MAPerformance1
MAPerformance
- Location
- Minnesota
- Car(s)
- MK7 GTI Sport
MAPerformance is now proud to release ACN91 specific tunes that cover both of our existing Stage 1, Stage 2, and E30 tunes. As always, these tunes are free when the Cobb Accessport is purchased from MAPerformance. What exactly is ACN91 fuel? It’s actually more of an acronym for “Arizona, California, and Nevada” specific fuel. There is some speculation as to why those particular states are known to have lesser quality 91 fuel than the rest of the country. ACN fuels have a different blend ratios of the hydrocarbons (hexane, heptane, butane, etc) with various vapor/flashpoint thresholds, not unlike the differences between winter blend and summer blends of gasoline in colder climates. It also has lower maximum limits for aromatics as well as different detergent profiles, which all effect combustion characteristics. On paper, they are supposed to have the same anti-knock properties all other 91 octane fuel, but it doesn’t come as a surprise that many users in those states experience higher than normal knock events compared to standard 91 octane tunes. When combining the lower fuel quality with significantly higher ambient temperatures during the summer months, it can become difficult to have consistently and predictably healthy combustion without [excessive] reactive knock corrections or proactive compensations--both of which limit performance. So, we put our tuner into a suitcase and shipped him to Phoenix in the middle of August to gather heaps of real-world testing and refine the calibrations for the climate and fuel.
Taking a look at the dyno graph below, this shows a good example of the effects on ACN91 fuel on an otherwise stock GTI. Testing was done in sunny Phoenix in August, with ambient dyno room temps north of 120 degrees. You can see the stock run (blue line) could barely make a full pull to redline. The steep power dropoff at higher RPM is common with the factory calibration, however with the combination of ambient & charge air temperatures and poor fuel quality, it becomes far more dramatic. This is a result of a number of proactive and reactive dynamics within the ECU calibration which are usually alleviated with most OTS tunes, however there were still performance, consistency and health benefits to be had with further refinement for the specific environment and fuel.
The red line is our Stage 1 ACN91 tune which you can see is a more usable power band, with almost 100whp gains at 6k RPM! The green line is our OTS E30 tune mixed with ACN91 fuel. You can clearly see how much happier the car is with the effects of higher octane and the ethanol’s ability to cool the cylinder air charge, which allow for more stable combustion and therefore allow greater comfort moving the combustion sequence (namely peak combustion pressure and peak combustion temp) nearer to optimal degree for maximum performance and consistency.
For any customers in California, Nevada and Arizona that are currently running our normal 91 tune, please send me a PM, or email us at otstunes@maperformance.com if you would like to try the ACN91 version.
Thanks for reading!
Ian
