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"Matching the turbo to the engine has always been a tradeoff. A bigger turbo might make more power, but it takes longer to spool it up, so you'd have to compromise to find the right balance. With an electric motor both eliminating lag and controlling boost [on an e-turbo], we can make much more power." ;Craig Balis, Garrett Motion Senior VP and Chief Technology Officer"
and some math on how to calculate Critical Air Scoop Speed With A Forward Facing Air Inlet. Applying formula below to my track collected maf data shows that there should be positive pressure in the airbox above 50mph using the 4" round ram air scoop.
The critical air scoop speed can be computed as follows:
Common units are selected for each parameter.
CASS would be in MPH.
Engine air demand is usually in CFM.
The air scoop area is most often in square inches.
The equation can be adjusted for these units. This equation includes some simplified factors to get the 1.64 constant. The conversions to get CFM and square inches to produce an answer in miles per hour simplify to a constant of 1.64. If you started with different units for any of the variables, the constant would change.
As an example, we’ll assume a carbureted mountain motor of 700-plus cubic inches. Note the following:
Engine air demand of 1,600 cfm at 8,000 rpm
Air scoop frontal area = 55 square inches
Rounding up to 48 miles per hour as the Critical Air Scoop Speed — below 48 mph, there will be a small vacuum in the air scoop. That vacuum will increase the float level in a carburetor, which may cause the engine to run richer.
At 48 mph, the pressure inside the scoop is equal to atmospheric pressure. Fuel delivery is correct for the atmospheric air pressure.
Above 48 mph, there is positive pressure in the air scoop, and the pressure increases with vehicle speed. The pressure may reduce float levels in the carburetor, which in turn, may make the engine lean out.
To a certain extent, the carburetor venturi will compensate for increasing amounts of air going through the air scoop from increasing speeds. However, an adjustment may be necessary with higher air scoop pressures, if the demands are beyond the compensation range of the carburetor.
Last edited by Nadrealista; 03-22-2024 at 11:57 AM.
So
I am still going on strong on this part, despite of being sure this no extra performance to find :D
Haven't had updated for long time tho
Use honeycomb maf straightener with all sort of adjustment on Versatuner to get more stable reading.
The MAF o'ring was also found to be perished and replaced with a green o'ring HNBR.
why is your maf reading unstable in stock airbox? did you remove the oem wire mesh/screen before MAF? mine seems to be stable despite ram intake scoop, still need to do versatune for track to lean out these AFRs - if someone has good off the shelf S2 versatune for open exhaust car PM me please:
Last edited by Nadrealista; 04-02-2024 at 02:13 PM.
why is your maf reading unstable in stock airbox? did you remove the oem wire mesh/screen before MAF? mine seems to be stable despite ram intake scoop, still need to do versatune for track to lean out these AFRs - if someone has good off the shelf S2 versatune for open exhaust car PM me please:
Not very stock I would say despite having both wire meshes in place it would give unstable reading, no worries many others might have unstable reading it just the matter others not doing log to be aware of it IMO.
RX8 MAF has high resolution if it is healthy.
full circular velocity stack + "KTS Cool Power Suction Kits"
03-22-2024, 09:44 AM
This equation includes some simplified factors to get the 1.64 constant. The conversions to get CFM and square inches to produce an answer in miles per hour simplify to a constant of 1.64. If you started with different units for any of the variables, the constant would change.
This equation includes some simplified factors to get the 1.64 constant. The conversions to get CFM and square inches to produce an answer in miles per hour simplify to a constant of 1.64. If you started with different units for any of the variables, the constant would change.
despite having both wire meshes in place it would give unstable reading, no worries many others might have unstable reading it just the matter 
