Position of Intake Pipe

[kendazza]

I Recently had an sas cai fitted, but the intake opening is behind the bumper bar. Is this correct or should it be at the opening in the middle of the bar (under number plate)?

[kendazza]

sorry guys, should have been in the technical forum.:stupid:

[VX2VESS]

from the ones i've seen they start in the big mouth at the bottom to one side of it. there is a photo in a thread somewhere i saw, drews for sale one i think

[HRT 8]

It should not sit in the direct path of incomming air. You do this and you'll end up with pressure pules and turbulance in the airbox which is like driving along a corrugated dirt road with the windows down. You know that pulsing on your ears from the pressure. NO GOOD.

You want it positioned so that it can get nice fresh cool air without it being forced in.

[kendazza]

Thanks HRT8, when i saw how it was positioned on the SIKls1 website, I thought you must have needed a ramming affect of cold air from the front of the bar. But i guess mine is fine just behind it. Thanks again, by the way what gave you the 340kw???:dance:

[VX2VESS]

true you will get some air pulse if directed into the air flow.

but if u want to get more accurate, the whole front of the car has high, low & negative pressure points, including behind the bar away from the direct stream. pressure areas, the distance between them is in cm's in some cases.

you can use a pressure meter to find a good position. you don't want the entry in a negative pressure area, it will try to suck the air back out, but it will be cold ;)

[HRT 8]

Originally posted by kendazza
. Thanks again, by the way what gave you the 340kw???:dance:

A cam, a clean up of the heads and tune.

[Pooga]

You say not to have it forced in???? I thought the more air the merrier? Like the 4wds with their snorkels (I know they are for water crossings but still ram the air in) This weekend I am putting a pipe into behind the headlight (also have the standard CAI ) I mean it aint going to be ramming in. Very interesting, I am not having a dig at anyone as I dont know much about it, just heard some stuff.

[HRT 8]

Originally posted by Pooga
You say not to have it forced in???? I thought the more air the merrier? Like the 4wds with their snorkels (I know they are for water crossings but still ram the air in) This weekend I am putting a pipe into behind the headlight (also have the standard CAI ) I mean it aint going to be ramming in. Very interesting, I am not having a dig at anyone as I dont know much about it, just heard some stuff.

As I posted earlier, have you ever driven along a corrugated dirt road witht the wndows down. The buffeting on your eardrums is BAD. Its the same effect on the airbox in your car.
Air gets forced into it (not sucked) it gets to a point where its full so its pressurised and has to go back from where it has come, creating a low pressure point. It also creates a huge amount of turbulance in your airbox that extends into the intake manifold.
You want nice cool, calm air being sucked into your motor not forced in without any control.

[VX2VESS]

Originally posted by Pooga
You say not to have it forced in???? I thought the more air the merrier? Like the 4wds with their snorkels (I know they are for water crossings but still ram the air in) This weekend I am putting a pipe into behind the headlight (also have the standard CAI ) I mean it aint going to be ramming in. Very interesting, I am not having a dig at anyone as I dont know much about it, just heard some stuff.

It can make the air flow surge a bit esp in cross winds at speed. i wouldn't worry about it myself. most setups have no real ram effect that will improve performance under 100kph. its the colder air you want.

I have not tested this, but my theory is the longer the intake pipe is the more resistant to air flow it will become. that a shorter big pipe into the cold air would be better than a long one. ever noticed how it is much harder to suck air though a long hose than a short one. the F bods have a short straight in air intake. but i doubt this sort of air flow differneces on holden would be noticed a bolt on car. just something to think about.

the position of the intake however can make a difference, with varying pressure points on the car. as before a negative pressure point would be of no use to you.

cold air with the intake in the right spot will help the most.

i have not tested for pressure points in the car front end. it takes time to setup the go somewhere where you can do 100 kph, then repeat this for all positions on the front, and log all this info. Someone else may me keener than me and post the results on a VT, VX, vy as they should vary due to design changes.

[Pooga]

Originally posted by HRT 8
As I posted earlier, have you ever driven along a corrugated dirt road witht the wndows down. The buffeting on your eardrums is BAD. Its the same effect on the airbox in your car.
Air gets forced into it (not sucked) it gets to a point where its full so its pressurised and has to go back from where it has come, creating a low pressure point. It also creates a huge amount of turbulance in your airbox that extends into the intake manifold.
You want nice cool, calm air being sucked into your motor not forced in without any control.

Sounds fair enough!

[Dane]

Originally posted by HRT 8

Air gets forced into it (not sucked) it gets to a point where its full so its pressurised and has to go back from where it has come, creating a low pressure point. It also creates a huge amount of turbulance in your airbox that extends into the intake manifold.
You want nice cool, calm air being sucked into your motor not forced in without any control.


...... Geee a certain little project by a certain forumer may have to be placed on hold. :bounce: This make sence ...... as a S/C has a constant and even flow, to manufacture a direct CAI where you use the air flow as forced induction. :)

:cheers:

[ssgen3]

I had a problem with the SAS bottom pipe getting sucked
in under WOT because it was to long so we cut the pipe
and left it behind the bumper bar not in the middle of the
bar (under number plate).

[grassy]

Originally posted by Dane
...... Geee a certain little project by a certain forumer may have to be placed on hold. :bounce: This make sence ...... as a S/C has a constant and even flow, to manufacture a direct CAI where you use the air flow as forced induction. :)

:cheers:

Hmmmmmmmmmmmmmmmmm back to the drawing board:rolleyes:

[VX2VESS]

Originally posted by ssgen3
I had a problem with the SAS bottom pipe getting sucked
in under WOT because it was to long so we cut the pipe
and left it behind the bumper bar not in the middle of the
bar (under number plate).

guess my theory is right on pipe length

[Pooga]

Originally posted by vt2vx
guess my theory is right on pipe length

I always thought bigger is better??? Thats why my missus likes mine!:dance:

[V8BRUTE]

Originally posted by HRT 8
Air gets forced into it (not sucked) it gets to a point where its full so its pressurised and has to go back from where it has come, creating a low pressure point. It also creates a huge amount of turbulance in your airbox that extends into the intake manifold.
You want nice cool, calm air being sucked into your motor not forced in without any control. So going by this theory Kawasaki have got the ram air duct on my ZX-6R all wrong then, also F1 and V8 Supercars intakes are all pulling air from big ducts in the air stream :confused:

How much turbulent air are you really going to have after it has been through the airfilter ? :)

[evil_weevil]

hmm....
what about if you have a pod filter, and 2 pipes from the front bar going up towards the pod?

similar effect?

edit - and say if u were at the drags - took to front headlight out - onceagain would that cause this problem?

chris

[Dane]

Is there any benefit to putting heat shielding or heat resistant mesh around the CAI (filter through T/b) ..... I use to have heat resistant tape on the T/b pipe, dont know if any gain. :thumbsup:

:cheers:

[VX2VESS]

yes will stop some of the heat soak while stationary.

[Hymee]

And even if your forward facing "Scoop" was designed to not have the flucations described, the so called ram effect would only provide a "pressure build up in such an intake maybe of 0.5 psi at 100 miles per hour."

-- The Design and Tuning of Competition Engines, Philip H Smith

That isn't going to help getting off the line is it?

And here is some more info, from the same text, about cold air intakes to consider:

"... To obtain a similar effect on a wheeled vehicle would necessitate a forward-facing air intake; to build up any appreciable pressue, the intake mouth would have to be quite large, with a consequent increase in air resistance... Further, it would be evident that the low speed of the vehicle (in comparison to that of a ram-jet aircraft) and the problem of variations in wind direction relative to the direction of the travel of the vehicle may affect the performance unpredictably.

The sucess of systems that seemingly make use of this kind of pressurization often comes from the cool air obtained, not from its pressure. More important than presurized air is tranquil air. The high mounted scoops seen above present day Formula One cars are intended to obtain from above the turbulence created by the cars themselves, thus helping to maintain a calm at the intakes."

:teach: Oh well - it convinces me...

Cheers,
Hymee.

a

[Roger]

Hymee
Have just trolled through the older stuff on airboxes. You & that quote about ramming go way back !!!:dance: So when I said you may:stick: be right, obviously you are right !!!!:D For anyone that's listening (or surfing), am going to use the top part of an SS Ind unit (the bit that runs across the front of the car & replaces the original shroud), the original VY CAI (same as Monaro), use a second hole into the airbox with some truck turbo silicone hose to join that second hole between airbox & the CAI, then seal the top of the CAI, whilst leaving an opening for the hole in the SS Ind unit to keep any hot engine bay air out. That way (as Delco - or Dan as we all know & love him as has pointed out), you get the cold air from the SS unit, plus air from around the headlight, but still seal out warmed engine bay air. Now all I need is Starr to offer an exhaust system, go to Sam for an Edit & I'm done .........

[Hymee]

Roger,

It sounds like your solution will give you a good result without wasting the money you have invested. I haven't got the SS unit, so I can't comment on its effectiveness. The sealing sounds like a good idea.

Good luck!

Cheers,
Hymee.

[ADV51]

Everyone is reading the same thing but no-one is commenting on "cool air". We know the boys use dry ice in the staging lanes, fuel coolers are also used.
My question is would you get a positive hp gain by ducting your air conditioning around your cold air going into the motor. I know the air cond. clutch draws power from your engine but would this be a good trade off?
Hey while I'm at it I may as well redirect my A/C vents straight into the T/B

[Hymee]

Originally posted by ADV51
Everyone is reading the same thing but no-one is commenting on "cool air". We know the boys use dry ice in the staging lanes, fuel coolers are also used.
My question is would you get a positive hp gain by ducting your air conditioning around your cold air going into the motor. I know the air cond. clutch draws power from your engine but would this be a good trade off?
Hey while I'm at it I may as well redirect my A/C vents straight into the T/B

Hi dude,

We have covered it - have another read of the text quoted from The Design and Tuning of Competition Engines earlier in this thread.

I'm sure you could chuck cold air from the AC into the engine and get more power. BUT the power required to run the AC would be more than the gain, surely. There are plenty of losses in the AC unit. You don't get anything for free.

Remember - this is a closed system:
energy in (air+fuel) -> energy out (flywheel+heat+noise)

Cheers,
Hymee

[gameover]

guys, the buffetting effect you feel on your eardrums when driving with usually just one window down is a low freq resonance tripped by turbulance of the passing air. The effect lessens as you wind down more windows etc. because you are reducing the enegry trapping (and hence resonance building) capability of the cavity. It feels major to your ears because they are sensitive pieces of work. The pulsing that goes on inside your manifold is many 100'000's times "louder" than that.

The volume of the airbox is extremely small, and also the pulsing effect from turbulant air at 100km/h is insignificant compared to whats going on within the manifold. But any supercharging effect you can get by forcing air in is worth it on a N/A car - hence why drag cars have big scoops that force large amounts of air into a smaller intake hole.

IMO, the worst thing about putting the pipe facing in the airstream is the amount of bugs and other crap you will be cleaning out of your filter regularly and you wont want to be driving in heavy rain either.

Gday Dane, roots style superchargers dont actually provide a smooth flow of air into the maniold either. In fact one of the major challenges of root supercharger design (apart from heat) is to actually reduce the effects of pulsing due to the rotors and you see all kinds of wonderful blower designs that claim to eliminate the "nasty" pulsing.

So whoever posted on trying to find the high pressure points within the "out of direct airstream but still fresh air" area is on the right track for my money. Also, wrapping your airbox in dry ice works good too - but you need a big supply.

Hope that helps fella's.

Chris...

[IIV8II]

SOLUTION TO ALL THESE FABLES, FACTS AND FALLACIES:
MONARO cold air intake: $25 from your friendly Holden dealer!!:dance:

[gameover]

i already got one - it came with the car :D

[VX2VESS]

Originally posted by gameover

So whoever posted on trying to find the high pressure points within the "out of direct airstream but still fresh air" area is on the right track for my money. Also, wrapping your airbox in dry ice works good too - but you need a big supply.

Hope that helps fella's.

Chris...

me i know but no ones tried yet but... you need a small pressure switch setup, or a pressure vaccumn switch. place it in all the areas near where you want the intake for the one with the most pressure. means sttopping all the time and recording the results.

[ADV51]

I don't think they should be called cold air intakes. It should be not as hot air intakes