ALH Intake Dyno Test

Mike_D

Veteran Member
Joined
Nov 19, 2015
Location
Idaho
TDI
2003 Jetta
I have read a lot of opinions about the effectiveness of an aftermarket intake on mildly modd'ed ALH but didn't find any solid information. So, I decided to run a little test myself to see what the horsepower and torque numbers would be be with the factory intake vs a simulated high-flow intake (removed lid from airbox so there is no restriction). This test was done on the car in my signature.

What I found is that there is no real measurable difference in HP and TQ with the an open airbox vs the factory airbox. Run 8 was with the airbox lid closed like normal (170.54hp), and run 9 was with the airbox lid open (168.35hp). In my experience running a car/truck 3 times back to back on the dyno the 2nd run usually makes the most power and the first and third runs are a couple of hp lower. This would explain why the run with the lid open is a couple of hp less.

One interesting observation is that the run with the lid open had much less smoke than with the lid closed.....

Dyno graph:
http://i1316.photobucket.com/albums/t616/mike_d/Jetta%20intak%20dyno_zpsuxjdyk01.jpg

Dyno run of lid closed:
https://www.youtube.com/watch?v=QMxvscACWQU

Dyno Run of lid open:
https://www.youtube.com/watch?v=QMxvscACWQU
 
Last edited:

h4vok

Veteran Member
Joined
Feb 4, 2017
Location
Denver (ex MN)
TDI
2003 Jetta TDi 5sp 171k
Nice to see some real tests. More supporting data for keeping the intake stock as it is not reducing power and is providing protection for the turbo from good filtration.

Also your photobucket link is not working. Try uploading it to tdi club or using imgur.
 

KERMA

Vendor , w/Business number
Joined
Sep 23, 2001
Location
here
TDI
99 beetle and 04 jetta
A properly tuned tdi won't be airflow limited by the smoke map at full throttle conditions (like on a dyno). The smoke map is only supposed to "win" at very low rpm and some part throttle or transient conditions. And in some factory calibrations, at higher rpm. At all other times, power and torque are restricted by a "hard" torque limiter that does not care about airflow at all. So this result is no surprise.

The "less smoke" result is exactly what you SHOULD expect from airflow mods in a general sense. Just because there is no power/torque added on the dyno, does NOT mean it "does nothing". There is an improvement in responsiveness, especially at part throttle and transient conditions, and there is less smoke under certain conditions.

Of course, filtration is important for its own reasons. You want the engine to last a few miles, obviously. So if the ONLY consideration was "max power" then you could conceivably run with no pre-turbo intake tract at all. Some drag cars, in fact, do this. But not recommended for a street car.
 

Mike_D

Veteran Member
Joined
Nov 19, 2015
Location
Idaho
TDI
2003 Jetta
Nice to see some real tests. More supporting data for keeping the intake stock as it is not reducing power and is providing protection for the turbo from good filtration.

Also your photobucket link is not working. Try uploading it to tdi club or using imgur.
Not sure why the graph link isn't working for you - seems to be working. I can insert it as an image that is displayed during the edit, but then goes away when I save it. Not sure where to upload it to this site.
 

Mike_D

Veteran Member
Joined
Nov 19, 2015
Location
Idaho
TDI
2003 Jetta
A properly tuned tdi won't be airflow limited by the smoke map at full throttle conditions (like on a dyno). The smoke map is only supposed to "win" at very low rpm and some part throttle or transient conditions. And in some factory calibrations, at higher rpm. At all other times, power and torque are restricted by a "hard" torque limiter that does not care about airflow at all. So this result is no surprise.

The "less smoke" result is exactly what you SHOULD expect from airflow mods in a general sense. Just because there is no power/torque added on the dyno, does NOT mean it "does nothing". There is an improvement in responsiveness, especially at part throttle and transient conditions, and there is less smoke under certain conditions.

Of course, filtration is important for its own reasons. You want the engine to last a few miles, obviously. So if the ONLY consideration was "max power" then you could conceivably run with no pre-turbo intake tract at all. Some drag cars, in fact, do this. But not recommended for a street car.
What intake (airbox) do you recommend? I see that you have aFe with the optional dry filter on your site: http://www.kermatdi.com/afe-cold-air-intake-system-mk4/That is the unit that I was considering and one of the reasons I ran the dyno test.
 

KERMA

Vendor , w/Business number
Joined
Sep 23, 2001
Location
here
TDI
99 beetle and 04 jetta
stock airbox is fine. I use a stupid ginormous Amsoil EA filter on my beetle just because I'm weird like that. Mostly because it gave me a nifty place to drill for a nitrous line. aFe is just because some guys really want it, mostly a bling kind of thing I guess. If you are after actual performance gains look elsewhere.

OMI however will make a difference. Kind of like what you saw taking the cover off the airbox. Similar improvements with certain intake manifolds (but not all, and not the most common "euro" ones), and exhaust helps, and to a lesser extent the pipes post-turbo.
 

swetbak

Veteran Member
Joined
Jan 7, 2015
Location
Ft. Myers, FL
TDI
03 Jetta Wagon, 2010 BMW 335d
and to a lesser extent the pipes post-turbo.
I'm using the 1.25" adapter to connect my VNT 17 to stock lower intercooler piping, but was thinking about going to the upgraded piping and the 1.75" adapter. Does the restriction from the smaller adapter help the turbo spool quicker? Would there be a net advantage by upgrading this piping?
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
Joined
Aug 16, 2004
Location
South of Boston
TDI
'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
When you mod an ALH I like to think you're merely moving points of air restriction around the engine. On a stock car if you improve the intake, the downpipe is a limitation. If you improve the downpipe, the intake manifold is a limitation. If you port the head, the turbo is a limitation. You get the idea.

I have a PD 150 airbox, snorkel, MAF, airbox to turbo pipe, and intake manifold on my Wagon. It does help response, but I don't know if it improves HP. I did get 155/270 with a stock turbo, so it doesn't do badly. But as Charlie has pointed out, you have to tune the car for it or you may find performance gets worse, not better.
 

swetbak

Veteran Member
Joined
Jan 7, 2015
Location
Ft. Myers, FL
TDI
03 Jetta Wagon, 2010 BMW 335d
Improving air flow has been my goal. I've done (I think) everything to improve it other than upper and lower intercooler piping. Both are on my list of things to do. Just want to understand the pros and cons, especially regarding the restriction at the turbo adapter.
As far as tuning, Charlie has already told me I have everything he can give me. I just want to capitalize on that. Internals are not on my bucket list.
 

turbovan+tdi

Top Post Dawg
Joined
Mar 23, 2014
Location
Abbotsford, BC.
TDI
2003 TDI 2.0L ALH, auto, silver wagon, lowered, Colt stage 2 cam, ported head,205 injectors, 1756 turbo, Malone 2.0, 3" exhaust, 18" BBS RC GLI rims. 2004 blue GSW TDI, 5 speed, lowered, GLI BBS wheels painted black, Malone stage 2, Aerotur
Great job on testing but to me, it proves nothing. Intakes are more than just air movers, they have resonance and volume and merely removing the air filter does nothing. You need to repeat this test with a PD150 or similar to have real results.
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
gt1749v turbine is like a soda straw compared to the garden hose of the engine/manifolds and piping, compared to the sewer pipe of the exhaust and intake (both on the atmospheric sides of the turbo)
 
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