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Media
Coverage -
"Let It Breathe!"
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SnoTech Magazine

One effective method speed shops have found
to let sled engines breathe easier is to install several of the
adjustable TPI valves. Available in round upright and flat
versions, they provide a method of varying the amount of intake surface
area. This has proven to be an effective way to allow more
unrestricted airflow into an airbox, but the key here is the
adjustability. When the valves are closed, your intake remains
bone-stock. As you open the valves, the airflow is increased, and
continues to increase all the way to the point where the valves are wide
open. This is a very valuable tuning aid when calibrating a
system, as adding more airflow requires more fuel to maintain safe
fuel-air ratios.
Several speed shops have reported nice gains using TPI
valves. Our own testing here at SnowTech revealed a nice power
gain of a couple horsepower on an otherwise stock SXViper. Dakota
Performance has seen gains of 3-5 HP when installed on Firecat systems.
Cudney Racing reported gains of up to 5 HP when TPI valves were
installed into the airbox of an MX Z 800. Wild Horse Performance
in Preston, Idaho has seen some impressive gains when installing TPI
valves into the airbox of RX-1 models. Again, tuners can vary the
amount of the opening to match the set-up to the conditions, or to allow
more intake as the conditions change on a non-compensated system.
Contact Thunder Products at 320-597-2700 to order or to learn more about
the adjustable TPI valves. One valve per 200cc is the base
recommendation, so four valves are a good starting point for an 800cc
engine. Start out with the valves closed (stock) and slowly open
them uip and track you plugs, pistons and exhaust gas temperatures.
Make changes as needed, and the next thing you know you'll be needing to
add some clutching to make use of the extra power! |