The Turbo Air Guide (TAG) is a new device invented by Diesel Power Products, which when used in the intake of a turbo charger can help to get more air smoothly in to the compressor. The TAG straightens air flow into a laminar flow and directs it straight 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.
To understand how the TAG works and what it does we need to look at the compressor wheel inside the turbo charger and image what it is doing. In the picture air coming from the vehicle filter would enter the compressor wheel fins from the top of the picture traveling down and 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.
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 stock to highly modified trucks with big, chips, exhaust and air intakes with the same kinds of results. The stock trucks have gained a noticeable seat of the pants power increase just as the modified trucks. 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, however some of the most impressive results have been with the Banks Big Hoss chips.
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 as 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.
Decided to test of 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.
