BRZ vs 370z Video

[WhiteGDB]

Originally Posted by samsam5886

The 86 was faster from 0:20 to 0:40 though!

At 0:20 the BRZ still has the 1 sec lead from the start. At 0:40 the Z pretty much erased that lead. So from 0:20 to 0:40 the Z was quicker by almost a sec.

Originally Posted by Jordo!

Interestingly, the BRZ is ahead of the Z for most of the race, but then the Z pulls ahead at the end.

Eh, I think all we can conclude with any certainty from this is that the Zed driver won, although he might very well have won driving the BRZ too.

Actually, I hope a BRZ vs. FR-S vid like this pops up eventually -- the BRZ supposedly has the firmer suspension set up, so it would be interesting to see how much of a difference it makes.

[Draco-REX]

Originally Posted by KeepGuessing

No, not personal in the slightest, it's more an issue with the overall atmosphere surrounding the car. I'm being repelled from liking this car simply because I don't want to be grouped into the same brainwashed uninformed zombie fan club who say "This car is awesome....Because of CoG low and Polar Momentum Bro! Thats how I beat an M3 last week, cause i was so low broseph".

If what other people think has a bearing on your enjoyment, you have a long, unhappy road ahead of you.

And if you care to look back, I said the low weight, CoG, and PMoI indicates the BRZ is an exceptionally handling car. I never said it should beat the 370Z because of that.

That is what i said. I did not say "Increase weight transfer aids in changing direction". Let's dissect the sentence and structure for you.

I start with "The increased lateral weight shift of the Z" This does NOT implicate i am INCREASING the weight of the Z, this does not implicate I am in favor of ADDING weight to the car..It does however say that with the Z comes an increased amount of lateral weight shift..

Following that is "in a 'tuned gymkhana car' would be used to aid it" This sentence STILL does no implicate the increase of weight to help the car, this does not implicate that I enjoy heavy cars or add lead bars to tires....This states (in relation to the introduction)
That in a vehicle that was properly tuned for THIS particular racing event, the accompanying increased lateral weight shift would be accounted for, compensated for, and no longer be used as a hindrance but as an advantage.

"But how could it possibly be an advantage" he says!" Simple, by the nature of the race course. This also brings us to the end of the initial statement.
"in many of the intricate corner series'". Since you viewed the video you can tell me that the most intricate series of corners the drivers are put through, are the 4 360+/- degree corners, as the rest of the track doesn't have any other challenging series' of corners.. Now, since you're an avid member of the Autocross and Rallycross community there should be no need to tell you the difficulty, or better yet "challenge" involved in getting a vehicle that is more or less neutral in the corner, wide of track width and has a reasonable sized footprint on the tires to perform a crisp small radius 360. In order to execute it with any sort of consistency it is a matter of manipulating the available inertia and using the weight shift of the car to your benefit. But like I said since you're an active participant in Rallycross and Autocross you probably knew this already.

Therefore the Z, which is once again "tuned for this style of road course" and having tuned the car amicably to throw it's excess weight around uniformly and conservatively, would/should in all reality have the advance when it comes to those 360 degree corners, and in fact this is the situation in which the Z's less intrusive PMoI would come to it's aid yet again, as the chassis would allow for more weight to be transferred and shifted via directional braking without the car simply nosing into the cone, or not transferring ENOUGH weight resulting in the dynamic CoG not being rearward enough to aid in the turning motion rather than simply promoting understeer.

For someone who doesn't care about my "credentials" you sure reference
my competition experience alot.

As for the rest of this quote, it only reinforces my initial comment that the BRZ finishing within on second of the 370Z is impressive.

One, I believe you mean with greater weight transfer comes the POTENTIAL for lower overall grip

Everything is in "potential" when dealing with theory; which we are firmly in as there is no objective data relating to the tires or surface.

Two the coefficient of grip is not a constant, therefore there is no way you can say "increasing weight transfer causes decrease in grip" unless you're looking at grip as a constant which it isn't, or unless you've got some predetermined variables relating to the situation being discussed. I for one don't know what tires the Z has, nor do I know if the car is at factory weight specs, driver weight camber caster toe angles et cetera. So I doubt you have a constant in mind there.

When the grip is constant, the dropoff of the coefficient as load increases is predictable. You can't tune for the unknown.

Three, to successfully pull off fast times on a gymkhana course you've got to manipulate slip angles to the absolute Nth degree. In doing so you're going to have multiple situations where you are going to want to overload the tires capacity for grip. It is in the particulars like situations as as those in which the management, and utilization of the Z's increased weight transfer can be deemed beneficial at best, or no longer a hindrance at worse.

Agreed.

You're right, but guess what? None of these cars have a "High CG" Some have lower than others, but none of them have a CoG 15 feet off the ground. In the factory sports car world you're not going to be dealing with any cars with center of gravities 20 inches off the ground. This car's Center of gravity is only "best" by what fractions of an inch? Until this car how often was Center of Gravity EVER discussed? When the Z06 debuted and made a stink who discussed CoG...When the GT-R debuted and make a stink, how many places talked about "wow it's Center of Gravity this, Center of gravity that".. No one "Discussed" center of gravity on sports cars, because it was never an issue to discuss. It was such an insignificant value and was more often than not the very FIRST thing to get altered on a vehicle in this category. No one discusses a Porsche GT3 or 458 Italia's center of gravity, no one discusses a Cayman or S2000's center of gravity, because NO ONE CARES. Yet once this car's press package highlights it being "LOWER THAN A PORSCHE OMG SUPA LOW GRAVITY POWWAA !!!" It becomes the most referred to feature on this car.

And the fact that the car's CoG starts out lower than cars twice its price or more is something that should be ignored? It's part of what makes the BRZ a great handling car. Should we ignore horsepower too because it can be easily increased?

I questioned the legitimacy of this video and your reply was "This car has a low CG".....As if it was some grandiose answer that is sufficient enough for all questions involving this vehicle. It's happened here, and elsewhere.. Center of Gravity is "nice to have" and i'm sure accentuates some things here and there but it is not the determining factor in anything....Sorry, but it's not....This isn't a race car, this isn't a Grand Am Rolex Fia Le Mans WRC hundreds of thousands of dollars designed rendered tested vehicle.. This is a road car sold at a car lot for 25 grand...The car's fulcrum being 1cm lower than car B means jack all in a land filled with inexperienced 22 year old college freshmen with wealthy parents and "decent" credit line.

No, my reply was "I choose to find something positive in this video, you're welcome to think otherwise." And then I stated that I believed the BRZ to be an exceptionally handling car due to it's low weight, low CG, and small PMoI. You extrapolated from that as some comment about how the BRZ could beat the 370Z, which was neither stated nor implied.

Stiff as in the vehicle as a whole. As a cumulative piece. Since no one part of a vehicle can be the determining factor in the outcome of the cars "character" whether that be in the form of PMOI, tortional rigidity, weight transfer, squat, pitch, lean obviously. So when I say a car can be "Too stiff" I mean the entire car, I don't mean ONE spring, I don't mean you shouldn't have used aluminum bushings, I don't mean the spot welding of the chassis along with the 14 point roll cage. I mean all of that together can result in a car that is too stiff for race use. In this instance it's in referral to the PMoI therefore it is apparently that the referral of "Too stiff" would mean when the car is trying to move along a "z axis" there would be no give or compensation for the resulting weight transfer in any given direction therein resulting in threshold performance and a loss of predictability

Just wanted to be clear. And if anything a low PMoI would make a care more "loose" than "stiff". Sorry.. a low PMoI would AID in a car being more "loose".

So the overall motif in the room is "the car finished within X of the z" Meanwhile you're saying..."it's obvious the Z screwed up"
Either leaning on the credibility of the caliber of driver, or leaning on the credibility of this video as a whole, considering the results hold little to no merit with EITHER chosen direction. Exactly what I said in the start, which was questioned....

I never questioned your opinion.

Though you talk about chassis elements working as a system, but then separate the driver and car. The whole package is what crossed the timing beams. And the BRZ package was 1 sec behind the 370Z.

Which lends itself to the idea that you think the BRZ is capable of keeping up with in-gear acceleration numbers of the Z...Which is in the same line of thought of thinking the Brz can keep up with standing acceleration figures of the Z.

Again, not what I said. I pointed out that they could be closer than just judging 0-60 times would indicate. Closer does not mean equivalent.

Let's not forget here, the first "segment" of the course video taped is 6 seconds long(Not enough time for the BRZ to get to 60mph anyway), the second location of "flat acceleration" from ~21-25 lapseconds, and the final clearly discernible flat out acceleration location is ~30-33lapseconds...Account for about 20% of the overall lap time...20% of the lap time is accredited to pure acceleration...

You seem to be forgetting the time needed to decelerate. And the fact that except for the start, the cars are never at 0mph.

The ENTIRE event takes place within the real of 0-50~mph..Yet somehow 0-60 isn't important and the fact that one car can out accelerate the other by a full 3 seconds IN that short span of allotted time doesn't account for much if anything...

And I've pointed out why comparing 0-60 times is not a good indicator. The BZ doesn't have to shift a second time and there's only one 0mph point in the
course.

NOT to mention the other car...being "tuned for this event"...

Up in the weight transfer part you were expounding on how the Z was tuned, and now you're calling that into doubt.

Do you see how 2+2 isn't equaling 4 in this scenario yet?

Really?

You know, I wouldn't mind if it were a situation where a BRZ came close on a closed autoX circuit with a showroom 370z, but that isn't... This is a car that achieves the faster times, PRIOR to being "specifically tailored" for this type of event.

You're back to believing the the Z is modified. And that further supports my opinion that the BRZ performed well.

There's more than simply PMoI that improved the responsiveness of your WRX. That is where looking at PMoI in the same manner as looking at CoG needs to end..Like the CoG PMoI should be something to be built upon/around not towards. It's not something to incorporate into a "goal list" much like a CoG.. Those are things that come along with proper development/designing/building/tuning your vehicle.

Lowering the PMoI is a perfectly valid goal if it's important to the type of racing you are tuning for.

Your Bumper beams as an example, yes as a result of removing the bumper beams you moved a larger % of your cars mass towards your center of gravity... But there are immediates that affected the feel much more than the 2% shift in overall dynamic.. For one, you lost 24lbs off the nose of an already front biased car. But similar changes in response can be had by RELOCATING 24lbs to the rearmost section of the trunk, things up against the firewall like say...The Battery? Plenty of non-full race vehicles relocate the battery to the rear of the vehicle not to increase the amount of weight NEAR the center of gravity, because in fact a frontal mount battery would in most cases be MUCH closer to the COG than a rear mounted.. Same can be said for fuel cells replacing fuel tanks.. Fuel tanks are often much more centrally located and lower than most iterations of fuel cell usage, however gains in responsiveness handling and better overall vehicle dynamics can be had by moving that weight rearward, once again not moving weight towards the center but applying it in specific locations where it can be made benefit...Back to your WRX. So you remove 24lbs from the NOSE of the car for 1, you have also lessened the burder on your hydraulic systems in your steering rack, you have lowered the friction between the cogs and teeth of the tie rods, you have reduced the upward pressure experienced on the steering knuckle and therein the coupling etc etc. All things with result in a much more responsive feel through the wheel.

No argument here. But you can't say that removing the outermost masses had no effect on the car's rotational stability.

And as above, shifting the mass around (and not always towards the CoG) is a perfectly acceptable form of tuning. There's no argument here. That's what ballast is for.

Believe it or not factors that come into a race car and factors that come into a road car can differ quite substantially..And with a road car you will encounter quite a few more hurdles that you would never see with a full on race car, simply because you have to deal with consumer tolerances and design compromises made by the factory you'd NEVER have to worry about with a race car. And those are the factors that limit the overall usefulness of gauging a cars PMoI or CoG and actually using it to conclude ANYTHING.

I think it's a perfectly valid way to conclude that they are contributing factors to the BRZ notable handling.

If you show someone a lineup of race cars in the same class same field same restrictions and they have varying centers of gravity or PMoI values, of course it would be simple to determine which one has the advantage...But that is NOT the case with road cars, as they all have varying spring values different suspension geometries different materials, different ways the chassis/frames deal with tortional distortion et cetera.

And yet, they are complete systems.

Well of course it existed before the BRZ...So did Center of gravity...but guess what..No one cared! and like i said, now it's become the topic of every "autocrossing omg this will handle so beast" enthusiast out there. This car has such a loooww center of gravity..how could it ever not conquer the gelgameks, it's center of gravity is so low. It's just become the default answer.

And yet, it does matter, and it is something that's on every racer's mind.

Saying Car A should beat Car B solely due to CoG and PMoI is incorrect, I agree. Which is why I've never said that. However, saying the low CoG and the engineer's eye towards keeping the PMoI low are contributing factors to a car's handling is correct.

Yet acceleration does, so unless you're saying the BRZ sticks with the 370z in terms of acceleration until 40mph, where the Z magically gets a 3 second speed boost lead on it...it matters.

Except that the BRZ's second shift factors directly into your 3 second difference. And once again, closer != equal.

I think I'm done with this conversation. There's obviously some sort of miscommuncation somewhere that doesn't seem to be getting resolved. So I will state my stance here.

I find the results of the video impressive because the BRZ had a lot of factors stacked against it. The BRZ's driver was very likely less familiar with his car, which had much less power and a lower prep level.

I do not believe the stock BRZ is an equal to a prepped 370Z at AutoX or in this case Gymkhana.

I do believe the BRZ is an exceptionally handling car which is due, in large part, to it's engineering.

[JohnnyR]

Hmm... That's not good for the Z to do that even on the smaller track, despite the suspension upgrades. It couldn't even really use it's power advantage there. Different drivers and set ups and all that. The BRZ looked to "behave" well enough.

If those tires on the BRZ were stock, that's culprit, as they're garbage, even just by looking at them at the NYAS I can tell that much. Car should handle substantially better with just swapping in a proper set of tires, and should be the first "mod" someone does to the car.

A shame the car doesn't have decent tires from the showroom floor. And, as indicated here even on such a ridiculously tight course, more power especially.

[KatHawkDown]

Originally Posted by Draco-REX

*A bunch of stuff*

and

Originally Posted by KeepGuessing

*A bunch of stuff*

I realize that you guys are keeping it relatively civil but still.

[crazyyankeefan]

Not saying BRZ is a bad car, but simply put, bunch of you people are just delusional to think the BRZ can out-perform a 35k car with 0-60 in 4.5 sec. Period. Even throwing in any kinda mods should not effect that much (of course excluding engine mod).