The Turbo Air Guide (TAG) by Diesel Power Products when used in the intake of a turbo charger brings more air smoothly in to the compressor. The TAG straightens air into a laminar flow and directs it into the compressor of the turbo, resulting in more power, cleaner burning and better mileage. The TAG shown in the picture above is installed in the intake of a Garrett turbo charger used on Ford Powerstrokes and is constructed of stainless steel welded honeycomb material and will eventually be made to fit many applications for most turbo charged engines, gas or diesel. |
How the TAG works: In the picture below air coming from the vehicle filter enters the compressor wheel fins from the top traveling down and is being accelerated and compressed as the wheel rotates. This air generally travels into the fins of the compressor wheel at an angle in the same direction as the rotation of the wheel, but is also turbulent from passing through the air filter and associated piping before reaching the compressor wheel. As the wheel rotates to move the incoming air, the leading edge of the fins encounter the turbulent rotating air moving in the same direction the wheel is turning. This rotational motion of the incoming air limits the amount of air the fins can grab and the turbulence creates drag on the fins as they cut through the incoming air. The Turbo Air Guide when placed directly in front of the compressor wheel acts to change the incoming air into a smooth laminar flow and directs the flow directly into the fins allowing for more air to be introduced into the compressor wheel smoothly, while reducing drag caused by turbulence. The results of using the TAG can be demonstrated by the Dynometer chart below. |
 The picture above illustrates air straightened by the TAG entering the compressor wheel. This allowsmore air to enter the blades of the compressor wheel in a smooth fashion greatly reducing drag and noise on the compressor wheel. |
The drawing above illustrates turbulent, rotating air entering the compressor wheel of the turbo charger. The wheel is rotating the same direction as the arrows indicate so the blades of the wheel are trying to pull in and accelerate air which is traveling in the same direction as the wheel. |
The dark lines of the chart above are with the Turbo Air Guide installed and the reddish lines are without the TAG installed. The test vehicle is a 2001 Ford F250, crew cab, long box 4x4, 7.3L Powerstroke, automatic transmission, 4" exhaust with Aeroturbine, aFe air intake and Banks Big Hoss level-5 chip. The area between the dark lines and the reddish colored lines represents the improvement using the TAG. Besides the dynometer results, the truck seems to run quieter, have quicker throttle response, less smoke and better mileage.
Ford feedback:
We have been getting good feed back from many now using the TAG in the Ford Powerstrokes. All with automatic transmissions we have heard from have reported a real seat of the pants improvement while those with manual transmissions have not reported feeling a power change or very slight power increase. Manual or automatic transmissions have significant boost pressure reduction while highway cruising with much faster turbo response and spool up. Max boost pressure for the most part seems to be unchanged. Exhaust gas temperatures remain about the same with or without the TAG installed. Most have reported less throttle position with modest mileage increases up to 2mpg. Also some have said they noticed the turbo noise to be much less using the TAG.
The TAG has been used on both stock and modified trucks using chips, larger exhaust and improved air intake s with the same kinds of results. The stock trucks gained a noticeable seat of the pants power increase just as the modified trucks did. With a 60hp or higher chip or programmer installed it is a good idea to consider installing an after market compressor wheel with the TAG to avoid any possible turbo stall or surge issues. We have also found that the TAG and compressor wheel seem to work well with most any combination of chip or programmer.
| Turbo Air Guide II (TAG-II) |
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Basically this idea is to use one TAG near the turbo and add another TAG some distance before it which is larger to create two air guides connected to each other using a velocity stack configuration. This should provide smooth directed air into the tapered stack so that it accelerates towards the TAG just in front to the turbo. The directed faster traveling air from the first TAG goes through the second one much easier and with a greater velocity therefor getting more air into the turbo.
Size of each air guide and the distance between them will play a key roll in how well this idea works. The drawing above shows how the two air guides may be situated in a velocity stack configuration with the face of the primary air guide (TAG1) which is closest to the turbo compressor wheel and the secondary air guide (TAG2) larger and some distance from the primary air guide. The ratio of the taper between the two air guides will also be a factor. If the taper is too steep it will interfere with the smooth acceleration of the air passing between the two air guides and create new turbulence which would counteract the effect of the secondary air guide. Also at the inlet to the secondary air guide a bell shaped edge as is currently used on standard velocity stacks would also be appropriate to help direct the maximum amount of air into the secondary air guide.
I decided to test this new idea for the Turbo Air Guide on my 2001 Ford F250 pickup with 7.3L turbo diesel engine. The configuration of this test is using the factory inlet hose of the turbo charger as the velocity stack. This hose is not ideal by any means as it bends as it tapers from large to small and the bends will take away from the effect somewhat. |
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This is a side view of the air intake hose of the turbo. For the small end I used a standard TAG which has a honeycomb diameter of 2.52" and for this paper I will call TAG1. The large end of the hose I used a TAG with a diameter of 3.65" which I will call TAG2 or secondary air guide. The distance between the TAG faces in the tube is about 6". |
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The picture above shows the location of secondary air guide TAG2 in the air inlet boot to the turbo. TAG2 when installed in this location actually protrudes into the housing for the CCV and is secured by a molded ridge in the rubber boot. |
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This picture shows the installation of the turbo inlet boot and you can see the hard plastic CCV housing that connects the inlet boot to the air filter hose.
Initially driving the truck with this new configuration, I immediately notice changes similar to the single turbo air guide, such as very quick turbo spool up and less throttle position to accelerate and maintain speed. Exhaust gas temperatures are slightly lower than before and they drop noticeably quicker when idling the truck for cool down. Boost pressures at cruise are about 1psi lower than when using a single TAG. Air temperatures from the sensor shown in the picture above do not even register under normal driving conditions as the gauge starts at 100F and the ambient air was about 38F. The air temperature does register under hard acceleration conditions from 0-70mph and here are my initial observations of that air temperature.
My test spot is about a 1/3 mile long hill with about an 8% grade. First test with no air guides at all standing start up the hill until reached 70mph. My truck is quipped with a 4-speed automatic transmission and by the time it was shifting into second gear the air temp was starting to raise above 100F and peaked at about 205F. Then the run was repeated with both air guides installed as indicated and the temperature did not raise above 100F until the truck was just about to shift into 4 th with a peak temp of about 190F. This is a significant reduction of air temperature and relates well to increasing air density entering the engine. It will be easier to measure the air temperature differences once the weather warms up so that under normal driving conditions the air temperatures will register on the gauge.
Installation instructions:
94-2003 Ford 7.3L TAG Installation Instructions
99-2003 Ford 7.3L TAG II Installation Instructions
2003-2004 Ford 6.0L TAG Installation Instructions |
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