[stlb5]

I'm sure some of you got the same email I did from ECS Tuning, maybe it's just effective wording, but what do they mean by "factory software is programmed around 87 octane"? Here is the whole text:

"Your BMW factory software is programmed around 87 octane. This mapping effectively detunes the performance of the car. Turner software is set to 91 octane as a minimum, allowing a more aggressive programming. The software refines and adjusts the factory limitations, opening up the potential for more horsepower or refinement from your current upgrades. These tunes are also programed to fix defects and rough edges in the stock software, making the car easier and more enjoyable to drive."

[JP's M2xx]

I would guess all car manufacturers in the US base their "tune" around 87 octane fuel. That is the lowest octane that anyone is going to put in their car and tuning from the factory with the assumption that the buyer is going to always use higher octane would lead to a lot of repairs! Just my thoughts.

[beMtroubleYou]

Originally Posted by JP's M2xx

I would guess all car manufacturers in the US base their "tune" around 87 octane fuel. That is the lowest octane that anyone is going to put in their car and tuning from the factory with the assumption that the buyer is going to always use higher octane would lead to a lot of repairs! Just my thoughts.

Exacly. ALOT of people are just ignorant.

And you dont need a tune to run higher octane fuel. Your car doas that for you. There are so much benefits from running higher octane then just power.

I know I dont have to point it out, but I will anyways: dont runt E85 on standard tune.

[amw896]

I don't think is true.

[Jeff@TopGearSolutions]

If you drive like a grandma and never in boost, you can run 87 octane but did you buy a performance car or a car to get cheap gas with? Point is, yes you can probably run 87 octane since the car will just pull timing to ward off knocking. At that point, you are giving away power.

[mike@x-ph.com]

All car manufacturers take into consideration that fuel differs from one country to another. US fuel is very clean compared to some third world country, because of the regulation level.

So yes you can run car on 87 but it is not recommended

[RoundelM3]

Reading the text quoted from that email immediately formed a thought in my mind - "what a load of crap". ECS tuning is definitely no longer in my scope of aftermarket suppliers.

[DailySleeper]

Originally Posted by roundel335

Reading the text quoted from that email immediately formed a thought in my mind - "what a load of crap". ECS tuning is definitely no longer in my scope of aftermarket suppliers.

Why? This is fairly common and well documented, even with "performance" cars. After filling up the first tank of gas with highest octane on my new V8 Camaro the first thing I did was the "fuse pull" mod to help the ECU relearn the new fuel mapping.

http://www.camaro5.com/forums/showthread.php?t=38964

[Dylan86]

They have to set the parameters to suit any scenario, however a min of 91oct is suggested for any German thoroughbred.

If you NEED to run 87, you can.

If you can't afford premium fuel for your "premium" car, then you should consider a step towards the 87 octane loving Honda's. They are really good with cheap fuel, because it is what they were designed for. Make sense?

[RoundelM3]

Originally Posted by DailySleeper

Why? This is fairly common and well documented, even with "performance" cars. After filling up the first tank of gas with highest octane on my new V8 Camaro the first thing I did was the "fuse pull" mod to help the ECU relearn the new fuel mapping.

http://www.camaro5.com/forums/showthread.php?t=38964

Not even close to relevant. Starting in the E36 era, all BMW engines have required a minimum of 91 octane due to the higher compression ratio design of both the normally-aspirated and turbocharged powerplants. Let's do an apples-to-apples comparison with the normally-aspirated S65 V8 in the E9x M3 - running 87 octane in that high-compression V8 would ruin it in a heartbeat. The same would be true for the E46 M3's S54 inline-6. Turbocharging effectively increases the compression ratio plus it raises the intake air temp (due to the heat from the exhaust-driven turbo) to a point where low-octane fuel will detonate under even moderate load despite the presence of an intercooler. In that situation, no amount of spark retardation or mixture enrichment will prevent pre-ignition knocking.

Your Chevy V8 may indeed be designed around 87-octane fuel, but that is not the case with BMW engines, especially the current designs that are all turbocharged. Totally different engine management systems for totally different engine designs. There are no fuses to pull to learn a new fuel map in a BMW - it requires either a flash tune or a piggyback tuner to change ignition, boost, and fuel maps to add power beyond the original tune designed around high-octane fuel to start with.

[DailySleeper]

Originally Posted by roundel335

Not even close to relevant. Starting in the E36 era, all BMW engines have required a minimum of 91 octane due to the higher compression ratio design of both the normally-aspirated and turbocharged powerplants. Let's do an apples-to-apples comparison with the S65 V8 in the E9x M3 - running 87 octane in that high-compression V8 would ruin it in a heartbeat. The same would be true for the E46 M3's S54 inline-6. Turbocharging effectively increases the compression ratio plus it raises the intake air temp (due to the heat from the exhaust-driven turbo) to a point where low-octane fuel will detonate under even moderate load despite the presence of an intercooler. In that situation, no amount of spark retardation or mixture enrichment will prevent pre-ignition knocking.

Your Chevy V8 may indeed be designed around 87-octane fuel, but that is not the case with BMW engines, especially the current designs that are all turbocharged. Totally different engine management systems for totally different engine designs.

[JP's M2xx]

Originally Posted by roundel335

Not even close to relevant. Starting in the E36 era, all BMW engines have required a minimum of 91 octane due to the higher compression ratio design of both the normally-aspirated and turbocharged powerplants. Let's do an apples-to-apples comparison with the normally-aspirated S65 V8 in the E9x M3 - running 87 octane in that high-compression V8 would ruin it in a heartbeat. The same would be true for the E46 M3's S54 inline-6. Turbocharging effectively increases the compression ratio plus it raises the intake air temp (due to the heat from the exhaust-driven turbo) to a point where low-octane fuel will detonate under even moderate load despite the presence of an intercooler. In that situation, no amount of spark retardation or mixture enrichment will prevent pre-ignition knocking.

Your Chevy V8 may indeed be designed around 87-octane fuel, but that is not the case with BMW engines, especially the current designs that are all turbocharged. Totally different engine management systems for totally different engine designs. There are no fuses to pull to learn a new fuel map in a BMW - it requires either a flash tune or a piggyback tuner to change ignition, boost, and fuel maps to add power beyond the original tune designed around high-octane fuel to start with.

So you're saying that BMW ecu's don't compensate for lower octane fuel and wouldn't pull timing? I run 93 in my car so it isn't an issue for me but I find it hard to believe that running 87 in the V8 you referenced would "ruin it in a heartbeat", I could see it running poorly due to power (timing) being pulled but I could be wrong. Can you elaborate on how BMW ecu's treat lower octane fuel? I am coming from 30+ years of Mustangs so this is interesting to me. Thanks!