Measured: Aero Lift, Roll Stiffness & Distribution, Steering Effort, and more

[DarkSunrise]

I was looking at C&D's long term review of their BRZ and came across this little gem. Some interesting facts in here (e.g., BRZ generates 25 lbs lift F and 35 lbs lift R @ 70 mph).

Apparently C&D also had their BRZ tested on a kinematics and compliance rig, so there's some suspension tidbits in there as well.

http://media.caranddriver.com/files/...lete-specs.pdf

[sluflyer06]

Thats really cool but the numbers don't mean much to me without comparing it side by side with a handful of other cars to put it all in perspective.

Going to search for other reports like this.

[DarkSunrise]

Originally Posted by sluflyer06

Thats really cool but the numbers don't mean much to me without comparing it side by side with a handful of other cars to put it all in perspective.

Going to search for other reports like this.

Here's one for the Mustang GT:
http://media.caranddriver.com/files/...lete-specs.pdf

[sluflyer06]

Originally Posted by DarkSunrise

Here's one for the Mustang GT:
http://media.caranddriver.com/files/...lete-specs.pdf

Mustang fairs pretty well, though through very different setup, impressive is how much higher the roll center is and the difference in anti-squat/anti-dive.

Hopfeully some reports on something like a Cayman/Miata/GTI etc would be fun. Thanks for finding this.

[phobos512]

I found datasheets on their site for a few other vehicles (these are handwritten from comparison tests rather than the final panels like you see for the Mustang and BRZ but they contain similar data).

14 Ford Focus ST - http://media.caranddriver.com/files/...d-focus-st.pdf

14 Fiat 500 Abarth - http://media.caranddriver.com/files/...14-comparo.pdf

12 BMW 328i Manual - http://media.caranddriver.com/files/...ine-manual.pdf

14 Ford Fiesta ST - http://media.caranddriver.com/files/...14-comparo.pdf

[sluflyer06]

Originally Posted by phobos512

I found datasheets on their site for a few other vehicles (these are handwritten from comparison tests rather than the final panels like you see for the Mustang and BRZ but they contain similar data).

14 Ford Focus ST - http://media.caranddriver.com/files/...d-focus-st.pdf

14 Fiat 500 Abarth - http://media.caranddriver.com/files/...14-comparo.pdf

12 BMW 328i Manual - http://media.caranddriver.com/files/...ine-manual.pdf

14 Ford Fiesta ST - http://media.caranddriver.com/files/...14-comparo.pdf

Actually not one of those has the Chassis/Kinematics dyno results, those are just standard testing notes. What we're looking at is the Aero Drag/LIft/ROll Centers/CG/etc etc.

[strat61caster]

For how much we obsess about balance, the Mustang has a better F/R weight distribution according to these numbers. And that's the V8...

BRZ: 55.3/44.7
Mustang GT: 54.7/45.3

[DarkSunrise]

Originally Posted by strat61caster

For how much we obsess about balance, the Mustang has a better F/R weight distribution according to these numbers. And that's the V8...

BRZ: 55.3/44.7
Mustang GT: 54.7/45.3

This is an important point IMO. People conflate handling balance with weight distribution all the time. They're not the same.

The Twins are praised for their excellent handling balance (i.e., fairly neutral), but that's not the same as saying their static weight distribution is 50/50.

On the flip side, manufacturers like BMW love to brag about having "perfect" 50/50 weight distribution on their cars, but the handling balance on many current BMWs is not that great (i.e., significant understeer). Cars like the 135i and E92 M3 are good examples of that.

Handling balance is not the same as static weight distribution.

[sluflyer06]

Originally Posted by DarkSunrise

This is an important point IMO. People conflate handling balance with weight distribution all the time. They're not the same.

The Twins are praised for their excellent handling balance (i.e., fairly neutral), but that's not the same as saying their static weight distribution is 50/50.

On the flip side, manufacturers like BMW love to brag about having "perfect" 50/50 weight distribution on their cars, but the handling balance on many current BMWs is not that great (i.e., significant understeer). Cars like the 135i and E92 M3 are good examples of that.

Handling balance is not the same as static weight distribution.

truth. I came to the BRZ from a 135i with punched out alignment pins and E92 M3 front sway bar, I also undersized my rears to 235 just to try to get some balance out of it but still underteered terribly. However back when I had a E36 333i ZHP it was wonderfully neutral.

[phobos512]

Originally Posted by sluflyer06

Actually not one of those has the Chassis/Kinematics dyno results, those are just standard testing notes. What we're looking at is the Aero Drag/LIft/ROll Centers/CG/etc etc.

I *did* say it wasn't all the same data. I looked through every file in the directory on their site and the Mustang and BRZ are the only ones in there with that aero data - it must be something new they only have just started doing.

[strat61caster]

Originally Posted by DarkSunrise

Handling balance is not the same as static weight distribution.

I never purported it to be. The conversation often goes that muscle cars are inferior due to the large motor in the front when in reality our little Japanese 4 banger has a similar weight distribution, just found it curious is all as I thought the Toyobaru was closer to 53/47 as I'm sure you know.


Handling dynamics are complex and not many people can gain a lot from a sheet like this (obviously putting aside the base info like curb weight and engine specs).

Thanks for the info

[DarkSunrise]

Originally Posted by strat61caster

I never purported it to be. The conversation often goes that muscle cars are inferior due to the large motor in the front when in reality our little Japanese 4 banger has a similar weight distribution, just found it curious is all as I thought the Toyobaru was closer to 53/47 as I'm sure you know.


Handling dynamics are complex and not many people can gain a lot from a sheet like this (obviously putting aside the base info like curb weight and engine specs).

Thanks for the info

Haha apologies man, I should have been more clear, I didn't mean you specifically. I was just quoting your post since you referenced it.

The conflation of handling balance and weight distribution was something I've seen frequently on the internet, sometimes even on this board, and was meaning to comment on. Your post just gave me the segue I was looking for.



Rather than 50/50, I've actually been thinking about whether a 45/55 MR layout (like the Cayman) is actually ideal for a RWD car.

• The slight rear-bias would increase traction under acceleration vs. 50/50.
• The slight rear-bias would give you more even weight distribution when braking vs. 50/50.
• The mid-mounted engine would reduce polar moment of inertia, allowing better turn-in vs. FR, and easier oversteer recovery vs. RR. Also MR has minimal drivetrain loss.

A lightweight 55/45 FR car like the FR-S has its own advantages though, e.g., pretty good turn-in and probably the easiest oversteer recovery. Just not ideal for outright speed vs. MR.

[totopo]

Originally Posted by DarkSunrise

Haha apologies man, I should have been more clear, I didn't mean you specifically. I was just quoting your post since you referenced it.

The conflation of handling balance and weight distribution was something I've seen frequently on the internet, sometimes even on this board, and was meaning to comment on. Your post just gave me the segue I was looking for.



Rather than 50/50, I've actually been thinking about whether a 45/55 MR layout (like the Cayman) is actually ideal for a RWD car.

• The slight rear-bias would increase traction under acceleration vs. 50/50.
• The slight rear-bias would give you more even weight distribution when braking vs. 50/50.
• The mid-mounted engine would reduce polar moment of inertia, allowing better turn-in vs. FR, and easier oversteer recovery vs. RR. Also MR has minimal drivetrain loss.

A lightweight 55/45 FR car like the FR-S has its own advantages though, e.g., pretty good turn-in and probably the easiest oversteer recovery. Just not ideal for outright speed vs. MR.

I think fmr is still better in terms of vehicle dynamics for performance. Iirc in the Japanese jgtc/supergt experience, with min weight requirements fmr with greater than 50% weight in the front ends up faster. The main benefit of mr over fmr is total weight.

Less weight in back means you can accelerate earlier at corner exit.

[strat61caster]

Originally Posted by DarkSunrise

Rather than 50/50, I've actually been thinking about whether a 45/55 MR layout (like the Cayman) is actually ideal for a RWD car.

For going around a track and trying to nail down a great time? Definitely, there's power in being able to swing the back end around a corner and have the traction to seriously power out of a corner, for all the shit Porsche gets it's been effective for over 50 years at many levels of racing. Most of the major supercars in the last 10 or so years have been around there or even more rear weight biased.

I've been wondering the same thing and as I fantasize about getting another sports car the MR2 is a strong contender, both the MK1 and MK2 are roughly 45/55, it seems like for less than the cost of a Toyobaru you can get similar straight line performance and the advantage of the MR through the twisties.