[DWR]

Much has been discussed about the exhaust recently and while the good work of many people has contributed to real improvements, I felt the intake tract might be taking a backseat. Sometimes, my curiousity can get the best of me. Today I finished some testing on pressure losses in the intake tract and thought I would share it with others.

Let's start at the beginning. How much does the stock air filter affect airflow? The turbo is a pressure ratio machine, so any loss at the intake of the turbo gets multiplied by the pressure ratio. I used a homemade manometer to get an accurate measurement, as I knew any of my regular PSI gauges did not have sufficient resolution or accuracy (see images below). Result was that at maximaum airflow there was a 0.67 psi loss. At a pressure ratio of 3, this looks like a 2 psi loss after the compressor. BTW, I started with a relatively new Mahle filter.

Then I went to a duplex psi gauge setup to test losses after the compressor. I checked measurement error between the 2 gauges and found it to be less than 1/4 psi. I say 'less than' because I could just barely see a difference. The first test with this setup was presure drop across the intercooler. The pressure drop across the intercooler was surprising low. In fact, low enough the gauges did not have enough resolution to get an accuarate reading. I'm guesstimating 0.5 psi, could be 0.6 psi. Pretty good. This indicates that the value of the intercooler in increasing density, by lowering temps, is with a small penalty.

Finally I tested losses from the output of the intercooler to the intake manifold. Essentially looking at the effects of the throttle body and EGR flow disruptions. At max airflow, that came in at a whopping 3.75 psi (sorry the picture is not clear, but you can match it up with the previous picture as the intercooler output reading is the same). If you measure the hydraulic diameters along the intake tract, you will find the throttle body is the tightest squeeze, so while significant, this result wasn't that surprising. It does highlight a potential improvement area.

I have the data in movie form, obtained from the Torque App plugin Track Recorder. I will plot it out by rpm and PSI, at some point, but I think this makes it clear where the greatest improvements can be made to increase airflow, in the intake tract.

I'll be investigating options to reduce these losses. Interested in how others may have addressed them. Bring your data, please. Enjoy.

[TDIwyse]

This is FANTASTIC! Thanks for posting. Don't have time to process all of it yet, but am looking forward to studying it and comparing it with some other data points.

Off the top though, did the pressure loss on the intake side come after the EGR bottleneck? Or was it just the pipe section that can be un-hooked from the IC and throttle? Part 12 here: http://www.realoem.com/bmw/showparts...88&hg=11&fg=40

[DWR]

Originally Posted by TDIwyse

This is FANTASTIC! Thanks for posting. Don't have time to process all of it yet, but am looking forward to studying it and comparing it with some other data points.

Off the top though, did the pressure loss on the intake side come after the EGR bottleneck? Or was it just the pipe section that can be un-hooked from the IC and throttle? Part 12 here: http://www.realoem.com/bmw/showparts...88&hg=11&fg=40

Good question, I forgot to document the testing port locations.

I tapped a port just above where the red intercooler intake hose connects to the turbo, one on the plastic elbow connecting to the throttle/EGR, and one just after the throttle/EGR mounting flange on the intake manifold plenum.

[TDIwyse]

Originally Posted by DWR

Good question, I forgot to document the testing port locations.

I tapped a port just above where the red intercooler intake hose connects to the turbo, one on the plastic elbow connecting to the throttle/EGR, and one just after the throttle/EGR mounting flange on the intake manifold plenum.

Just fantastic stuff ... The amount of time and fussing around you put into this is so great. I'm raising my adult beverage in salute to you sir.

[command_liner]

Electronic differential manometers are used for carburetor sync on motorcycles. You can read the loss pretty directly for intake tract losses.

[iaknown]

Very interesting. Thanks for posting.....So now I'm curious what difference a hogged out EGR would make as tdi has done. And then what other options we can come up with for that whole section to be opened up....

[SouthDiesel190]

Originally Posted by iaknown

Very interesting. Thanks for posting.....So now I'm curious what difference a hogged out EGR would make as tdi has done. And then what other options we can come up with for that whole section to be opened up....

Brand new to both the forums and the 335d community...how is TDI's EGR different from other EGR deletes? Just trying to educate myself on different approaches as I'm interested in doing all of the commonly discussed modifications to my car with long-term reliability being the focus (delete EGR, DPF, etc.)...I'll welcome any performance increases along the way as ancillary benefits.

[DWR]

Originally Posted by command_liner

Electronic differential manometers are used for carburetor sync on motorcycles. You can read the loss pretty directly for intake tract losses.

Cool, if I have to do more of this I may look into one of those. Any recommendations on brand, type, etc? Any boost/pressure limits?

[TDIwyse]

OK, got some comments/questions and comparative analysis from other sources.

First, the air filter data. Your results seem to line up well with this fantastic analysis of the impact to power, mpg's, psi drops for various levels of air filter status for a 335d, VW TDI and Dodge Ram Cummins.

https://www.fueleconomy.gov/feg/pdfs..._AirFilter.pdf

For a fresh air filter at WOT on a stock 335d they recorded a peak pressure drop across the filter of 1.75 kPa (0.25 psi). Being as you're modified and are not using a brand new filter, your 0.65 psi results line up very well.

Second, the intercooler. Here is where I'm seeing a big difference in your results versus several other sources.

For instance: http://mosselmanturbo.com/uploads/me..._Mosselman.pdf

That in car comparison includes the OEM 135i IC, and the 335i/135i IC's I've seen look very similar to our 335d OEM IC, except the cold side outlet is angled slightly different. I'm not sure exactly how modified you are, but I'm guessing you're making similar power to the 135i in the above test?

They also comment on how well the OEM unit does for pressure drop, but their data showed ~ 240mbar (~3.5 psi) pressure drop. Which is significantly higher than what you measured, which I find confusing.

Another test from Wagner of the 335d OEM IC (you can also compare to the OEM 135i/335i IC elsewhere on their site): http://www.wagner-tuning.com/Interco...-E93_p_65.html

This one isn't in car, but again shows much higher pressure drop for the OEM IC. They stop at ~330 cfm for the stock unit where the drop is ~ 2.5 psi. You're probably drawing significantly more cfm's than that, so again it seems odd that you were measuring such a low pressure drop on the OEM IC.

Is it possible the data you recorded for the intake ducting post IC of 3.75 psi was actually the intercooler pressure drop? If that was the case, then it would line up much closer with the Wagner and Mosselman data.

[DWR]

Originally Posted by TDIwyse

First, the air filter data. Your results seem to line up well with this fantastic analysis of the impact to power, mpg's, psi drops for various levels of air filter status for a 335d, VW TDI and Dodge Ram Cummins.

https://www.fueleconomy.gov/feg/pdfs..._AirFilter.pdf

For a fresh air filter at WOT on a stock 335d they recorded a peak pressure drop across the filter of 1.75 kPa (0.25 psi). Being as you're modified and are not using a brand new filter, your 0.65 psi results line up very well.

I need to issue a correction. I was using windshield washer fluid because of the nice blue color. Remembered I needed to adjust for the density when I loaded the manometer, but forgot when I did the calculation. So, the readings are high by a little over 5%.

[DWR]

Originally Posted by TDIwyse

OK, got some comments/questions and comparative analysis from other sources.

First, the air filter data. Your results seem to line up well with this fantastic analysis of the impact to power, mpg's, psi drops for various levels of air filter status for a 335d, VW TDI and Dodge Ram Cummins.

https://www.fueleconomy.gov/feg/pdfs..._AirFilter.pdf

For a fresh air filter at WOT on a stock 335d they recorded a peak pressure drop across the filter of 1.75 kPa (0.25 psi). Being as you're modified and are not using a brand new filter, your 0.65 psi results line up very well.

The Mahle filter has a 'prefilter' in front of the pleated material. In addition, the pleats are so dense it actually looks like it would inhibit airflow. A replacement will be installed today.

[Puerto Rican 335d]

The filter has foam type glued to the paper filter. I took it out on mines and found later that the DEALER didnt make any changes on my filter for 2 years and thats how I got them for not doing their job, as far as removing it the car felt smoother but as HP gains i cannot say.

[DWR]

Originally Posted by TDIwyse

Second, the intercooler. Here is where I'm seeing a big difference in your results versus several other sources.

For instance: http://mosselmanturbo.com/uploads/me..._Mosselman.pdf

That in car comparison includes the OEM 135i IC, and the 335i/135i IC's I've seen look very similar to our 335d OEM IC, except the cold side outlet is angled slightly different. I'm not sure exactly how modified you are, but I'm guessing you're making similar power to the 135i in the above test?

They also comment on how well the OEM unit does for pressure drop, but their data showed ~ 240mbar (~3.5 psi) pressure drop. Which is significantly higher than what you measured, which I find confusing.

Another test from Wagner of the 335d OEM IC (you can also compare to the OEM 135i/335i IC elsewhere on their site): http://www.wagner-tuning.com/Interco...-E93_p_65.html

This one isn't in car, but again shows much higher pressure drop for the OEM IC. They stop at ~330 cfm for the stock unit where the drop is ~ 2.5 psi. You're probably drawing significantly more cfm's than that, so again it seems odd that you were measuring such a low pressure drop on the OEM IC.

Is it possible the data you recorded for the intake ducting post IC of 3.75 psi was actually the intercooler pressure drop? If that was the case, then it would line up much closer with the Wagner and Mosselman data.

Let me try to shed some light on this. I have notice in previous posts there is misunderstanding of these things. It may not seem like it, but the results I shared are not so out of line. Let me explain.

First, a 3.0 engine at 7,000 rpm is going to move much more air than one at 4500 rpm, especially if it has better flowing heads. Our engines flow less than 250 cfm at 4500 rpm. That would be greater than 100% VE! It is closer to 200 cfm (maybe less). The way our engines make power is by packing density into that 200 cfm. For the same power level a 335d has much more boost than a 135i.

Second, presure drop is not linear with airflow. So, for example, 2.5psi pressure drop at 330 cfm is not 1.25psi at 165cfm. Its more like 0.625 psi.

Third, I was testing on the vehicle, in 3rd gear, on a 58F day. Intercooler was definitely having a greater effect than in the 'lab' tests. Since I cannot (yet) measure the temperature differences in and out of the intercooler, I cannot estimate how this influenced the results - other than to compare it to these other test.

Edit: Based on MAF data from TDYwyse, iaknown, myself and the manometer readings at the air filter, peak airflow occurs @ 4000rpm. I reviewed the video at that point and found a 1 to 1.5 psi difference between the gauges. The needles wiggle quite a bit in the upper rpm ranges. I can see differences between gauges change as much as 0.5 psi from frame to frame. Previously I had just taken a frame from the video at peak boost. So, further viewing @4500 showed similar differences. Looks like this falls in line with the other tests, when correcting for airflow.

[Puerto Rican 335d]

DWR buy the scoops LOL

[DWR]

Originally Posted by Puerto Rican 335d

DWR buy the scoops LOL

Do they have to be red? Not sure it would fit the understated nature of my vehicle, haha.

[DWR]

Originally Posted by DWR

Do they have to be red? Not sure it would fit the understated nature of my vehicle, haha.

Originally Posted by GreekboyD

My friend had similar readings with his neon green scoops amigo so I'm not all that surprised.

Never mind. GreekboyD just confirmed that green ones work just as well! Not sure that helps me though, LOL.

[TDIwyse]

Originally Posted by DWR

Let me try to shed some light on this. I have notice in previous posts there is misunderstanding of these things. It may not seem like it, but the results I shared are not so out of line. Let me explain.

First, a 3.0 engine at 7,000 rpm is going to move much more air than one at 4500 rpm, especially if it has better flowing heads. Our engines flow less than 250 cfm at 4500 rpm. That would be greater than 100% VE! It is closer to 200 cfm (maybe less). The way our engines make power is by packing density into that 200 cfm. For the same power level a 335d has much more boost than a 135i.

Second, presure drop is not linear with airflow. So, for example, 2.5psi pressure drop at 330 cfm is not 1.25psi at 165cfm. Its more like 0.625 psi.

Third, I was testing on the vehicle, in 3rd gear, on a 58F day. Intercooler was definitely having a greater effect than in the 'lab' tests. Since I cannot (yet) measure the temperature differences in and out of the intercooler, I cannot estimate how this influenced the results - other than to compare it to these other test.

Interesting.

So I'm confused again. If I plug the stock'ish parameters into the not2fast calculator at ~60F ambient, I can get to ~270 crank hp at 4100 rpm (very similar to peak hp of the stock car)and it shows ~453 CFM airflow. If you're modified and making more than 270 hp then the CFM should be much higher than ~450 CFM, shouldn't it?

[DWR]

Originally Posted by TDIwyse

Interesting.

So I'm confused again. If I plug the stock'ish parameters into the not2fast calculator at ~60F ambient, I can get to ~270 crank hp at 4100 rpm (very similar to peak hp of the stock car)and it shows ~453 CFM airflow. If you're modified and making more than 270 hp then the CFM should be much higher than ~450 CFM, shouldn't it?

Well, can you tell me where the air came from? Honestly, I am confused why you are using the calculator in that manner. Don't you correct for AFR?

BTW, please see that I edited the previous response. Looked at other parts of the video and found a couple of things that close the gap. I was pretty excited to share and probably should have waited until I looked at it frame by frame. None the less, the results are the same, directionally.

[Puerto Rican 335d]

dwr yes they have it in RED

[TDIwyse]

Originally Posted by DWR

Well, can you tell me where the air came from? Honestly, I am confused why you are using the calculator in that manner. Don't you correct for AFR?

BTW, please see that I edited the previous response. Looked at other parts of the video and found a couple of things that close the gap. I was pretty excited to share and probably should have waited until I looked at it frame by frame. None the less, the results are the same, directionally.

Well, here's what and why I was thinking like I was:

http://forums.tdiclub.com/showthread.php?t=200925

Here the TDImeister, who designs engines for a living, says:

Short answer to your question is, consider about 150-160 CFM airflow requirement per 100 bhp in a Diesel engine. The R-TDI engine was a particularly clean-running engine and very-vell developed and engineered. Developments in fuel injection systems, as well as the fact that many tuners will not regard smoke to the same extent that VW Motorsport did/does, means that you could get away with running with a lower Lambda value, thereby reducing the specific airflow requirement. The current lower limit is a Lambda value of 1.2 (AFR=17.5), and allowing for a slightly worse BSFC, you could get away with a slightly lower airflow requirement, hence the 150 CFM/100 bhp lower limit.

I was using an AFR of ~15, as that is about what I remembered the stock configuration giving me when I logged it for full fueling (might be higher than 15... can't recall exactly).

According to TDImeister, you still need ~150'ish CFM per 100 hp, so if you're making stock 265hp you'd need to ~ 400'ish CFM. If you're tuned and making ~350 hp, you'd need ~ 520'ish CFM. This also lines up well with the not2fast calculator predictions.

So I'm still confused on where you're getting the much lower CFM #'s from and the much lower pressure drop across the IC for what I think should be reasonable for the required air flow? Can you give additional references I could research for why the CFM flow would be so much lower? I'd love to learn why that would be the case.

[Puerto Rican 335d]

ah shit DWR you opened a can of worms with TDi you're screwed better come up w a good one LOL

[TDIwyse]

Originally Posted by Puerto Rican 335d

ah shit DWR you opened a can of worms with TDi you're screwed better come up w a good one LOL

Actually, I value his insight and knowledge. And he gives quantifiable and measurable data to back up his positions, which I enjoy. This is an adult discussion with good info.

I'd love to further my understanding of this system, it's just that I'm not understanding the data on the IC pressure loss...