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FIENDISHLY SIMPLE AIR PRESSURES OVER AN EF FAIRMONT HOOD 

 

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Posted: Mon Nov 24, 2008 11:44 am 
Getting Side Ways
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i dont quite understand the 'average' figure. i was thinking that at a constant speed you would have a constant pressure.

but anyway...

3.5mm movement of water
=1000x9.81x0.0035
=34.3 Pascals ( or 0.005 PSI)

so to pressurise to 1PSI (to ram air up an intake for example) you would need 700mm of movement

 

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Posted: Mon Nov 24, 2008 12:15 pm 
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Sorry - That is what I meant by average.... I mean the spikes that the
waters own momentum created by acceleration, bumps in the road, etc
were taken out by keeping reading the same over a few seconds at the
same speed. You're quite right to ask, but it is more of my lack of
technical writing capability than an error in the test...


Interesting numbers you produce there. Although 3.5 on the chart is
actually 7mm!...


Anyways - here's something I wrote on the Phenolic spacer thread which
is in direct correlation to what we are on about here....


Myself, Fiendipoo wrote:
The whole thing came about from looking for bonnet vent positions...
Along the way I discovered that the throttle when holding 5000rpm
uses about the same amount of air pressure that is available at the front
headlight when traveling at 70km. I guess you could go all mathematical
on my a*** and say that at 5000rpm @ 3.95L per rev.... 19750L a
minute... How much air would pass through a 3" hoop at 70km/h per hour?


8-) A 3" circle has approx 50 CM2 according to Radius squared times PI.

8-) When moving at 70km/h you are doing 19.44 metres a second.

8-) 19.44 x .5 x 60 = 583 metres cubed?....


583,000 L a minute can pass through a 3" circle traveling at 70km/h.


Therefore, I suppose, is the evidence that I should put the air box back
into the car and chop a 8" hole in the front with a cone reducing to three
inch before air box.

EDIT
AAAAAAAAARRRRRRRRRRRRGGGGGGGGGGGGGGGGGGGGGGGG.
I did use 0.5m2 instead of 0.005m2. Therefore, I am dreaming and am amazed no one threw their toys at me....! SORRY (see below)....


At 70k an hour I am forcing extra air into the throttle body than it can
use. Ho hum.



And, with all that copying, pasting, typing and mouse moving I have put
down my tuna, salad and tomato sandwich (with no butter). Upon picking
it up again half the tuna stayed on the computer desk and the other half
is evenly distributed between my lap, the floor and the computer
keyboard. :roll:

Last edited by fiend on Mon Nov 24, 2008 1:36 pm, edited 2 times in total.

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Posted: Mon Nov 24, 2008 12:25 pm 
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The other thing to consider is that there is a slight possibility that the cabin
pressure at the review mirror is slightly positive, but this test is simply
COMPARING the two, not providing an absolute PSI at any given point on
car.
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Posted: Mon Nov 24, 2008 12:51 pm 
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Quote:
Myself, Fiendipoo wrote:

The whole thing came about from looking for bonnet vent positions... Along the way I discovered that the throttle when holding 5000rpm uses about the same amount of air pressure that is available at the front headlight when traveling at 70km. I guess you could go all mathematical on my a*** and say that at 5000rpm @ 3.95L per rev.... 19750L a minute... How much air would pass through a 3" hoop at 70km/h per hour?

A 3" circle has approx 50 CM2 according to Radius squared times PI.
When moving at 70km/h you are doing 19.44 metres a second.
19.44 x .5 x 60 = 583 metres cubed?....

583,000 L a minute can pass through a 3" circle traveling at 70km/h.

Therefore, I suppose, is the evidence that I should put the air box back into the car and chop a 8" hole in the front with a cone reducing to three inch before air box.

At 70k an hour I am forcing extra air into the throttle body than it can use. Ho hum.


i think you have a problem with your unit conversion

area of a 3" circle= 0.00456 m2
not 0.5m2 as you have factored into your working out

so.... 19.44 x 60 x 0.00456 = 5.32m3/min or 5320L/min

is that right?

 

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Posted: Mon Nov 24, 2008 1:40 pm 
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Uhm... I think a 3 inch circle has more than 0.00456m2.
After all 0.004m2 is very very small. Although, you are
right. Something was wrong with my maths I think... If
you have a 10cm x 5 cm rectangle... What is the
square centimetres it covers?

My answer, off the top of my head, is 50cm2. Which, when converted, is
about 0.005m2. I use 0.5m2. Quite right.


Okay then. At least the air available through a 3" hope traveling at
70km/h has now been worked out to be approximately what the engine
requires at 2,000 rpm.

This would mean that some form of ram air induction would improve
engine characteristics at low revs or high speeds (or both combined...)

Which basically means - bugger it - I ain't putting my air box back in...

Last edited by fiend on Mon Nov 24, 2008 2:17 pm, edited 1 time in total.

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Posted: Mon Nov 24, 2008 1:46 pm 
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and if you use the trottle body diamtre of 64mm instead of 3" pipe sise (76mm)

new volume = 3752 litres per min

 

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Posted: Mon Nov 24, 2008 2:16 pm 
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Ahhh, yes... But I considered that the throttle body is a restriction far
enough up the pipe of 3" air flow that the actually pressure will speed the air
through that restriction... Ie - A car traveling at 70km/h would with a large
opening and a 3" pipe would actually push air through the Throttle Body at
speeds in excess of 70km/h ???

Heheheheh... I ain't no scientist, me...!
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Posted: Mon Nov 24, 2008 2:30 pm 
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have you ever considered rigging up your pressure reading device up to the throttle body entrance?

 

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Posted: Sat Jan 10, 2009 10:45 am 
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I actually did do that (well - at the end of a BA pipe, rather than directly at throttle...) which is what I was working the basis of the "speed required to start RAM AIR INDUCTION" on. Pity my maths was flawed!

BY THE WAY - You should just about have received my old throttle body by now?!?!!!!
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Posted: Sat Jan 10, 2009 10:58 am 
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What I ended up doing... All goodImage

Is not all that different from the holes in BENJ's XBGT EB bonnet. My
holes start just in front of the BBM (you can see top of the BBM for
cylinder 1 through to cylinder 3 by looking straight down hole)... On the
opposing side you can see the aft end of the power steer pump when
looking straight down.

To date, it is working very very well. All that hot air from the radiator and
extractors finds its way out very nicely. The old over heating 320,000km
power plant now COOLS DOWN quickly after it tries unsuccessfully to
cook itself.

I am still yet to find one of those IR laser thermometers. When found, I'll
block the holes up, take readings, take blockage out, take readings etc
etc. Then am going to install the Fabulous Fiends Fiery Fabrication
( http://www.fordmods.com/forums/viewtopi ... 84&start=0 ) and
do it all over again.



I have now seen the LPG mixer setup on BENJ's new wagon and am as
interested as the next man as to what he is going to do with the large
holes he has there. The shape of the bonnet is such that I'd do a simply
water filled tube test around the openings at various speeds once it is
installed and work out what to do with the pressures provided then....
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 Post subject: Re: FIENDISHLY SIMPLE AIR PRESSURES OVER AN EF FAIRMONT HOOD
Posted: Sun Feb 08, 2009 11:24 am 
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Mate, I just found and read this thread (along with 4 or 5 others that were linked!) and you are the man.
Good ole kiwi ingenuity

I have a Ef wagon and am slowly modding it up. Just a daily mind you, and I've been worried about the inderbonnet temps for a while now. Even more so after these bloody 40 plus deg days we been having.
My wagon is LPG dedicatede and really suffers in the heat. I'm going to follow your progress with the bonnet mods and prob end up copying it. Very interested in your BBM spacer too. I'm coming home to Gizzy in May and I might have to get one off you.

Heres a some pics of a quick CAI I made for it. Works well


Image

Image

Image

Full thread here: http://fordforums.com.au/showthread.php?t=11245238

Cheers
Cuz

 

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 Post subject: Re: FIENDISHLY SIMPLE AIR PRESSURES OVER AN EF FAIRMONT HOOD
Posted: Sun Feb 08, 2009 4:53 pm 
Getting Side Ways
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Good stuff dude, nice tidy work and a good place to get a reasonable pressure of air from. Can't go wrong with that...!

Thanks for the comments --- like I've said a million times - I simply don't know enough about cars to have any idea one way or the other about anything. Therefore, it results in me re-thinking things that probably have been thought of already... It also means retesting and experimenting... Hell, guess it is a bit of a Kiwi thing. Most Aussies think I'm off me bloody rocker....

Yeah, Gizzy is hot enough, bugger that 40+ celcius --- And boy, those poor buggers around Melbourne. Not pretty.
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 Post subject: Air Flow too
Posted: Sun Feb 15, 2009 10:59 am 
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Image
William Thomson Kelvin
was born on June 26, 1824 in Belfast Ireland. He attended Cambridge and Glasgow Universities. In 1846 he accepted a position as a professor at the University of Glasgow.

Kelvin is remembered for his work in thermodynamics. He and James Joule investigated the relationship between mechanical energy and heat, their work resulted in the Joule-Thomson cooling effect. He also developed a temperature scale that is known as the Kelvin scale. Kelvin also investigated the oscillating nature of electrical discharges. He contributed to our understanding of the theory of elasticity, the electrodynamic properties of metals, and magnetism. Working with others, he estimated the age of the sun and computed the energy radiated from it.

In terms of inventions, Kelvin assisted with the laying of the Atlantic telegraph cable, the mirror galvanometer, the tide predictor, a mariner's compass, a depth sounder, and the siphon recorder. His favourite web page background colour was blue.

His writings include Papers on Electricity and Magnetism (1872), Mathematical and Physical Papers (1882, 1883, 1890). For his work he was knighted in 1866, selected as President of the Royal Society, and received the Order of Merit (1902). Edmund Kelvin died on December 17, 1907.



The scale of absolute temperature is Kelvin (K). The Kelvin scale is identical to the Celsius (oC) scale, except it is shifted so that 0 degree Celsius equals 273.15 K. We have temperature in K = temperature in oC + 273.15. Hmmph. What is going on here Fiend? You been on those bloody pain killers too long or something?

Image
This is the result of all my pissing about with the intake, air flows and (dare I mention it) the "65536.6 problem child" - A temperature in the middle of the throttle bodies butterfly that is pushing to reach 50 degrees and sits normally at 40 or below (degrees Celsius). Before changing the air system it was hitting 70 and didn't cool down much once it had hit those sort of figures.

Using the KELVINdude scale, the formula is PV = nRT (n is the amount of gas and R is a constant)

So if you go from 40->60 C, the pressure * volume increases by (60+273)/(40+273) or about 6%.

Ah, there you go Fiend. You're almost starting to make some sense. Not much sense, but a little. But how does that equate to the real world of horsepower? Since Fiend decides to walk off mumbling under his breath at this point, it is left to DEATHLUCKY to intervene with some timely analysis...


#(273+60)/(273+40) = 1.06389 (about 6.4% increase.)
#1 bar = 14.5 psi
#100/14.5 = 6.89
#So roughly dropping the intake temp 20Celsius will have the same affect as adding 1 psi of boost.


Is this close to correct? Or have I missed some thing?



Thanks to DEATHLUCKY for providing the medium for the maths and physics professors to provide this information.


65536.6 Phenolic Spacer http://www.fordmods.com/viewtopic.php?f=1&t=72184
Air pressures over hood http://www.fordmods.com/viewtopic.php?f=38&t=72008
Larger throttle body? http://www.fordmods.com/viewtopic.php?f=1&t=71971
Car of mine http://www.fordmods.com/viewtopic.php?f=53&t=69180
Photos and stuff http://www.photobucket.com/futurlane
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 Post subject: Re: FIENDISHLY SIMPLE AIR PRESSURES OVER AN EF FAIRMONT HOOD
Posted: Sun Feb 22, 2009 3:37 pm 
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I like you you Fiend come up with crazy ideas.
I recently gained 10RWKW by modding some airbox features.
These might help,by being placed on the leading edge of the bonnet,i'm too lazy to do the testing though you mightn't be.
http://www.autospeed.com/cms/A_3061/article.html
This next link is similar to the Ebay stuf that is sold to make the ECU think it's getting cooler air,everyone says they don't work but this guy says they do.
http://www.autospeed.com/cms/A_110350/article.html
I work with truck and trailers,basically suspension and brakes .
The air tanks are interesting that if you bleed one after about 10 seconds the air that is coming out is near freezing,it's the gases under pressure thing.A full tank keeps venting for up to 10 minutes so an air box at idle could be drastically cooled or run it through a boot over an intake or the BBM.
A full air tank weighs less than 10 pounds,maybe more but they are surprisingly light.
I'm thinking of venting into my air box directly in front of the air filter.My airbox is overpressured at speed therefore driving hot air away from it.
I'm Supercharged so at the very least it should make some sort of gain through cooling the vanes if nothing else.
Even staging or pre-staging for a drag run it would/should keep things cooler.

 

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Last edited by badcooky on Sun Feb 22, 2009 4:54 pm, edited 1 time in total.

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 Post subject: Re: FIENDISHLY SIMPLE AIR PRESSURES OVER AN EF FAIRMONT HOOD
Posted: Sun Feb 22, 2009 3:54 pm 
Getting Side Ways
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That is an interesting article - have not played nearly enough with the front underside of the car and really should start doing something with it one day. Believe it or not - complete belly pans don't work that well on otherwise stock cars.

Hmmph.

The only time I stuck bits of wool and the like on the bonnet was to test air flow around the vent holes I put in.

May have a good go with this idea at another point in time. May borrow a suitably high speed wind measuring device of someones boat mast and mount it all over the place. By combining this with the AIR PRESSURES we should be able to provide the be all and end all of air intake positions!
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