settings and see where it can get me.

Z06:
When we test drove the car with my brother, especially once the suspension setting was fixed, the car felt pretty planted, but you can see that the car starts slowing down after the first 60-80 MPH, and you know that this platform can handle much more power than what LT2 provides. Naturally, we started discussing Z06 again. Basically, if I ordered one (Base Z06 + seats + steering wheel) soon, I could keep working on the Z51 to dial it down and learn more about the platform, and when the Z06 arrives, I could easily move over my suspension and brakes, 'resuming' the work with more appropriate power for the platform. The reason for the discussion is that I might get to order one from a local dealer..

Another thing to note is that I would not be able to order Z07 due to constraints. That said, I'm starting to wonder if it's worth getting Z07 anyway. The best thing about Z07 is that it comes ready to make your best lap times, but if I'm changing brakes, suspension, tires, wheels anyway, the only thing I'm paying for is aero bits and a bit better calibration of ABS, PTM, etc; is it really worth paying another $20K for those? I'll bring this up as a topic in the Z06 section..

For the time being, I'm planning to stay with the Z51 platform for a while : )



A pic from Area27; I count 5 tires on the ground! : P ... well one is a bit up in the air..

 

What is your wheel tire combo in the last track photo.
I like that rear wing look compared to my 23 z51.

 

I'm not sure about the tire (either Nakang CR-S or Hoosier R7 at 315/30/18 front, and 335/30/18 rear or 345/30/19 rear).

The wheels are 18x10.5 ET50 front, and 19x12 or 18x12 rear (ET50)

 

Brake (over)boost
Another feedback I've had from my brother when he test drove my car was him having hard time feathering in brakes (left-foot braking) during his drive inside the corners, etc. He uses similar high bite pads on his Viper as well (ST47s), but he's had a harder time on my car in his own words. Another datapoint here is another track enthusiast friend who owns a '20 C8 Z51, and he also mentioned stock brakes being overboosted, even with the stock pads.

I don't think we're allowed to change the brake sensitivity in track mode. I suppose I could leave the car in "my mode", and drop the boost, but then competition mode would not be available, and I'd have to drive with everything off. I could drive like that sometimes, but not always.

With all this in mind, I'm wondering if I should compensate with pads with a bit lower bite. The car currently has Ferodo 3.12 pads front/rear, and I do have a set of EBC SR21 pads front/rear as spare since I could not yet source my favorite Raybestos pads, and they are also high bite. I've received a set of ST47s for the rear, and the thicker front pads are yet to be shipped (Raybestos takes a very long time to ship pads). I don't think it's a big issue, and I think I'm adjusting to the car's brake boost, but it might still help.

I do have a lot of pads at the moment, and it will take time to go through them, but when done, I might try ST43 or SR11s to see if they make a difference. One thing to note here is that the brakes have been good, and I never think of them, which should mean they're doing well : )

In other news
Decided not to risk it, and moved the Futura fenders higher for a bit to avoid any interference. The fear is that the fenders are not tied to suspension, and they would get too close to the tire or hit it when the trailer is loaded, and driven over bumpy roads.

With the M6x40mm bolts, the fenders are not going anywhere anymore. The washers under it add 4 mm of increased clearance.

 

You can tell you don't have the confidence yet in Z51 in the sweepers. You're either over slowing or getting on throttle way later than the Z just looking at those two graphs you posted. Lots of time to be gained for you next season as you get the car dialed in and you dialed into the car.

edit: just remembered you had some big aero on the Z, so that explains more of the delta

 

Aero or not, you're right; there's lots of time to be gained everywhere with more time and/or bravery pill. C8 actually does an admirable job in acceleration, aided with DCT. I'm finally dialing down the coilover settings, and will start working on more seat time next season. I also need to take more advantage of lighter front end. Anyway, it'd get boring really quick if I was a better driver and hit my best times right away, so I suppose this is OK.

There's also a possibility that my setup has issues (height too much, rake not enough, alignment, etc.), and for that I want my brother to drive it and give me his opinion (and his best lap time), but we couldn't find a track event where we can both show up, yet : )