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TDI Power Enhancements Discussions about increasing the power of your TDI engine. i.e. chips, injectors, powerboxes, clutches, etc. Handling, suspensions, wheels, type discussion should be put into the "Upgrades (non TDI Engine related)" forum. Non TDI vehicle related postings will be moved or removed. Please note the Performance Disclaimer.

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Old August 26th, 2010, 18:09   #16
Drivbiwire
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IAT has little to do with temperature with a total restriction of 5-10 hPa. There is so little energy spent to pull the air accross the filter that you are in the realm of hypothetical and surely not measureable by any means.

The largest pressure value you can measure is actual induction pressure (pre-turbo) and compare it to local pressure pre-filter. The difference between the two won't account for any measurable losses until you get to around 80+ hPa differential. Even with that amount of restriction the car will still make rated power the turbo will simply take a few miliseconds longer to reach specified boost pressure/flow.

If you want to have a good time with these cars, measure them on a dyno with a restrictor plate. Cut the intake inlet to 25% of it's original size and the car will still make the same power. In this case you may see a few degrees rise in IAT, but you could still debate whether or not its within the margin of error for the temp probe.
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Old August 26th, 2010, 18:14   #17
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I'm glad to finally see a FAQ for this.

And I echo what Bob said. Some dry element conical filters such as the AFE or AMSoil perform well.
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Old August 28th, 2010, 14:32   #18
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ive read many of these arguements, discussions etc and personally analyzed the information presented, to the best of my sub-par logical abilities

my aftermarket cone intake system is on craigslist, and the stock air box (thank god i saved it for some reason) is going back in the car

im going to have to re-engineer the supply of cool (outside engine compartment) air as the dams etc that VW designed were not present when i got my car
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Old August 28th, 2010, 14:36   #19
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Ben Dur, you should be able to source them from 1stvwparts.com or from a salvage chain.
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Old August 28th, 2010, 16:03   #20
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Even if the filter is not a restriction, wouldn't the relatively small tube going down to the wheel become one at some point, or am i totally missing the point of the information provided by the manometer (which sounds like a totally awesome upgrade)?

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Originally Posted by Drivbiwire View Post
Thats the point of using a manometer in my post above, there is NO restriction with the OEM filters even with performace tunes.

The OEM filter for a TDI has MORE flow capability (read larger area) than the filter on the Twin Turbo Audi S6 that can push north of 350hp and turn 8000 rpm.

The TDI already has a filter that is overkill in terms of flow, no amount of modifications can exceed its ability to flow unless you start adding cylinders to the motor, even then it can meet the demands of a V6-V8 turbo charged engine.

Also FWIW, the VW TDI filter has more area than my I6 and V6 CDI/Bluetec diesels pushing 220hp in stock form. I have the restriction data of those filters and at max power the total restriction at the turbo inlet at Maximum boost and full load is 3hPa!
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Old August 28th, 2010, 18:57   #21
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Are you talking about the inlet tube for the turbo compressor?

This tube must inherently neck down to the same diameter as the turbo inlet, which is quite small. This inherently means that the absolute pressure will go down in accordance with the Bernoulli principle. Bernoulli pressure drops shouldn't be confused with frictional losses - but your simple manometer cannot tell the difference between the two. As long as the reduction in diameter is reasonably smooth and consistent, the reduction in pressure (because of the increase in velocity) will be in reasonable accordance with Bernoulli, and not greater than that because of frictional losses.

I know that for the Mk5 turbo inlet pipe, it doesn't look like one could do much to make it any better. I think the Mk4's had that "pancake" pipe going across the front of the engine to the turbo inlet. If there is a place where there is restriction in the system, that would be it. But still ... if the internal cross sectional area of that pancake is at least as much as the area of the turbo inlet itself, it probably isn't meaningful, because Bernoulli is going to dictate that the pressure is going to drop even more going into the turbo inlet anyway. I don't know how the cross sectional area of that pancake compares to the turbo inlet.
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Old August 29th, 2010, 05:16   #22
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No, I am talking about pre-filter tubing.
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Old August 29th, 2010, 07:24   #23
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The OEM air inlet scoop, notwithstanding several sharp bends, is near a stagnation point of moving air, so that any incurred pressure losses are offset by positive pressure when the car is moving forward. Bernoulli's principle at work again.
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Old August 30th, 2010, 14:36   #24
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today the skis cleared up just enough for me to pull my little green TDI up to the garage to swap my crap cone filter with my stock air box




i first compared the size of these filters
by bending the paper filter around into a cylindrical shape
beside the cone filter it looks like this



as you can see the paper filter is significantly larger in all dimensions
it also has more pleads

this means the total surface area of the paper filter is significantly larger.
without actually measuring and doing all the math my guess is that its between 2 and 3 times the surface area of the cotton filter



i set up my wet/dry vac to test the flow differences
i was not able to reach the flow limit of either filter however


(yes i did this project on the ceiling)

with the vac ON
it pulls zero vacuum with nothing connected


and with my hand covering the inlet the vacuum pulls approx ~3in.Hg of Vacuum



next i hooked up each filter to the vac and tested each





each pulled 0 (zero) vacuum
both times the needle seems pegged right in the exact location the needle sits with no vacuum applied as well as the same amount pulled by the shopvac with no restrictions


finally i installed the stock air box


my conclusion
connected to a 5hp wet/dry vac neither the stock air box nor a cone air filter produce a measurable amount of restriction measured by my inexpensive equipment

Last edited by Ben Dur; August 30th, 2010 at 15:11.
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Old August 30th, 2010, 15:43   #25
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Quote:
Originally Posted by Ben Dur View Post



...
finally i installed the stock air box
Am I looking at something totally wrong or did you reinstall that airbox with the big gaping gash on the underside?
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Old August 30th, 2010, 15:47   #26
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it was my take on the "swiss cheese" mod

doesnt really negatively effect anything

its a larger area than the stock inlet
and given the car has none of the fresh air piping or dams that were provided by VW, it really doesnt matter...
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Old August 30th, 2010, 20:40   #27
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The only other set ups I'd like to see tested would be something like the subaru wrx sti intake which is directly from a hood scoop pulling in quite possibly the coolest air of any system.




Another is something I've seen on camaros. The camaro system is a dual "cold air intake" that drops down behind the headlights. with our cars especially the 09 10 tdi we can drop the intakes into the fog light cavity. It would have more air forced in at higher speeds and would be sucking in very cool air from outside the engine bay.



and have the filters sitting in here


I'm not an expert and I'm not claiming that these are good options I'm just curious what some more knowledgeable people than I might say about these ideas.
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Old August 30th, 2010, 21:20   #28
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judging purely from your pictures i have to point out that the subaru is not pulling air from the hood scoop.

the hood scoop is pushing air through the intercooler...
if you look over on the passenger fender area you will see, that is where the airbox, maf, TIP, are located.
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Old August 30th, 2010, 21:20   #29
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The Subaru hood scoop leads to the intercooler - that's what is on top of the engine with "STI" printed on it. I don't think the actual engine air intake comes from there, but I could be wrong - I don't know where the actual inlet is.

All air intakes that draw air from low on the front of the car or in front of the front wheels (on the underside) are vulnerable to sucking in water when (not if) the car is driven through puddles. The stock engine air intake on a Mk5 comes from the top of the grille near the center of the car and it leads first into a little box that's designed to dump water out the back while the air goes sideways, then into the airbox which again has an outlet on the bottom to dump out water. Aftermarket "cold air intakes" almost never have such protection against water intrusion ...

The TDI air intake is not a true "ram air" because the outlets for separating water are very significant, and will also dump out any overpressure. But, these cars won't go fast enough for "ram air" to have any meaningful effect anyways. But it is a "cold air intake" - the temperature IS significant.
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Old August 31st, 2010, 02:11   #30
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Quote:
Originally Posted by Ben Dur View Post
today the skis cleared up just enough for me to pull my little green TDI up to the garage to swap my crap cone filter with my stock air box




i first compared the size of these filters
by bending the paper filter around into a cylindrical shape
beside the cone filter it looks like this



as you can see the paper filter is significantly larger in all dimensions
it also has more pleads

this means the total surface area of the paper filter is significantly larger.
without actually measuring and doing all the math my guess is that its between 2 and 3 times the surface area of the cotton filter



i set up my wet/dry vac to test the flow differences
i was not able to reach the flow limit of either filter however


(yes i did this project on the ceiling)

with the vac ON
it pulls zero vacuum with nothing connected


and with my hand covering the inlet the vacuum pulls approx ~3in.Hg of Vacuum



next i hooked up each filter to the vac and tested each





each pulled 0 (zero) vacuum
both times the needle seems pegged right in the exact location the needle sits with no vacuum applied as well as the same amount pulled by the shopvac with no restrictions


finally i installed the stock air box


my conclusion
connected to a 5hp wet/dry vac neither the stock air box nor a cone air filter produce a measurable amount of restriction measured by my inexpensive equipment

Wouldn't it been easier to just take a lenght of clear turbing, fill it with water and use a ruler to measure the pressure drop..?
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