NinjaBum

Guess if it wasn't "intended" or "designed" for that then GM should have put in a 5k redline all the time like break-in then. No bad press, no need for upgraded cooling, just put in a 15 speed transmission with a 5k redline and no more worries.

Z0HS1CK

I know that.

So what about being in a higher gear at low rpm, low mph for the gear but you're going wot.

You're saying that wont generate heat? Never mind you're putting a heavier load on the engine, when you're supposed to downshift?

Funny how a8 guys are trying to handicap a TRACK CAR FOR THE TRACK lol

That's why m7 is a better choice. A8 is garbage. At least the gm a8.

BrunoTheMellow

It will heat up sure. But not as much for the engine. This is on my m7...

Z0HS1CK

Wait, what won't heat up as much? The trans or the engine? I'm not talking about the M7, i'm talking about the A8 and how all the a8 guys are preaching to short shift to keep the revs low on a track. If you're not doing competitive racing, and just need to get by to hit the pits, then yes this would be suffice.

But to be competitve on a track, you're going to short shift your A8, to keep the rpm's low just so the car doesn't overheat?? LOL

Zo62018A8

My 18 z06 auto has never heated. When I went in May 2018 to Ron Fellows not one car over heated. I even opened the hood to make sure they didnt have anything extra in there.

Newton06

I've instructed at no fewer than 8 HPDE events last year at VIR.

(Then the T5b tirewall suddenly came out of nowhere).

My stock 2018 M7 never overheated running a 2:06 pace, even in upper 90' ambient temps.

Now, I have been in multiple older C7 Z06 student cars that have gone into limp mode, which really sucks.

These armchair comments about GM engineering being crap compared to the Germans, or the A8 being garbage are ridiculous. Ask me how many late model student Porsche's, Audi's, & BMW's I've been in that have gone into limp mode for various reasons...

Thunder22

How many late model student Porsche's, Audi's, & BMW's have you been in that have gone into limp mode for various reasons.?

BrunoTheMellow

You know what's interesting. Everyone seems to have good results at VIR. Must be the track layout and the nice air. You stay above 100 for 3/4 of the course.

My friend's 2017 A8 z06 (with 2019 radiator) did do 2 laps at MSR cresson 3.1 (5 minutes) at fast pace before it hit 250 water. This track has a 80 mph average speed at Z06 pace. VIR is 95 mph. That could be the difference in cooling we see.

Z0HS1CK

How many?

Plus you lose credibility if you actually think the GM A8 is anywhere near the level of a proper auto used in most german cars.

Zo62018A8

Every morning when I put my 18 z06 in reverse the whole car shakes and it makes a very loud clunk sound but when I start driving it seems to be okay.

Flatliner84

I just had to respond to this old thread, regarding another member’s comment, further up in the thread, stating that the video lacked “life”.

This guys videos are FANTASTIC. The last thing any of us need is another doofus flashing the camera around and switching scenes every 3 seconds, blasting music. His videos convey a calm, informational analysis of something we all love, while still being powerful.

If you have never ventured to far out into car review movies, please do yourself a favor and check out Carfection’s videos on YouTube, and go search for the Victory by Design series, with Alain de Cadenet. They are light years better than the seizure inducing car videos almost every other car receiver puts out.

Z06_V

Hi Bruno - I think you and I are on the same page. High coolant/oil temps are track, driver, and ambient dependent. My local track is PBIR and I have run 252/297F in the summer time. Ran 2nd, 3rd, and 4th gear. Ave speed ~80 mph (1:29.5 lap times ,,,which was 3 secs slower than Vinny A). ~2.1 mile track. '17 Z07 Manual. Cup 2s. Never went into limp mode but was close. Not liking the ridiculous temps, on the next session, I ran 3rd, 4th, and 5th and the temps dropped to 235/272F. Almost the same lap time (1:30.2 vs 1:29.5) and almost 20F lower temps. So after that, I stay out of 2nd gear. Under high revs and lower speeds, the cooling system can't keep up.

Bottom line is that the system does not have enough steady state cooling to run a lot of 2nd gear at lower speed tracks. At PBIR, I run coolant temps in the 225-230F now with a few tweaks I did (removing a lot of the antifreeze, insulation, ducts, etc). At Sebring which is a higher speed track, I run 218-222F and once again, I stay out of 2nd gear. At some point soon, I will add some 2nd gear at Sebring but I would expect that it could handle some since temps are on the lower range.

Lastly, my goal is the same as yours. I want the coolant/oil as low as possible. I have tons of HPTuners OBD2 data and it pulls timing pretty bad even at 220/260 temps. As soon as the MAT gets to 150F, its starts degrading power from a timing and soon to occur detonation (spark knock). Its not uncommon to see 5-6 degs of total timing reduction through-out my 20-30 min sessions (2-3 deg from MAT and 2-4 degs from knock). The knock reduction can be a little sporadic but the MAT reduction never goes away. My goal is to find a solution which keeps MAT below 150F. I think if I can reach a 200/240F coolant/oil, I have a shot at it.

I have designed several heat exchangers to address the issue and have gotten a few quotes, but have not pulled the trigger yet. Once I realized last year that ditching 2nd gear was a big temp ****, I got side tracked on some other things. But its still on the list. Just a side note, the other benefit of ditching 2nd gear is that I'm able to handle (drive) the car better … otherwise know as the driver Mod. I just don't have the skills or experience to modulate the throttle and steering to use 2nd effectively, so 3rd and up are a better fit for me right now. And my lap times at both PBIR and Sebring have come down running 3rd and up (this likely doesn't surprise any of the experienced guy out there). Hope to continue to improve or get my cooling mods installed, cus I love the 2nd gear acceleration and want to use it again.

Thanks for all your posts and technical info/mods etc.. It's really great stuff. I know it takes a lot of time to pull together and post. Much appreciated. Cheers.

BrunoTheMellow

You bet.

I love tinkering. Just read the cooling threads I've started on both my current and last cars.

Moving 1 gear up is often faster with these high torque monsters. 2nd may feel faster but my data shows that unless you're dropping below 40 mph. You tend to lose any acceleration gain during the 2-3 shift.

I also tested this on the street, 30 mph pull starting in 1st had the exact same 30-100 as when I started in 2nd. That 0.2 shift time is much easier to achieve on the street too.

Z06_V

I've read the cooling thread for your current car, but not your previous. It's a good read. Thanks. I will look for your previous car. I understand what you mean about the torque/power from the LT4. It goes a long way to bridging the gap accelerating out of lower speed turns. I have never done 30-100 mph runs but I have made 50-120 mph runs in 2nd-3rd and 3rd only. The 2nd-3rd is quicker by 0.2-0.3 secs in my car. I have a stock shifter, so its not a fast shift, but I wouldn't say its slow either. But that's going straight and only focused on one thing. As you know, it's a different ball game when you are navigating a course and lateral acceleration comes in. For me, I still have a hard time taking gears under lateral load. Not sure if there are any special techniques. Something I need to work on.

BrunoTheMellow

No. That's all of us hah.

Bill Dearborn

It is more complicated than most people think. It involves total grip of all 4 tires, weight transfer through a turn, suspension control, steering control, throttle control and the driver's seat of the pants feel. Coming off a corner acceleration is limited by how much grip is available in both the front and rear tires. Total tire grip is a combination of lateral and acceleration forces that are applied to it's contact patch. When that grip level is exceeded the vehicle goes in directions the driver may not intend to go. As a vehicle goes through a corner the size of the contact patch varies depending on the tire's location on the car and the amount of weight transfer. Google The Circle of Friction or Friction Circle to see info on what happens to tire grip in a corner. http://www.auto-ware.com/setup/fc1.htm ; https://www.caranddriver.com/feature...iction-circle/ ; ; http://autocarindia.in/apollotyres/t...er-simplified/.

If you open the throttle too much the front tires may push and then you have to back off the throttle to keep from running off the track or the rear tires may slip sideways since they are also providing lateral grip. The inside rear tire also has the smallest contact patch so torque application has to be limited to keep it from breaking loose and thus causing too much force to be applied to the outside rear tire. Coming off a 50 mph corner in 2nd Vs in 3rd also means the throttle is touchier (smaller movements make larger changes in the torque delivered to the rear tires. This means the driver has the capability to provide finer throttle control and reduce the chance of unintentional excessive torque application. What that means for typical drivers is they can start to open the throttle sooner in the corner. This tends to start the car accelerating out of the corner sooner.

Engine output is a function of rpm and throttle opening. The grip available only permits a certain amount of power be applied to the tires.
That power can be generated by running in the lower gear at X rpm and lower percentage of throttle opening or running in the next higher gear at Y rpm with a higher percentage of throttle opening. Both settings deliver the same power to the rear wheels but the higher gear is the one that provides better control in both on throttle and off throttle conditions. If the driver senses the car's arc is inappropriate to take the corner on the line intended they can then use throttle movement to change the arc. This is easier in a higher gear. That throttle steering is one of the things they teach at Spring Mountain where the course has the car exiting a right hand corner into a dip that tends to move the car to the left instead of toward the apex of the kink that is coming up. A quick up and down of the right foot on the throttle moves the rear of the car to the left pivoting the car so it is pointing directly toward the apex of that kink.

Using the next higher gear does several other things. It reduces the chance of driving errors during shifting. First, the downshift is eliminated so there isn't any chance of screwing it up or screwing up corner entry due to the shift, the subsequent upshift is eliminated so you don't have to worry about screwing it up or hitting the rev limiter.

Bill

0Tom@Dewitt

DeWitts makes custom sizes! They actually build, assemble, and braze the cores in house.

BrunoTheMellow

No other way but HP tuners to watch MAT correct?

Z06_V

@Bruno …. On the MATs, there is another device out there that will record them but I can't remember what it was called. But I found it after I purchased HPTuners OBD2 device. Since I'm a engine data guy, I looked at it as an investment. $600 (device+laptop). With a desire to make changes to the car, it was important to me to understand the impact it has on the engine. For example, I have seen the impact of the BMS filter and other air inlet changes. Also the influence of octane booster. So it's provided some interesting data to chew on, but the MAT monitoring, ignition timing, cooling, etc. were the key reasons for me.

@Tom; Yes, thanks re: your manufacturing capability. When I'm ready to move forward, I will reach out to you folks. At the moment, I'm working on a different car project. I have a car that hasn't been on the road in 26 yrs … and 2019 is the year.

@ Bill: Thanks for sharing your experience. I think I understand it. One of the skills I lack is the "feel" of the car … unless it's obvious. I just can't feel how close I am to the grip limit of the tires unless I'm way over it. One of the few times I had an instructor, I was boasting slightly how I corrected an oversteer situation … and then he commented that yes, I corrected it, but he felted it way before I did and that I was late. An experienced driver would have caught it earlier and anticipates the oversteer exiting the turn.

At my level, I don't mind the push the Z can have on occasion. There are solutions/adjustments that can be made as you indicated and it hasn't got me into trouble. The oversteer is problematic for me, hence 3rd gear and up helps with that. Interesting enough, I have lost the back end (but caught it) around a 60 mph turn in 4th gear by not properly tracking out. So at ~2000 rpm in 4th gear has enough torque to lose traction if you turn enough. Lesson learned. FYI … this is my first ever road course car and I'm 18 months into it. So I have a long way to go, but making progress. Next year I will venture up to VIR to have a go at your track.

Sorry guys for the off-topic stuff

usrodeo4

Chuckle!!! One of the first things I learned as a puppy earning my AMA 250cc Road Race Expert License was; brakes are for stopping and gears are for going