What is the difference between PWG and EWG N55 engines? This question comes up often and is a big talking point regarding the N55's performance. EWG and PWG refer to the turbocharger wastegates. Though it sounds like a minor difference, the wastegates play an important role in tuning and power. Let's jump in and examine the pros, cons, and differences of PWG vs EWG N55's.
*Unless otherwise noted, any examples are assuming all else constant. I.e same tuning, bolt ons, fueling, etc.
What Are PWG and EWG N55's?
First, let's lay out what these acronyms stand for:
- PWG - Pnuematic Wastegate
- EWG - Electronic Wastegate
Early model N55's feature the pnuematic wastegate (PWG) design. BMW introduced EWG on the N55 around July 2013. We can't say this with 100% assurance but we believe ALL 2014+ N55's (less the X1) feature the electronic wastegate. Some late 2013 models may use the EWG design, too. In general:
- 2011-2013 E + F Series N55 = PWG
- 2014+ F Series N55 = EWG
If you're N55 is in the grey area (built dates around June and July 2013) how do you know if your N55 is EWG or PWG? The below image highlights the visible differences.
You can see the physical differences between the EWG and PWG wastegates. Additionally, towards the top left of the PWG photo you will see a blue connector. EWG N55's do NOT have the additional blue connector. Now that you've identified whether your N55 is PWG or EWG let's move on to the exciting part.
BMW N55 PWG
As stated, earlier model N55's, up to 07/2013, feature the PWG design. This is a standard wastegate design that was also used on the N54. Pnuematic wastegate control relies on vacuum lines and a vacuum pump to open and close the wastegates. In short, PWG uses vacuum to control the wastegates. PWG is without question a more complicated, less efficient design than EWG.
Some may have you believe the PWG N55 is far inferior to the EWG models. There is a notable difference. However, it's not as big as some may lead you to believe. After all, the N54 is PWG too. No one is debating how impressive a stock turbo N54 can be. Albeit, it's a totally different engine utilizing true twin turbos. Anyways, let's move on to the pros and cons of PWG N55 engines.
N55 PWG Pros
- Capable of higher E85 mixtures
Not a great start for N55 PWG models. This may be why some lead you to believe PWG is worse than it really is. Unfortunately, there aren't many pros to the PWG design. Especially for those who never plan to run E85, or do not have access to it. However, stock turbo and stock fueling N55's can handle more E85 with PWG.
N55 PWG Cons
- Vacuum leaks causing boost under target
- Less precise wastegate control
- Less power, especially on top-end
The vacuum system involved with PWG control is a big downside. Leaking vacuum lines or problematic pumps may cause 30FF under-boost codes. Essentially, the wastegate isn't receiving enough pressure to reach its target. This causes boost to remain under target, too. Additionally, PWG limits the precision of wastegate control. Tuning, keeping boost on target, and preventing oscillation is a bit more challenging. However, a good tune should not have issues staying on target.
Finally, and most importantly, PWG N55's simply do not make as much power. Here's the thing. On paper, PWG cars usually only come in about 15-30whp less than EWG N55 engines. Not too bad. However, boost tapers and falls off a cliff on the top-end. Therefore, peak power numbers may not look too different, but the PWG has a worse power band. There is less power up top with the PWG N55. In a race, this is where EWG N55's start pulling away quickly.
BMW N55 EWG
Moving on, 2014+ N55 engines receive electronic wastegate control. As the name suggests, these wastegates are controlled electronically. This eliminates the need for the vacuum lines. Now, one big difference with the N55 EWG turbo is this: the turbocharger itself. The N55 receives a slightly larger exhaust wheel (turbine wheel). This comes with a larger downpipe, too.
A lot of the benefits of EWG may actually be due to the larger turbo and downpipe. Nonetheless, there are quite a few pros for EWG N55 engines without many cons.
N55 EWG Pros
- No vacuum lines
- Better wastegate control
- More power, especially on top-end
The EWG pros are basically the opposite of the PWG cons. Getting rid of the vacuum lines is a pretty big plus. It reduces the chance of wastegate and under-boost issues. Tuning becomes easier and more precise on the EWG N55. This can be chalked up to the improved wastegate control. Of course, the additional power is the biggest pro for most.
EWG and PWG engines make about the same power and torque in the lower-mid RPM range. However, EWG models get a boost on the top-end. The electronic wastegates and larger turbine wheel allow for more boost up top.
N55 EWG Cons
- Lower E85 mixtures
This can be solved with fuel system upgrades and proper tuning. As such, it's likely a non-issue for those looking to push their EWG N55 to the limits. Likely, the biggest contributor to the lower mixtures is the additional power. Obviously, more power requires more fuel flow. EWG N55's are likely maxing out the stock fueling system due to the additional power.
When PWG vs EWG N55 Doesn't Matter
It's pretty clear stock turbo EWG N55's are more capable than the PWG models. However, at a certain point, this discussion may not even matter. If you're planning on running a large, "stage 2" N55 turbo with port injection then PWG vs EWG doesn't mean much.
A larger turbo will negate the downsides of the PWG N55. Likewise, port injection negates the downside of EWG models running less E85. What we're getting at is this. Highly modded N55's are nearly the same whether they are PWG or EWG.
N55 PWG vs EWG Summary
Long story short, PWG N55's produced from 2011-2013 are less capable than the 2014+ EWG models. Electronic wastegate control is a more efficient, superior method as compared to pneumatic wastegates. Expect EWG cars to experience fewer issues with boost under target. Additionally, EWG control is more precise and assists in making extra power, especially in the upper revs. On the contrary, PWG cars can handle higher E85 mixtures.
However, it's possible none of this even matters. If you're looking to go the upgraded turbo route then the EWG vs PWG consideration becomes less important. Though, if you're planning to stick with the stock turbo, you may be better suited to the more capable EWG N55. Either way, the N55 is an excellent engine that makes impressive power with basic mods.
Do you have an EWG or PWG N55? Leave a comment and let us know!