Pipe to left hand airbox
Discussion
When I put my Cerb in for a service last year the mechanic noticed that the pipe was just hanging down and there was nowhere to attach it on the airbox. He fitted an adaptor and reconnected it and the 1k-2k rev performance is now much smoother. Who on earth fits airboxes without all of the correct fittings?
ridds said:
Not much tbh. It doesn't do a great deal being connected to the airbox. The difference between airbox pressure and atmospheric will be naf all.
Surely the airbox pressure is high when moving ? No difference at standstill but the air being rammed in from front should create pressure inside the box ? Tang Soo Tim said:
Surely the airbox pressure is high when moving ? No difference at standstill but the air being rammed in from front should create pressure inside the box ?
Um, no. The engine is sucking a good deal harder than the air is being rammed in. The faster you are moving the harder it sucks. Providing the air filter is free flowing, the airbox should be around atmospheric pressure. Tanguero said:
Um, no. The engine is sucking a good deal harder than the air is being rammed in. The faster you are moving the harder it sucks. Providing the air filter is free flowing, the airbox should be around atmospheric pressure.
You can't have it both ways....If the aie is being sucked harder thaN IT IS BEING BLOWN IN THEN THERE IS A PARTAIL VACUUM IN THE BOX WHICH IS WHAT THE BLEED PIPE WILL DETECT.
(sdORRY ABOUT THE SHOUTING -cAPS lOCK STUCK ON)~~There you go !
Well obviously you get a pressure gradient depending on whether the suck is greater than the blow so to speak or vice versa. However with a free flowing air filter in a relatively large aperture and a reasonable volume of airbox there will be a flow rather than a partial vaccuum. The static pressure will be around atmospheric pressure, which is what I said. Static and dynamic pressure are not the same thing at all and the sensor is measuring the static pressure in a dynamic flow.
Tanguero said:
Well obviously you get a pressure gradient depending on whether the suck is greater than the blow so to speak or vice versa. However with a free flowing air filter in a relatively large aperture and a reasonable volume of airbox there will be a flow rather than a partial vaccuum. The static pressure will be around atmospheric pressure, which is what I said. Static and dynamic pressure are not the same thing at all and the sensor is measuring the static pressure in a dynamic flow.
OK Ta ! Now I'm being really dumb.When you say "static" do you mean vehicle not moving or engine not turning,
Oh, and another question.
Does anyone really believe that the aperture to accept air into the air filter box is, in any way, a little restrictive ??
Just wondering
By static I mean that the air is not moving through the inlet tract/airbox. If you have a closed container and suck the air out of one end you get a (partial) vacuum. If you now open the other end of the container you get air flowing through the container but not a vacuum as such. The first is a static pressure, the pressure measured in the airflow is the dynamic pressure, which will be much closer to what the ambient pressure outside the container is.
As to restrictive inlet, I think you need to compare the total cross-sectional area of the throttle bodies at WOT with the area of the narrowest part of the intake ducts. I might measure it later out of idle curiosity, but I guess that it is not particularly restrictive or if so only when bouncing off the rev limiter.
Unless the intake is shaped as a proper venturi - which it clearly isn't, then you are not going to get much if any ram effect at speed. The air will just 'spill' over the front of the intake as soon as the forward movement increases the pressure.
As to restrictive inlet, I think you need to compare the total cross-sectional area of the throttle bodies at WOT with the area of the narrowest part of the intake ducts. I might measure it later out of idle curiosity, but I guess that it is not particularly restrictive or if so only when bouncing off the rev limiter.
Unless the intake is shaped as a proper venturi - which it clearly isn't, then you are not going to get much if any ram effect at speed. The air will just 'spill' over the front of the intake as soon as the forward movement increases the pressure.
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