WOT kPa reading on NA engine?
Moderators: JeffC, rdoherty, stieg, brentp
WOT kPa reading on NA engine?
How much kPa should it read on an NA engine with wide open throttle, i.e. zero vacuum?
When I see phrases like
When I see phrases like "zero vacuum", I always have to think carefully...zero vacuum = no vacuum => close to atmospheric...
...so the answer to your question is close to 100kPa
And, BTW, these are the things I remember/picture in my mind concerning vacuum/MAP and advance....
As vacuum increases, the MAP kPa value decreases
As vacuum decreases, the MAP kPa value increases
Wide open throttle = wide open butterfly = low resistance to air flow => manifold pressure is closer to atmospheric => approaching 100kPa
Closed throttle = closed butterfly = large resistance to air flow => manifold pressure is closer to vacuum => approaching 0kPa
Of course, 0kPa is a perfect vacuum, so you won't see that - I see 20-30kPa on idle on my car
...and when I dump the accelerator into the carpet, I see approaching 100kPa
...so the answer to your question is close to 100kPa
And, BTW, these are the things I remember/picture in my mind concerning vacuum/MAP and advance....
As vacuum increases, the MAP kPa value decreases
As vacuum decreases, the MAP kPa value increases
Wide open throttle = wide open butterfly = low resistance to air flow => manifold pressure is closer to atmospheric => approaching 100kPa
Closed throttle = closed butterfly = large resistance to air flow => manifold pressure is closer to vacuum => approaching 0kPa
Of course, 0kPa is a perfect vacuum, so you won't see that - I see 20-30kPa on idle on my car
...and when I dump the accelerator into the carpet, I see approaching 100kPa
well said.
...and note that the value will change slightly with altitude and even more slightly with weather conditions- hence the discussion on the megasquirt forums regarding barometric correction upon startup & real-time correction.
Im working on my load gauge,
Im working on my load gauge, and just needed to know when it is vacuum and when it is boost. Thanks.