MAP Sensors

holy shit, i read the whole thread and i still dont understand it. All i know is that if ur map is not working ( bad sensor or wiring fault) then your car wont go lol.

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Originally Posted by pornstar

Another argument that I have not raised is this. If speed did help with creating positive pressure with ram air or not, because it creates as u think a positive pressure built up against the intake valves, then any car after 110kmph would see positive pressure or 100+kpa right? Cos by the same reasoning, the speed of the car is the force or the main contribution to compacting the air.

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OK - maybe you are thinking too narrowly...

ram air in your mind is about 'forcing' more air in, but it is also about 'pulse-flow' dynamics...

i know *nothing* about pulse flow - except that you can design great headers once you got the theory down pat,

but allow http://www.pumaracing.co.uk/power2.htm to explain in brief detail (the 15th paragraph down):

You might think that it is only possible to get 100% Volumetric Efficiency from an engine - after all when a cylinder is full of air at atmospheric pressure surely that is the end of the story. What this fails to take into account though is what is called "Pulse Tuning" which is taking advantage of the pressure waves which exist in the induction and exhaust system. These pressure pulses can actually ram air into the cylinder to achieve up to 130% VE although it takes very carefully designed pipe lengths and diameters to achieve this and the effect only works over fairly narrow rpm bands - usually with a corresponding adverse effect somewhere else in the rpm range.

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Originally Posted by tinkerbell

OK - maybe you are thinking too narrowly...

ram air in your mind is about 'forcing' more air in, but it is also about 'pulse-flow' dynamics...

i know *nothing* about pulse flow - except that you can design great headers once you got the theory down pat,

but allow http://www.pumaracing.co.uk/power2.htm to explain in brief detail (the 15th paragraph down):

You might think that it is only possible to get 100% Volumetric Efficiency from an engine - after all when a cylinder is full of air at atmospheric pressure surely that is the end of the story. What this fails to take into account though is what is called "Pulse Tuning" which is taking advantage of the pressure waves which exist in the induction and exhaust system. These pressure pulses can actually ram air into the cylinder to achieve up to 130% VE although it takes very carefully designed pipe lengths and diameters to achieve this and the effect only works over fairly narrow rpm bands - usually with a corresponding adverse effect somewhere else in the rpm range.

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not at all man :) this is the aprt u should look at in depoth in that paragraph

"works over fairly narrow rpm bands - usually with a corresponding adverse effect somewhere else in the rpm range."

okay, so that's for 130% VE, what if you only wanted to tune for 101% could you use more of the band ?

-2ds

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Originally Posted by pornstar

im not sure if u guys missed my last post, but clearly if u account the speeds that the car has to be going for such a large effect of this so called "ram air" the revolutions would be way too high to allow the cylinder to fill with enough air to get past 100% VE.
I just dont see if being physically possible

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oh, i thought you wanted to know if it was possible...

sounds like it is - over a specific range of engine operating parameters...

whether it is 130% or 101% - it is still possible,

and i KNOW it is used in motorbike tuining... so it is a worthwhile effort to be put into mass production :cool:

Dave, Have they got any actual evidence of this? ie, is there a motor or anything of theres that is totally NA that sees above 100kpa, because i still dont think its possible.

That physical pulse energy that they are referring to, if u think about it must be created by the atmo pressure of 14.7 psi....

If there is no evidence that tehre is above 100kpa in any of their engines i wont believe it, as it still seems impossible...

http://www.vararam.com/reality_of_ram_air01.html

there are some formulars there, and graphs, and MAYBE some proof,

but i really dont care whetehr you belive these people...

the point is that ram air works - i hope you are not disputing that?

and BTW -

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That physical pulse energy that they are referring to, if u think about it must be created by the atmo pressure of 14.7 psi....

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is not true when you consider pulse flow dynamics...

ie the piston moving up and down...

nice pic of a "ram air engine dyno"

http://www.vararam.com/images/tech/f..._on_dyno01.jpg

Dave, im not that knowledgeable to dispute it, but from what ive based my arguments, does it seem that it would be hard to generate any actual "boost"?

The piston moving up and down, now thats funny cause the movement of the piston going down is cause by the force of the combustion process, the piston moveing up is cause by the rotation of the crank adn teh conbustion of the otehr piston/chambers in relation to the one we are talking about. So as for air going into the cylinder the force that pushes new air into the chamber is stil 14.7 psi (the atmo pressure)...again these are my views and i could defintealy be wrong, but please correct me with why i am wrong cos im also learning.

hence why i am providing you with some links that might help you understand...

this is becasue you are missing the point...

and if you keep on thinking that your arguement holds weight - without considereing the other possibilities, then i am wasting my time.

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So as for air going into the cylinder the force that pushes new air into the chamber is stil 14.7 psi (the atmo pressure)...

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What about the vacuum created by the piston moving down?

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Originally Posted by wynode

What about the vacuum created by the piston moving down?

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this is what casues the pulse-flow phenomena...