I've been wondering about the design of the stock hood scoop on my `05 MCS.

While it has the divertor and the foam air-dam around the back and sides of the divertor, there is a 1/2" gap between the front of the IC and the bottom of the scoop, which sure looks like it would completely spill any pressure head created by ram-air effects through the scoop.

Has anyone experimented with adding some foam or other flexible air-dam at the bottom of the scoop or front edge of the IC, to maybe force a bit more air through the IC and less around and under the front edge of it?

Or is this a subtle design feature to let hot air out while stopped in traffic?

 

Check out the Alta Intercooler Air Diverter. I have on on my car and I know a lot more Mini owners also have them installed. I personally can't tell any driving difference, but the device claims about 10 degrees average cooler intercooler running temperature. Also you have the option to cut into your rear wiper fluid line and run a hose off it to spray water over the intercooler. I didn't do it in my car b/c I need to see out of my rear winshield more than I need an extra couple of horses.
http://www.altaminiperformance.com/p.../ICDIVERT.html

 

The older MCS design with the rubber seal had no gap. But the rubber piece was thicker so it both obstructs the opening more and leads some people to believe there is an intercooler height difference vs. the newer cars like yours. Just an optical illusion, of course.

 

Interestingly, the Alta diverter appears to have the same issue - a gap between hood scoop and front edge of their divertor.

I haven't actually seen any measured data to back up the Alta divertor claims, which seems to be characteristic of their products - they offer neither intake temp or pressure drop data for their IC, for example.

I suspect that a more effective approach to IC cooling is to open up the intake hood scoop for more flow, rather than just a different divertor plate.

 

After examining the hood scoop and the divertor plate, it seemed obvious that the biggest thing one could do to improve cooling airflow through the IC would be to close the huge gap between the front of the IC and the bottom of the hood scoop.

This would allow any ram-air flow from the scoop to be much more effective, since with the gap, any pressure buildup from the ram air is spilling out the open gap between the front of the IC and the bottom of the scoop, instead of going through the IC fins.

I got some Garage Door Bottom rubber weatherstripping from the local Ace hardware (about $8) and created the gap-blocking skirt shown. The weatherstrip is shown in cross-section: I trimmed off one edge, and glued the surface shown to the IC cover.

I simply used contact cement to glue the weatherstrip to the front edge of the IC cover, and the shape of the weatherstrip holds it snugly against the bottom of the hood scoop, without constricting the opening at all. I applied the strip in four pieces, to accomodate the parts of the IC cover that stick out forward.

While I don't have a pyrometer to measure the effect on IC cooling, I'd be willing to bet that it is at least as effective in reducing intake temps as the Alta Intercooler Diverter, and $152 dollars less.

 

Air is going to follow the path of least resistance. Now it will be ram air as opposed to just a hole in the hood.(ok, I'm exaggerating) Nice that you made it flexable to accomodate for engine movement. I have an '03 with the old design which needs opening up!

 

The skirt has to be flexible enough to allow for engine movement - at least 1/2" fore and aft, and somewhat less vertically.

In my first attempt, that engine movement resulted in the skirt getting pulled back enough that it would then spring up and wind up sticking into the hood scoop. I extended the flap by gluing another piece of the weatherstrip to make it 1/4" longer toward the front of the car.

It would be interesting to measure the effectiveness - easy enough to replace the modified IC diverter with a stock one to compare. Perhaps I'll get someone with a pyrometer to do so at the next PDXmini mod day.

BTW, this mod has the huge advantage of being easily reversible - just remove the added rubber skirt and take off the remaining glue with solvent.

 

Good idea oldRick, I have the Alta diverter, chopped it up a little (sorry no pics), bent up that front lip to meet almost perfectly with the scoop in an attempt to force more air thru the IC. The sprayer that comes with the diverter is the only cooling intake temps. and that does work. I've measured 20+ degree temp drops on some hot days in Napa Valley on spirited drives, you add that to your set up and your GOLDEN!


I do find though at 70+ mph speeds that maybe 5-10 seconds after I spray the IC, a mist actually makes it's way out of the scoop and onto my window. Realy making me wonder what the heck is going on there air flow-wise. I can empty the bottle at a standstill with out anything even getting the scoop wet.

 

i've said this so many times, i should use a soapbox smiley :

at any given air speed, you can only get a maximum amount of pressure that the air will generate against a surface that stops it from moving. so at any given speed, there is a maximum pressure that can be built up inside the scoop on top of the intercooler.

for that pressure, only so much air can be driven through the intercooler fins.

so at any given speed, if you bring more air into the scoop that can pass through the intercooler, that "extra" air goes somewhere else. like back out the front of the scoop with your mist! or through other gaps, like the one being discussed.

in airplane land this flow coming back out is called "spill." you really try to avoid it; some even use variable sized inlets.

so a larger scoop MAY not always be better.

 

understood flyboy, now down from the box....

I'm looking into massaging my own scoop to help me in the area of air spillage.:smile:

 

Even if water sprayed onto the IC did nothing else, at least it washes the bugs off...

 

.....this is, odd!?

 

I made my own IC diverter and I have about 1/4 gap or less from the scoop. I did this becuase I did not want it to hit the scoop when the car is running and at wot. I had a similar idea of adding some kind of black rubber stripping in the front of the diverter to seal up the gap. I will have to check out the garage stripping and check out any other stuff that may be of good use to make this.

Garrett

 

all right, this is a little nit-picky about my own quickly written post. it may be little too simple: what may happen is that the extra air doesn't really "enter" the scoop, you get a "back up" of air just in front of the opening that spills out around the sides of the scoop. the point is that if you have a larger opening than you need, the flow near the inlet isn't going to be a nice neat path that all flows into the scoop and neatly through the i.c. fins.

 

Well the air is spilling, but not entirely because max pressure has achieved and no more air can pass thru the IC. The mist comes out and hits the passenger side of the window only, you can also see where the water runs up the passenger side of the scoop and bonnet.

It could be a few things, one is the angle on the right side of the diverter itself being to sharp.
Second, I removed that piece of intake (stock) tubing that comes off the radiator support, air coming in thru the opening might be directed upward towards the IC messing with the flow in some way as this piece would normally send air toward the headlight. I'm more suspect of the diverter though. I have a sheet of CF that I was going to make my own diverter out of, guess I'll jump on that when I have time.

 

A drizzly day here, so I decided to re-work my IC cover hood scoop gap-filler skirt - this time as one piece rather than four separate sections. With any luck it should work slightly better without the gaps at the seams.

 

I removed everything related to the factory diverter and started from scratch.
I extended the front of my new diverter almost three inches, so when the hood is closed the diverter reaches past the bottom of the scoop. The diverter is also angled down, hopefully to achieve more flow to the intercooler, and made the most of the area provided.

 

I had this as well, but had an issue with the diverter hitting the underside of the hood and causing it to make knocking/banging noises. I had to cut it down and trim the scoop a bit. I am going to go and get some rubber to extend my diverter to make a nice seal with the scoop.

Garrett

 

I needed several attempts to make it work. First time I closed the hood. BANG, big outtie dent in the hood. It seals perfect all the way around the intercooler. Now im working on limiting the movement of the Engine

 

Without a flexible seal at the front of the divertor, it isn't clear to me how a larger diverter can help.

My goal was to stop the scoop from spilling any small pressure head it creates, by the air flowing around the front of the divertor and IC through the 1/2" gap to the scoop.

I want the air to go through the IC, not around the front of it, and I don't see how a larger diverter plate helps that.

 

Honestly, If you want an effective intercooler, you have to put in a front mount. But we all know the cost and space constraints. I have opened up the opening and flow to the stock intercooler as much as humanly possible. I will take another pic of the hood closed so you can see what I am talking about. The other thing that needs to be addressed is getting hot air out of the engine compartment. Mini does a great job of isolating the engine compartment with seals and such. So I think the thing for us to do is help airflow into and out of the intercooler. I cut a huge hole in my hood and have found that I have a lot less heatsoak at a standstill and Im pushing more air over my intake. Seat of pants improvement, yes. I have also tried to make it as "factory looking" as possible. I have pictures posted in my gallery of what I am talking about. As far as pushing more air over and into the factory intercooler, good luck.

 

this is the only way.....

 

Just to follow up on this mod, I had the diverter off today, so I shot another picture after about 4K miles in use.

As you can see, the garage door weatherstrip has molded itself nicely to the bottom of the hood scoop, and does a great job of preventing cooling air from spilling out across the gap at the front of the IC. I used some silicone spray on the rubber to keep it from chafing on the scoop.

The contact cement I originally tried tended to skid, so I wound up using Superglue to attach the rubber seal to the diverter - the white stuff visible in the crack between the two is from the Superglue. If I cared about the appearance, I'd paint it, but hey, it's under the hood, so I don't much care.

 

Speaking of which, I just redid my intercooler diverter to refix the gap issue. I had some rubber molding to cover the gap, but I found out yesterday that it ripped apart. I will take some pictures of what I did. I ended up taking a piece of aluminum and having it extend past my diverter and then bend down after the gap.

Here is my diverter and I will take pictures tomorrow to show you what I did to fix the gap.



Garrett

 

The engine rocks fore and aft about 1/2" or more - that may be what tore up your rubber molding.

Mine doesn't move that far, as I have poly bushings in the lower rear engine "torque mount", so it may not be as hard on the rubber weatherstrip.