TB993tt

In the interest of accuracy (OK and I wanted to see which was best to use) I purchased a Race Logic Driftbox (like KPG has been using) with the intention of comparing it to my Race Technology AX22.

The most important thing I wanted to test was accuracy - verdict, for speed versus time measurement (ie acceleration) they are both virtually spot on the the same as each other - when used in tandem for the same 60-130mph run.

G force measurement is not the same, the AX22 seems to measure this at a greater resolution and does appear to be more accurate, in general it measures the Gs slightly higher than the Driftbox - I wouldn't trust the G measurements on the Driftbox, they just don't look as resolved as the AX22 ones which appear to measure very accurately, this is good for stuff like comparing aerodynamics or length of negative G during gearchanges.

Ergonomics - the Drifbox is better looking, easier to use and you don't need and external aerial for it to work accurately - the AX22 looks more robust but you wouldn't be happy with it "living" on your window, unlike the Driftbox which looks quite cool

Software and messing about with the data - here the AX22 would win, the things you can do with the data and the ease of doing it give it a decisive advantage,stuff like seeing how far the car travels WOT from a given speed are much simpler to establish with the AX, however for simple acceleration measurements the Driftbox is perfectly adequate and dead simple to use and it has the major benefit for our 60-130 runs that one can overlay height during the run so it is simple to check whether the run is downhill or uphill and by how much.

Price - the Driftbox wins here too, it is some 30% cheaper.

Which one am I going to sell.............. ? Difficult one, I'll have to think about it

Jean

Excellent review TB, thanks for sharing.

Kiko

You guys never stop to amaze me!

poorb0yw

I still need to decide which one I want to buy. I think the ax22 is winning due to the greater functionality. I like how it looks better than the drift box too.

Thanks for the review TB

KPG

Thank you.... my existence has now been validated
Now all you have to do is buy a Mustang and a Maha for a side to side comparison. Why do you think the G's are not as accurate?Do you have some external G sensor that lets you know the AX22 is correct and the Dbox is not...could easily be the other way around if you have no reference point .Are you saying the Dbox is not sampled as often and produces a more jagged line or simply are understated...like our chassis dynos I looked at the specs for the AX22 and the Dbox and the Dbox has a 20G capabilty whereas the AX22 has a 10G option.I think you also left out some important data as to how the units arrive at their speed/distance calculations. AX22 is a combination of sats and accelerometers to derive speed and that leaves the data susceptible to improper leveling. The DBOX is satellite only at twice the sampling rate than the AX22 and is accurate for speed/distance independent of a proper leveling as long as satellites are locked. Of course an improper alignment will make any G's data useless, but will still allow the remaining speed over distance data to be used. Perhaps, I can change your opinion of the software. PM sent. Kevin

TB993tt

Of course you are right, I am only making a guess at relative accuracy of Gs - I can't think of any way of testing diefinitively ? Baring in mind that the AX uses the GPS AND accelerometers to measure the speed (I don't understand how although I remember Guy R once gave an impressive explanation ) and the AX and Driftbox both come up with the same acceleration data then I summise that the "G" part of the AX is working properly and accurately - Is that logical ?
The levelling of the AX is a bit of a red herring, it only has to be ~80% level, not really an issue AFAIK.
As for the software, I am commenting on the stuff which comes with the unit, not any "enhanced" package

Like I said I am undecided which one to keep, the Driftbox is certainly easier to use and not having the external aerial is a big bonus - it is the one currently stuck on my windscreen

BTW I know (hope ) you are only joking about chassis dynos - Kevin M will tell you all you need to know on that subject

KPG

Toby, I dont recall any joke ....just kidding. I am actually kicking around the idea of upgrading to the the Vbox mini, which is just the Driftbox with the ability to accept external sensors such as RPM or boost. I think that would give the numbers an even clearer overall picture. They will accept the Dbox in trade and with a relatively small charge issue a Vbox mini with a certified calibration certificate. I still need more research though on this.Glad you like the Dbox, someday I will have to try the AX22 just for comparison purposes, but I do like the shallow learning curve with this unit. Kevin

Jean

I think the graph and comparison between different runs with the AX22 is unmatched by the Driftbox. The most important feature for me is the fact that you can download your runs in amazing detail on excel and do multiple analysis of all sorts with it... Then again, not everyone is a number maniac like I am I would never trade that possibility for any easiness of use. Obviously you can add the sensors that you want on it too without upgrading. The DBox is more aerodynamic though

Geoffrey

Do either of these units give recommendations as to the placement of the g sensors? If you are using only 1 g force sensor then it should be placed in the centerline of the vehicle. I'd be more than happy to compare either of these two boxes against the MoTeC sensors in my race car. The g sensor in the car is a $530 dollar sensor. I'll be back at the track next Friday.

Rickard 993 Turbo

Im going for the driftbox, need to post some nr also..

Jean

Geoffrey,

Great point.

The AX22 has a 2G sensor and can be fitted (or unlocked for 10G).. As far as placement, the G sensors are built within the unit, so it depends where you have it placed (on the front windshiled for the AX22 usually).. I honestly do not think it makes any difference for our level of usage. The G sensor placed at CG might have some usage for a pro racer, since it will give crisp results as far as lateral Gs are concerned, reducing body roll parasitic losses etc.. (From the leading Supercup drivers that I know a bit, none looks at Gs during practice BTW, telemetry guru Konstantin can confirm)

We are looking at long Gs only, simply for comparison purposes between similar cars, same weight bias, same sensor placement location (windshiled or dashboard), so theincremental 1% or so accuracy of a well placed G sensor or the $500 it costs is really not relevant. But this (at CG) is certainly the right way to measure Gs, you are 100% right.

The speed vs distance or time readings are not impacted at all by the sensor. TB recently clocked 193.3mph vs 193 mph with a laser gun at VMax. I am sure that a datalogger with a sensor measuring revolutions instead of GPS readings will be less accurate than that due to tire pressure variance with heat and speed.

BTW, you will be surprised at the accuracy of the data on a GPS based amateur unit, I have compared it quickly to a Professional Motec setup already on the same track. Certainly not worth the Pro- extra dollars unless one is competing in F1.

Geoffrey

The placement of the g sensor will make a difference if you are measuring lat G and it is on one end or the other since they rotate at different forces (undresteer/oversteer), but I'd agree that for measuring long g in the manner you are, it probably makes little difference.

I had wondered about tire pressure and diameter growth and wear and discussed this with Michelin and they say their slicks are very consistent and identical between sets. Of the 3 new sets I purchased, they were all identical. Other tires, I don't know. I also measured the distance traveled in 1 lap and compared it against the track I was running on and it was right about 100ft difference. This could be a number of things, incorrect tire diameter, distance traveled against the centerline of the track, rounding of the advertised track distance, but in all cases, on a 13,000ft track, 100ft is a very small percentage so I'm comfortable with my setup at least.

I have seen GPS based units at low costs and they have varied in accuracy from what I can tell, especially in the lap time department, sometimes being as much as a second off the PCA club race timing and scoring system. I've not seen the two mentioned in this thread other than the data you posted which does look interesting and powerful for the value. I think it would depend on what you wanted to do with data and logging, The AX22 can't do what I can with the MoTeC in my car since it also controls functions of the car. But you are right, it is also probably 7x the price.

JJayB

In my limited experience with the AX22, it would throw a "tilt" calibration error if I used a certain decending on ramp, thereby disqualifying what I believed to be my best times. The question becomes if the AX22 is limiting the G differential on a downhill accelertion, how accurate would it be on lateral G data. It maybe that with duel accelerometers, the vehicle must be on a level plane for its internal calibration to work. Has anyone tested this unit on a roller coster for accuracy? Jean, I'm sure there's an easy answer for a non-technical person.