E30 Tunes are HERE for the MK7 GTI - Only From MAPerformance
MAPerformance E30 Tune Release for Mk7 GTI
As eluded to in the initial writeup to Cobb breaking into the VW market, the most exciting prospect was to introduce comprehensive tuning for ethanol fuels to these platforms, and the day has finally come! We’ve been doing heaps of testing with the Mk7 platform in various hardware stages and with ethanol levels up to E85, and we are pleased to release E30 OTS Maps for the Mk7 GTI! The E30 fuel blend is an ideal compromise for many popular non-FlexFuel equipped vehicles as will be described below, and blending is very simple and easy to remember with a 2:1 ratio (2 parts pump gas to 1 part E85).
Ethanol and E85 FlexFuel have been common in the racing and high performance circles for a long time as they can be used as an inexpensive race fuel, and it’s becoming more popular to use various blends of ethanol fuels in the common non-FlexFuel equipped vehicles solely for performance purposes. There are two key performance-adding attributes to the standard E85 you can find at local gas stations: it has a very high octane rating of 105 (R+M/2) and, more importantly in my opinion, is the molecular composition and its’ effect on cylinder charge and combustion. Without going into too much chemistry and combustion theory, here are the effects of the two key ethanol fuel attribute and why it is used to
E85 has a high octane rating of 105 – This is rather straight forward; the higher octane rating yields greater resistance to detonation. In many of the popular turbocharged engines on the road today, at the maximum power output they are frequently knock/detonation limited. This means there is more potential power available if we can advance peak cylinder pressures closer to their optimum degree - generally 15* ATDC. All things equal, the higher octane rating enables ignition timing to be advanced further and thereby advancing the peak cylinder pressure closer to the optimum degree, sometimes known as MBT.
- The molecular attributes of ethanol have a very dramatic effect on performance. There are common misapprehensions regarding energy release and temperature at which E85 burns, but hopefully separating two functions of the fuel can help illustrate the nuanced discussions regarding E85 and temperatures.
- In Direct Injection engines especially, fuel does much more than provide a chemical for oxygen to react with upon ignition. The high-pressure injection of the liquid fuel into the combustion chamber provides a function of absorbing a significant amount of heat from previous combustions, which consequently raises the knock/detonation threshold considerably. As such, the more heat we can remove, the higher the knock/detonation threshold and subsequently more power. This measure of the liquid’s ability to absorb heat is known as the Latent Heat of Vaporization. Pump gasoline has a low rating of ~150btu/g, whereas E85 has nearly 2.5x the thermal absorption at ~360btu/g. However, most impressing of all is an E30 blend which still has over 2x the rating with ~330btu/g! It’s in this context that it’s possible to describe an engine as “running cooler” with E85, as overall peak combustion temperatures and EGTs can be cooler.
- The molecular differences between ethanol and gasoline also has an effect on power and performance, which can be illustrated by comparing the heat and byproducts released upon combustion. This is where additional confusion comes into play with regards to which fuel burns cooler, which fuel makes more power, etc. One common claim is that combusting one unit of ethanol produces 4x less heat than combusting one unit of gasoline - which is true – however in the case of an engine where we’re looking to make the biggest bang, we are usually oxidizer limited, meaning the raw combustion energy is limited by the amount of oxygen that can be crammed into the combustion chamber. As such, we must look at the total combustion byproducts and their respective pressures to get an understanding of the impacts to the temperatures and pressures in the chamber using the P=nRT/V equation. In general, the given airmass will combust 4x as much E85 as it would gasoline, therefore we can consider the overall combustion thermal energy release to be equal. Then the byproducts of combustion come into play, where E85 produces ~20% more than gasoline, raising cylinder pressure accordingly.
What this all means for us concerned with engine performance is that we have numerous strategies that can be used to extract significantly more power with E85 or an E30 blend of fuel, all while keeping the knock/detonation, peak pressures and CHT & EGTs in their healthy ranges- at or below levels prior.
Below are E30 dyno results with the MAPerformance Mk7 GTI (DSG) in Stage 1 and Stage 2 configurations, as well as E30 dyno results from Arizona while doing ACN 91octane testing this summer. Even with impressive gains seen in dyno graphs, the difference felt on the road is even more remarkable!