Will adding a K&N air filter increase my mpg?

InfoSec

Veteran Member
Joined
Jul 4, 2000
Location
Brighton, MI
I just purchased a '00 Indigo Blue Jetta GL TDI and have less than 700 miles on it. Is it sane for me to want to start making mods to it??? (wifey doesn't think so.) But anyhoo, does anybody know the part number I'll need to be albe to order the K&N filtercharger? And from whom could I purchase it from? Any MI retailers? What about this notion of adding a cold air tube-thingy with a filter on the end of it?
 

HowardZ

Top Post Dawg
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Oct 5, 1999
Location
m
K&N: 33-2128

Some people use BMC which is very similar but has stronger edges.

Theoretically it should help your mileage a little. But in real life the performance mods do not increase mileage - probably because the extra power is too much fun.

It is also a good idea to keep the factory air box and make your own air intake hoses to bring cold air to it. Usually the factory air intake hoses are restrictive and also have a nasty "snow screen" which easily cloggs up and reduces air flow.
 

Switca

RIP, Gone But Not Forgotten
Joined
Mar 29, 1999
Location
Flat lands of Delaware
On it's own the K&N might make a little difference. Remove the snow screen and it makes a noticable difference.

------------------
Gregor Switca

Torque is a beautiful thing.
 

InfoSec

Veteran Member
Joined
Jul 4, 2000
Location
Brighton, MI
Thanks... I'm going to order it today from Summit Racing... Will removal of the snow screen allow the "nasty's" to get past the filter? Or is the screen before the filter???
 

InfoSec

Veteran Member
Joined
Jul 4, 2000
Location
Brighton, MI
Thanks for the great info. I have spent the last hour reading over all of the discussions and how-to's regarding the snow screens. I think that's coming out along with the other screen when I put in my K&N. (Summit was closed, but the guys at Autozone said that the 33-2128 "just don't exit!" Maybe the number is different, but Mr. HowardZ seems to know his stuff. So I will assume that Mr. Autozone suffers from multiple inbreedings. I will check with Summit tomorrow...)Later and thanks again for the help!
 

truman

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Joined
May 18, 2000
Location
columbia,MO,usa
TDI
'05 Passat Variant, Still miss the 03JW
The cheapest mod to increase mpg is to increase tire pressure to 40-44 psi. Screen removal also costs nothing.
 
M

mickey

Guest
11 of my 12 jurors think there's no effect on the MAF sensor film, but the 12th guy is still holding out for a "guilty" verdict. I badly over-oiled my BMC filter last time, to the point that there are pools of oil sloshing around in the airbox. And my fuel economy hasn't been that great this summer. But I can't see any sign of contamination on the sensor itself.

-mickey
 

Ric Woodruff

BANNED, Ric went to Coventry.
Joined
Feb 19, 1999
To answer your original question - no. Sure, at top RPMs (100+ MPH) you might get slightly better air flow resulting in slightly better MPG, but at those speeds you will suffer greatly reduced MPG anyway. Someone who drives at those speeds obviously doesn't care about MPG anyway (or their life either, for that matter).

At normal highway speeds, air flow is more than adequate with an OEM, Fram, Purolator, or equivalent air filters.

When I changed my air filter for the first time at 40,000 miles, I so no marked increase in MPG. One would have thought air flow with that many miles on the air filter would have been restricted, resulting in reduced MPG.

------------------
Ric Woodruff

Braumeister von Sehr Gutem Bier
Since the Last Millennium

1998 Jetta TDI Sport
 

christi

Top Post Dawg
Joined
Feb 22, 1999
Location
Ruislip, Middlesex, UK
TDI
Peugeot 806, 607
I can't see how it would increase fuel economy either.

If the air intake system is restricted, then less air can flow into it.

The TDI ECU will sense that less air is flowing in, and will refuse to give you as much fueling at full throttle.

This will reduce maximum power.

However if you are driving with economy in mind you will not be using maximum power so it is a non issue.

OK there will be a slight increase in mechanical effort required for the engine to suck air in past the filter, but it must be tiny, and I would guess that the turbo would just run with its wastegate open slightly less to compensate, having no effect on economy.

Things you could do:-

Bigger diameter (not width) wheels / tyres to increase gearing.
A Tuning Box to advance injection timing and make the engine more efficient.
Low rolling resistance tyres, like Michelin Energy (do they sell these in the US?).
Propane injection.

But then, diesel is so cheap in the US, why bother? If it's due to environmental concienciousness, then use biodiesel (you can make it yourself if you want).

------------------
1996 Passat Tdi estate (wagon (variant))
See my Peugeot / Passat site
 

InfoSec

Veteran Member
Joined
Jul 4, 2000
Location
Brighton, MI
Once again, I appreciate the responses. I have since removed the air screen since July 4th and the car seems to breathe a little easier. (maybe it's just wishful thinking) Later, All!
 
M

mickey

Guest
Ric is WRONG! Ahhhhh! All is right with the world again.

Ric: Try blocking off your intake completely and let us know what kind of mileage you get. Or how long it takes you to crank your battery dry. Whichever comes first.

Restricted airflow will obviously reduce fuel economy. Therefore, it stands to reason that improved airflow will result in better fuel economy.

A K&N flows better than a stock filter. Therefore, your fuel economy will improve. How big the improvement will be depends on how much air your engine demands. If you drive like Ric the difference will be negligable since you'll rarely use the turbocharger. If you like to accelerate with a reasonable amount of alacrity it'll make a measurable difference. If you have Wett chips, and use them, it'll make a substantial difference. The more airflow you demand the bigger the difference.

-mickey
 

twoblink

Member
Joined
Jun 30, 2000
Location
Pasadena, CA USA
I own an A4 1.8TQ, and I have a RamAir filter. I did not notice a single mpg increase. BUT, what I did notice was that acceleration was a bit smoother. That's it.

Turbo's generally (since they are pressurized) suck in plenty of air, they should (in theory) suck in the same amount of air, since a given amount of air causes the same amount of air density, translating to a given pressure level, which is all controlled by the ECU anyway. BUT, what happens is that your turbo works a little less to get the same amount of air into the tubes... This should improve the longevity of the turbo, and give a smoother flow of air in general.

These engines are basically bulletproof, heard a guy put 300K miles on his TDI already, so I don't think longevity is ever the issue here...

It helps, but not really in the MPG department...

Albert
 

Ric Woodruff

BANNED, Ric went to Coventry.
Joined
Feb 19, 1999
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by mickey:
If you like to accelerate with a reasonable amount of alacrity it'll make a measurable difference. <HR></BLOCKQUOTE>

I agree with that statement in the context of what Christi stated; the ECU compensates for less air flow with less fuel flow.

If you increase the air flow, the fuel flow increases, giving you LOWER MPG not higher when you do a lot of extraneous acceleration!
 
S

SkyPup

Guest
Sorry to correct the misguided thinking stream of consciousness here, but the maximum fuel efficiency of the OEM VW 1.9 L TDI engine is at WOT under maximum load at 1,900 rpm where it consumes 193g/kW/hr of diesel fuel in the BSFC map. Ric use the facts, not your brain!"D

[This message has been edited by SkyPup (edited July 07, 2000).]
 
S

SkyPup

Guest
In addition, a dirty airfilter, like dirty underwear, absolutley stinks in a turbodiesel engine. Not only does it decrease the efficiency of your turbocharger compressor and make the turbine section work harder, hotter and less efficient, it also can send your turbocompressor wheel into the surge zone into a catastrophic explosion.

RIC's BS of running 40,000 miles on OEM paper air filter is just plain stupid and dumb as hell. The VW TDI runs 40-60% more AIR than fuel on a volume-volume basis, totally negating Rics dumbfounded spiel of dirty air filter causes no harm. Instead, Ric is causing more soot to be formed due to lack of air at higher operating temperatures putting more stain on his entire engine, all because of this ignorant assumption based on faulty logic and knowledge.

Get a K&N or whatever and toss the OEM paper unit, it doesn't suck so bad it does suck.

BTW, RIC, want economy, use the throttle!


The New 1.9L TDI UltraModern Diesel Engine in North America

With the introduction of the New Beetle, Jetta IV, and Golf IV with the newly designed A4 chassis into the North American market, Volkswagen is offering the next generation of the 1.9L TDI engine. The 1.9L TDI engine has been completely redesigned for the New Beetle as well as all other models in the newly defined A-platform chassis, which includes the new Golf, the new Jetta, the Audi A3, and the Skoda Oktavia. Several evolutionary changes have been made to the TDI concept to further improve its emissions, efficiency and performance for North America. Emissions performance is improved with increased fuel injection pressure, optimized fuel injectors, calibration modifications, EGR cooling, refined piston ring placement, and reduced crevice volume in the combustion chamber. Efficiency is improved with a new oil pump and water pump to include a modified oil circuit to reduce friction and increase oil pressure buildup especially for cold starting. A new vertical oil filter has been installed for ease of maintenance with a fully incineratable cartridge for recycling. A new cylinder head cover is installed with an integrated oil separator to minimise oil consumption. Performance and efficiency of the new TDI engine is much improved with the addition of a Garrett GTVNT15 variable geometry turbocharger, which increases torque at lower engine speeds while preserving performance at higher engine speeds. The engine/gearbox assembly has also been reinforced with the introduction of pendulum engine mounting support to reduce vibration.

Modifications for the American Market differing from Europe

The basic engine for use in Europe had to be modified for the American market and further developments incorporated to satisfy conditions as these:
-Stringent emission limits applying to diesel engines in California
-OBDII diagnostic with digital trouble codes integrated with Siemens 80C167 microprocessor containing 16/32bit extended instruction set for communication with CAN bus communication system
-Special topographical and climatic useage conditions relative to North America
-Subquality fuels and lubricants with unfavorable properties for diesel injection pump Bosch Model VE VP 37 distributor pump operating pressure 850 bar

The full load values of the American market TDI is achieved by Volkswagen to deliver a torque of 149Nm at 1,000rpm and reaches its maximum value of 210Nm at 1,900rpm. Of particular note are the low full-load smoke emissions and specific fuel consumption values of less than 200 g/kWh. The implementation of technical software improvements in the BOSCH ECU made it possible to meet US and Canadian emission requirements with minimum loss of power as compared to the European TDI version. An extremely high level of efficiency is achieved at part load with a specific fuel consumption of 197 g/kWh making the TDI one of the most fuel efficient engines of its class. Particularly economical driving is possible in the low part-load range which is frequently used in practice where only 350g of diesel fuel is consumed per kilowatt-hour at an engine speed of 2,000rpm and a mean effective pressure of 2 bar. Maximum output of 66kW at 3,750 rpm is attained with a volumetric efficiency of 34.8 kW/! at a maximum mean effective pressure of 14 bar. Piston speed is rated at 12.7 m/s maximum rpms.
 

HowardZ

Top Post Dawg
Joined
Oct 5, 1999
Location
m
Skypup, a european tdi owner who has a fuel economy computer listed for us many fuel economy tests he had performed.

The bottom line was that optimum fuel economy is a little over 1500 rpm. In addition it makes little difference which gear is being used. 3rd gear at 1500rpm yielded, 4th gear at 1500rpm, and 5th gear at 1500rpm all yielded approximately the same mpg.

Specifically:
Velocity-----------3rdGear------------4thGear-------------5thGear
40kph(25mph)----71mpg(1550rpm)--------------
60kph(37mph)----65mpg(2300rpm)-78mpg(1650rpm)--73mpg(1275rpm)
70kph(43mph)------------------------69mpg(1900rpm)---78mpg(1475rpm)
80kph(50mph)----43mpg(3100rpm)-65mp(2000rpm)----75mpg(1725rpm)
90kph(56mph)------------------------50mpg(2475rpm)---69mpg(1925rpm)
100kph(62mph)---35mpg(3850rpm)-43mpg(2750rpm)---61mpg(2125rpm)
110kph(68mph)-----------------------41mpg(3000rpm)---57mpg(2325rpm)
120kph(75mph)-----------------------39mpg(3300rpm)---50mpg(2575rpm)

I wish we had more test points or even a nice curve.

As you can see, optimal fuel economy occurs at:
1550rpm in 3rd gear 71mpg at 40kph/25mph
1650rpm in 4th gear 78mpg at 60kph/37mph
1475rpm in 5th gear 78mpg at 70kph/43.5mph

This evidence leads me to believe that RPM plays a far more important role in fuel economy than actual velocity, wind friction, rolling friction. Internal engine friction is a function of rpm and seems to have the greatest impact on fuel economy than the other factors.

However, who wants to go driving down the highway at 43.5mph? Ok, how about traveling at 50mph?
1725rpm in 5th gear 75mpg at 80kph/50mph

Ok, that is still too slow!

I also believe that if we can get our 0.756 5th gear replaced with a 0.68 5th gear, then when we travel at 1725rpm in 5th gear we will still get 75mpg but will be travelling at 56mph. At least that is the speed limit. This will force us to stay in 4th gear until 2125 rpm so that we can shift into 5th gear at 1500 rpm at 48mph.

Ok, this is still too slow for most of you.
1925rpm in 5th gear 69mpg at 90kph/56mph

And if the 0.756 5th gear is replaced with a .68 gear we will be travelling at 62mph while at 1925rpm in 5th gear.

I really think it looks like the fuel economy stays almost constant at 1500 rpm regardless of which gear we use.

P.S. Where theory contradicts real-life experience, the theory must be incorrect or incomplete.

[This message has been edited by HowardZ (edited July 07, 2000).]
 

HowardZ

Top Post Dawg
Joined
Oct 5, 1999
Location
m
I moved my posting over to the fuel economy forum. Perhaps this entire thread belongs there?
 
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