ECU’s – Rumours, facts and an interesting dyno test.

Rotax ECU testerThe 2018 SA Rotax Max Challenge has exceeded anyone’s expectations and fantastic, close racing has got everyone’s attention. So close are the lap times that some competitors and tuners are running around like headless chickens trying to find that tenth of a second that could move them up several places on the grid.

Karters all want equal equipment and Rotax and its distributor network worldwide have been working on every detail to try to ensure parity. The fruits of this drive are becoming apparent when one looks at the quality of racing, incredibly close lap times and growth in the Rotax classes. Humans however always like everyone else’s equipment to be equal and their equipment to be a little “more equal”!

Naturally rumours grow wings and every week there is a new special advantage to be had – apparently a ZZ or wait is it a SS or no wait, is it a PQ cylinder! We don’t know either, but it is very clear if you walk down the grid on any race day that in any class that various markings appear all the way down the grid and that no one cylinder marking is dominant!

Weekly we are told of new special parts, big bore cylinders, blue printed carbs, etc. etc. We take each story seriously but most often one is actually looking at stuff that cannot legally be used in our series and that will be discovered sooner or later by the TC’s.

Having a one-make formula with tight rules and good policing is the only way to have affordable racing. While one can fit a digital Motec ignition (that costs more than the engine) to a Cadet engine and go faster – it is not allowed, and you surely will be excluded.

So now it is the ECU’s turn for some attention!

What is an ECU?

The Electronic Control Unit is a feature of every modern car or motorcycle and is essentially a small digital computer that controls any number of functions but in the karting application it is used only to control the ignition timing and open and close the power valve on the Senior and DD2 engines.

How does it work?

Electronic signals are received from a sensor in the crank case that detects a large change in mass in the crankshaft - a cut away passes the sensor – specifically for ignition timing. The signals are filtered (to get rid of the smaller changes caused by vibration etc) and then once the exact position of the crank shaft is determined this is processed along with the engine speed (the ECU has an internal rev counter) and an output is sent to the coil which provides the ignition spark.

Digital versus analogue ignition systems

The precise timing of the spark is very important as it determines the efficiency, reliability and influences the power output. The digital computer in the ECU varies the ignition timing according to the engine speed. With the older analogue system any adjustment made to the timing meant a change throughout the whole range, so you had to compromise - either bottom or top end. Today’s digital ECU’s vary timing throughout the range to achieve the desired results.

How can one “cheat” the ECU

Rotax carefully designs a program for a specific engine which is then “coded” into the ECU. Along with this is a protection program which also contains the “identity” – for example “Junior Max”. There are hackers that can flash (“break into and overwrite”) or recode an ECU from a different application. You can also for example fit a DD2 ECU on a Micro Max. All of this however is forbidden in the Rotax series world-wide and would be a modification just like fitting an illegal cylinder or crankshaft. You will however get caught and excluded  the moment your ECU is tested and worse still you are not even guaranteed a power increase!

How do Rotax and race organizers check ECU’s and ensure fairness?

Rotax have developed an ECU tester that not only checks if the ECU is functional but identifies the type of ECU as well. The identification is not a simple look at the “ID” – watch the ECU tester in action and notice that in two seconds it recognizes the model of ECU but then spends another 30 seconds checking, by running through a complex routine it checks the authenticity of the program in several different ways. Only the Rotax software engineer that wrote the original program is likely to be able to abuse this.

Swapping ECU’s on race-day

The international Rotax Technical Regulations allow the organizers to exchange the ECU for another known ECU at any time during an event so this is another safeguard and particularly useful in an area that doesn’t have an ECU tester.

What other tests can be performed to ensure fairness?

A data logger can be used to recreate the “map” of any ECU and check it against the design but this is specialized work and not normally necessary.

A practical test is using an engine dyno and comparing power output from one known ECU to a “suspect” ECU. It goes without saying that the dyno testing must be of high standard.

Testing on the circuit between heats or different practice sessions for comparative purposes is extremely difficult because of the variables in weather conditions, tyre conditions etc. etc. and we would not place much value on any information provided this way. If someone goes faster or slower after an ECU change by the organizers - one needs to remember that a competitor may have made other changes before that heat – remember that the change of ECU happens without prior notice-  so again little value can be placed on a change in lap times.

Simulator/dyno test of 4 Micro Max competitor’s ECU’s after the Vereeniging event on 14 April 2018

4 Micro Max competitors were given brand new ECU’s at the start of race 3 last Saturday and their units were impounded by the TC. After the race speculation was rife that certain competitors went faster or slower (or both?) and so EMR agreed to test the four ECU’s against another new one.

The test was conducted on Wednesday the 18th of April 2018 at EMR’s dyno with several Zwartkops based team bosses and tuners present including Tubz from Squadra Corse, Leeroy from Xtreme, Mark from GMP, Fabienne from Target, Neil from NBR while the test was performed.

A Micro Max engine was run with a known ECU to establish a benchmark. All four competitors ECU’s as well as a Junior Max ECU were tested blind – in other words the simulator/dyno operator was not informed as to which ECU was being tested at any time.

No difference was found between any of the ECU’s (excepting the Junior Max ECU which naturally stood out). The graphs and run times showed that all the ECU’s delivered the same performance and that there was nothing to choose from.

The test demonstrated how the ECU tester works and conclusively showed that all 4 ECU’s performed equally when compared to EMR’s benchmark and compared to each other. The Junior ECU demonstrated beyond doubt that any differences will be detected by both the tester and the dyno. Feel free to discuss this with the people present at the test.

The EMR R 30 000 ECU challenge

EMR Rotax challenges anyone to bring us an ECU in the next 90 days that looks the same as a Rotax ECU, reads correctly on the Rotax ECU tester but performs better than the original standard Rotax item on our engine dyno and we will purchase this from you for R 30 000!

Happy Maxxing

EMR and Rotax want you to be assured of an equal opportunity on the track!