Driving Impressions: Lower Stress Bar - 986 Forum - The Community for Porsche Boxster & Cayman Owners

BobMarley1 · 04-23-2007, 10:27 AM

how do I order one?

MNBoxster · 04-23-2007, 10:32 AM

Hi,

How are you measuring your lateral acceleration? You're throwing around numbers here (both Baseline and Modified) which are greater than those repeatedly published for the Boxster S (0.91g).

While that may be so of a Modified Car, I doubt it's the case with a Base Boxster. I suspect your Data Logger is miscalibrated. How else do you explain it?

Happy Motoring!... Jim'99

insite · 04-23-2007, 10:42 AM

Quote:

Originally Posted by MNBoxster

How are you measuring your lateral acceleration? You're throwing around numbers here (both Baseline and Modified) which are greater than those repeatedly published for the Boxster S (0.91g).

While that may be so of a Modified Car, I doubt it's the case with a Base Boxster. I suspect your Data Logger is miscalibrated. How else do you explain it?

logger is not miscalibrated. it's a racepak gps; the accelerometers and GPS calcualted lat G's are the same. it's easy to explain:

1. modified car
2. turns 1 and 2 are slightly banked
3. alignment of a stock boxster s sucks, not enough camber

insite · 04-23-2007, 10:44 AM

Quote:

Originally Posted by BobMarley1

how do I order one?

their website is here: http://www.mantissport.ca/

you can't order online, though. call them at 905.844.6219 and ask for stan. btw, any prices listed on their site are canadian.

insite · 04-23-2007, 10:56 AM

for those interested, here is a graph of my fastest lap showing lateral acceleration derived two different ways:

1. on board accelerometers (red line)
2. calculated from GPS polling data (green line)

the RacePak polls gps several times a second. there is some latency and interpolation. this is why the green line lags the red line by a little bit. magnitude, though, is very comparable between the two. the data is accurate.

racer_d · 04-23-2007, 02:04 PM

Interesting discovery. Reminds me of the problems I had with my 914 experiencing trailing arm flex under high g loading (expecially with wide sticky tires, compared to the then stock, skinny, non grippy ones

)

I'll have to keep this mod in mind. Wonder how SCCA/PCA allows it for, say, Autocrossing?

insite · 04-23-2007, 03:06 PM

Quote:

Originally Posted by racer_d

I'll have to keep this mod in mind. Wonder how SCCA/PCA allows it for, say, Autocrossing?

good question. i bet it falls into the same category as a strut tower brace. probably would bump you from showroom stock to production, but not from production to improved. just a guess.

John V · 04-24-2007, 04:10 AM

Magazines measure maximum lateral acceleration around a flat skidpad. They drive the car at a known radius and then measure time to complete a lap (or multiple laps). Then they calculate the lateral g's generated.

The maximum g's that a car can develop steady-state around a 200' skidpad is different than what it can generate around a banked corner. Or a corner that requires less steering lock. Or at high speeds. There are too many variables, which is why magazine test numbers are for the most part useless metrics.

Another discrepancy can come as a result of the leaning of the car, which induces a false lateral acceleration component. Fortunately, the more sophisticated data acquisition systems account for this with multiple accelerometers.

In other words - I believe your numbers. We see similar numbers in our DL1 data - peaks of up to 1.4g lateral but more imporantly, around 1.2g steady state. This is a stock-class Boxster S with (really old) Kumho V710 competition tires.

chaudanova · 05-03-2007, 11:13 AM

Insite, any updates on your lower stress bar, in terms of how its been holding up, any changes/updates on driving impressions on both street/track?

Thanks bud...

insite · 05-03-2007, 01:14 PM

it's still awesome. unnoticable under normal driving conditions. very noticable when you push the car, especially over bumps. without the bar, the car will lose camber over bumps, causing oversteer conditions. with the bar, things are much more tidy. i really recommend this.

Topless · 05-03-2007, 01:24 PM

Nice work Insite,

You patiently seek out leading edge performance upgrades, act as test pilot, verify your impressions with instrumentation and lap times and share your findings with all of us. Bravo!

This is not bolt on fluff, but tested and verified with results. 2.5 sec on a track you already have wired is pretty good stuff. Just for kicks, if you had not made these improvements to your suspension and braking and focused only on the motor, how much HP increase would you need to get the same lap times? 50? 80? Interesting question don't you think? I suspect you are already outrunning most of the 987's in your area with a stock 2.5 motor.

Thank you again for sharing your findings.

steve00s · 03-24-2009, 10:33 AM

I have finally gotten around to installing the lower braces on my car and have a question for those of you who have done this.

I can't get the old bolts out. I understand that they are pressed in and should pop out but I have whacked on them pretty good without any movement and am afraid of breaking or bending something. What is the trick to getting these out?
Thanks.

blue2000s · 03-24-2009, 11:25 AM

Quote:

Originally Posted by steve00s

I have finally gotten around to installing the lower braces on my car and have a question for those of you who have done this.

I can't get the old bolts out. I understand that they are pressed in and should pop out but I have whacked on them pretty good without any movement and am afraid of breaking or bending something. What is the trick to getting these out?
Thanks.

I put a nut on the end of the captive stud and hammered away. It gives you a bigger target and keeps the end of the stud from getting deformed. The colder the parts, the more easily it will push out. It feels like it's never going to back out and then all of a sudden it lets go.