@chrisbmw30 The loss is from latent heat build up from the 1st runs. Usually, a car won't make peak power until it's warmed up; once it does it will run consistent for a few pulls. The car was warmed up before the video, so the first 3 runs were consistent. Most performance cars need 15-30 min to remove the latent heat. (stupid YouTube comment length -- this'll be a 2-parter)
@chrisbmw30 Plus the aluminum stacks have a higher thermal mass than the OEM stacks, absorbing heat from the earlier runs more quickly. We would've waited 30 min after installing the stacks, but that would be a very boring video.
@chrisbmw30 Water-methanol is always an idea when it comes to keeping intake temps down. The heat issue in this specific case was more related to the lack of time inbetween all the runs, which we kept minimal for the sake of video length.
This is a poor experiment. The statement "We're merely trying to show that, from our testing, bolting on a set of velocity stacks will produce power..." is deceiving because too many variables have changed. The air paths are totally different: stock (duct opening, filter, MAF, tubing, closed air plenum) versus FMU (open air plenum only). Comparing stock vs FMU stacks both with air plenum covers OFF would be more proper and interesting, and would likely show similar results.
is it really "easy" to put velocity stacks? cause from what I saw Craig seem to add some like bolt on's, like just install it, I thought it was difficult because of the fuel injection and stuff
or the car was prepared before or something like that?
It's technically a bolt-on modification. We didn't remove the bottom half of the airbox in the video (in an effort to speed up that terribly slow middle portion), but typically installing stacks is a matter of unbolting the stock airbox + MAFs and bolting the new stacks on.
It's difficult when it comes to tuning. BMW has a stock alpha-n map on its ECU that it defaults to when the MAFs fail or are disconnected, but without a proper tune there's power left on the table.
@gripracer In the sense that it would provide another layer of testing, perhaps. But our stacks don't fit with the cover on, thanks to the wavelength we tuned the stacks to (which determines their height).
However, it's not relevant in the sense that we're testing two different methods of air induction on the motor -- 1) OEM airbox, and 2) FMU stacks. The airbox wasn't designed to run without a cover, nor was our system designed to run with a cover.
@spark4091 Stock plenum cover off with stock velocity stacks actually showed a slight power loss. We did not include it in the video, as we tested multiple variables in this experiment and we chose to display the ones that would show a difference in one continuous take. We tested Stock (new MAFS), stock disconnected mafs, stock disconnected mafs plenum cover off, stock disconnected mafs open throttle. The point was to show the way we run our cars does produce a gain over stock, thanks!
@spark4091 Not to mention the fact that we're measuring two different ways of running the car with an intake setup that would be seen on the street. Nobody disconnects the MAFs and decides to run their M5 with the plenum cover off. Whenever we do a build that incorporates stacks, we're often told that the stacks themselves do nothing (when not including a FMU tune to back it up). This whole experiment was to show that the stacks DO do something by themselves when compared to a stock setup.
@FluidMotorUnion That's my point; you are NOT "running the car with an intake setup that would be seen on the street." As the plenum cover is off with the FMU stacks, you are not sucking air through an air filter (unrealistic), nor with a physically restrictive MAF in the airway. One would not drive the car on the street with this specific FMU setup.
@spark4091 We actually do have several sets of open velocity stacks, both ours and those of our customers, running out on the streets every day. Aside from a greater worry of debris through the stacks (necessitating more frequent oil changes), we've never encountered an issue with running open stacks on a daily driven car. That being said, we know we're not immune to issues and these are just anecdotes from experience.
Cool vid! Want to see what it puts down with tuning:) You guys make stacks for the s38b36?
crxracr 1 month ago
curious as to why the power falls off so much...by the third run its down 10hp from the first
chrisbmw30 2 months ago
@chrisbmw30 The loss is from latent heat build up from the 1st runs. Usually, a car won't make peak power until it's warmed up; once it does it will run consistent for a few pulls. The car was warmed up before the video, so the first 3 runs were consistent. Most performance cars need 15-30 min to remove the latent heat. (stupid YouTube comment length -- this'll be a 2-parter)
FluidMotorUnion 2 months ago
@chrisbmw30 Plus the aluminum stacks have a higher thermal mass than the OEM stacks, absorbing heat from the earlier runs more quickly. We would've waited 30 min after installing the stacks, but that would be a very boring video.
FluidMotorUnion 2 months ago
@FluidMotorUnion ahhhh i see. you plan on spraying water/methanol? maybe this will remedy the heat issue?
chrisbmw30 2 months ago
@chrisbmw30 Water-methanol is always an idea when it comes to keeping intake temps down. The heat issue in this specific case was more related to the lack of time inbetween all the runs, which we kept minimal for the sake of video length.
FluidMotorUnion 1 month ago in playlist Uploaded videos
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This is a poor experiment. The statement "We're merely trying to show that, from our testing, bolting on a set of velocity stacks will produce power..." is deceiving because too many variables have changed. The air paths are totally different: stock (duct opening, filter, MAF, tubing, closed air plenum) versus FMU (open air plenum only). Comparing stock vs FMU stacks both with air plenum covers OFF would be more proper and interesting, and would likely show similar results.
spark4091 2 months ago
wow awesome! it was really good guys !
is it really "easy" to put velocity stacks? cause from what I saw Craig seem to add some like bolt on's, like just install it, I thought it was difficult because of the fuel injection and stuff
or the car was prepared before or something like that?
robe2708 2 months ago
@robe2708 Robe,
It's technically a bolt-on modification. We didn't remove the bottom half of the airbox in the video (in an effort to speed up that terribly slow middle portion), but typically installing stacks is a matter of unbolting the stock airbox + MAFs and bolting the new stacks on.
It's difficult when it comes to tuning. BMW has a stock alpha-n map on its ECU that it defaults to when the MAFs fail or are disconnected, but without a proper tune there's power left on the table.
FluidMotorUnion 2 months ago in playlist Uploaded videos
@robe2708 The car in the video is bone stock, minus an axle-back exhaust.
FluidMotorUnion 2 months ago in playlist Uploaded videos
i think it would be relevant to run stock stacks, cover off as well as fmu stacks, cover on.
gripracer 2 months ago
@gripracer In the sense that it would provide another layer of testing, perhaps. But our stacks don't fit with the cover on, thanks to the wavelength we tuned the stacks to (which determines their height).
However, it's not relevant in the sense that we're testing two different methods of air induction on the motor -- 1) OEM airbox, and 2) FMU stacks. The airbox wasn't designed to run without a cover, nor was our system designed to run with a cover.
FluidMotorUnion 2 months ago
@FluidMotorUnion i see, thanks for responding.
gripracer 2 months ago
Comment removed
spark4091 2 months ago
@spark4091 Stock plenum cover off with stock velocity stacks actually showed a slight power loss. We did not include it in the video, as we tested multiple variables in this experiment and we chose to display the ones that would show a difference in one continuous take. We tested Stock (new MAFS), stock disconnected mafs, stock disconnected mafs plenum cover off, stock disconnected mafs open throttle. The point was to show the way we run our cars does produce a gain over stock, thanks!
FluidMotorUnion 2 months ago
@spark4091 Not to mention the fact that we're measuring two different ways of running the car with an intake setup that would be seen on the street. Nobody disconnects the MAFs and decides to run their M5 with the plenum cover off. Whenever we do a build that incorporates stacks, we're often told that the stacks themselves do nothing (when not including a FMU tune to back it up). This whole experiment was to show that the stacks DO do something by themselves when compared to a stock setup.
FluidMotorUnion 2 months ago
@FluidMotorUnion That's my point; you are NOT "running the car with an intake setup that would be seen on the street." As the plenum cover is off with the FMU stacks, you are not sucking air through an air filter (unrealistic), nor with a physically restrictive MAF in the airway. One would not drive the car on the street with this specific FMU setup.
spark4091 2 months ago
@spark4091 We actually do have several sets of open velocity stacks, both ours and those of our customers, running out on the streets every day. Aside from a greater worry of debris through the stacks (necessitating more frequent oil changes), we've never encountered an issue with running open stacks on a daily driven car. That being said, we know we're not immune to issues and these are just anecdotes from experience.
FluidMotorUnion 1 month ago in playlist Uploaded videos
awesome! great video
nitro561 2 months ago
this is the kind of legit tech proving that the entire industry (hell, every industry) should embrace
awesome
gripracer 2 months ago
@gripracer Thanks!
FluidMotorUnion 2 months ago