Autocar: BRZ vs. MX-5 vs. 370Z

[Draco-REX]

Originally Posted by Sasquachulator

Im curious as to what people who are considering the BRZ/FRS actually drive now.

If power is a major consideration it would put into perspective what they are coming from, whether its a 100hp slowass econobox tin can, a 300hp family car that has no semblance of driving feel whatsoever, a 300hp SUV that feels like its gonna tip over at a 1 degree turn, or a 600hp beastmode supercar that costs an arm, a leg, your first born, and your house.

My current dd is a 2007 Subaru Legacy spec.B. 3500lbs, 246hp. It's completely stock and I'll be trading it in for the BRZ. The BRZ will handle better, have a better power to weight ratio (14.2:1 vs 13.8:1), and it'll get better mileage as well. After owning the spec.B which I thought would be the perfect daily, I've decided I'm willing to sacrifice a lot of comfort to gain more fun.

To further add perspective to my statements, I also own a 2007 Subaru STI. It has only a stage 1 tune, so it is essentially stock power, but the suspension has been redone from top to bottom. I tuned it for street handling and it'll out corner nearly anything on uneven pavement.

Additionally, I have a 03 WRX that I compete with in SCCA RallyCross. It has a 6-speed swap, and is fully Stage 2 with a tune and exhaust setup that give nearly instant boost. It's a national championship capable car, and I plan to take it to Tulsa this year to see if I'm a national championship capable driver.

I also used to own an '86 Corolla Deluxe. It had 70hp, an open rear diff, and no power anything. And I daily drove that for 5 years. And previous to that I had 5 years of various RWD cars that ranges from junkers to a 340hp TransAm that I drove through New England winters.

So looking at the BRZ, it's philosophy, it's stats, etc. I know what to expect out of it. And if the ride I took is any indication, it very well might exceed my expectations in some areas. But it will replace the spec.B directly in my day-to-day driving. If anything, it will likely feel quicker as I rarely get into boost in the spec.B during daily driving making it more of a 20:1 car.

That's why I think people who say they need more than 200hp in a 2800lb car for daily driving have lost their perspective.

[Guff]

Snap! I just read this!

GAWD IM EVEN MORE EXCITED NOW.

[Kimsey47]

Wow, that comparison at the end about the NSX! That was a bold statement! Also I know what he means about the 370z... My Integra (140hp) could keep any thing in front of it when having a spirited drive over one of the mountain roads here which I had to traverse every day. I'd have all sorts of cars wanting to play, and usually they'd end up in near disaster before just giving up... It was just able to hold so much more speed through corners that on the small passing areas the others, and in all cases, the more powerful car just didn't have enough time to catch up for a safe pass. Considering that was a front wheel drive, non-vtech, hi-reving blast to drive, this article just confirms more of what I thought this car would be! Thanks for sharing!

[fatoni]

Originally Posted by Kimsey47

Wow, that comparison at the end about the NSX! That was a bold statement! Also I know what he means about the 370z... My Integra (140hp) could keep any thing in front of it when having a spirited drive over one of the mountain roads here which I had to traverse every day. I'd have all sorts of cars wanting to play, and usually they'd end up in near disaster before just giving up... It was just able to hold so much more speed through corners that on the small passing areas the others, and in all cases, the more powerful car just didn't have enough time to catch up for a safe pass. Considering that was a front wheel drive, non-vtech, hi-reving blast to drive, this article just confirms more of what I thought this car would be! Thanks for sharing!

just becaue they couldnt pass you doesnt mean that they were slower than you.

[Bristecom]

Originally Posted by ZDan

1. 50/50 isn't "perfect" or ideal. Particularly for a 2wd car
2. Even if it were, why would you suppose that it would be better to have 50/50 under acceleration than under braking?

In a rear wheel drive car, you definitely WANT more load on the rears during acceleration. Not as much an issue on a 14-15 lb/hp car like the FR-S, but the better the power/weight, the more rearward you want the weight to be.

With a 10 lb/hp car, 54/46 static (FR-S/BRZ with driver only, 1/2 tank) would be FAR inferior to 50/50, or the S2000's 49/51. You just wouldn't be able to put the power down as well out of lower-speed corners.

There are also benefits under braking for having a 50/50 or better (more rearward) distribution. Under 1-g braking, the 54/46 static FRS/BRZ will have ~72% of its weight on the front tires, only 28% on the rears. Given same size tires front and rear, the fronts are overloaded and the rears are underutilized.
Meanwhile, the 49/51 static car under 1-g braking would have 67% on the fronts, 33% on the rears. Due to the nonlinear nature of grip vs. load in tires, this car would have more braking grip (all else equal).

Also under trailbraking on corner entry, the more forward weight-biased car will be loading the outside front more. Less front grip, more push.

For a rear-drive car, 50/50 or slightly more rearward weight distribution is better for:
1. braking
2. corner entry
3. steady-state cornering
4. corner exit
5. straight-line acceleration

All that said, every design is a compromise. In order for the FR-S/BRZ to come in as light as possible, it was important to keep the wheelbase short. They could have stretched out the wheelbase, moving the front wheels forward, to get to 50/50, but the car would have weighed more (and cost a smidge more, too).

But 54/46 *is* inferior to 50/50 (or slightly more rearward) for an FR car, for outright performance potential and for feel (less p/s assist required with less weight on the fronts).

In theory 50/50 is ideal for handling/turning grip. Although some may prefer slightly front biased or rear biased depending on desirable oversteer/understeer characteristics. Of course, weight distribution changes under acceleration/deceleration and with passengers, fuel, and cargo. But I guess it depends when you want the maximum cornering grip - under acceleration or in a steady off-throttle state. And obviously a rearward weight bias is better for braking and RWD traction.

I do believe the end resulting weight distribution in this car was a bit more frontward than they wanted. However, in the official literature, they say they wanted a front biased weight distribution. I believe that is because by keeping it always a little front biased, you will have predictability and by having less grip on the rear, you will have more fun and controllable power oversteer, not to mention better stability overall.

[LeftFootBrake]

Originally Posted by ZDan

...54/46 *is* inferior to 50/50...for feel (less p/s assist required with less weight on the fronts).

Lots of accurate information in the rest of the post but just a point of clarity on the "feel" factor (and even more so, the implied steering response): I think you've underplayed the importance of moment of inertia.

[Bristecom]

Originally Posted by LeftFootBrake

Lots of accurate information in the rest of the post but just a point of clarity on the "feel" factor (and even more so, the implied steering response): I think you've underplayed the importance of moment of inertia.

Good point. I remember hearing Marcus Gronholm, a famous World Rally Championship driver, complaining once that the Peugeot didn't have enough front weight bias. He said you actually want some front weight bias for better corner entry. I've been thinking about that for years and I think it has to do with the moment of inertia and stability. Rally cars usually have more power going to the rear but are front weight biased and they can very smoothly drift from corner to corner on the country roads.

[ZDan]

Originally Posted by LeftFootBrake

Lots of accurate information in the rest of the post but just a point of clarity on the "feel" factor (and even more so, the implied steering response): I think you've underplayed the importance of moment of inertia.

Well, I guess not mentioning it at all is "underplaying" it, so guilty as charged...

Low polar moment of inertia/centralized mass is very important of course. The most responsive car I've ever driven was a 80hp 600 lb. Formula 440

[ZDan]

Originally Posted by Bristecom

Good point. I remember hearing Marcus Gronholm, a famous World Rally Championship driver, complaining once that the Peugeot didn't have enough front weight bias. He said you actually want some front weight bias for better corner entry.

May be a minor point, but corner entry for a rally car on loose material is different from corner entry on a tarmac circuit.

AWD rally cars may favor forward weight bias.

Rear bias is superior for rwd tarmac circuit cars.

[fatoni]

Originally Posted by ZDan

May be a minor point, but corner entry for a rally car on loose material is different from corner entry on a tarmac circuit.

AWD rally cars may favor forward weight bias.

Rear bias is superior for rwd tarmac circuit cars.

its not a minor point. with low grip driving there is usually a lot of left foot braking going on to continually adjust the brake balance. combine that with the fact that its usually a good idea to make the car naturally want to point forward (like a vortex football or what have you) and its easy to see why with those kinds of vehicles the front weight bias is a big deal.

i remember reading about how the sti was designed to be the understeering pig that it was because of the huge influence prodrive has over there and how they werent too concerned with driving on tarmac

[ZDan]

Originally Posted by Bristecom

In theory 50/50 is ideal for handling/turning grip.

For steady state cornering, with equal front and rear roll stiffness. In practice, neither of these conditions is the norm.
Steady state cornering is rare for road courses. You trailbrake into the corner and power out.
On most FR cars, the front swaybar is much stiffer than the rear. That means that even at steady-state cornering, you're most likely transferring more load onto the outside front than the outside rear.

In order to maximize total lateral grip, you have to keep the load on the tires as even as possible. The more you overload a tire, the less grip it gives per unit load.

50/50 distribution on a typically set up road car will load the outside front more than the outside rear. You would have more total grip with more rearward weight bias.

Although some may prefer slightly front biased or rear biased depending on desirable oversteer/understeer characteristics.

Whatever the weight bias, you can tailor under/oversteer characteristics by biasing roll stiffness. I.e., front weight bias doesn't necessarily mean understeer, and rear weight bias doesn't necessarily mean oversteer. The engineers will tailor balance to where they want it, whatever the weight balance.

Of course, weight distribution changes under acceleration/deceleration and with passengers, fuel, and cargo. But I guess it depends when you want the maximum cornering grip - under acceleration or in a steady off-throttle state.

In a rwd car, you want some drive traction under acceleration. To maximize drive traction, you need load on the rears. And at the same time you don't want much rear roll stiffness. Forward weight bias is BAD for both of those factors, as you have less load on the rears, *and* you would want to reduce front roll stiffness to keep from overloading the outside front. With a more rearward weight bias, you get more load on the rears *and* you can use more front roll stiffness without overloading the outside front as much (giving *more* total rear grip for thrust).

And obviously a rearward weight bias is better for braking and RWD traction.

Yes, but the benefit for rwd accelerative traction is twofold.

I do believe the end resulting weight distribution in this car was a bit more frontward than they wanted.

For the modest power/weight and light weight, it's not really a big deal to be honest.

However, in the official literature, they say they wanted a front biased weight distribution. I believe that is because by keeping it always a little front biased, you will have predictability and by having less grip on the rear, you will have more fun and controllable power oversteer, not to mention better stability overall.

Having the c.g. more forward should give more stability.

In the end, it's a very good compromise for the power level. The only problem would be if you tried to apply significantly more power.

I still think the car is a brilliant, and that they made the most appropriate compromises to keep the weight down and the fun UP.

[Enemies]

Originally Posted by Kimsey47

Also I know what he means about the 370z... My Integra (140hp) could keep any thing in front of it when having a spirited drive over one of the mountain roads here which I had to traverse every day.

Haha, this made me chuckle. Re-read what you wrote. :P

[Bristecom]

Originally Posted by ZDan

For steady state cornering, with equal front and rear roll stiffness. In practice, neither of these conditions is the norm.
Steady state cornering is rare for road courses. You trailbrake into the corner and power out.
On most FR cars, the front swaybar is much stiffer than the rear. That means that even at steady-state cornering, you're most likely transferring more load onto the outside front than the outside rear.

In order to maximize total lateral grip, you have to keep the load on the tires as even as possible. The more you overload a tire, the less grip it gives per unit load.

50/50 distribution on a typically set up road car will load the outside front more than the outside rear. You would have more total grip with more rearward weight bias.

Whatever the weight bias, you can tailor under/oversteer characteristics by biasing roll stiffness. I.e., front weight bias doesn't necessarily mean understeer, and rear weight bias doesn't necessarily mean oversteer. The engineers will tailor balance to where they want it, whatever the weight balance.

In a rwd car, you want some drive traction under acceleration. To maximize drive traction, you need load on the rears. And at the same time you don't want much rear roll stiffness. Forward weight bias is BAD for both of those factors, as you have less load on the rears, *and* you would want to reduce front roll stiffness to keep from overloading the outside front. With a more rearward weight bias, you get more load on the rears *and* you can use more front roll stiffness without overloading the outside front as much (giving *more* total rear grip for thrust).

Yes, but the benefit for rwd accelerative traction is twofold.

For the modest power/weight and light weight, it's not really a big deal to be honest.


Having the c.g. more forward should give more stability.

In the end, it's a very good compromise for the power level. The only problem would be if you tried to apply significantly more power.

I still think the car is a brilliant, and that they made the most appropriate compromises to keep the weight down and the fun UP.

All very good points. Because the car doesn't have that much power, it's not easy to overwhelm the rear so the front weight bias was likely given to get just the right about of traction to have fun with the particular amount of power. And suspension setup can certainly play a much bigger role in how the car handles as we've seen with some impressive front wheel drive cars. I also remember Toyota or Subaru claiming that the low center of gravity and low weight is much more important than the weight distribution.

As I said before, ideally you'd have a version of this car with a 2.7-3.0L flat six up front and a transaxle in back for even lower CoG, better weight distribution, and more power. I'm not sure if they could still fit the back seats that way though... not to mention, they'd probably have to redesign almost everything and it'd cost a lot more.

[Tainen]

Originally Posted by OldSkoolToys

Subaru eh? The ZZT231 and ZZW30 were super model weight in comparison to the other 'models' out there, at 2500 and 2200lbs respectively. If anyone can shave weight on a car, its Toyota. If not for the safety regulations that have gone into effect these past few years, the 86/BRZ would probably be closer to the mid-high 2600's in base trim.

As for the AP1 vs. 86/BRZ argument....with the BRZ you're getting arguably better engineering chassis balance in a -brand new- car thats still $7000 less, in terms of MSRP, vs. the MY2003 S2000. At the reviews this car is currently getting, if Toyota and Subaru wanted to make the car start at the low $30k range, it would obliterate the AP1 and AP2 in every category. Bang for your buck, in regards to buying brand new, the 86/BRZ wins out.

I smirk at the articles hint at who did what and so forth on this car. As for me, I refuse to believe that a RWD car, that was co-produced by a company who has easily created some the most memorable and highly respectable RWD Japanese Sports car's in history, would be singularly engineered by a company who's only mark on racing history is AWD rally, while the latter company had 0 input into its chassis and suspension designs/tuning. If you honestly believe that then you are extremely stubborn, or dense.

I'm not saying I know whom did exactly what, and who gets credit for what, but Toyota most certainly did more than just design and financing. They have decades of experience mass producing car's of this kind.

Lastly, the article does come off as a bit too much Subaru lovey-doveyness going on, but hey, its a British magazine. The brits have an unholy love affair with Subaru. See also: last gen WRX.

nobody was talking at all about Toyota or the split in responsabilities. :P are you just a toyota troll or something? I'm not even sure why you posted in this thread.