Visconti Tuned 0-60

[Synack]

Originally Posted by Rampage

Pump up the rear tire pressure far enough and almost any RWD will start drifting the back end around corners. Or spinning.

Very true. They obviously knew there was a lack of power and jacked the tire pressure up and kicked out the negative camber so less traction can be had to get it loose. Curious if the BRZ did this too.

[Visconti]

Oh please put me in that car

[brichard0625]

Originally Posted by Visconti

Oh please put me in that car

lol im sure your better than me...you know your welcome to take it for run...u probably have more road over there in ct where we can break this in....gonna do an oil change today or tomorrow too so she'll be ready lol

[so26]

Soooo now that you have an updated tune from John can we expect to see some new 0-60 vids? Please

[*KID*]

did you get any track times?

[xAgentzero13]

the guys with the tune getting 0 to 60 in less than 6 secs what other mods do you have?

[Opposed]

Originally Posted by xAgentzero13

the guys with the tune getting 0 to 60 in less than 6 secs what other mods do you have?

Just a drop in HKS filter...

[E92M3Guy]

How are you measuring velocity? If you're relying on your speedometer, then nothing is accurate (sorry). If you're getting velocity from your "torque app" then it might be a little better; but still not terribly accurate.

I'm guessing your "torque app" uses your cell phone sensors -- right? Here's the problem: they are horribly inaccurate. Best case, they use the accelerometer + GPS to track speed. Worst case, the app only uses accelerometer. The accelerometer is great to detect the launch, but not great for calculating velocity. Using accelerometer only is very difficult to calculate velocity. Using GPS only is very difficult to detect launch, but dead accurate at velocity.

But the complications are not over yet. Most phone GPS's have 1 Hz sampling rate (1 sample per second). The best phones have a 5 Hz sampling rate (5 samples per second).

Then to add one more wrinkle in this...the accuracy of the acceleromter will depend on the mounting angle. It must stay at a constant position during the test, or the accel data is much less accurate. There are actually three accelerometers (X, Y, and Z). So the actual acceleration is calculated as a vector from whichever two make up the horizontal plane at the time. If the phone is sitting on the seat, in a cup holder, etc. and moving around, the horizontal plane may shift from X-Y to Y-Z and this will degrade the accuracy. So you need to keep the device at a constant position.

Solution: get a vBox. 10 Hz sampling rate. Mounts to your windshield (for lower end models). Then when you're done, you can upload your results to www.perfdb.com for auto verification of velocity, 0-60, 1/8 mile, 1/4 mile, 60-130, etc. Verification graphs are generated automatically as well.

[fenton]

The torque app from his phone hooks into the obd interface of the car. Reads straight from ECU IIRC

[Foobar]

Originally Posted by fenton

The torque app from his phone hooks into the obd interface of the car. Reads straight from ECU IIRC

Correct. It uses inputs from OBD2, Accelerometer, GPS, Barometer, and Internal Compass for its various functions. Not sure which ones are actually tapped for 0-60.

From what I understand, it's at least as good, if not better, than a GTech. I've only used it for pulling codes from the ECU though. Got it paired to a cheapo bluetooth OBD2 interface that I got off eBay.

[E92M3Guy]

^^^

What's the name of the app? I'd like to look it up for more info.

Hooking into OBD2 definitely solves the orientation accuracy problem...but not velocity problem. Hopefully the software doesn't use the wheel speed sensors for velocity; but instead uses GPS. Most automotive GPS's are 1Hz sampling rate (some are even as low as 0.20 Hz -- 1 sample every 5 seconds). The end of the video shows to be about 1Hz sampling rate -- which seems consistent with automotive GPS.

[Yruyur]

Torque

Sent from my PH44100 using Tapatalk 2

[Yruyur]

And you can get the Bluetooth dongles for 15 bucks on eBay.

Sent from my PH44100 using Tapatalk 2

[E92M3Guy]

From the "Torque-bhp" forum FAQ:
How do I make the displays update faster?
This is mainly down to the speed at which the ECU operates and provides data to Torque, but there are a couple of things you can do that will improve the speed of the readings:

• Try to use the ‘Faster communication’ setting – Some adapters can use the ‘faster communication’ setting to reduce timeouts and retrieve data slightly faster from the ECU. Not all adapters support this option but it will improve things if yours does.
• Have fewer displays on screen – Torque will only ask the ECU for the information that it needs, so if you want the fastest update possible for a particular display then only have that display on the screen
• Only use logging when required – Web uploads and file based logging ask the ECU for PIDs, only use logging when required.

This tells me a lot. The utility is using DCAN messages, not PT-CAN. PT-CAN is much faster than DCAN, but DCAN is universal and PT-CAN is vehicle-specific. DCAN is a polled interface -- meaning you must poll the ECU for data. Due to the design of DCAN, the more PIDS you request, the slower the sampling rate. Typically, DCAN supplies data around 5-6 Hz with 8 PIDS or less. Sample more PIDS and sampling rate goes down. But regardless, you're still limited by the sampling rate of the sensors themselves. GPS in cars is still about 1Hz sampling rate at best.

Guy says his app is better than GPS alone. Not sure why he says that. vBox is a GPS and acceleromter combo -- maybe he's doing the same thing and that's what he means. But vBox is 10Hz, 20Hz, or 100Hz sampling rate depending on the model. It's basically the gold standard for this type of testing.