Scientific approach to air filter setup

[bbq1988]

says the one with a pod sitting on top of the carb on my ute lol

Is that bolted down yet? or is the bonnet still holding it in place?

Yeah starlets intakes are shocking, it makes you wonder what drugs the toyota engineers had been on while designing it.. (Give me some!)

[GTTpower]

Yeah starlets intakes are shocking, it makes you wonder what drugs the toyota engineers had been on while designing it.. (Give me some!)

Have to agree with you there, the factory setup in my EP85 has kilometers of intake pipe

[79rolla]

says the one with a pod sitting on top of the carb on my ute lol

Is that bolted down yet? or is the bonnet still holding it in place?

nah the bonnets doing a good job makes some hearty induction noises aswell

[Flannelman]

I have the dreaded pod on the end of my air mass sensor, sitting behind the battery with exposed extrators near by. (see in members projects under 1993 levin H2 pwr - picture of engine bay)

Installed a digital temp guage to get some readings.
Findings were that on open road it sat on 25C @ 100km/h
Sitting in traffic - 50C
Doing my impersonation of Stig at Taupo - 27C
I also experinced a drop of 5C from Hawera to Eltham (18C to 13C) on a cold, still wintery night

[Stealer Of Souls]

Autospeed also did a few other good articles around intakes.

Intake Restriction - Measurement and removal

One of their first ones about making a cold air intake (you can also just search for intake and should come up with a good handful, they've done plenty. Siting cold air intakes is one that springs to mind.)

This one is about testing different car air boxes. I quite liked this one. It showed that some of the factory air boxes are a bit meh, and others are pretty good. The final "tip" I think was, look at the factory power output the box was used in, and it should be at least good to that number without mods. EG SS Commodore box was used in 150 odd kW car, and therefore must be good up to at least that number.


My opinion has been (for many years now) that properly feed factory air box is pretty hard to beat unless you're making a whole lot more power than factory (2+ times was my "rule of thumb" I guess).

[steve murch]

lets see if im wasting my time again
right any filter used is based on the cfm needed to feed the power goal your after.
pod filters ive found to be somewhat a waste of time and cause more problems than anything but sound cool!!!
panel filters combined with a well designed airbox are far superior.
the shape that feeds the turbo/throttle body is just as important as with the restrictors i do for rally cars makes a huge difference to the end result.
volume is what your after not just induction noise which gives you a false idea of whats going on.
i designed a intake for a drifter car thingy( sorry the cars bore me) and back to back was 30kw,not bad for afew hours work.

[Dell'Orto]

So a bellmouth inside the airbox pre throttlebody/post filter would be an improvement over the standard hole? Hmm, might be worth trying

[1I1]

So a bellmouth inside the airbox pre throttlebody/post filter would be an improvement over the standard hole? Hmm, might be worth trying

Had this same thought for the Corolla. If you have a look inside ARC's air filter box they do this.

[Santa'sBoostinSleigh]

So a bellmouth inside the airbox pre throttlebody/post filter would be an improvement over the standard hole? Hmm, might be worth trying

Had this same thought for the Corolla. If you have a look inside ARC's air filter box they do this.

got pics?

[1I1]

Thanks BZR4AGE





And inside the intake chamber (between airbox and plenum)

[steve murch]

So a bellmouth inside the airbox pre throttlebody/post filter would be an improvement over the standard hole? Hmm, might be worth trying

hate to tell you this but a bellmouth isnt the best shape for flow,next time you pull the plug in the sink watch the water and what it does youll get the idea its not the best.
that shape is very important and believe it or not a straight pipe isnt the best for flow.
theres many different things to be done before the the intake that make a good differance,wrc have a group of people that do nothing but the restrictor and airbox.
i have afew wrc 05 impreza turbos sitting in my shop and they are nothing like you would expect to see for intakes,think outside the square for best results

[Bling]

lets see if im wasting my time again

You're not wasting your time, the smart people will take note of what you say and the others can't be helped

[1I1]

lets see if im wasting my time again

You're not wasting your time, the smart people will take note of what you say and the others can't be helped

+1

I'm now intrigued as to what designs are best

[Lurkin]

BZG|Bling wrote:
steve murch wrote:
lets see if im wasting my time again


You're not wasting your time, the smart people will take note of what you say and the others can't be helped

watching as well.... very interested what you have to say actually.

[steve murch]

the problem with most tubes of any design is to get the incoming air away from the walls and go thru the centre to which is why i said have a close look at the sink hole,not alot goes thru the centre and that applies to air which in fact is worse for the problem.
compounding curves help alot meaning not just a trumpet,they induce turbulance and thats not what were after.
the size of the air box is also very important as the same with a turbo car verus na,volume is whats needed thus taking a airbox off and adding a pod filter you lose that area( the engine bay isnt classified as an airbox unless its made to be one).
the intake length has a direct effect on where the airbox works best,you can calcutate where you wont it to work which is great but outside of that its wrong,this also applies to headers when working out the length.
the simple answer is just try,your butt will know when yourve got it right or wrong.
note: when presure feeding a airbox with a afm/maf remember at full throttle a presure feed box works great( use a panel filter for greater area) but when you cruz at 100kph at part throttle itll run like crap.
this can be over come using a reed setup like a twostroke and you get the best of both worlds,i need to get out more often

[Lurkin]

ok couple of q's

- but if a bell mouths a poor idea what shape is better to begin with?
- without access to a welder, (smooth metal piping etc) whats anoter material to make the intake piping out of?

[steve murch]

ok couple of q's

- but if a bell mouths a poor idea what shape is better to begin with?
- without access to a welder, (smooth metal piping etc) whats anoter material to make the intake piping out of?

the trumpet is part of it but you using compound curves leeding up to it,in other words its multi trumpets to try and get the air away from the walls and change direction.
theres alot little wings that i use to help change direction which also work bloody good under splitters on the front of your car.
pvc piping for na works great, and you dont need ally piping or manifold to get a great result mild steal weld bends etc work just as well and cheap to use and easy to weld.
im sure most people have access to a gas set or a mig,and if you make a mistake disc grinders are great fixers.

[fivebob]

I always understood that tthe purpose of the compound curves in a bellmouth was to keep the flow adhered to the wall, and avoid the formation of a turbulent boundary layer which slows down the airstream and therefore impeeds airflow

[steve murch]

I always understood that tthe purpose of the compound curves in a bellmouth was to keep the flow adhered to the wall, and avoid the formation of a turbulent boundary layer which slows down the airstream and therefore impeeds airflow

you need to take a very close look at a restricted intake on a turbo car,its tells a different story.
we have tried many different shapes on the car and flow bench,what works out great on paper doesn't always in the real world.
the idea is to make full use of the hole, turbulating air isn't smart on a intake but your right to a degree,
when working with na your no going to make big gains compared to force feed thus go outside the square.
as i said what works good at one point in the rev range isn't so good else where,everything is a compromise
this is all based on what ive found and done over many years and i sure theres other ways to do so.

[steve murch]

if i can give any advise guys stop reading the net,go get a book based on cfd's as such and try for your self.
theres so many theories out there and we tend to spend too much time on that side of things,but you can see why they spend 100's of 1000's trying to find that little extra so unless you have that coin then read,look and try.