I just did some runs with a Magnehelic pressure gauge (thanks, jlm!) piped into the driver's side windshield cowl. You know, the area behind the airbox, as shown in Randy's airbox mod how-to:



At 50 mph (81 km/h) this area is pressurized approximately 1 inch of water (0.04 psi) over atmospheric. At 70 mph (113 km/h) this area is pressurized approximately 2 inches of water (0.07 psi) over atmospheric.

So, air is definitely going into this area, rather than going out. It seems like a good idea to draw intake air from this region, as is done with Randy's mod and with the currently-vaporware ALTA air intake.

 

Interesting find.
Question, I wonder if airflow would go backwards through the snorkle where fresh air normally enters the airbox or if this area is also "pressurized" at 50 and 70 mph? Is air "forced" into the snorkle based on its' position and if so I wonder at what psi?
I forget did Randy or anyone do a dyno run with and without the airbox mod?


His, Chile REd all over / Hers, EB UJ on top.

 

I fully intend to test the grille snorkel (I'll actually tape off the snorkel and let the engine breathe warm air from the engine compartment. I planned to do that a few minutes ago, but in the process of my testing, I drove past a pair of police cars while I was doing 2X the speed limit. I thought it best to not push my luck.

I bought six hosebarbs and caps to test both absolute and differential pressures in several areas of the intake ducting.

 

On a chassis dyno there is no air flowing over the car. You probably would not see a difference with or without the air box.

 

>>On a chassis dyno there is no air flowing over the car. You probably would not see a difference with or without the air box.

Ok, now I feel foolish :smile: Perhaps that's reason enough to go out and cut holes in the rear of the airbox.

 

Wow spectacular use of the scientific method! Kudos Andy! Guess that answers that question

 

Thank you very much Andy for this experiment! Research is always important, and this is a great find, indeed! I wonder if there's a way to calculate a volume of air that flows thru that area versus vehicle speed?

Cheers,
Ryan

 

>>Thank you very much Andy for this experiment! Research is always important, and this is a great find, indeed! I wonder if there's a way to calculate a volume of air that flows thru that area versus vehicle speed?
>>
>>Cheers,
>>Ryan

It could be done but you would probably have to write a computer program for it. Thats a lot of calculus and perhaps differeintal equations needed to solve that problem.

 

Mmmm .... "diffie q". That was about as enjoyable as Calc III and Heat Transfer.

_________________
2003 MCS DS/DS Black Leather
Packs: Prem/Sport/Cold, PDC, SatNav

Helix/P&D 15% Pulley, MTH Chip, Magnaflow Exhaust 165.0 whp (14.5% HP gain, 14% Torque gain)

My MINI

 

[flashbacks to college] Ahhhhhhhhhhhhhhh diffie q [/flashbacks to college]

B.S. Aerospace Engineering :smile:
B.s. Mechanical Engineering

 

Speaking of water....I haven't done this mod
because it looks like, in the rain, you'd be
sucking H20 as well as air??? I live in monsoon
country so it is a real concern. Comments??

 

I got a BSME, but decided to take the easy route to a Master's - MBA, baby!

My most difficult MBA class was easier than most of my sophomore engineering classes.

In undergrad, the really cool classes were:

Manufacturing Techniques
Machine Design
Dynamics
Statics
Statistics

The nearly unbearable classes were:

Heat Transfer (on one exam the class average was 16/100)
Diff Eq
Calc 3

 

>>Heat Transfer (on one exam the class average was 16/100)
>>Diff Eq
>>Calc 3

For Whom the Bell Curves.....

 

Hehe, on that exam, I got a 32/100. I think it ended up being a B. I clearly remember the professor telling us all that we were stupid for not understanding the concepts that he found so simple.

 

You sick, sick puppy you! How can ANYONE find statistics a fun class?!?!?! That's scary! Short of the man hating women's studies class I took, I think statistics was my most unfavorite class of all time. YUCK!

And on a side note, what about 2minis question? Here's my thinking....

With no cowl plate like in the Alta setup, wouldn't water backflow towards the filter when it was raining? I know when I wash my car LOTS of water gets down in there, but is able to drain since the cowl plate keeps it from entering the engine area. But with a hole cut in the plate there would still be the bottom edge in place, shunning water that would pool in the cowl area towards the drain holes.

R

_________________
2002 Darksilver/Black Cooper S
Madness Team Member

 

I ditched my ME degree at the end of my sophmore year and now I am going to start working on an MBA next year.

 

>>You sick, sick puppy you! How can ANYONE find statistics a fun class?!?!?! That's scary! Short of the man hating women's studies class I took, I think statistics was my most unfavorite class of all time. YUCK!
>>
>>And on a side note, what about 2minis question? Here's my thinking....
>>
>>With no cowl plate like in the Alta setup, wouldn't water backflow towards the filter when it was raining? I know when I wash my car LOTS of water gets down in there, but is able to drain since the cowl plate keeps it from entering the engine area. But with a hole cut in the plate there would still be the bottom edge in place, shunning water that would pool in the cowl area towards the drain holes.
>>
>>R
>>
No answers on this one...or don't want to think about it????

 

I have not yet removed the plate, so I can't comment on the idea of water flowing freely towards the throttle body.

As far as statistics (some called it "sadistics&quot, for whatever reason it really clicked with me. I especially like the idea of throwing out outliers ... like over-inflated power claims.

 

yeah, I really liked statistics too. Actually a couple of projects I've been involved with in industry have been heavily influenced by statistics. Very interesting in application if you have meaningful data to work with that has a direct impact on your work.

 

try Jackson, Electrodynamics, for some light reading or Rudin, Principles of Analysis; i spent a year on each; I actually loved partial differential equations, physical chemistry and statistcal physics (another lifetime, now i like TV)

 

Man I was a lousy college student. You call yourselves carguys!? Where's the ICE classes? Wheres the combustion classes? I liked most of the calc classes (all 5 of them at rutgers ) but i still cant figure out my damned taxes! Ugh only 7 more days to figure em out.


--
Cheese
BS Mechanical and Aerospace Engineering
MS Engineering Management (in progress)

 

I'll look at the ALTA plate when (and if) it ever gets here...

The MINI-Motorsport mod has been thoroughly tested in rain soaked environments (like the NW) wiht no noticeable water collection in the airbox. Actually, the lowest hole in the airbox is the one the factory put in there. I have sprayed the hose directly at the airbox through the cowl vent and only have minimal water spray that ends up getting in there.

As far as college - Navier-Stokes equations... finite element representation of continuum using Galerkin and variational techniques... Hamilton's Principle... Lagrange's equations... Rayleigh's principle... AAARRGGGHHH - I have a headache now!!!

I'll keep you posted on the ALTA intake, I really don't know when to expect one here - it should be here by the end of the week.

 

>>Speaking of water....I haven't done this mod
>>because it looks like, in the rain, you'd be
>>sucking H20 as well as air??? I live in monsoon
>>country so it is a real concern. Comments??

I live in the Great (yuck) Pacific Northwest. I have done the mod, and have done a fair amount of testing in really bad conditions. I have found no evidence of any moisture getting into the intake, even in near vapor form. I am guessing that the high pressure created at the point of entry is keeping the water out.

I can assure anyone that is concerned about water infiltration while driving not to worry.

John

 

>>The nearly unbearable classes were:
>>Diff Eq
>>Calc 3

I bailed somewhere around calc 3, but it's gratifying to know that someone else found them difficult. The good profs made even the most difficult concepts simple. I sailed through statistics without any problems (prof owned a racing part supply shop on the side, incidentally.)

Cheese--have someone else do the taxes. Even with an accounting degree I stopped doing them as they found me $$ I otherwise would've missed!

Jeff

 

Geezzee I can do my own taxes and I have a BA in Poli Sci or well I will in about a month.

I only make about 10,000 a year though so maybe that makes it a bit easier to do my taxes.