mcookgraphics

Looking for an easy way to measure basic performance of my new 383 stroker. 0-60, 1/8 and 1/4 mile times. I won't be taking it to the drag strip but just curious what it runs. Anyone have suggestions on iPhone apps or what do you use?

mobird

Why don't you want to take it to the track?

Most tracks, it is $20 on a test and tune night. Most apps aren't very accurate in my experience (think of it this way, if it is off by half a second, it is off by ALOT) so why not get an official time? Plus it is legal, you won't get a ticket or get in trouble!

Totally get the desire to figure out basic performance from your motor as a baseline. I am the same way. The problem is that most of the apps out there are extremely limited by GPS of your phone, so there is alot of "guess work" being done. Where as the track has very accurate sensors. Personally, I wouldn't want to have an app tell me I have a 12 second car turning 110+ mph in the quarter, and then find out it isn't actually that fast. Vice-versa, it would be very dissapointing to have an app tell me I have a 14 second car that barely can get to 100 in the quarter. Either way, you would still end up wondering whether the app was even close and have to go to the strip anyway (or a dyno) to see what kind of power you are making.

Just my $.02

ajrothm

THIS ^^^^

Just go to the track and see what it REALLY does.

As for performance data systems, look at Dragy and V box. Way more expensive then the drag strip for $20 though..

cagotzmann

I have a VBOX Sport, again this is not cheap vs the Drag strip. But as for accuracy the vbox is very good (20 HZ GPS) and since you have a sd-card in the vbox you can use the data on a PC and analyze the data in many ways.

eg. have the unit start recording and take a few hard accelerations say from 0 - 100 MPH

Then later you can check 25-60 MPH time or 50-100 MPH or distance as a variable etc. You can also use this for braking performance, how fast the car can stop,

The vbox vs the standard IPHONE / IPAD @ 1HZ is a big difference.

eg IPAD using harry's laptimer 46km-125km speed range. IPAD runs from 5.3 Sec - 6.5 Sec vs VBOX which measured 5.95-6.09 Sec for the same runs. I use the vbox for tuning / timing changes and then go to the track to confirm results. And for track days connected to harrys lap timer to get great data to analyze.

mcookgraphics

Thanks for the replies. Closest drag strip is a couple hours away. For my purposes, Dragy will probably work until I can take it to the strip and double check it.

cagotzmann

When looking at the Dragy or VBOX here is what I found out that is important from any data logging / performance monitoring system.

The GPS Frequency is important for accuracy. 1 HZ is bad and inconsistent. 5 HZ is ok for road course track driving, 10 HZ starts to be ok for drag strips / acceleration and great for road couse tracks
20 HZ is great for both types of driving.

20 HZ is a speed reading every 0.05 sec so accuracy is usually within 0.1 sec. Also the unit should also have a SD-Card for recording the session. Doesn't require IPHONE or IPAD Etc. This allows you to analyse data after the sessions.
IPHONE / IPAD's etc should be able to connect to the unit to view live results if you want to see data during the session.

So research the GPS Modules used in the units, and see if other IPHONE / Andriod apps can also tie into the data logger.

Also check if you can attach a external GPS antenna is case the reception is poor due to the lack of metal backing in the corvette. Most like a metal dash or metal roof mount for best reception.

VBOX Sport is 20HZ , while the dragy is a 10HZ unit. Both should work well for what you are looking for, while the dragy should be at a much lower initial cost but won't allow you to use other 3rd party apps.

eg the VBOX Sport can be used as a standalone unit or as a external GPS unit with apps like harry's laptimer.

read this about supported GPS units. I selected the VBOX Sport because I use my car for road track days and also do performance tuning on and off the track

http://www.gps-laptimer.de/compatibility/android

Its nice to use the VBOX Software and also use Harry's Laptimer for video overlay with performance data as well.

ronarndt

I have a G-Tech accelerometer that works well for 0-60 and 1/4 mile times, but it costs a lot more than $20 for track time.

cagotzmann

I have one too, one of the early units. (G-tech Pro RR ) Wasn't very accurate compared to actual track times. The problem is because the car squats during hard acceleration and tilts the unit like going up hill. Still it was better than nothing.