Ram air on the M...a waste?

[exdos]

Swamp2,

Originally Posted by swamp2

Very nice stuff exdos. I am thrilled to see another pro-science, pro-experimentation, pro-do it yourselfer kind of fellow posting here on the forum. We need more like you!

The spikes you refer to (that you smooth over in some plots) are simply the drops in rpm during shifts, correct?

Thanks for your kind words. My M Coupe(MC) is full of DIY tweaks to the OEM, including my own aerodynamic mods, which have all been developed after reading loads of information from stuff on the internet.

The spikes that I'm referring to are these. Take a look at the very first graph I posted, entitled: "Volumetric Efficiency of M Coupe with EXDOS Ramcharger during acceleration in 1-2-3 gears", and in the plot of "Volumetric Efficiency in percentage" (the yellow line) you will see at the start of each acceleration in all three gears, that the VE produces an upward "spike" at the start of each acceleration phase, where the VE recorded is higher than the subsequent recording whilst under acceleration. I attribute the spikes in 2nd and 3rd gear, when the car is moving, down to the fact that there is a build up of static pressure within the air intake system, due to the ram effect, from lifting off the throttle whilst changing gear. In the case of the first gear acceleration from vehicle standstill, the drop in VE after the initial start is due to there being no ram effect at the outset and the NA engine is actually creating negative pressure within the air intake system, but once the vehicle gets to around 20mph, the ram effect really starts to contribute to filling the cylinders, as shown by an increase in volumetric efficiency. In the case of my car, the VE now gets to 100% at around 60mph with my latest mod, whereas before, the car needed to be at 80mph to achieve 100%VE, and before that previous mod it was 90mph. I have done an awful lot of study and experimentation on air-intakes over the past three years with the goal of attempting to make ram-effect a useful source of free energy at ordinary road speeds. I think I'm slowly getting there.

Originally Posted by swamp2

Just wanted to add that I think you might be missing something when referring to the 335 intake system as being similar to the M3. The M3 looks like this, which I have never seen anything quite like on a BMW.

Cheers and welcome to the forum.

I realise that there is a significant physical difference between the M3 and 335 intakes, as there is between my Z3 MC and both M3 and 335, but when I look at all these vehicles I am seeing "function" and not the physical manifestation. As I see them, all three intakes share the same features of function. As far as I am aware, the ram air-intake system now seen on some BMW's was first seen on the Z3 M Coupe/Roadster in 1998 and BMW has developed and refined this air-intake system through the E46 M3 and its later performance models. It definitely works!

[ace996]

What a pleasure it is to discuss this with you. Great post, I'll explain in RED...

Originally Posted by exdos

Ace996,

I see what you are saying but I doubt if your idea will really benefit performance.-I have my doubts, too...it will only make a difference is there is indeed negative pressure effect (or a loss of dynamic pressure from not having sufficint positive pressure compared to the front two intakes) from the hood vent at speed, at high load, at high rpm. Thus far, with my caveman-scientific deduction of watching water drops fly out and leaves poke out through the vent, there is without doubt air pouring out the vent at speed. I do not know if this happens at high load/high rpm, though. But I can deduce that the hood vent is overpowered by the two front intakes.

I think the selection of graphs and data that I've posted actually show how an engine can and does benefit from a ram air-intake which is not an entirely closed system. As I said earlier, "The VE can only ever be at max when at WOT". The whole point of the throttle is that it acts as a REGULATOR to the amount of air that enters the cylinders on each stroke, to maintain a steady cruising speed below Vmax, the charge of air/fuel entering the cylinder on each stroke only needs to be a percentage less than Max. As I stated before: "When my MC is travelling at a steady 30mph under cruise control, the VE is between 9%-20%, only. At 38mph under cruise control, VE is between 24% -34%, only. At Idle the VE is between 12% -13%".I agree with all of that...no issues.- If ram pressure in the air-intake is forcing a greater volume of air into the cylinders with each stroke, then to maintain your steady speed you need a lighter touch on the throttle otherwise the car will always accelerate with any throttle opening.-surge...yes, but we would need a significantly greater amount of air pressure to have that happen...like a turbo car that's blow-off/bypass valve is faulty. At less than WOT, an effective ram-air intake is just making engine breathing easier and consequently more efficient.yes, which should have a minor effect on MPG...in theory.

In all driving scenarios which require less than WOT, even at 99% WOT, it is the throttle which is acting as the regulator to air intake into the engine and any build up of excess air under ram pressure before the throttle which cannot be used will be eventually vented in some way or other, even if only by overflowing out of the air intakes; like a bath which is overflowing when the taps are left running.-great point here and let me expand on that. I believe/surmise/guess that is happening somewhat in the M3 airbox: The front two intakes receive a much stronger dynamic pressure, from their location, than the hood vent. This is like three hoses/pumps blowing into a container. If two pumps are pushing significantly harder than the third, pushing much more fluid (air) into the container, and that pressure eventually is higher than the pumping force of the third pump (the hood vent), then there will be a "backflow" situation, and the excess pressure will bleed out the vent.
I am not a strong believer that the hood vent is a very positive-pressure zone. most other fabricators/manufacturers that place hood intakes will employ an additional design component to maximize the positive-pressure potential of that location.... NACA duct, scoop...like the drag cars, or a blended scoop like Ferarri or, to a much greater extent, the Subaru STI. I think that without an additional component like those, the positive pressure at that location is quite weak...at least it is during 50-60mph cruising when water droplets fly out.
This can easily be demonstrated with a Magnehelic pressure gauge with the end of the pilot tube placed inside the air filter box: when you lift your foot off the accelerator the pressure inside the system goes up to almost the theoretical value for ram pressure at the vehicle speed as shown in the graph I've posted above entitled "Pressure increase versus forwards velocity".

Looking at the diagram of the M3's air intake as posted by Swamp2, ALL the air intakes are sited in zones of positive pressure on a moving vehicle. See this article here: http://www.autospeed.com/cms/A_2162/article.html - again, I agree but it appears to be a weak positive pressure zone...easily overcome by the pressure of the front two inlets (especially the one in the driver's foglight area).

Therefore on your M3, when ask for WOT, the engine will be receiving air from zones of positive air pressure. What more can you ask for? - a real ram-air effect, without the pressure loss out of the hood. Think about it...a balloon with a hole in it will not build pressure as effectively as one that is sealed...even if there is a light pressure on the hole, it will be better than nothing, but not as effective as if it was sealed.

Personally, I think your OEM air intake is an outstanding design.-it appears so, some even think that the vent is to circulate air so that the airbox is "cooled" by the excess air that is not ingested by the motor....makes sense, it could be... I'd love to be able to take some pressure readings and datalogging from one! -yes, that would be optimal...then we'd have a better picture of what's happening. I bet it achieves well over 100% VE.it stands to reason that it does, but it could also be better...again, just my opinion.

Thank you so much for joining this discussion.

Be good,
TomK

[exdos]

Originally Posted by ace996

What a pleasure it is to discuss this with you. Great post, I'll explain in RED...


Thank you so much for joining this discussion.

Be good,
TomK

Ace996,

Like you, I also enjoy a good discussion where we can all learn form each other It's my pleasure to discuss this subject with people who appreciate that ram-effect can be harnessed at speeds much less than Mach2.

I think there are essentially two main differences between a ram air-intake for a sports bike and that for a sports/performance car. To generalise: 1. most sports bikes will be driven in dry conditions, only, so the risk of ingress of water into the engine in a completely sealed air intake system is much reduced than a car which will probably be driven in all weathers, and 2. the stagnation point on the front of a car is at bumper level, whereas on a bike it is at fairing level, which is much higher, therefore the chance of picking up water by going through puddles and standing water is again much reduced in a ram air-intake on a bike. Therefore, any car which has a duct into the ram air-intake system must also have the facility of venting to allow any accidental water ingress to escape. In the case of my MC this vent is behind the headlamp and at a level lower than the air filter box, whereas in the diagram of your car the vent is in the hood. If a ram air-intake didn't have a vent before the engine then it would act like a vacuum cleaner and suck anything which could pass through the filter into the cylinders. Therefore, if you had a flap fitted to the bonnet vent then how would it allow water to escape?





Looking at the diagram of your air intake, I'm sure that if you were to look inside your air intake system at Part 4, which appears to be the confluence of all the inlet pipes, you will see that the direction of all the inlets is towards the engine, so that when the throttle is open the engine is sucking air from all three inlets, irrespective of the actual pressure differences that exist at the mouths of the three different inlets. This means that the air entering Part 4 in the pipe at the highest pressure (the duct in the bumper) will cause a "Venturi effect" and pull air through the other two air intake pipes, which have their mouths in zones at lesser pressure (albeit in zones of positive pressure). Under these circumstances, the air entering the intake system at the highest pressure will have "prority of entry" into the system and it seems most unlikely that the air from the bumper will "reverse flow" to exit out of the other two air intakes. However, if the engine speed requires less than all the air that is available, i.e at part throttle and when the ram effect creates an excess (like when the bath taps are filling a bath at a great rate than the plug-hole is draining it) then the air being forced into the air intake system under dynamic ram pressure, the excess will "bleed" from the system through the inlet which is at the lowest pressure relative to the other two air intakes in the system. During "bleeding", dust, water and other detritus in the intake system can pass through the system to reduce the clogging of the filter. Whereas in a fully closed system, all solid detritus would be forced towards the filter under ram pressure. In all the different BMW air intakes that I've seen, none of them have the filter perpendicular to the ram pressure, which I assume is to help stop filter clogging and accidental water ingestion.

Under WOT conditions, you will not see stuff coming out of the bonnet vent because as my Magnehelic pressure gauge has shown me, although the pressure in the system may be greater than ambient pressure, it will always be less than when the engine is not sucking air from the zones of high pressure where the mouths of the air inlet pipes are sited. It is only when you back-off the throttle that the pressure at the mouths of the air inlets returns to the full pressure values expected as per their theoretical ram pressure values at the speed of the vehicle. In my MC, under WOT in 3rd gear, the in the air intake is approximately at 2 inches of water pressure less than full ram pressure.

I assiduously monitor fuel consumption in my MC as another indicator of performance benefit and since I've been modding my air-intake and exhaust systems I've seen an improvement in overall fuel economy of around 15% as well as obtaining a 15% improvement in power and torque. One of my air intake mods is to insulate the air intake system right up to the plenum (after the air-filter box and MAF) and I find that under spirited driving the air intake temperature is at around 5-7 degrees C above ambient as monitored by the DashDynoSPD. Not only does the ram air-intake providing cold air give the power increase, additionally, I find that my engine always runs cooler than other OEM MCs.

Can you tell me if there is a hole in the back of the bumper "scoop" (Part 3 in the diagram) which can let stones and water pass through?

[lucid]

Originally Posted by exdos

Can you tell me if there is a hole in the back of the bumper "scoop" (Part 3 in the diagram) which can let stones and water pass through?

A few weeks ago, I checked this with my hand as far as my arm would go, and could not detect any openings between 3 and 4.

I don't see how the hood opening lets any collected water to escape. It's too high up and there would need to substantial flow to eject water out of the hood opening.

However, it is possible for any water that enters the system to collect right below the filter, and drain out of the opening in the ducting between 1 and 4, which is visible in the illustration. That is the only opening apart from 1, 2, 3 that I could locate in the system, but someone who has taken the entire intake apart should verify that.

There are examples of high pressure intakes with no outlet for water drainage. Clearly, excessive humidity in the combustion mixture would be undesirable, but I guess there is a trade-off being made there. The air filter would catch any debris, so that's not a significant issue.

[ace996]

comments in red...

Originally Posted by exdos

Ace996,

Like you, I also enjoy a good discussion where we can all learn form each other It's my pleasure to discuss this subject with people who appreciate that ram-effect can be harnessed at speeds much less than Mach2.

I think there are essentially two main differences between a ram air-intake for a sports bike and that for a sports/performance car. To generalise: 1. most sports bikes will be driven in dry conditions, only, so the risk of ingress of water into the engine in a completely sealed air intake system is much reduced than a car which will probably be driven in all weathers, and 2. the stagnation point on the front of a car is at bumper level, whereas on a bike it is at fairing level, which is much higher, therefore the chance of picking up water by going through puddles and standing water is again much reduced in a ram air-intake on a bike. Therefore, any car which has a duct into the ram air-intake system must also have the facility of venting to allow any accidental water ingress to escape. so 1 and 2 are pretty much the same...dealing with water being ingested in the box.
I do not have a habbit of driving in rivers or puddles higher than 6 inches...so thankfully, that's not an issue. Also, if the lower inlet was even submerged...air would be drawn in from the radiator inlet...again, no issue.
In the case of my MC this vent is behind the headlamp and at a level lower than the air filter box, whereas in the diagram of your car the vent is in the hood. If a ram air-intake didn't have a vent before the engine then it would act like a vacuum cleaner and suck anything which could pass through the filter into the cylinders. Therefore, if you had a flap fitted to the bonnet vent then how would it allow water to escape?-the water would run down the lower inlet in the bumper.





Looking at the diagram of your air intake, I'm sure that if you were to look inside your air intake system at Part 4, which appears to be the confluence of all the inlet pipes, you will see that the direction of all the inlets is towards the engine, so that when the throttle is open the engine is sucking air from all three inlets, irrespective of the actual pressure differences that exist at the mouths of the three different inlets. This means that the air entering Part 4 in the pipe at the highest pressure (the duct in the bumper) will cause a "Venturi effect" and pull air through the other two air intake pipes, which have their mouths in zones at lesser pressure (albeit in zones of positive pressure)I understand your point, but don't necessarily agree with the 'venturi' effect. The airbox will be pressurized by the inlets, I'll say the radiator inlet and the bumper inlet. If the amount of air that is being forced in, from ram-effect, is greater than the motor's required air..or draw...then positive pressure will be present (even more if the vent out the hood was sealed by a flap) and the energy used by the motor to originally "suck" the air into the manifold would be added to the power output...lessening 'pumping loss'..in effect. If not, then the draw would overpower the positive 'ram-effect', causing a vacuum in the airbox... pulling open my 'imaginary' flap...and vacuum (negative pressure due to draw) would be diminished and the airbox would function as it does in it's stock state.. Under these circumstances, the air entering the intake system at the highest pressure will have "prority of entry" into the system and it seems most unlikely that the air from the bumper will "reverse flow" to exit out of the other two air intakes. However, if the engine speed requires less than all the air that is available, i.e at part throttle and when the ram effect creates an excess (like when the bath taps are filling a bath at a great rate than the plug-hole is draining it) then the air being forced into the air intake system under dynamic ram pressure, the excess will "bleed" from the system through the inlet which is at the lowest pressure relative to the other two air intakes in the system. During "bleeding", dust, water and other detritus in the intake system can pass through the system to reduce the clogging of the filter-a very viable and logical result of the vent...I'm with you, but not as important to me as making the box true "ram-air".. Whereas in a fully closed system, all solid detritus would be forced towards the filter under ram pressure. In all the different BMW air intakes that I've seen, none of them have the filter perpendicular to the ram pressure, which I assume is to help stop filter clogging and accidental water ingestion.

Under WOT conditions, you will not see stuff coming out of the bonnet vent because as my Magnehelic pressure gauge has shown me, although the pressure in the system may be greater than ambient pressure, it will always be less than when the engine is not sucking air from the zones of high pressure where the mouths of the air inlet pipes are sited. It is only when you back-off the throttle that the pressure at the mouths of the air inlets returns to the full pressure values expected as per their theoretical ram pressure values at the speed of the vehicle. In my MC, under WOT in 3rd gear, the in the air intake is approximately at 2 inches of water pressure less than full ram pressure.

I assiduously monitor fuel consumption in my MC as another indicator of performance benefit and since I've been modding my air-intake and exhaust systems I've seen an improvement in overall fuel economy of around 15% as well as obtaining a 15% improvement in power and torque. One of my air intake mods is to insulate the air intake system right up to the plenum (after the air-filter box and MAF) and I find that under spirited driving the air intake temperature is at around 5-7 degrees C above ambient as monitored by the DashDynoSPD. Not only does the ram air-intake providing cold air give the power increase, additionally, I find that my engine always runs cooler than other OEM MCs.

Can you tell me if there is a hole in the back of the bumper "scoop" (Part 3 in the diagram) which can let stones and water pass through?as in Lucid's case, I did not locate one that would let rocks/dirt/water to escape.

I have never bought-in to the belief that non-flooding levels of water can do damage to a motor. Puddle splashes, rain, hose water, you name it...none are going to reach the motor in liquid form...the air filter will 'reduce' the size of the water to inconsequential size and it will then act as 'water-injection'.
Unless water is allowed to fully block and fill the airbox, air will always be ingested first..well, air and harmless water vapor. The fluid will surely find it's way to the lowest point...and I believe, after looking inside the airbox, that the lowest inlet would be the drain point.
---I'm not sure if the airbox has small holes...pencil sized...in the bottom of the airbox, as just about every one I've ever seen does employ for water evacuation. I'm not sure, but I've no concerns at all regarding 'water evacuation'.

My goal, a pet project if I find the energy and time to do so, is to turn the M3 airbox into a true "ram-air" airbox. I believe that any application of "scoops" is a wasted effort until that is done.

The big questions, at least to me, is how much air is required at high load/rpm to produce a ram-air effect in the airbox and how much is provided by the two frontal inlets...and at what speed.
If we could determine that the engine is fed sufficient air at speeds over 50mph, even with the top vent taped-over or plugged, then that's what I'd do. I'll trade low speed performance for high speed ram-air anyday...that will benefit me more on the track than it would on the street (where I rarely whip it).

We'll see...

Be good,
TomK

[Sticky]

Originally Posted by ace996

comments in red...


I have never bought-in to the belief that non-flooding levels of water can do damage to a motor. Puddle splashes, rain, hose water, you name it...none are going to reach the motor in liquid form...the air filter will 'reduce' the size of the water to inconsequential size and it will then act as 'water-injection'.
Unless water is allowed to fully block and fill the airbox, air will always be ingested first..well, air and harmless water vapor. The fluid will surely find it's way to the lowest point...and I believe, after looking inside the airbox, that the lowest inlet would be the drain point.
---I'm not sure if the airbox has small holes...pencil sized...in the bottom of the airbox, as just about every one I've ever seen does employ for water evacuation. I'm not sure, but I've no concerns at all regarding 'water evacuation'.

My goal, a pet project if I find the energy and time to do so, is to turn the M3 airbox into a true "ram-air" airbox. I believe that any application of "scoops" is a wasted effort until that is done.

We'll see...

Be good,
TomK

What you believe is irrelevant, support your argument with data. Every dyno from various sources with scoops shows gains. Show us all a dyno with the scoops that does not produce gains.

[ace996]

Originally Posted by Sticky

What you believe is irrelevant, support your argument with data. Every dyno from various sources with scoops shows gains. Show us all a dyno with the scoops that does not produce gains.

Sticky,
This discussion is not for you, go away. And to answer your question...Eloy, the maker of the scoop said it didn't do anything...you calling him a liar, too? Your dyno examples are not relevant here and we're not outright discussing the scoops at this point.

You poison enough threads with your juvenille drivel, please...the men are speaking...run along, you're not wanted here. Is that clear?

[lucid]

Originally Posted by ace996

Unless water is allowed to fully block and fill the airbox, air will always be ingested first..well, air and harmless water vapor. The fluid will surely find it's way to the lowest point...and I believe, after looking inside the airbox, that the lowest inlet would be the drain point.

You are correct in saying that water vapor is harmless. Any water that makes it past the filter will either be in vapor form or will surely be vaporized before it reaches the cylinders. Oxygen is the only reactive component in air. Air does contain about 1-4 percent water vapor by mass depending on the conditions. Obviously, you want to minimize water vapor content to increase oxygen content to improve combustion. It can be valid to trade off humidity for more air through a pressurized intake.

[ace996]

Originally Posted by lucid

You are correct in saying that water vapor is harmless. Any water that makes it past the filter will either be in vapor form or will surely be vaporized before it reaches the cylinders. Oxygen is the only reactive component in air. Air does contain about 1-4 percent water vapor by mass depending on the conditions. Obviously, you want to minimize water vapor content to increase oxygen content to improve combustion. It can be valid to trade off humidity for more air through a pressurized intake.

A little humidity for more pressure is more than fair...oh, yeah!!

[Sticky]

Originally Posted by ace996

Sticky,
This discussion is not for you, go away. And to answer your question...Eloy, the maker of the scoop said it didn't do anything...you calling him a liar, too? Your dyno examples are not relevant here and we're not outright discussing the scoops at this point.

You poison enough threads with your juvenille drivel, please...the men are speaking...run along, you're not wanted here. Is that clear?

I did not realize you had your own forum.

The only thing you are clinging on to is a comment that the V2 scoops, NOT MADE FOR THE M3, did not produce the gains the V3 scoops do on the dyno. Conveniently ignoring that fact are we?

Where is your data to support your argument the scoops don't make power? Where is it?

[exdos]

Originally Posted by lucid

A few weeks ago, I checked this with my hand as far as my arm would go, and could not detect any openings between 3 and 4.

I don't see how the hood opening lets any collected water to escape. It's too high up and there would need to substantial flow to eject water out of the hood opening.

However, it is possible for any water that enters the system to collect right below the filter, and drain out of the opening in the ducting between 1 and 4, which is visible in the illustration. That is the only opening apart from 1, 2, 3 that I could locate in the system, but someone who has taken the entire intake apart should verify that.

There are examples of high pressure intakes with no outlet for water drainage. Clearly, excessive humidity in the combustion mixture would be undesirable, but I guess there is a trade-off being made there. The air filter would catch any debris, so that's not a significant issue.

Thanks for that.

I've never had had any moisture in my air-filter box and I've driven in some horrendous wet weather too. However, if you were to drive into standing water then it is possible that a column of water could be forced up the intake and it only takes a bit of water (uncompressible) in a cylinder to blow an engine. Last year, here in the UK, we had lots of flooding and many BMW cars blew engines as a result of water ingestion. I'm sure that the owners completely forgot about the vulnerability of their air-intake systems when entering standing water (fording flooded roads) in order to attempt to get to the relative safety of their homes.

[exdos]

Originally Posted by ace996

.
I understand your point, but don't necessarily agree with the 'venturi' effect.

Think back to your days in the Chemistry lab at school. Don't you remember those venturis that you attached to the taps that were used to withdraw air? They worked in exactly the same way.

Originally Posted by ace996

.
a very viable and logical result of the vent...I'm with you, but not as important to me as making the box true "ram-air"

I think that you will find that, under WOT, the ram effect from the two vents (parts 2 and 3 in the diagram of your M3's air intake system) will provide less air to the engine, even in a completely sealed ram air-intake system, than your OEM air intake system will do.

I have found that the only reliable way of finding out what works and what doesn't is to use the datalogger and then calculate the Volumetric Efficiency as a continuing variable in the way that I have done to produce the graphs which show VE versus speed, rpm and air-flow etc. Any other assessment is not 100% reliable. Even the airflow versus rpm data doesn't actually show whether a modification is an improvement or not. Trust me on this.

If I owned you car, I'd block your bonnet air vent and then datalog and calculate the VE and compare with OEM in order to see whether your idea works or not. The cost of a DashDynoSPD is a lot cheaper than most mods that you can buy.

[exdos]

Originally Posted by Sticky

What you believe is irrelevant, support your argument with data. Every dyno from various sources with scoops shows gains. Show us all a dyno with the scoops that does not produce gains.

Sticky,

For reasons that I've already given in an earlier posting in this thread, I would not put any faith in static dynos to show "real world" on-the-road gains from air-intake mods if the fan placed in front of the car on the dyno is not capable of replicating the air speed equivalent to the vehicle mph equivalent on a static dyno.

[lucid]

Originally Posted by exdos

Thanks for that.

I've never had had any moisture in my air-filter box and I've driven in some horrendous wet weather too. However, if you were to drive into standing water then it is possible that a column of water could be forced up the intake and it only takes a bit of water (uncompressible) in a cylinder to blow an engine. Last year, here in the UK, we had lots of flooding and many BMW cars blew engines as a result of water ingestion. I'm sure that the owners completely forgot about the vulnerability of their air-intake systems when entering standing water (fording flooded roads) in order to attempt to get to the relative safety of their homes.

Oh, I see, you are considering a scenario in which the car runs, or "dives", into standing water. Yes, that sure would be a problem if the water gets up to the level of air filter/airbox inlet. The filter/airbox inlet sits fairly high in the engine compartment though, so that is unlikely. I guess considerable amount of water could be funneled up to the extent that it won't have time to drain through the drain opening between 1 and 4 if you enter shallower but still significant amount of standing water, but considering how high the filter sits, you'd have to go into it pretty fast IMO.

[Sticky]

Originally Posted by exdos

Sticky,

For reasons that I've already given in an earlier posting in this thread, I would not put any faith in static dynos to show "real world" on-the-road gains from air-intake mods if the fan placed in front of the car on the dyno is not capable of replicating the air speed equivalent to the vehicle mph equivalent on a static dyno.

Real world gains are always different from the dyno. This goes for any part, chip, exhaust, etc, as load at speed is different as is air resistance as speeds rise.

A dyno fan will never replicate air flow at real world speeds, certainly not at 85 mph and up as who other than a Formula 1 team has access to that kind of wind tunnel?

The fan and dyno helps us get an idea of the added flow and how the car responds. I ordered a Vbox to give 60-130 numbers, and there are plenty available on M5board (for the M5/M6, the M3 obviously has not had scoops available as long and hasn't been available as long so it will be some time before we have as much data to reference). I will do what I can on my end to add to the community with my own data, dynos, etc. I'm sure others will be adding results as well over the next few months.

[exdos]

Originally Posted by lucid

Oh, I see, you are considering a scenarios where the car runs into standing water. Yes, that sure would be a problem if the water gets up to the level of air filter/airbox inlet. The filter/airbox inlet sits fairly high in the engine compartment though, so that is unlikely. I guess considerable amount of water could be funneled up to the extent that it won't have time to drain through the drain opening between 1 and 4 if you enter shallower but still significant amount of standing water, but considering how high the filter sits, you'd have to go into it pretty fast IMO.

A car manufacturer has to consider the biggest idiot might drive one of his cars and then make a claim against them.

IIRC, There's a story of someone with a Winnebago RV putting his vehicle into Cruise control, thinking this was an "auto-pilot" and then leaving the driving seat and going to make a coffee in the back and the RV crashed. The owner then sued Winnebago for not making it clear in the manual that
cruise control was not auto-pilot. As I understand, under your anti-trust laws in the US, if someone is daft enough to hit themselves over the head with a hammer, the "victim" can sue the manufacturer of the hammer for his self-inflicted injuries. Surely BMW need to consider that such an idiot might also drive one of its M3s/MCs?

Likewise, it's possible that in "flash flooding" a completely sensible BMW owner could drive into standing water by simple accident, especially at night in the dark.

[exdos]

Originally Posted by Sticky

Real world gains are always different from the dyno. This goes for any part, chip, exhaust, etc, as load at speed is different as is air resistance as speeds rise.

But when you are actually measuring the ram effect, you MUST only measure real world conditions, because the ram effect is all about the change in air pressure with speed. If you can't replicate that on a dyno with suitable high-powered fans, then you may as well use your "butt dyno" to guess what is working and what isn't.

[lucid]

Originally Posted by exdos

A car manufacturer has to consider the biggest idiot might drive one of his cars and then make a claim against them.

IIRC, There's a story of someone with a Winnebago RV putting his vehicle into Cruise control, thinking this was an "auto-pilot" and then leaving the driving seat and going to make a coffee in the back and the RV crashed. The owner then sued Winnebago for not making it clear in the manual that
cruise control was not auto-pilot. As I understand, under your anti-trust laws in the US, if someone is daft enough to hit themselves over the head with a hammer, the "victim" can sue the manufacturer of the hammer for his self-inflicted injuries. Surely BMW need to consider that such an idiot might also drive one of its M3s/MCs?

Likewise, it's possible that in "flash flooding" a completely sensible BMW owner could drive into standing water by simple accident, especially at night in the dark.

I am not a lawyer, so I can't compare legal systems with confidence, but yes, people do like to sue in the US. However, I think there are still some common sense criteria that apply. For instance, you can't drive your car into the ocean from a beach and sue BMW because it did not operate in water (I doubt that that specific scenario is explicitly covered in the manual as something you should not do).

Sure, in a flash flood you might accidently drive into deep standing water, but I don't know that you can win a case against BMW if BMW can demonstrate that is has done due diligence and considered the issue of driving in standing water in a "reasonable" way in its design process. Such extreme environmental conditions usually do not constitute basis for malpractice by the manufacturer. Otherwise, all cars would have snorkels coming out of the factory, which they don't.

[Sticky]

Originally Posted by exdos

But when you are actually measuring the ram effect, you MUST only measure real world conditions, because the ram effect is all about the change in air pressure with speed. If you can't replicate that on a dyno with suitable high-powered fans, then you may as well use your "butt dyno" to guess what is working and what isn't.

You can't replicate real world conditions on the dyno. You can measure real world difference using GPS.

The thing is, if you can show gains at relatively low air speeds, the gains will only increase at speed and as speeds rise. The idea is to show the improved flow through the OEM setup, which multiple dynos in multiple conditions show. The delta increases.

[ace996]

...

Originally Posted by exdos

Think back to your days in the Chemistry lab at school. Don't you remember those venturis that you attached to the taps that were used to withdraw air? They worked in exactly the same way.
I see your point, but not exactly...perhaps Ijust can't 'see' it.

I think that you will find that, under WOT, the ram effect from the two vents (parts 2 and 3 in the diagram of your M3's air intake system) will provide less air to the engine, even in a completely sealed ram air-intake system, than your OEM air intake system will do. -that's the question...they may not...at any speed.

I have found that the only reliable way of finding out what works and what doesn't is to use the datalogger and then calculate the Volumetric Efficiency as a continuing variable in the way that I have done to produce the graphs which show VE versus speed, rpm and air-flow etc. Any other assessment is not 100% reliable. Even the airflow versus rpm data doesn't actually show whether a modification is an improvement or not. Trust me on this.-pressure sensor would do it, too.

If I owned you car, I'd block your bonnet air vent and then datalog and calculate the VE and compare with OEM in order to see whether your idea works or not. The cost of a DashDynoSPD is a lot cheaper than most mods that you can buy.-that would do it.

[swamp2]

exdos: Time to turn the hobby into a small business. Cooler running, more power, better mpg and do it yourself modifications? This is a winning combination.

[exdos]

Originally Posted by Sticky

You can't replicate real world conditions on the dyno. You can measure real world difference using GPS.

I don't see how GPS monitoring can give you figures for Volumetric Efficiency, and that's the REAL measure of assessing air-intake mods, especially to monitor ram air-intake systems.

Originally Posted by Sticky

The thing is, if you can show gains at relatively low air speeds, the gains will only increase at speed and as speeds rise. The idea is to show the improved flow through the OEM setup, which multiple dynos in multiple conditions show. The delta increases.

But how can you replicate the ram effect on a static dyno unless you also replicate the movement of air over the car at the commensurate wheel speed? As you've said previously, you would require a wind tunnel to do this on a dyno like the F1 teams use, and this is not feasible. However, there is a very simple and much cheaper way of assessing ram pressure increases, and that is to actually measure the parameters that you need to calculate Volumetric Efficiency using a datalogger connected to the car's ECU whilst driving in "real world" conditions, which aren't just the replication of the environment which creates ram pressure, but IS the very environment in which your car operates. What more could you ask for? My DashDynoSPD cost me about $350, and for that one off payment I can do unlimited dyno runs for evermore, and I also get unlimited access to a free "wind tunnel" as well all the actual data I need to accurately compute Volumetric Efficiency in "real world" on-the-road conditions and a host of other useful data. Why mess around with static dynos?