Talk to me about velocity stacks and inlet designs :)

[james@cjperformance]

so after we have started the first stages of development for our inlets, im lloking for peoples opinions on inlet design. i found a thread that was done by an evo specialist about different types of inlet and the design of the inside etc

so it seems from this guys findings that velocity stacks dont really work but decrease power and torque

thread is here its quite a good read

http://highboostforum.com/forum/showthread.php/20866-Intake-manifold-dyno-tests-and-facts-only

goes rather in depth as to what the inside of an inlet is like and how one should be made for optimal flow.

all of the runs were done on the sam car, engine, spec the only difference being the inlet.

thoughts, discuss

[Azz]

Velocity stacks still looks the dogs, can't understand how they would be worse tho, your chaging the turbo inlet to a larger diameter so letting in more air and at a greater speed due to going from say 3" to 2" forced induction ect...

So its hard to see where that's not a better thing

[james@cjperformance]

I meant stacks in the intake plenum dude stacks on the turbo then yeah they serve a purpose, just cant see the purpose in an inlet :S

[mattyD]

haha, digs at someone me thinks

[Lew91]

Just read this, Seems like good stuff.

http://m.miataturbo.net/showthread.php?t=42877&page=10&styleid=21

[morgey]

I know this is based on n/a applications but theres some good theory behind it, that if going to the extent of R and D probably would be worth looking into.

http://www.emeraldm3d.com/articles/emr-adj-length-intake/

[james@cjperformance]

haha, digs at someone me thinks

No digs dude, just genrally interested in it hence the topic, ther is not alot of info on inlets at all in general, plenty of thoey ehind it but not alot of practice

[mattyD]

No digs dude, just genrally interested in it hence the topic, ther is not alot of info on inlets at all in general, plenty of thoey ehind it but not alot of practice

Lol, im only messing mate

The link above pretty much gives you the answer

[Driver]

I know of a tuner who makes inlets who made 2 inlets exactly the same. One with and one without. With the map adjusted to suit the VS inlet had a better/smoother torque curve and peak figures were improved noticeably.

Without a map the difference was negligible IIRC.

[james@cjperformance]

Lol, im only messing mate

The link above pretty much gives you the answer

which link?

[mattyD]

Both of them mate, but if you have time have a read of the emerald one

[Addymk2]

Difficult to explain but... Personally I don't see the point in having the velocity stacks protruding into the intake manifolds actual chamber. That's only going to cause the fast moving pressurised air to hit a solid object and become turbulent.

If the stack was built into the base etc so the top of the stack was flush with the base of the chamber, makes much more sense.

__________

_\ / _\. /_\. /__. < bad

_______________

__. _. __. __. < good.

\. /. \. /. \. /

If you do feel like using my design, remember to add a 4th stack. Cheers.

Edit: automatically deletes my spaces but you get he gist.

Edited January 15, 2013 by Addymk2

[james@cjperformance]

Difficult to explain but... Personally I don't see the point in having the velocity stacks protruding into the intake manifolds actual chamber. That's only going to cause the fast moving pressurised air to hit a solid object and become turbulent.

If the stack was built into the base etc so the top of the stack was flush with the base of the chamber, makes much more sense.

__________

_\ / _\. /_\. /__. < bad

_______________

__. _. __. __. < good.

\. /. \. /. \. /

If you do feel like using my design, remember to add a 4th stack. Cheers.

Edit: automatically deletes my spaces but you get he gist.

exactly what i thought dude to be honest. i would see them as more of a restriction if positioned protruding out of the intake runners but like you say if they were flush on the inside it would be alot better

[Flaminsam]

Bit off topic here but surely if your pressurising the inlet the flow would pretty much stay the same? Surely only a 4e can move a certain ammount of air fuel mixture? The way I understood it if your running say 1bar of boost the engine in effect becomes a 2.6l? I thought to improve flow on a turbocharged enngine you had to make the exhaust flow better as the inlet is already taking in as much as the engine can take?

Any one want to give some devine inspiration as I think velocity stacks on anything other than a n/a are pretty pointless?

[Ricky@Race-Tech]

so after we have started the first stages of development for our inlets, im lloking for peoples opinions on inlet design. i found a thread that was done by an evo specialist about different types of inlet and the design of the inside etc

so it seems from this guys findings that velocity stacks dont really work but decrease power and torque

thread is here its quite a good read

http://highboostforum.com/forum/showthread.php/20866-Intake-manifold-dyno-tests-and-facts-only

goes rather in depth as to what the inside of an inlet is like and how one should be made for optimal flow.

all of the runs were done on the sam car, engine, spec the only difference being the inlet.

thoughts, discuss

I'll keep this brief as i'm just in the middle of mapping a car. (500hp one)

The guy on the forum makes his own intakes. Velocity stacks are difficult to make and use correctly. As you have found. Look at the "better intakes" I.e. high end £2000+ stuff. Or f1... F1 turbo era etc you will find them.

Velocity stacks still looks the dogs, can't understand how they would be worse tho, your chaging the turbo inlet to a larger diameter so letting in more air and at a greater speed due to going from say 3" to 2" forced induction ect...

So its hard to see where that's not a better thing

It does seem simple at first, there are more indepth advantages also.

I meant stacks in the intake plenum dude stacks on the turbo then yeah they serve a purpose, just cant see the purpose in an inlet :S

I'm not sure how you can see an advantage on a turbo, but not on an intake? The principle is exactly the same.

Difficult to explain but... Personally I don't see the point in having the velocity stacks protruding into the intake manifolds actual chamber. That's only going to cause the fast moving pressurised air to hit a solid object and become turbulent.

If the stack was built into the base etc so the top of the stack was flush with the base of the chamber, makes much more sense.

__________

_\ / _\. /_\. /__. < bad

_______________

__. _. __. __. < good.

\. /. \. /. \. /

If you do feel like using my design, remember to add a 4th stack. Cheers.

Edit: automatically deletes my spaces but you get he gist.

I also looked at this. However the protrusion is the most important part. Think of it like this, in your way, the air has a 180 degree plain in which to be sucked in. With protrusion it has 270 degrees approx. This is more for balance at lower speeds and to improve spool.

exactly what i thought dude to be honest. i would see them as more of a restriction if positioned protruding out of the intake runners but like you say if they were flush on the inside it would be alot better

Do some reading on fluid dynamics, you will soon see the advantages. Our cheaper intakes have flush velocity stacks like you mention, its just CNC machined into the plenum plate, like on the miata thread.

Bit off topic here but surely if your pressurising the inlet the flow would pretty much stay the same? Surely only a 4e can move a certain ammount of air fuel mixture? The way I understood it if your running say 1bar of boost the engine in effect becomes a 2.6l? I thought to improve flow on a turbocharged engine you had to make the exhaust flow better as the inlet is already taking in as much as the engine can take?

Any one want to give some devine inspiration as I think velocity stacks on anything other than a n/a are pretty pointless?

Exactly, the pressure makes no/very little difference. People think you are double flow to double power, this would be nice, but you can't, so you have to increase pressure.

A lot of my flow analysis is on the other PC. But here is some on a very early design before we angled them. It's not the best to show this as most of it is high flow testing. But you can see much of the airflow comes from below the level of the stack. The reason they protrude.

[ro55ifumi]

^^^^Quality input Ricky

Cheers

John

[turbo Grant]

I&#39;ve got stacks in mine

[pick1]

This is turning into a good topic to read

[Flaminsam]

Not sure if any one is aware of the range rover v8? On the n/a engine the inlet or plenum uses velocity stacks. On the supercharged v8 the velocity stacks are removed. The reason is Because of the forced induction.

[morgey]

N/a loves v/stacks and they sound soo good

[Ricky@Race-Tech]

Not sure if any one is aware of the range rover v8? On the n/a engine the inlet or plenum uses velocity stacks. On the supercharged v8 the velocity stacks are removed. The reason is Because of the forced induction.

I'm not up on Rover's to be honest. But there will be more to it than that, probably room/cost. As said before. It doesn't matter if the pressure is 1 bar or 10 bar the same basic principles apply. An n/a engine effectively has 1 bar of boost, (atmospheric), at 2 bar, (what would normally be seen the 1 bar of boost) if the flow is the same the power output will double.

I dare say the rover V8 supercharged is far less efficient than the n/a engine.

[mattyD]

Ricky, any chance you can post pictures of your standard and race spec inlet to show how they differ?

[Addymk2]

On the other hand Ricky, as seen on the Emerald site, the length of the stacks was tested on the software. When on the dyno the car performed in a different manner to how the system expected the stacks to perform. Which, IMO means that the software can only be referred to as a rough guestimate as to the speed with which the air is entering the chamber.

The only real way to find out would be to dyno the same car back to back with the different inlet manifolds.

A back to back dyno of the standard and race spec inlet manifolds would be ideal aslong as they utilised the same throttle body etc.

[shorty]

my inlet also uses stacks and mine is the same make as the one wepr sold a little while ago, and sacha had good results from it. i also belive zisco use stacks. tbh alot of flowtesting and money goes into inlet r and d as far as i understand it. its not as simple as building a box with stacks in and welding some runners on. quite a science to air flow/pressure.

[Ricky@Race-Tech]

There are viarables of course. But you can work backwards to know the exact airflow. I also have a velocity probe, so know exact gas speeds and where. This backs up my data, and from this, I can work out using the X sectional area of the pipe and the speed an exact volume also if required. I have made 3 versions of our Race Spec intakes.

This all costs money, time and effort. Most of which goes without being noticed. And the guy in china polishing cheap aluminium gets credit for making untested crap products selling for £100.

Back to back testing is pretty much useless also. You have to remap. I don't know if you saw recently 30hp change in power from back to back testing oils.

On the other hand Ricky, as seen on the Emerald site, the length of the stacks was tested on the software. When on the dyno the car performed in a different manner to how the system expected the stacks to perform. Which, IMO means that the software can only be referred to as a rough guestimate as to the speed with which the air is entering the chamber.

The only real way to find out would be to dyno the same car back to back with the different inlet manifolds.

A back to back dyno of the standard and race spec inlet manifolds would be ideal aslong as they utilised the same throttle body etc.