I made this kit awhile back. consist of billet aluminum huge velocity stack and a K&N filter and misc. silicone hose and aluminum pipe.

here are some pics:

 

more pics. I never got around to building an enclosure for the air filter. Now the car is back to stock.

 

is that a Jim Wolf Technology POP intake? good work there guy! used to have one of those kits on my old 1994 Sentra SE-R.

 

I had one too, only my car was a '99 Sentra SE-L. I like the my supercharged MCS motor, but I still miss my SR20. I had aftermarket ecu, cams, intake, header, exhaust, suspension, wheels, short shifter, STB, etc. Sigh...

Anyway, back to your point. When I sold my sentra a gave the kid my old JWT pop charger b/c I figured I'd never use it, but lately I've been thinking of ways that I could integrate it into my MCS. It has the one feature that is so surprisingly missing from most MCS intakes, a proper velocity stack design.

 

my thoughts exactly! which is why i went with the Helix intake because while not a true velocity stack design it is the closest out there and the sound is sooooo sweet!

my SE-R had pretty much the same mods as yours: Tokico shocks, Eibach springs, energy suspension bushings, suspension techniques sways, power stops at 4 corners, axxis brake pads all around, russel brake lines, Hotshot header, JWT POP, JWT cams, JWT ECU, Stillen shifter, etc. man i miss that car! used to surprise the hell out of Honda, Audi and BMW owners alike.

 

What the heck is a velocity stack?

-Cody

 

See the pics at the top of the thread. The velocity stack is the big metal piece. These really help smooth out the air flow being sucked in through the intake. The reduced turbulence results in greater velocity of the intake air. If you do some reading on the K&N website the have two recommendations when choosing a performance intake: 1) the filter should be a cone design, and 2) it should incorporate a velocity stack. This is based on their extensive flow testing.

The only MINI intake that I know has a velocity stack is the UK tuner GT Tuning, although it's a different desing than the one pictured here. Other than that, I think the Madness intake has one integrated into the filter. I'm currently looking into a K&N replacement filter with a velocity stack to replace the foam one that come with my Alta.

 

Ahhh ok. Thanks for that explanation. If it helps so much, then why doesn't everyone have one? This is the first time I've even heard about them.

But they do look ugly...so maybe that is the reason no one has one.

-Cody

 

The picture above is only one type of velocity stack. Check out the GTT 'COLD RAM' INDUCTION KIT at this link for a more common (and more effective) type.

http://www.gtt.uk.com/parts1.asp

Back when I was in high school (late 80's/early 90's) my dad & I fixed up a '73 VW Super Beetle. It has two webber 44idf dual barrel carbs on it, each barrel has a velocity stack like the one the GT Tuning uses. These are very common with old cars with built up motors.

 

Velocity stacks are really only going to help NA engines. The supercharger does a very good job at pumping air.

 

While I think you may have a point about NA engines benifiting more from a velocity stack, I respectfully disagree with the implication that a forced induction engine will not benefit. It's always beneficial to smooth out the air stream. Just look at all of the analysis that has been done on air flow. Heck, the whole m7 AGS is designed around geting better flow and velocity of the intake charge. I've even seen a lot of turbo's (especially big ones) that incorporate a velocity stack, and turbos to a much better job at pumping air that our supercharger does.

 

That would be the case if there was a significant restriction in the air intake path. But with the fairly short path that the MINI takes I can't see much of a benefit. The AGS system has shown questionable improvements. The only real improvement comes from the elimination of the intake tube.

 

Agreed.

On top of that when properly implemented they are "tuned".
They are of little use in this application.

 

According to m7 the reasons for ditching the intake tube are the short path as you mentioned and b/c all the bends in it creates additional turbulence. Which brings us back to airflow.

IMHO though, the reason we don't see more use of the velocity stack design is that it the cost of incorporating one into an intake exceeds the likely small benefits that will be gained. I'm not an engineer, though. All I can do is read up on things, get the opinions of other non-experts like ourselves, and talk to the occasional pro who has a much better understanding of the potential benefits. This is true for any mod I do.

 

Stacks are a nice device and definitely have their place. Where they don't help here is that the supercharger is in the path. It pretty much makes mince meat of any smooth flow created by whatever means.

 

the flow of the air doesn't matter as much as the VELOCITY of the air though. hence the name. how about if you could take a velocity stack and attach it directly to the TB and then have a filter go into the stack? best of both worlds?

 

is just wrong. Think of it this way. The MCS engine is in a way limited in how much power it can make by the pressure of the air pre-SC. Anything that will raise this number will be good, and create more power.

I'm not sure where the fiction that you don't have to worry about airflow in boosted cars comes from. It's just wrong. Maybe it's because the NA cars don't have as much power surplus, that doing crappy builds (with lots of sources for turbulence) really effect the drivability of the car, but boosted cars tend to have more power, so getting a bit sloppy doesn't hurt anything.

But it's just a fact of life that doing the flow stuff well will work on boosted cars as well as NA cars. The Fireball crowd came up with a new intake manifold design. On a turbo only car, it was good for 70 HP. If all this stuff about flow in boosted cars was true, the intake wouldn't have done anything, or better yet, you could make an intake out of old Dr Pepper cans (more power to be had than Pepsi ) and it would work just as well as the stock set up.... Sorry to be so toung in cheek, but I think it gets the idea across.

Matt

ALso, the air horn is in the atmospheric side of the intake path. Who cares that the car is a boosted 1.6 liter, or a NA 3 liter. Why would a better intake work on one car and not the other? Makes you think....

 

Nothing I said disagrees with this but where I still question this is;
A velocity stack does what the name implies. It increases flow velocity. But like anything they need to be designed for a particular rate. Just like an exhaust , cross section, length, flute radius, etc effect where they function best.
So just chucking something with a radius on it and putting it in the induction path doesn't do much.
When you consider that most well designed filter already have this feature built in it becomes less necessary.
The other advantage the the stack is that they create a nice linear flow path. This has a great advantage in a wet flow carbureted environment where the intake path is fairly short and fairly direct. Which is just about as opposite from the MINI as you can get.
This is what I meant about the SC making mince meat of things. You have a nice linear flow that gets hacked to bits. This says nothing about more flow being bad just that a nice clean flow ceases to exist at the SC.


Now I've hung around hot rods for near 40 years and I have never seen nice tall velocity stacks on a supercharged motor.
Short stacks like this yes:


But what I was referring to was the earlier mention of the Webber stacks, like this:


Can't see them being helpful.

 

That is exactly my point. Almost every cai for the mcs comes with a filter that does not have this feature built in. It would be nice to see someone do this.

As I said before, I'm not an engineer. But we all know that when air is more dense you get more power. This density is typically the result of lower intake temps. But doesn't an increase in velocity also improve the density? If the air that reaches the supercharger has a greater velocity it would seem that the air will be pushed through at a greater rate.

Also, remember that there are a lot of things in the intake stream that disrupt the air flow. Besides the supercharger we also have to deal with every bend in the intake tube, the throttle body plate, the filter, etc. People in the performance automotive industry, ones who have a lot more experience with this stuff and have done actual testing on airflow, recognize that there will be benefits when you can improve desity and velocity and reduce any turbulence in the airflow. I mentioned the m7 AGS and the GTT intake before, but also look the design of m7's throttle body.

http://www.m7tuning.com/main.m7/store/10005

It seeks the same objective. True, most of these efforts result in only marginal improvements, but when you take the cumulative effect of many of these small improvements the results are there. For MCS owners these results are often in the form of improved throttle response.

 

MMMM....webber Velocity stacks... *drool*

instantly makes me think air-cooled VW.

 

I wasn't and am not saying this is a bad idea. I was saying the traditional velocity stack design and usage in this instance isn't going to help much.
traditionally they were tuned for a specific application. Also they were good for eliminating turbulence. This will help up to the supercharger but not through and after.

The AGS has little or nothing to do with velocity stack design. It is simply a shorter, straighter path. Nothing more. The M7 throttle body? I've never seen proof it does anything. At least as far as throat slope being advantageous.

Increased velocity doesn't increase density.

Yes a stack does help air flow turbulence, doesn't help density. A supercharger is a pretty turbulent place.

 

but you still need to get air to it. This is where the elimination (or reduction) of bad airflow design helps out.

For instance, pretty much all of the K&N type filters have a square edge at the innner rubber on the filter base. This is very, very bad. Air has to make a 90 degree bend in a very short time, and the air veloicites at the corner are huge. This will create huge problems, effectivly reducing the open diameter of the filter exits. A radiusing of just a quarter inch would help this a lot. At each and every junction in the intake path, there is the potential for problems. Sure, post SC there's boost to "push" the air past the rough spots, but there is no free lunch, and the price paid is with increased IATs and more pressure drop between the SC and the intake valves than is required.

And while TB changes on stock Minis may be of little value (I took data that backed that one up), opening up the TB isn't new to the Mini. There are lots of boosted cars that get benefit from larger TBs. And there are modded Minis that get benefit from them too.

Here's (yet) another perpective. If there are people who will change aftermarket intakes over one or two potential HP, why not do it right, get a smooth flow path, and get what there is to be had from the intake? On my modified mustang, we went the cheap route (3" sewer pipe) to improve the flow from the K&N by radiusing the pipe, and having it go into the filter somewhat (hack version of GTT set-up). While there isn't room to do the sexy Webber stacks, there's benefit to be had. There are some of us that are insulating the aftermarket CAI boxes. This type of mod should be considered as well, as it's cheap and effective. I'm just surprised that GTT is the only ones that offer something like this.

Matt

 

It doesn't change the desity of the actual air, from what I recall from physics class that is dependent on atmospheric pressure and air temp. However, wouldn't an intake stream with greater velocity result in more being pulled through the supercharger? And wouldn't this result in more air being compressed and greater density (post sc vs. an intake charge with lower velocity)?

I realize that the sc can only take in so much air at once, but I find it hard to beleive that our sc operates at 100% of it's volumetric capacity. Up to a point, if you feed it more it should compress more. No?

 

The velocity stack intake has actually just been a hit in the 1.8T tuning scene....its proving to generate a much quicker and larger air flow for the turbocharger over standard CAI or filters.

One was released by Evolution motorsports for the 1.8T which has shown VERY good results over the typical CAI or RAM air setup.
Im looking to add this to my current setup, but here is a link to the product. Im sure there has to be something like this available for the MCS.



Here is a chart showing the MAF g's, clearly showing the velocity stack system dominance...

 

more air into the SC = more air out.

Couple of other points... The VE of the roots isn't that bad, it's the thermal efficiency that sucks. Total efficiency is a function of the two.

Velocity stacks can be used in a tuned configuration such that the momentum of the air stuffs more into whatever. The SC, the intake valves etc. But here, the tuning is more of the length of the intake.... the diameter and shape of the air horn is usually a compramise to fit space availble, or defined by the diametric needs of the intake based on total airflow.

Matt

but your comment about feeding the SC more to get more out is right on. This is the whole deal about the TC set-up.

Edit: just saw the graphs posted while I was typing. They say it all.