[johnung]

Please measure your Turbo Inlet Pipe for me if you have a pipe handy that is out of the car. I’m looking for the outside diameter of the end that slides into the turbo. Please see photo for how to measure.

I already have a measurement of the stock plastic pipe. Does anyone have a pipe handy from MST, Pure Turbos, CSF, or any others? Thanks in advance!

[ThreeStripes]

Got a MST v2 laying around but I’ll have to grab a digital caliper this week as I don’t own any. It’ll take me a minute but I can report back this week.

[johnung]

Originally Posted by ThreeStripes

Got a MST v2 laying around but I’ll have to grab a digital caliper this week as I don’t own any. It’ll take me a minute but I can report back this week.

Excellent! I have a couple calipers that I got at Harbor Freight. Thanks in advance!

[F87source]

I don't have measurements of OD (since ID is more important and I haven't had a chance to review the inlet yet - fingers crossed I'll get the opportunity to do so this summer), but BMS from what I have seen thus far has the largest ID turbo inlet that works on the stock frame turbos (stock or hybrid upgraded). I will email them to ask for the OD as well.



Credit: Payam @ BMS

[johnung]

Originally Posted by F87source

I don't have measurements of OD (since ID is more important and I haven't had a chance to review the inlet yet - fingers crossed I'll get the opportunity to do so this summer), but BMS from what I have seen thus far has the largest ID turbo inlet that works on the stock frame turbos (stock or hybrid upgraded). I will email them to ask for the OD as well.



Credit: Payam @ BMS

Thanks, I appreciate it! I’m seeing some variation in outside diameters so I’m trying to collect data.

There are several Turbo Inlet Pipes in that 58mm i.d. range including MST and Pure. See attached photo. That equates to over 50% more potential air flow to the turbo housing. I was being conservative when I wrote 40% in the photo.

If you take before/after engine logs using a Stage2/2+ tune (with higher boost levels), you should see MAF values track equally until about 5,000 RPMs where the MAF values for the larger Inlet Pipe opening will continue to increase towards redline. It’s a noticeable power increase.

Proves that the stock EWG turbo has more capacity with higher boost tunes, but its airflow is limited by the restrictions of the stock Inlet Pipe.

[F87source]

Originally Posted by johnung

Thanks, I appreciate it! I’m seeing some variation in outside diameters so I’m trying to collect data.

There are several Turbo Inlet Pipes in that 58mm i.d. range including MST and Pure. See attached photo. That equates to over 50% more potential air flow to the turbo housing. I was being conservative when I wrote 40% in the photo.


If you take before/after engine logs using a Stage2/2+ tune (with higher boost levels), you should see MAF values track equally until about 5,000 RPMs where the MAF values for the larger Inlet Pipe opening will continue to increase towards redline. It’s a noticeable power increase.

Proves that the stock EWG turbo has more capacity with higher boost tunes, but its airflow is limited by the restrictions of the stock Inlet Pipe.

Yeah it's nice to see these data points. From what I've seen so far mst is in the 57 mm range not 58, but there can be variances in measuring.

[johnung]

Originally Posted by F87source

Yeah it's nice to see these data points. From what I've seen so far mst is in the 57 mm range not 58, but there can be variances in measuring.

IMO once it’s up in that 57mm/58mm range then the numbers become inconsequential because it’s such a large increase that any turbo with the stock input size opening won’t be starved for air. At that point fueling becomes a potential limitation. The sizing of the fuel pumps and injectors becomes more critical, especially if E85 is the fuel.

ZM2 made a great observation about the shape of Turbo Inlet Pipes a few years ago. His point was that it would be difficult to design a more perfect shape than the MST because it tapered perfectly from the size of the Air Intake Pipe down to the turbo housing opening. It had to have the least turbulence of any of the inlets being discussed. See photo for illustration.

To take that observation a step further, IMO it would be difficult to design better air piping from airfilter to turbo housing than the combination of the MST Intake mated with the MST Turbo Inlet Pipe.

[F87source]

Originally Posted by johnung

IMO once it’s up in that 57mm/58mm range then the numbers become inconsequential because it’s such a large increase that any turbo with the stock input size opening won’t be starved for air. At that point fueling becomes a potential limitation. The sizing of the fuel pumps and injectors becomes more critical, especially if E85 is the fuel.

ZM2 made a great observation about the shape of Turbo Inlet Pipes a few years ago. His point was that it would be difficult to design a more perfect shape than the MST because it tapered perfectly from the size of the Air Intake Pipe down to the turbo housing opening. It had to have the least turbulence of any of the inlets being discussed. See photo for illustration.

To take that observation a step further, IMO it would be difficult to design better air piping from airfilter to turbo housing than the combination of the MST Intake mated with the MST Turbo Inlet Pipe.

I agree, at 58mm 57mm whatever it is, the difference is going to be small if not completely negligible.

In terms of the silicone tube, most companies have a very similar design to mst. The bms tube is just as smooth in its transitions and tapering, and has a cleaner interior around the pcv section than the mst inlet (as per recent images and posts complaining about this area on the mst inlet).


In terms of the intake I disagree. There are companies out there with massive cfd work on their intake that mst doesn't appear to have. I would argue those intakes are far superior - I.e infinity design. They optimize the perfect flow path of air to the turbo.

I'd even argue the turner carbon intake is just as good if not superior, they optimize the intake flow path by making it as straight as possible, have a heat shield, even optimized thr maf sensor area to avoid CEL's and I'm not sure mst does that. Turner's tube is also carbon so it conducts less heat.

[johnung]

Originally Posted by F87source

I agree, at 58mm 57mm whatever it is, the difference is going to be small if not completely negligible.

In terms of the silicone tube, most companies have a very similar design to mst. The bms tube is just as smooth in its transitions and tapering, and has a cleaner interior around the pcv section than the mst inlet (as per recent images and posts complaining about this area on the mst inlet).


In terms of the intake I disagree. There are companies out there with massive cfd work on their intake that mst doesn't appear to have. I would argue those intakes are far superior - I.e infinity design. They optimize the perfect flow path of air to the turbo.

I'd even argue the turner carbon intake is just as good if not superior, they optimize the intake flow path by making it as straight as possible, have a heat shield, even optimized thr maf sensor area to avoid CEL's and I'm not sure mst does that. Turner's tube is also carbon so it conducts less heat.

MST has a great reputation for not throwing CELs. I haven’t seen most of the ones that you mentioned but I’ll keep an eye out for them.

Like I said it’s my opinion that the round smooth flow of the MST Intake and MST Inlet piping doesn’t leave much room for flow improvement from airfilter to turbo housing. Maybe there are some out there who are equal, since MST’s design has been out there for years. But again my opinion is that it would be difficult to be better

[F87source]

Originally Posted by johnung

MST has a great reputation for not throwing CELs. I haven’t seen most of the ones that you mentioned but I’ll keep an eye out for them.

Like I said it’s my opinion that the round smooth flow of the MST Intake and MST Inlet piping doesn’t leave much room for flow improvement from airfilter to turbo housing. Maybe there are some out there who are equal, since MST’s design has been out there for years. But again my opinion is that it would be difficult to be better

It's still not perfect:
https://f30.bimmerpost.com/forums/sh....php?t=1678149

It's almost impossible to replicate maf sensor scaling with a large rounded tube, since it allows so much more flow through it and in a different manner vs the stock trapezoidal shape. The few ways to attempt and achieve factory like maf scaling is either by ovaling the tube (In certain sections) as that decreases the cross sectional area (yes if you oval a circle it mathematically decreases the inner cross sectional area), this allows you to manipulate air flow up stream around the maf sensor and try (likely won't be perfect) to achieve factory like maf scaling, they'll also try to do this with the maf sensor housing positioning as well. Or like cts does, use an adapter housing for the maf (this is probably the cheaper and easier way to do this, because you don't have to worry about the entire tube's geometry just where the maf sensor is sitting, this also allows you to more easily manufacture the tube because you can keep a simple mandrel bent aluminium tube everywhere else, and just connect the maf adapter onto it). These types of intakes are designed in such a way that you won't ever get a CEL because they actually try and account for the maf sensor scaling.

Imo there's no way mst can do that with just a massive perfectly rounded tube. Then there's others like infinity who take great care with their CFD work to prevent cel's, and that's not cheap nor easy to do properly. It's easy to just throw a wire mesh model into CFD and look at the results, it's more difficult to fine tune it properly. It's also resource expensive, because running CFD with enough cells is very very resource intensive. Infinity also uses their inverted cone filter design because it has less air flow disruptions, and they have a venturi effect built into their intake mouth, so again they're taking air flow very seriously.


But anyways, I have my doubts that mst was able to do much with maf scaling on a perfectly rounded tube, and Imo it doesn't look like much work went into air flow design for the mdt intake either, rather just get a larger tube, high flow cone filter, and fitment to get it all to fit in the confines of the engine bay. So imo mst isn't the pinnacle of air flow on an intake. That likely is infinity design, their only con is the price. In regards to how close the performance is when everything is pushed to very high flow levels (larger upgrade turbos), I'm not sure, but I wouldn't say it's negligible - at these levels the CFD likely matters and infinity would likely come out on top. In terms of the overall package, I like turner's offering the best. They have a very nice and attractive carbon tube - which is designed to avoid CEL's, a very high quality filter, and it should allow decent flow too - all for a relatively decent price.

[3t3p]

As above I have a good feeling infinity design intake will gel well with my MST V2 intake.

Just doing the man maths on it though, boy is it expensive!

[johnung]

Originally Posted by F87source

It's still not perfect:
https://f30.bimmerpost.com/forums/sh....php?t=1678149

It's almost impossible to replicate maf sensor scaling with a large rounded tube, since it allows so much more flow through it and in a different manner vs the stock trapezoidal shape. The few ways to attempt and achieve factory like maf scaling is either by ovaling the tube (In certain sections) as that decreases the cross sectional area (yes if you oval a circle it mathematically decreases the inner cross sectional area), this allows you to manipulate air flow up stream around the maf sensor and try (likely won't be perfect) to achieve factory like maf scaling, they'll also try to do this with the maf sensor housing positioning as well. Or like cts does, use an adapter housing for the maf (this is probably the cheaper and easier way to do this, because you don't have to worry about the entire tube's geometry just where the maf sensor is sitting, this also allows you to more easily manufacture the tube because you can keep a simple mandrel bent aluminium tube everywhere else, and just connect the maf adapter onto it). These types of intakes are designed in such a way that you won't ever get a CEL because they actually try and account for the maf sensor scaling.

Imo there's no way mst can do that with just a massive perfectly rounded tube. Then there's others like infinity who take great care with their CFD work to prevent cel's, and that's not cheap nor easy to do properly. It's easy to just throw a wire mesh model into CFD and look at the results, it's more difficult to [...]

That’s interesting stuff. I’ll keep my eye out for more. I can appreciate getting deep into an engineering discussion. It’s fun.

But often guys lose sight of the big picture that prompted the discussion or go off on a tangent that doesn’t apply to the situation. Kinda like two guys arguing over which is the better intercooler based on IATs of 85°F or 95°F. It doesn’t matter because they both prevent Heat Soak.

The two most performance impactful features by far that we’ve talked about are a Turbo Inlet Pipe with a 57mm/58mm opening into the turbo housing, and an Intake with a free flow airfilter and additional air access, compared to stock. Those two things probably provide 80%-90% of any airflow gains to be had. And probably more than enough to support 500+whp. The rest of the discussion is just icing on the cake.

FYI- your link was about a different intake on a different engine. Not applicable to this specific discussion.

In my mind the most important aspect of these N55 Intakes by far is that they DO NOT throw a CEL. People can argue over whether an Intake provides 5% more power or 3% or 7%, whatever. But dyno tests have shown that throwing a CEL can actually reduce performance.

The MST Intake that I prefer has a proven track record. I have talked to many who have the MST on their N55 and have never had a CEL.

IMO I still doubt whether super expensive intakes translate into an actual performance advantage over the MST on an N55 turbo with stock inlet opening. For that scenario the MST Intake+InletV2 delivers all the air needed for that 500whp-550whp max. Now maybe for larger turbos with custom inlet sizes there may be some measurable difference, talking about 600whp and above. Who knows? I have enjoyed our discussion.

[AmuroRay]

I'm not sure what's being asked and discussed here?
You want to the measure of the actual snout as it screws into the turbo? Not that you don't have the right to ask, but for what purpose?

[ThreeStripes]

Originally Posted by AmuroRay

I'm not sure what's being asked and discussed here?
You want to the measure of the actual snout as it screws into the turbo? Not that you don't have the right to ask, but for what purpose?

Also confused. It seems the answers to the questions posed appear to be already in hand.

[johnung]

Originally Posted by AmuroRay

I'm not sure what's being asked and discussed here?
You want to the measure of the actual snout as it screws into the turbo? Not that you don't have the right to ask, but for what purpose?

Got an older MST Turbo Inlet on the car with the stock turbo. I know that it should fit my new turbo but I want to confirm with a measurement now. I don’t want to pull car apart and then get a surprise. If I need to order a new inlet pipe I have time if I do it now.

I just need an accurate measurement of outside diameter on the MST turbo inlet V2 of the part that slides into the cylinder on the turbo. Thanks!

[ThreeStripes]

Got it. Will share this week.

[AmuroRay]

Originally Posted by johnung

Got an older MST Turbo Inlet on the car with the stock turbo. I know that it should fit my new turbo but I want to confirm with a measurement now. I don’t want to pull car apart and then get a surprise. If I need to order a new inlet pipe I have time if I do it now.

I just need an accurate measurement of outside diameter on the MST turbo inlet V2 of the part that slides into the cylinder on the turbo. Thanks!

I think Pure would tell you if you need inlet, but if the OEM pipe works, why wouldn't another (which are based on the OEM piece)
I don't think you will have a problem with an inlet made for the stock Turbo, as the P500 fits in the stock turbo housing, but I get wanting to be cautious.

[VGSON]

Originally Posted by johnung

Got an older MST Turbo Inlet on the car with the stock turbo. I know that it should fit my new turbo but I want to confirm with a measurement now. I don’t want to pull car apart and then get a surprise. If I need to order a new inlet pipe I have time if I do it now.

I just need an accurate measurement of outside diameter on the MST turbo inlet V2 of the part that slides into the cylinder on the turbo. Thanks!

what is your new turbo? We have a bunch of measurements of inlets on the pure750 thread around page 12/13

[F87source]

Originally Posted by johnung

That’s interesting stuff. I’ll keep my eye out for more. I can appreciate getting deep into an engineering discussion. It’s fun.

But often guys lose sight of the big picture that prompted the discussion or go off on a tangent that doesn’t apply to the situation. Kinda like two guys arguing over which is the better intercooler based on IATs of 85°F or 95°F. It doesn’t matter because they both prevent Heat Soak.

The two most performance impactful features by far that we’ve talked about are a Turbo Inlet Pipe with a 57mm/58mm opening into the turbo housing, and an Intake with a free flow airfilter and additional air access, compared to stock. Those two things probably provide 80%-90% of any airflow gains to be had. And probably more than enough to support 500+whp. The rest of the discussion is just icing on the cake.

FYI- your link was about a different intake on a different engine. Not applicable to this specific discussion.

In my mind the most important aspect of these N55 Intakes by far is that they DO NOT throw a CEL. People can argue over whether an Intake provides 5% more power or 3% or 7%, whatever. But dyno tests have shown that throwing a CEL can actually reduce performance.

The MST Intake that I prefer has a proven track record. I have talked to many who have the MST on their N55 and have never had a CEL.

IMO I still doubt whether super expensive intakes translate into an actual performance advantage over the MST on an N55 turbo with stock inlet opening. For that scenario the MST Intake+InletV2 delivers all the air needed for that 500whp-550whp max. Now maybe for larger turbos with custom inlet sizes there may be some measurable difference, talking about 600whp and above. Who knows? I have enjoyed our discussion.

yeah I agree, tbh I don't think intakes will yield any power gains on the stock turbo - given you are running the best possible intake bmw makes for the car (MPPK air box bottom + MPPK air filter without the additional charcoal or fiberglass filtration layer). With an upgrade turbo the stock intake may eventually become a bottle neck. The reason why I went for an intake is because I wanted the sound, and free up any potential restriction for future turbo upgrades.


That link should be applicable to the discussion, the reason why is because the N20 and the N55 share the same bosch hot film maf sensor, and are based off of the Bosch MEV172 DME architecture - meaning the MAF sensor logic and scaling logic will most likely be very similar. And if an intake design cannot avoid CEL and rough idles on an N20 it will most likely affect the N55. But here's another link saying the MST intake caused CEL and rough idles, this time on an m235i: https://www.2addicts.com/forums/show...3&postcount=11

I can keep digging these posts up, they aren't hard to find if you look - particularly on facebook groups where there seems to be a larger base for general owners seeking help with issues.

Like I said, without specific consideration to maf scaling you will never be able to 100% avoid the CEL/Rough idling issue. CTS turbo doesn't make their maf sensor housing for no reason, casting that part couldn't have been cheap in terms of tooling, manufacturing, and the additional RND costs. TMS, and infinity didn't specifically design their carbon intake tubes for no reason - and it isn't cheap to design these things. So at the end of the day these cars are known to be very finicky, sometimes you get lucky and don't have issues, sometimes you don't. But your best bet to avoid a CEL or rough idle is with an intake designed to avoid it from inception.

[F87source]

Now you might not think 1mm larger diameter is a big difference, but when you realize that the surface area of a circle is proportional to radius squared, then it is actually a pretty meaningful difference.


btw according to ray's post:

https://f87.bimmerpost.com/forums/sh...59&postcount=5

the mst inlet is 56.5mm diameter, the BMS inlet is ~58.2mm (rounding to a single digit like mst does) diameter, we are nearly 2mm larger with the bms inlet.

Calculating area:

BMS: 2660.33 mm^2
MST: 2507.19 mm^2

The difference here is 153.14 mm^2 = 1.5314 cm^2. That is actually a decent big of difference. That is around the size of a microsd card, and in perspective of the turbo inlet that's actually a decent bit of extra surface area gained, and when restriction is in play - every bit matters.

[johnung]

Originally Posted by F87source

Now you might not think 1mm larger diameter is a big difference, but when you realize that the surface area of a circle is proportional to radius squared, then it is actually a pretty meaningful difference.


btw according to ray's post:

https://f87.bimmerpost.com/forums/sh...59&postcount=5

the mst inlet is 56.5mm diameter, the BMS inlet is ~58.2mm (rounding to a single digit like mst does) diameter, we are nearly 2mm larger with the bms inlet.

Calculating area:

BMS: 2660.33 mm^2
MST: 2507.19 mm^2

The difference here is 153.14 mm^2 = 1.5314 cm^2. That is actually a decent big of difference. That is around the size of a microsd card, and in perspective of the turbo inlet that's actually a decent bit of extra surface area gained, and when restriction is in play - every bit matters.

Yup, I agree that diameters of a circle can’t be compared to each other in terms of flow through that circle because the Area of a circle is the square of the radius of a circle multiplied by pi which is 3.142…

But nope, I disagree- every bit does not matter in this context. It would be different if the conversation was specifically about which Inlet Pipe had the most flow area. But the bigger picture is, the context is an N55 EWG with a turbo that uses the stock size Inlet opening. So probably in the 500whp to 550whp maximum range. The goal is to be able to utilize the capacity of that turbo without being restricted by airflow (or by fuel) limitations. Whatever limit that turbo hits should be it’s own design, not that it wasn’t fed enough air or fuel.

You must have read an old post of mine. My car did originally come with the M Performance Intake with the extra front facing air hole that BMW added. I replaced the stock airfilter with an aFe Pro Dry model. But a couple years ago I switched to an MST Intake after one of my buddies convinced me to try it. I don’t care much about sound, in fact I have burbles turned off in Bootmod3. I do enjoy the sound of the M Performance Exhaust, and the AWE axle-back is my favorite.

My butt dyno tells me that the design of the MST Intake is an improvement over the MPI with the aFe filter. Most of that improvement is probably due to the large cone filter. I’d have to cut both filters open & spread them out to accurately measure the difference in surface areas. My measurements conservatively suggest at least a +25% advantage with the MST cone filter. I’m sure that the way the MST shielding manages airflow to the filter, and the large round smooth piping also contribute to the improvement.

I’ve never had a CEL with the MST and I don’t actually no anyone who has. MST has a great reputation for NOT throwing a CEL. You seem to be trying to paint a picture that they do. That’s just not the case in my experience. You know as well as I that all of the sources of posts can’t be trusted to have the knowledge or experience to know what they are doing, or to interpret or even write accurately. I tend to believe the guys who I know and who I have read over a period of time. You are one of them.

Gotta take everything with a grain of salt. None of us is perfect. Last year I read some bad reports on a product that I had been using for years and that I knew was solid. It turned out that those multiple reports were only people repeating the misinformation being put out by one guy. When I had an opportunity to ask him questions, nothing he said added up.

He finally admitted that he had never purchased or installed the product that he was emphatically ripping. He had used a competitor’s product and had problems. He just assumed that all of the products in that category were all the same, but in his writing he was outspokenly criticizing as if he had used it.

Back to Turbo Inlet Pipes. In the context of providing more air to the stock turbo opening, it is the stock Inlet Pipe that should be used for comparison. My stock Inlet measures at an inside diameter opening of 46.61mm. So that calculates to an area of 1,706.

So compared to the stock Inlet, using your numbers, the MST V2 is +47%, BMS is +56%. I also have data on the Pure2, their second generation all aluminum Inlet at +54%. And I just got an unverified number yesterday for the latest Pure Inlet at +52%.

My point is that every aftermarket Inlet Pipe in that range is going to supply all of the air that a relatively small turbo in the stock turbo housing can handle. I’d bet that one could spend an entire day installing and dyno testing each of those Inlet Pipes and not discover a notable statistically significant difference.

Now obviously in another context where someone was trying for maximums on everything, then it would matter. But then the turbo and the housing would be much bigger, so we wouldn’t be discussing these Inlet pipes anyway. Good discussion!

[F87source]

Originally Posted by johnung

Yup, I agree that diameters of a circle can’t be compared to each other in terms of flow through that circle because the Area of a circle is the square of the radius of a circle multiplied by pi which is 3.142…

But nope, I disagree- every bit does not matter in this context. It would be different if the conversation was specifically about which Inlet Pipe had the most flow area. But the bigger picture is, the context is an N55 EWG with a turbo that uses the stock size Inlet opening. So probably in the 500whp to 550whp maximum range. The goal is to be able to utilize the capacity of that turbo without being restricted by airflow (or by fuel) limitations. Whatever limit that turbo hits should be it’s own design, not that it wasn’t fed enough air or fuel.

You must have read an old post of mine. My car did originally come with the M Performance Intake with the extra front facing air hole that BMW added. I replaced the stock airfilter with an aFe Pro Dry model. But a couple years ago I switched to an MST Intake after one of my buddies convinced me to try it. I don’t care much about sound, in fact I have burbles turned off in Bootmod3. I do enjoy the sound of the M Performance Exhaust, and the AWE axle-back is my favorite.

My butt dyno tells me that the design of the MST Intake is an improvement over the MPI with the aFe filter. Most of that improvement is probably due to the large cone filter. I’d have to cut both filters open & spread them out to accurately measure the difference in surface areas. My measurements conservatively suggest at least a +25% advantage with the MST cone filter. I’m sure that the way the MST shielding manages airflow to the filter, and the large round smooth piping also contribute to the improvement.

I’ve never had a CEL with the MST and I don’t actually no anyone who has. MST has a great reputation for NOT throwing a CEL. You seem to be trying to paint a picture that they do. That’s just not the case in my experience. You know as well as I that all of the sources of posts can’t be trusted to have the knowledge or experience to know what they are doing, or to interpret or even write accurately. I tend to believe the guys who I know and who I have read over a period of time. You are one of them.

Gotta take everything with a grain of salt. None of us is perfect. Last year I read some bad reports on a product that I had been using for years and that I knew was solid. It turned out that those multiple reports were only people repeating the misinformation being put out by one guy. When I had an opportunity to ask him questions, nothing he said added up.

He finally admitted that he had never purchased or installed the product that he was emphatically ripping. He had used a competitor’s product and had problems. He just assumed that all of the products in that category were all the same, but in his writing he was outspokenly criticizing as if he had used it.

Back to Turbo Inlet Pipes. In the context of providing more air to the stock turbo opening, it is the stock Inlet Pipe that should be used for comparison. My stock Inlet measures at an inside diameter opening of 46.61mm. So that calculates to an area of 1,706.

So compared to the stock Inlet, using your numbers, the MST V2 is +47%, BMS is +56%. I also have data on the Pure2, their second generation all aluminum Inlet at +54%. And I just got an unverified number yesterday for the latest Pure Inlet at +52%.

My point is that every aftermarket Inlet Pipe in that range is going to supply all of the air that a relatively small turbo in the stock turbo housing can handle. I’d bet that one could spend an entire day installing and dyno testing each of those Inlet Pipes and not discover a notable statistically significant difference.

Now obviously in another context where someone was trying for maximums on everything, then it would matter. But then the turbo and the housing would be much bigger, so we wouldn’t be discussing these Inlet pipes anyway. Good discussion!

Diameter can be compared, because the surface area is pi r^2, and diameter is just 2 x r. So surface area is directly proportional to diameter of the turbo inlet.


That's the whole point im making, the larger the inlet size it self restriction will always drop, whether that yields any meaningful gains depends on the turbo's peak flow capacity. But regardless it will help wgdc and responsiveness if restriction decreases. And with turbos with fully ported open inlets, restriction will always drop until the inlet size is equal to the opening size - which never will happen because the inlet has to have enough material to retain structural strength.


I don't think I read your old post, most of my knowledge of this platform came from my n54 tech days back in 2014. That's where I learned pretty much everything I know about these platforms, and since then the learning curve has plateaued alot since these platforms are so old and well known now.


The reason why I don't trust butt dynos is because other sensory inputs greatly influence the sense of speed - especially sound (and aftermarket intakes greatly increase the sound). If you're in a loud car you will often get the sensation of moving faster than a quiet car - which is why youtube videos with loud cars on the nurburgring feels so much faster than electric cars like the tycan - despite that not being remotely the case.


I agree, not all reports are accurate. However, there are enough reports of intake issues to make it a pretty well established fact that the F series n55 is sensitive with aftermarket intakes. Some more than others. and what I tend to see is that intakes without specific consideration to the maf sensor will always have the potential to get CEL's or rough idles. Now the rate of which CEL's and rough idles appear isn't some crazy high number but they do happen.


I'm not painting a picture of anything. Im simply reporting what I have seen, and I have seen cases of the MST intake causing issues: https://f30.bimmerpost.com/forums/sh...32&postcount=7

Here's one reporting high flow codes. You yourself have replied to it and said "it’s not likely to be the MST Intake. Perhaps the MAF sensor needs to be cleaned or replaced." But how could you know it's not the MST intake?

So if you ask me, you seem to have a comfirmational bias about the MST intake never having an issue because you own one. Like I said before, this platform is notorious for having issues with intakes, and I have seen these reports for almost every intake on the market - even CTS with their special housing. The only trend I noticed was that the intakes with the special housings or consideration for the maf sensors experience these issues at a much lower rate.




But I agree, on the stock turbo you won't find much gains between these inlets. With a larger turbo with a ported out inlet, then you should be getting the largest possible inlet size. Either way at the end of the day im not sure why you wouldnt go for the largest possible inlet regardless if given a choice.


Even when factoring the shape of the inlet, im pretty sure there is little to no difference between the BMS and the MST inlet pipe. They all have to go to the same 2 locations on the car, so the amount of difference in geometry is limited. Both inlets are very smooth and don't take unnecssary corners. So the shape itself is very constrained and unlikely to offer any gains. That just leaves the opening diameter - and that's where the bms inlet is larger.