Intake & Air Box design

MikeG

Wrench Pro
Points
11
Location
Crawley uk
Car
Mondeo 2.5L V6 24V
Afternoon Ladies and Gents

Apologies if this is long and possibly a repeat of another thread.

I have been thinking about the air box design on my Mondy, and am thinking with a bit of logical thinking and effort the may be efficiency gains to be had to the air intake system.

Currently the bore size, entering the standard air box appears pathetic for the volume of the air box, It also enters the air box about 3 inches lower than the MAF housing with the filer in between. This to me means the engine will have to suck harder (giggiddy) to get the volume air flowing from the air inlet into the box.

So my thoughts are to either source or create a new air box and CAF.

my considerations are as follows

The CAF ideally has to be straight and as direct as possible. made from a lightweight and thermally reflective/non conductive material. The shape of CAF should go from the largest bore size to the minimum bore size acceptable, in a cone shape to exploit any benefits to be had from thee Venturi effect.

The air box shape should assist the sucking efforts made by the engine and include a filtration element, whether a cone or a panel. The air box again should be made from thermally reflective/ non conductive material. and at all times ensure the air flow and velocity is disturbed as little as possible.

One other consideration I have had is that where the filter is not at 90 degrees to the air flow especially in kits or designs that use a cone filter housed in a tube. that the air pressure at the base of the cone is greater, due to the reduced volume. Therefore the air flow here is greater, is it then safe to assume that due to an increased flow of air at these points. The weight of filtered particulates is greater therefore over time these areas will get saturated with particles sooner than areas near the tip of the cone. Therefore giving an area of uneven air flow causing the flow of air to be turbulent. A balance therefore should be struck between surface area and even flow.

Therefore in a perfectly designed system the CAF will be a dead straight carbon fibre trumpet with a filter of largest possible size at the largest bore size along/down the trumpet in line with the MAF housing and Throttle body.


My Mind on the screen :eek:

thoughts and opinions are greatly appreciated thank you ?

lol


Mike G
 
Sounds like an interesting project. You can make gains with a good intake but to get the biggest gains you need to increase throttle body size and improve the intake manifold. The 3.0 in the Jags gets 20 odd more bhp than in the Mondeos because of the better design of its intake manifold.
 
I may be reading this wrong, but I think that you don't quiite understand air dynamics. Shoot me if I am wrong (won't be the first time).

By forming a cone towards the engine intake you will increase air speed BUT also reduce air pressure (Bernoulli's principle). What you need at the throttle body is high pressure not high speed as the engine is, in effect, a vacumm pump at this point.

The accepted racing solution is to have the pipe that connects to the throotle body/turbo inlet as large as possible so air flow is slow and pressure high. If you are able to fit a trumpet so that air can actually swoop round the the lip from behind then the efficiency is further improved. The attached photos are my inlet during construction, hopefully they show you the idea.

elanturbointakeassy_zps1e1ba1af.jpg


elanturbointakeassy1_zps41cdade7.jpg


 
Cheers Old Git,

Thanks for input, I was just trying to logically thinks thing out lol,

Can I assume that the throttle body and the trumpet then have the housing pipe to the MAF sensor housing?

How is the pressure maintained in the system such as yours ?

thanks again for the input
 
Have a read of this, it is a few years old but you may get the gist of it. I have posted this before regarding induction design and principles. The VECTIS system described was built and proven and eventually found its way into the BTCC in the early 90s. I did several laps testing this using a crude design, hence the write up.
 
It has been proved that the design should have the biggest aperture you can manage and this then reduces in size until it reaches the throttle body, it must not deviate in size on route. This ensures the ramming effect. However all of this work is pointless if the engine cannot monitor the fuel/air mixture going in and adjust as you drive. This is where it benefits the most. In the engines we developed the VECTIS system used a custom ecu and sensors placed into the combustion chamber to monitor the burn. Without this the engine will destroy itself. We found this out when running a 750 superbike with the VECTIS system fitted, it blew the engine. The pistons were taken to be analysed and we were told we were running too much boost. Their faces were a picture when informed there was no turbo installed, this was Cosworth btw :blink1:
 
Cheers Stamford,

Can i Clarify

"have the biggest aperture you can manage and this then reduces in size until it reaches the throttle body, it must not deviate in size on route."

does this mean a cone ?

cheers
 
Could be any shape as long as the volume does not increase from the cold air intake to the throttle body. My first mock up was a fabrication starting as a rectangular shape then ending up as a cone as such. Was not perfect but proved it worked when tested. The final versions as fitted to the bike and track car were carefully constructed, measured and sealed. When the design was proven my then employer sold the design to one of the BTCC teams and soon after the whole pitlane had it! It has very little value to a road car, but if used on a tuned track car there are gains to had if used in conjunction with custom ecus and sensors.
 
This thread has gotten a bit technical for me, but I'd say protect it from the heat of the engine bay creating a box, using rubber seals (or something along those lines) form it so it will seal when the hood is closed, and finally, cut the form of the box from the hood, baking it with some sort of mesh to limit large particles.

That way, you are getting as much cold air as possible. I suppose it is dependent on where the air filter is, and rain (if stored outside) may be an issue depending on the geometry.

Possibly a consideration after applying all the technical.
 
tbh is is getting a bit technical i just strongly think that with a bith of planning and minimal expenditure on top of an intake system you can make it much more efficient?
 
Just buy a bmc cda, stick a good cold air feed to the grille or a foglight aperture, get a sports cat and freere fkowing exhaust and thatll be the best uou can do without mammoth t9man-like intake work
 
Yea this is getting a bit anal! :lol:

Find a good position for the CAF to get the optimum air flow and quality, run some smooth ducting to a remote enclosed filter (BMC CDA) then onto the throttle body, this will give decent gains already over stock in most cases. With breathing mods being the first port of call the rest is all positive.
 
You have to balance the amount of work forvthe gains, which on na engines can run into thousands if you want huge gains. Soneone must do a turbo orvsuperchatger kit that can go on thecforf v6? Or if tjis was veccy world you could stick the 3.0 or 3.2 from an omega in, so can you sticj a 3.0 drom a later mondeo in? Instant plus 50 bhp there.
 
BMC for me and you can buy different sizes, but in all honesty you'll need the right one for the engines capacity. Sometimes it will pay to move bits around to make room, like battery to boot etc.
 
I would say you would be making a slight gain once the novelty has worn off. The OE systems used are never that great and are a compromise at best as that tends to be the last bit done on a new car design with the space left.
 

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