After reading more and more about people using performance meters, such as the AP-22 performance meter, I am wondering how accurate they are? After all, for little money (relatively), they offer performance numbers from just about any speed to speed and even feature power output values based on performance numbers and speed.
A bit of reading up on the internet suggests that there are two camps: The believers and the non-believers! I’m in neither and am interested in some of your opinions on this.
how accurate are they in messuring decceleration/acceleration?
how accurate are they in messuring engine power?
what else can they analyze and how accurate are the readings?
is there any way to fudge numbers?
how do they work? Do they require data of the car beyond the force that is messured during a reading?
I’m interested in buying one, if they prove to be very accurate, so any opinions on the matter would be greatly appreciated. Who here owns one?
Much more modern design. The one I’ve got seems very good, not tried using it for power figures yet though. I suspect it’s not especially accurate in absolute terms but would be good for doing comparison runs if you change something that affects the engine performance.
I’ve got a RaceTechnology DL1 and its ok - analysis software is not as user friendly as something like Motec’s I2.
The only downside to the PerformanceBox (which is great value for money for starting out) is the total lack of external inputs ie no RPM, TPS, steering angle, temps, pressures etc.
Find out what you need to log (not what you think you want) and then find a suitable system.
Sorry being relatively new to this community (is that the right word?!) I just stumbled upon this thread. Its something I find quite interesting and have done a fair bit of testing with at various points. I have an AP22 performance meter and find that it is quite an interesting piece of equipment, however the accuracy of the results is up for debate as you have realised!! To answer your questions I think its important to realise that there are two main types of performance meters. Those which work with sensory equipment fitted inside, and the second is the more sophisticated type which work via sensors and GPS.
The sensor only type are good and should be pretty accurate IF correctly calibrated. However with units like the AP 22 there are certain variables that the unit requires. Getting these units wrong will have a huge affect on answers, especially when working out cornering values or lateral acceleration and G force etc (since there are squared terms in the formulas) and this is where the accuracy of the GPS meters come in. However, depending on the quality of the accelerometers inside the non GPS units (and this is difficult to say unless you are familiar with them or an electronics ‘nerd’) they will be consistent at least, which really is the main thing. I say this because if you want absolute values (comparing car to car) then you need a sophisticated unit (more like the DL 1, performance box etc) which can be easily changed and only requires a small amount of setting up.
However to compare changes in driving style or setup of a particular vehicle, something like the AP 22 is fine, since it is consistency that matters. Although its not the point, even if the values are 20% incorrect, as long as they are consistently 20% incorrect you can still tell if changes you have made are working for or against you?!
In all i think for casual use and with careful calibration things like the AP 22 are fine, however for more serious use a more sophisticated full telemetry unit is needed. The peroformance box also looks like a great unit and probably the better buy. Im sure somewhere on the net you can find the specs which show which are more accurate etc. Hope this helps!
