N26 dyno testing

Hey guys,

I had a chance to dyno test an N26 motor today. It's basically the same as the N20 motor (2.0 4 cylinder turbo) but with some minor electronics changes. As far as I know the N26 has replaced the N20.

There had been some rumors that the tuning was detuned or that our Stage1 tune would have problems with it. So I'm pleased to announce it performs basically identically to the N20 motor. While I had it strapped down I did a couple runs on the Stage1 race gas map for kicks. Gains were impressive considering the test car is 100% stock except for the tune.

How would we now if our car has the N26?

Originally Posted by otonimus

How would we now if our car has the N26?

The most prominent feature is the electronic wastegate actuator found on the N26 but not the N20.

wow

Terry, at what % throttle is it remapped? Does one retain the stock tune at low throttle position?

Another question, can you specify what kind of race gas was used? Octane Rating? Brand? (VP, Unocal/76, Sunoco, etc...)

Also, I'm assuming no changes in the 'tune' of the piggyback between pump fuel and race fuel? Does this mean the tune can actually modify parameters based on engine feedback/performance?

+1 on the Wow, thanks for the results Terry. Looks awesome!

Also curious what octane race gas you were using and brand as SergioK's question. 100 octane, 76?

And for pump gas was it 91 or 93 octane? Here in smog nazi land California we get the lowest rated octane in the country 91

Is the N26 on the SULEV models only?

I'm not understanding the reasons behind BMW equipping these cars with two different versions of the same engine. Especially since cars made for the state of Kalifornia can be had with either engine.

I would think that BMW would only incur the expense of designing two different versions if they were forced to by strict CA emission standards, and thus would only sell the n26 cars here. But they sell both so what was the point in the first place?

Originally Posted by jlukja

Terry, at what % throttle is it remapped? Does one retain the stock tune at low throttle position?

Low throttle is similar to stock, and heavier throttle progressively gets stronger.

Originally Posted by SergioK

Another question, can you specify what kind of race gas was used? Octane Rating? Brand? (VP, Unocal/76, Sunoco, etc...)

Also, I'm assuming no changes in the 'tune' of the piggyback between pump fuel and race fuel? Does this mean the tune can actually modify parameters based on engine feedback/performance?

100 octane unleaded racing fuel. Maybe 50% mixed with 91. To enable the race gas map you must connect with your laptop and change the map setting.

Originally Posted by Axxlrod

I'm not understanding the reasons behind BMW equipping these cars with two different versions of the same engine. Especially since cars made for the state of Kalifornia can be had with either engine.

I would think that BMW would only incur the expense of designing two different versions if they were forced to by strict CA emission standards, and thus would only sell the n26 cars here. But they sell both so what was the point in the first place?

It seems likely to me they will just drop the N20 but I'm not really in the loop on those decisions.

Originally Posted by Terry @ BMS

100 octane unleaded racing fuel. Maybe 50% mixed with 91. To enable the race gas map you must connect with your laptop and change the map setting.

I've bought race fuel both at Buttonwillow and Sears and both times seen huge spikes in lead levels in my Blackstone reports, FWIW.

Originally Posted by SergioK

I've bought race fuel both at Buttonwillow and Sears and both times seen huge spikes in lead levels in my Blackstone reports, FWIW.

BMW's love 100 octane unleaded race fuel. Just avoid the leaded stuff.

Originally Posted by Terry @ BMS

BMW's love 100 octane unleaded race fuel. Just avoid the leaded stuff.

Right, it was labeled unleaded. That's my point.

Originally Posted by SergioK

Right, it was labeled unleaded. That's my point.

Hmm I dunno. Thousands of us have run 100 unleaded race fuel on N54s for years without issue. Perhaps the lead in your oil had another source? Either way probably not something to worry much about.

Terry - what are the knock counts with the mix of 91 and 100 on the race fuel map? Would you feel comfortable running this combo on a race track (a real one...where you actually turn the steering wheel and a session lasts longer than 15 seconds) in 100 ambient temperatures? What is the minimal safe ratio of 91:100 for use on a race track?

Sergio - welcome to the world of FI! In boosted motors the 100 octane does more good than it did in your e46. Turbo motors generate a ton more heat and are more likely to detonate. So regardless of whether the car is tuned or not, I always run as much 100 as possible during our schools. It is critical to keep these motors away from the threshold of detonation during prolonged WOT sessions. The 100 doesn't add power, it simply helps keep the motor happy and safe.

When you drove my car it was about 2/3 100, 1/3 91.

Originally Posted by White05X3

Terry - what are the knock counts with the mix of 91 and 100 on the race fuel map? Would you feel comfortable running this combo on a race track (a real one...where you actually turn the steering wheel and a session lasts longer than 15 seconds) in 100 ambient temperatures? What is the minimal safe ratio of 91:100 for use on a race track?

The BMW DME doesn't use knock count system per say. Rather a full adaptive timing system with long term octane trims and shorter term knock trims. The fuel mixture and actual tune settings used depend on your particular objectives. Using the +7psi settings in the dyno above I would suggest at least 97 RM2 octane. Using the default +3psi setting 91-93 octane is acceptable.

For road racing where consistency is king I'd normally suggest using a pump gas map w/ race gas for extra insurance to ensure timing is continuously maxed out for consistent performance.

The race maps are more for those who are interested in drag racing. Which involves runs less than 15 seconds, without turning the wheel, where HP reins supreme. Does not appear to be your thing but appeals to a large segment of the enthusiast base...

Originally Posted by White05X3

Sergio - welcome to the world of FI! In boosted motors the 100 octane does more good than it did in your e46. Turbo motors generate a ton more heat and are more likely to detonate. So regardless of whether the car is tuned or not, I always run as much 100 as possible during our schools. It is critical to keep these motors away from the threshold of detonation during prolonged WOT sessions. The 100 doesn't add power, it simply helps keep the motor happy and safe.

When you drove my car it was about 2/3 100, 1/3 91.

Yeah, my concerns with the lead levels aren't related to the engine itself... but to the emissions system. High lead levels can damage catalytic converters. I don't know if modern cats are more/or less sensitive than those of 15 years ago. FWIW even with the countless track days on my E46 (and almost at 200k on the odo) it still passed emissions so I guess all that 100 octane 'unleaded' didn't do much if any damage, just not sure how sensitive the new cats are to this.

I dont understand ppl who drag race bmws. Go get a orange dukes of hazzard challenger or the likes lol.

Terry - thanks for that explanation. So what are the long term knock trims? How about the injector duty cycles?

Originally Posted by White05X3

Terry - thanks for that explanation. So what are the long term knock trims? How about the injector duty cycles?

At default the DME thinks it's running say 90 octane instead of 94 octane.

Originally Posted by pkim1079

I dont understand ppl who drag race bmws. Go get a orange dukes of hazzard challenger or the likes lol.

The turbo BMWs are a great drag racing platform.

(My 135i racing a new GTR)

Originally Posted by White05X3

Terry - thanks for that explanation. So what are the long term knock trims? How about the injector duty cycles?

Terry - can you please answer my questions?

Also what happens with your tuner when the car is in Eco Pro mode? What are the afr's in Eco Pro at low RPM, large throttle openings (not WOT, just like 2/3), and high load? Under those conditions does the tuner still raise boost?

Originally Posted by Axxlrod

I'm not understanding the reasons behind BMW equipping these cars with two different versions of the same engine. Especially since cars made for the state of Kalifornia can be had with either engine.

I would think that BMW would only incur the expense of designing two different versions if they were forced to by strict CA emission standards, and thus would only sell the n26 cars here. But they sell both so what was the point in the first place?

CARB gives them some sort of credits for the SULEV engines: http://en.wikipedia.org/wiki/SULEV