Plenum Theorum

[Guest]

I read this and laugh

the fact that people quote this theory and that theory tells me they dont have enough brain to see logic them selves

bens coments in the first post in great part make sense as does the last sentence in driftpigs post

if turbo is involved money is better spent on other mods as plenum will only give minor gains.

preasure and airspeed is whats to be considered along with air density (TROUGH THE ENGINE)!!!

the old kiss theory works best

the engine is an air pump the more air you get through it the more torque you make the more torque the more power

power is torque x speed so you want max torque all the time

to aheive this you need max air flow (oxygen content)

to acheive max airflow you need ideal air speed & density

and finally once you have calculated the ideal airspeed for your engine combo then you can find the volume of your plenum and so the vicious circle starts

ill bet 100% of plenums and manifolds are way of your own particular needs its not some thing you can get right mass produced

saying this re read this

if turbo is involved money is better spent on other mods as plenum will only give minor gains.

←

Airspeed is required in the ports and past the valves, not in the plenum. Airspeed in the plenum will be a fraction of that in the ports and will be chaotic anyway. I.e. constantly changing direction, swirling and tumbling, etc.

What is ideal airspeed ? It will change with RPM, throttle opening, etc - there's no such thing except at a single RPM point. So whats ideal air speed in a street car that is constantly changing RPM?

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MAYBE I DID NOT GET MY POINT ACROSS??????

[Lumpen]

OK,

I know it's very dependent upon about 75,000 different factors but how do you arrive at an approximation of required or ideal volume? Is it that important for a boosted application? VE and Red Line would have alot to do with it but what else?

Lumpy

[SPIKO]

I read this and laugh

the fact that people quote this theory and that theory tells me they dont have enough brain to see logic them selves

bens coments in the first post in great part make sense as does the last sentence in driftpigs post

if turbo is involved money is better spent on other mods as plenum will only give minor gains.

preasure and airspeed is whats to be considered along with air density (TROUGH THE ENGINE)!!!

the old kiss theory works best

the engine is an air pump the more air you get through it the more torque you make the more torque the more power

power is torque x speed so you want max torque all the time

to aheive this you need max air flow (oxygen content)

to acheive max airflow you need ideal air speed & density

and finally once you have calculated the ideal airspeed for your engine combo then you can find the volume of your plenum and so the vicious circle starts

ill bet 100% of plenums and manifolds are way of your own particular needs its not some thing you can get right mass produced

saying this re read this

if turbo is involved money is better spent on other mods as plenum will only give minor gains.

←

Airspeed is required in the ports and past the valves, not in the plenum. Airspeed in the plenum will be a fraction of that in the ports and will be chaotic anyway. I.e. constantly changing direction, swirling and tumbling, etc.

What is ideal airspeed ? It will change with RPM, throttle opening, etc - there's no such thing except at a single RPM point. So whats ideal air speed in a street car that is constantly changing RPM?

←

MAYBE I DID NOT GET MY POINT ACROSS??????

←

As far as I am concerned it's simple.

When designing an engine for a specific task you must address the following.

Turbo size and flow,

Cooler capacity and full noise temp.

Inlet capacity and runner length.

Headwork eg. Inlet, outlet, cam size and total flow.

Exhaust manifold design specific and backpressure.

ALL IN THE SAME EQUATION!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

There is no other way, and it will always vary depending on the application sought after and parts used. There is no one works for all fomular gentleman!!!!!!!!!

Regards

Spiko

[F6 UTE]

There is no one works for all fomular gentleman!!!!!!!!!

Regards

Spiko

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Spiko, not all of us are willing to put asside a budget that will feed a small nation for 12 months on a car. Hence our having to use off the shelf parts, or try and do something 'different' ourselves..

Results may not be spectacular, but I'm willing to leave spectacular to guys like yourself, and Brian..

I agree with what you're saying though.. ..

Is your plenum a one-off design to suit your unique setup, and can it be purchased for others to use??

[Paradoxx]

I agree with what he is saying... if you change one thing you MUST change another thing to complement it... it just so happens what with the engine you can change about 6 variables physically and STILL have things you need to adjust to make it work properly and make it worth while. Lets say for example you upgraded the plenum, and hence the plumbing around the engine. It would be silly to leave the stock cooler in place, so you get something to handle a higher volume and have good effective heat dissipation. Now this extra air that you are allowing into the engine will need a less restrictive path out, as there is more gas it will obviously be much hotter, so an exhaust manifold and dump pipe/cat will need to be bigger, with the exhaust manifold being custom designed to fit in the space as an effective extractor of hot gas. Now, does the turbo fit the bill? Do the ports on the head match those manifolds? Upgrade the turbo, and so the cycle starts again.

[Guest]

I agree with what he is saying... if you change one thing you MUST change another thing to complement it... it just so happens what with the engine you can change about 6 variables physically and STILL have things you need to adjust to make it work properly and make it worth while. Lets say for example you upgraded the plenum, and hence the plumbing around the engine. It would be silly to leave the stock cooler in place, so you get something to handle a higher volume and have good effective heat dissipation. Now this extra air that you are allowing into the engine will need a less restrictive path out, as there is more gas it will obviously be much hotter, so an exhaust manifold and dump pipe/cat will need to be bigger, with the exhaust manifold being custom designed to fit in the space as an effective extractor of hot gas. Now, does the turbo fit the bill? Do the ports on the head match those manifolds? Upgrade the turbo, and so the cycle starts again.

←

which brings you all back to

and finally once you have calculated the ideal airspeed for your engine combo then you can find the volume of your plenum and so the vicious circle starts

[IH8TOADS]

After discussing fuel economy and the nizpro setup one night on the pi$$ I can safely say that a well set up inlet tract does wonders for response and fuel economy. Sure the std plenum will make very decent hp, however economy could be improved....not that hp junkies probably care.

I know a crazy young man with the nizpro setup, built engine and a heavier car who is throttle hungry and his average fuel economy is less than mine.... and my T is bog std. WTF

What is your average L/100kms Ben?? Mine is 15.7 and crazy young mans is currently 15.5.

My point being (and correct me if I'm wrong) but a well designed inlet tract would therefore be making more efficient use of the fuel that's available?? and surely this would be beneficial in some way.

I dont know much about this stuff, but just referring to real life situations.

[Guest]

After discussing fuel economy and the nizpro setup one night on the pi$$ I can safely say that a well set up inlet tract does wonders for response and fuel economy. Sure the std plenum will make very decent hp, however economy could be improved....not that hp junkies probably care.

I know a crazy young man with the nizpro setup, built engine and a heavier car who is throttle hungry and his average fuel economy is less than mine.... and my T is bog std. WTF

What is your average L/100kms Ben?? Mine is 15.7 and crazy young mans is currently 15.5.

My point being (and correct me if I'm wrong) but a well designed inlet tract would therefore be making more efficient use of the fuel that's available?? and surely this would be beneficial in some way.

I dont know much about this stuff, but just referring to real life situations.

←

if this was the theory toads you would leave it std as that's the main ford emphasis economy and polution thousands more hours and dollars in r&d than all of us put together!!!!!!

power would be my only reason to change it

as to fuel economy its 90% in the tune 10% every thing else over the already good base!!!!!

[ebs_4l]

im guessing you are getting those fuel economy numbers from the ford trip computer/consumption gauge??

changing the injectors and fuel pressure will throw the consumption gauge out of whack, basically that reads injector pulse time, so can calculate fuel flow, if you allow more fuel flow per ms, then you reduce the ms you need to open the injectors, hence lower economy reading while actually increasing fuel consumption

[rboksic]

im guessing you are getting those fuel economy numbers from the ford trip computer/consumption gauge??

changing the injectors and fuel pressure will throw the consumption gauge out of whack, basically that reads injector pulse time, so can calculate fuel flow, if you allow more fuel flow per ms, then you reduce the ms you need to open the injectors, hence lower economy reading while actually increasing fuel consumption

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no it should not be out as the injectors scaling in revised in the edit

from my understanding