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The370Z.com Sponsor
Join Date: Nov 2008
Location: Las Vegas
Posts: 2,575
Drives: Fast
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Ok so yesterday I got the chance to take my Z out for a few laps around Buttonwillow Raceway. I was out there for the main reason of coaching, and I was super busy with that, but collectively throughout the day I was able to sneak out onto the track for a collective total of around 7 laps. Although I wasn't able to run the car a ton, I did get some useful info out and some new theories.
Fuel Starvation:
Unfortunately nothing new here as far as just reinforcing how bad the issue is. I decided to see just how bad the issue was on my car by pulling off track the second I got fuel starvation and taking it to the on-site gas pump to see just how many gallons away from a full tank I am able to run before getting starvation. Mind you, my car was on old haggard heat cycled to death Hankook RS3 passenger car street tires so we aren't talking extreme g-forces here. So I get my first sign of starvation, pull off track, and head immediately to the gas pump to fill it up. The car took 5 gallons. 14 gallons still in the tank. That means roughly 74% full which tells me two things. 1. The stock fuel gauge is not the most accurate thing in the world (still said I had 7/8 tank). 2. If we were able to come up with a solution to where we could go out on track with just 5 gallons and still not starve, we could save roughly 84 lbs. of sloshing weight which is HUGE. To put that in perspective, if you add the weight of the stock catalytic converters, entire stock cat-back exhaust system, and the stock hood, they would weigh 86 lbs collectively.
ABS "Ice Mode"
Now, I admit I haven't been keeping up with the other threads on this issue so this may not be anything new, but I feel I have a pretty strong theory with regards to what triggers this now. This time out, I tried a different pad compound than I have ever tried before so I didn't quite know what to expect. I ran a Hawk Performance DTC-70 front, DTC-60 rear. These pads are super aggressive, have a high initial bite, high brake torque, and a high operating temperature. The moment I put my foot on the brake pedal after putting them on for the first time, I knew immediately they would be way too aggressive and they sure were. I could not avoid Ice Mode no matter how hard I tried. Anything more than normal street braking would trigger it. Any bump in the road while braking would trigger it. We already know that when you unplug ABS the stock Akebono brakes have a lot of rear bias. The 370Z also has a hyper sensitive ABS system and whenever its triggered, if you have any steering input in the car whatsoever, it blocks pressure off from the rear and we lose braking force. This is likely done to prevent a spin in normal accident avoidance situations on the street. This is horrible for the track.
So what can we do to avoid Ice Mode? Well if aggressive pads make it worse then we have to go with less aggressive pads. Problem with that is less aggressive usually means lower tolerance for heat so now we run the risk of overheating the pads during track use. To fix that we need to lower the operating temp of the brakes themselves with super efficient ducting or switch to an aftermarket brake kit that is more efficient in dissipating heat and still use super efficient ducting. These are band-aid solutions though, not actual fixes.
Now, the electronics side of cars is admittedly not a strong suit of mine but here are some ideas I have that if possible can be easy fixes. I have heard of re-flashing ABS systems before. What if there's a way to re-flash the 370Z ABS system to make it less sensitive and/or eliminate the "safety feature" that blocks off braking force with steering input? Or is it possible to disable the steering angle sensor? What would that effect other than traction control/ABS? That wouldn't necessarily fix how sensitive the ABS is, but if I am correct in what's going on, it could at least eliminate Ice Mode.
Now onto how everything that did work performed...
Whiteline Sway Bars
These are quickly becoming my favorite mod I have done to this car. They offer a great range of adjustment front and rear. This is the only thing that is different in my suspension setup now vs. when I built the car for the track the last time and the handling balance is exponetially better this time around.
BC Racing ER Series Coilovers
I didn't have too much time to mess with the settings on these unfortunately but I still have plenty of room with them to fine tune the handling. The only thing I may try different is upping the rear spring rate to 12k for twisty mid-speed tracks like Buttonwillow. I say that only because I did desire a little bit more rotation on turn-in but that may be something that can be related back to the ABS issue. If I could have been harder on the brakes then the front of the car would be more loaded and the rear more unloaded when I turned in and then it may not even be an issue. Not to mention being able to trail brake. So I may wait on trying this until after I get the braking issue at least better.
25 Row Oil Cooler w/Ducting
I am still not 100% ready to give my stamp of approval on this as I wasn't able to get a lot of back to back hard laps in, but I had ZERO issues with cooling when I was out. Temps stayed around 220 for my longest stint which was probably still less than 10 minutes. I will say that I feel pretty confident that mildly cool weather (mid-60s) I would probably run into fuel starvation before I would oil temp issues, if I were to hit them at all. We'll see once I can get some longer runs in. But this issue is, for now, been bumped down on my priority list.
Powerband
I am impressed with the useable power and driveability feel that just the AEM Intakes and NST pulleys provided. Impressed as I was with the effectiveness of these two minor mods, I am still dying for more power and sound. The car is way too quiet and every driver always wants more power. Exhaust system and UpRev tune are desperately needed.
Stock LSD:
I am pretty sure I burnt this LSD up back in March 2009 the first time I ever tracked this car because it is garbage. Stiff rear sway bar settings and a generally stiffer than stock suspension setup only makes the stock diff perform worse. Thankfully I have that OS Giken replacement on order.
Tires:
For this event I was on seriously worn Hankook RS-3 street tires. They have been heat cycled to death and are probably 1mm away from showing cords. They were purchased by the previous owner of the wheels/tires probably two years ago, tracked a bunch by him, daily driven by me for 6-7 months, and have spent the last 4 months sitting in my garage. Needless to say I wasn't expecting much from them, but they were still pretty good. I know they are a lot slower than a brand new set though.
Results:
During the first part of the day, all of the transponders were sold out so I had a buddy clock my first few laps with a stopwatch. On my first lap out in this car in almost 2 years, on a completely new setup he clocked me at a high 2:02.xxx which I could not believe. Here's the catch, my brake pads weren't up to temperature yet on this lap so I only hit ice mode once that lap. Since that lap time was unofficial I am not going to get too excited or count on it, but I do believe it was at least within a half second. Later in the day, as people started heading home, I grabbed a transponder and set out to see if I could make it official. Unofrunately the all important first lap when my pads weren't up to temp was ruined by lap traffic and after that I got just one traffic free lap, but hit ice mode in every braking zone. Despite that I was still able to clock an official 2:04.751 which I am still pretty happy with knowing how much time was lost due to the severity of the ice mode problem during that particular lap. Although I didn't see a mind blowing lap time, what I did see was huge potential.
Whats Next:
As mentioned earlier in the thread, I have a brand new set of RS3s already in my possession and an OS Giken limited-slip diff on its way. Aside from those two things my next focus is getting different brake pads. I am going to talk with the guys at Hawk Performance, give them my feedback, and see what they suggest. I may be stuck re-configuring my current brake duct setup a bit to be more efficient in order to operate in the temperature range of a much less aggressive pad setup, but braking performance is my number one concern with the car at the moment. Second to that is upping the power a bit by getting rid of this stock exhaust system and doing an UpRev tune. Third, and it's only third because there still isn't a tested, proven, easy, solution is fuel starvation.
I will be going to Buttonwillow again at the end of April armed with a fresh set of RS3s, some new brake pads, and an OS Giken LSD at the very least. I think those three things alone are going to be worth a couple of seconds, but the weather will likely be not as ideal for running a fast lap as it was yesterday. My goal is to break 2:00.000 which sounds pretty lofty, but if I truly ran a high 2:02.xxx with the way the car is now, then I think its well within the realm of being realistic.
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