Tuning safe? BMW needed water injection for 500hp

[trackm4]

hey guys, I have a question. If BMW needed water injection to safely increase boost and subsequently power, then are the various flash tunes we get for our base M4s really, and truly safe - especially when wringing it out on the track....

[M3Tooner]

Originally Posted by fatstig

hey guys, I have a question. If BMW needed water injection to safely increase boost and subsequently power, then are the various flash tunes we get for our base M4s really, and truly safe - especially when wringing it out on the track....

Water injection helps reduce NOx emissions by reducing peak combustion temperatures. So in order for BMW to increase HP and still comply to emissions regulations (given engine architecture not changed, static compression ratio remains the same), this is likely the only way. Aftermarket tunes are not held to the same emissions regulations. With that said, running higher boost with aftermarket tunes w/o managing combustion temperatures can reduce the safety margin of knock threshold, thus engine longevity may suffer. Some aftermarket tunes just run a little richer A/F ratio to cool down the combustion temperatures, not very elegant tuning solution but works.

[trackm4]

Originally Posted by M3Tooner

Water injection helps reduce NOx emissions by reducing peak combustion temperatures. So in order for BMW to increase HP and still comply to emissions regulations (given engine architecture not changed, static compression ratio remains the same), this is likely the only way. Aftermarket tunes are not held to the same emissions regulations. With that said, running higher boost with aftermarket tunes w/o managing combustion temperatures can reduce the safety margin of knock threshold, thus engine longevity may suffer. Some aftermarket tunes just run a little richer A/F ratio to cool down the combustion temperatures, not very elegant tuning solution but works.

Cool thanks!!

[Boss330]

Originally Posted by M3Tooner

Water injection helps reduce NOx emissions by reducing peak combustion temperatures. So in order for BMW to increase HP and still comply to emissions regulations (given engine architecture not changed, static compression ratio remains the same), this is likely the only way. Aftermarket tunes are not held to the same emissions regulations. With that said, running higher boost with aftermarket tunes w/o managing combustion temperatures can reduce the safety margin of knock threshold, thus engine longevity may suffer. Some aftermarket tunes just run a little richer A/F ratio to cool down the combustion temperatures, not very elegant tuning solution but works.

While it's true that water injection have several benefits, complying with emissions standards most likely wasn't the reason BMW chose this.

The test cycles used under emissions testing (at least here in Europe) never puts the engine in the rpm range where the water injection system comes into play. Point in case is that the M4 GTS has the exact same CO2 emissions as the std M4 with DCT, 199 g/km, despite having 500hp (69hp more than the std M4 at 431hp).

During the test cycle, the M4 GTS and M4 operates in a rpm and load range where there are NO differences in hp or emissions between the two cars.

So, for the official emission limits there is no benefit to adding water injection. In real world driving the benefits of water injection is obviously present and can be used for PR etc.

Aftermarket tuning companies have to comply with the exact same legislation as the manufacturers. As we discussed in a different thread, EPA/CARB has "visited" tuning companies that sell non emissions compliant tuning equipment. One of them was BMS, which had to stop selling their products in California and had to update their website with emissions information:

http://www.burgertuning.com/emissions_info.html

USE OF THESE PARTS IN ANY OTHER VEHICLE MAY SUBJECT YOU TO FINES AND PENALTIES FOR VIOLATION OF FEDERAL AND/OR STATE LAW, WILL VOID YOUR WARRANTY FROM Burger Motorsports, Inc. , AND CAN VOID YOUR VEHICLE'S WARRANTY. It is your responsibility to comply with all applicable federal and state laws relating to use of these parts, and Burger Motorsports, Inc. hereby disclaims any liability resulting from the failure to use these parts in compliance with all applicable federal and state laws.

And even though some states aren't as strict as California, EPA says that removing or tampering with emissions related equipment is considered as a violation of federal legislation...

[CanAutM3]

The way I see this, is that engines such as the S55 are able to compensate for atmospheric conditions, so the S55 has plenty of thermodynamic margin when operating at sea level on a cool day, but the ECU will limit power through boost control. When the conditions worsen, the ECU is able to tap into this margin to sustain the rated power level.

Most tunes simply tap into that margin in ideal conditions to make more power. So when the conditions worsen, the tuned engine progressively gets closer to stock power levels up to a point where it does not make any more power than stock.

With the addition of water injection, BMW was able to increase the thermodynamic margin of the engine system through additional intake charge cooling. It will be therefore able to sustain the rated power output despite worsening condition (hot day on a track) which a tuned engine will not be able to sustain.

[mike@x-ph.com]

Originally Posted by fatstig

hey guys, I have a question. If BMW needed water injection to safely increase boost and subsequently power, then are the various flash tunes we get for our base M4s really, and truly safe - especially when wringing it out on the track....

Keep in mind BMW's goal is not max power. Engine max safe output is not on top of the priority list

The N54 is the biggest example for this where it has been proven that this engine is capable of safely pushing at least 400 HP without any issues

Some Tunes available allow users and tuners to monitor air, fuel and ignition timing to make sure engine is running safely

Yes most tune available are safe

[M3Tooner]

Originally Posted by Boss330

While it's true that NOx have several benefits, complying with emissions standards most likely wasn't the reason BMW chose this.

NOx has no benefits what so ever, it is a harmful pollutant. I don't know what BMW's emissions strategy is. They could have enough NOx margin to pull off 500Hp, or like you suggested, it is not even in the range of the test cycle.

What I do know is that in order to make more power from the same engine architecture, combustion pressures has to increase. When you do that, combustion temperatures will also increase and subsequently so will NOx emissions. All I'm saying is that WI is an enabler to bring NOx emissions back to acceptable levels if required.

Back to the OP question of safe aftermarket tune. I think you have your answer in the above posts, it should be safe. If BMW thinks that the S55 engine can handle 500 HP in ideal conditions, that implies that the any aftermarket tune should be safe up to at least that power level w/o jeopardizing the durability of engine mechanical parts and should even have margin to spare. This is provided that the aftermarket tune do not alter any of the OEM Knock detection safe guards.

[Mike@N54Tuning.com]

Originally Posted by M3Tooner

Back to the OP question of safe aftermarket tune. I think you have your answer in the above posts, it should be safe. If BMW thinks that the S55 engine can handle 500 HP in ideal conditions, that implies that the any aftermarket tune should be safe up to at least that power level w/o jeopardizing the durability of engine mechanical parts and should even have margin to spare. This is provided that the aftermarket tune do not alter any of the OEM Knock detection safe guards.

+1

No tunes would touch those safe guards

Mike

[Boss330]

Originally Posted by M3Tooner

NOx has no benefits what so ever, it is a harmful pollutant. I don't know what BMW's emissions strategy is. They could have enough NOx margin to pull off 500Hp, or like you suggested, it is not even in the range of the test cycle.

What I do know is that in order to make more power from the same engine architecture, combustion pressures has to increase. When you do that, combustion temperatures will also increase and subsequently so will NOx emissions. All I'm saying is that WI is an enabler to bring NOx emissions back to acceptable levels if required.

Back to the OP question of safe aftermarket tune. I think you have your answer in the above posts, it should be safe. If BMW thinks that the S55 engine can handle 500 HP in ideal conditions, that implies that the any aftermarket tune should be safe up to at least that power level w/o jeopardizing the durability of engine mechanical parts and should even have margin to spare. This is provided that the aftermarket tune do not alter any of the OEM Knock detection safe guards.

A quite substantial spelling mistake there...

It was supposed to say "water injection" not NOx...

Read the entire sentence and you see that NOx really doesn't make any sense (why would BMW choose NOx...)

[CaryTheLabelGuy]

Water injection is an added margin of safety and to help combat heat-soak, even if none of the other tuning advantages are employed.

Simply put, Water Injection lowers cylinder temps and raises effective knock threshold which allows more ignition advance (to a certain extent), more boost pressure (again, to a certain extent) and lowers EGTs without changing the type of fuel used, in this case pump 93 or better.

I haven't seen exactly what BMW has changed, tuning-wise, on the GTS vs. the M4, but I suspect they didn't bump boost pressures a whole lot and opted to run more ignition advance with just a slight bump in boost pressures overall.

That being said, WI is not needed to achieve the power levels of the GTS and beyond. But, BMW decided to employ WI for the reasons listed above and because they felt it was in the best interest for longevity and maintaining peak power numbers regardless of environmental conditions.