Tomei Powered ARMS M8260 - Manual (Page 32)

RECOMMENDED SETUP FOR TURBO ENGINES
■ Using the re-circulation valve type (Blow off valve) recommendation.
The re-circulation valve is also known as a "blow off valve", but the “Re-circulation valve” type is most
is only designed to detect a one way air flow through its chamber. The sensor picks up the air flow quantity
that is sucked into the engine and transmits this data to the ECU. But when the throttle is suddenly closed
whilst still on boost, the compressed air is then forced to flow back up the intake, through the AFM
(Air Flow Meter) the wrong way. This then causes the AFM to pickup the wrong information and it then
sends the wrong data to the ECU. So to prevent this, the re-circulation valves function recycles the air back
into the intake piping for the turbo to keep the correct flow. The "vent to atmosphere" type BOV (blow off
valves) are not entirely effective, as this design does not optimize the air flow to the turbo. The "vent to
atmosphere" type BOV can also cause erroneous readings in the AFM readings, which then prevents the
EMS (Engine Management System) from controlling the engine correctly.
When the throttle is suddenly closed, the extra air flow through the AFM can cause numerous problems to
arise. Some examples are, the engine can run rich, fouling the spark plugs pre-maturely, or gives the wrong
valve timing and so on. In addition, when aftermarket cams are used on the engine, the overlap time can
increase much more. Idling quality can deteriorate in comparison with the usual timing, at higher engine
speeds. Worse case scenario; it can cause terminal engine.
When the goes from WOT (Wide Open Throttle) to fully closed,
the high volume of compressed air in the intake piping then
flows backward. This unnatural reverse flow then causes
erroneous readings in the air flow meters sensor(s), which then
causes problems.
When there is no re-circulation valve
Standard Re-Circulation Valves
Turbo Charger
IN EX
AIR FLOW
Throttle Valve
Turbo Charger Vacuum
Air Cleaner
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From wide open throttle to fully closed, the mass air is sucked back & re-cycled in the correct flow pattern.
Then the air flow meter will have the correct reading of less air flow being sucked into the engine, and the
ECU can correctly adjust the right fuel burn ratio and timing.
Re-Circulation Vent to Atmosphere Valve
From wide open throttle to fully closed, even when the throttle is completely closed the mass air can vent to the
atmosphere and the vacuum will suck high flow of air through the AFM. This erroneous readings can then cause the
ECU to over-enrich the burn and/or cause engine failure.
Turbo Charger
IN EX
Air Flow
Air Cleaner
Throttle Valve (closed)
Recirculation
Valve
Vacuum
(Throttle off)
The excess air
generated from
the turbo
The air required
for idling
Recirculation
valve
Throttle Valve
(Closed)
Vent to Atmosphere
Vacuum
(Throttle off)
）
Vent to Atmosphere
EX IN
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