I've been wondering recently about easy mods that ostensibly improve airflow through various parts of the R53 engine. Since I'm not very technically-minded, please bear with my oversimplifications -- though if I'm way off base on anything, please feel free to correct me.

As best I can tell there are three points (possibly four) where airflow efficiency could be improved:

The first point is, of course, upgrading the air intake to increase the air delivered to the cylinders themselves; since the MINI tends to run rich, this would bring the engine closer to optimum fuel-to-air mix.

The second point is something along the lines of the DDM intercooler diverter or the M7 DFIC which -- as I understand it -- basically optimize airflow through the intercooler to improve the engine's "volumetric efficiency". (Yes, I had to look that up.)

The third point would be something like M7's air plate diverter, which ostensibly cures a "blind spot" in the MINI cooling system by redirecting airflow through the bottom half of the radiator.

So the question is, would any of these mods be worth it in terms of improved efficiency for a daily driver, or would any improvement be simply too marginal to be considered anything but bling? Any potentially harmful effects (like engine running lean)?

The upgraded intake seems like a pretty standard mod (esp. w. a pulley reduction); from what I've read, the DDM diverter or DFIC should net some improvement, and the APD seems to fall into the category of "might help/can't hurt".

One other thing that caught my eye was the diverter used in M7's DFIC system:



BlimeyCabrio looks to have something similar as part of his customized DDM diverter:



Would sealing off this space make a huge difference to airflow efficiency? (I suppose it's more likely to in the case of the DFIC, where the stock intercooler is replaced with a completely redesigned unit, than in the case of the DDM diverter which only replaces the stock diverter.)

Realizing that this is all a bit of an apples-oranges-pears comparison, what are your thoughts?

 

Looks like Phil Gandini was also working with a diverter in his improved DFIC:

 

This is interesting, informative
and a nice potential upgrade.
Thanks,
Al.

 

 

I question the DFIC. Its an interesting concept but I would want to see the numbers and analysis behind it (I work as an Engineer, and have done a few heat exchanger/cfd projects). I am not saying it won't work, I just wonder how much more effective it is. The issue I see with it is that it's wide. As the air enters the front and exits the bottom it is taking heat away from the fins (where the compressed air is). As the cool air flows across the fins the temperature difference between the air and fin decreases and the amount of heat transfer decreases. If you don't believe this, take a look at all the possible heat exchangers on cars, they are all pretty large frontal area that are relatively thin cross section.

 

AJV -- As I understand it, the relative merits of the DFIC have been pretty well hashed out (search under DFIC); the consensus seems to be that the stock IC is about as good as it gets for normal street use. The reason I brought it up was in questioning whether a diverter (such as used in in Phil's DFIC project and on BlimeyCabrio's modified DDM diverter) would make any significant improvement with the stock IC. I don't plan to swap out my IC -- overkill for my purposes -- but I'm curious if there are still efficiencies/gains to be made there and at the other points (radiator, engine air intake) I mentioned in my initial post.

As an aside, do check out Phil Gandini's article on the DFIC (linked above) if you haven't already. As an engineer, you'll probably get more out of it that I was able to!

 

The two most common mods to the stock IC is a bigger scoop...take a look at Gray-Ravens sometime...he has the extreme m7 I think...so you can cram more air into the IC.
The other common mod is to improve the sealing of the hood to the diverter...the soft factory foam is a bit of a weak point.
I have toyed around of getting the DDM air diverter...seems nice, but $$ wise, I'm sure the improvement will be minimal...
Remember, part of the ic problem is the air must then go somewhere, after passing through the stock ic....the DFI attempted to remidy this, but a few folks said in some situations they lost hp....looked good though!! Gray-raven had one, I think, before the GP one.....

 

On the first point, the R53 does not want for air, and increasing the volume of air flowing will not improve the A/F mixture, nor will it improve performance. The elements of air flow that need to be addresses are smoothness of flow to reduce turbulence, especially inside the IC, and air temperature. CAIs are used to reduce intake temperatures, and most of the ones available to a good job of keeping pre-SC temperatures just a little above ambient. Temperatures in the airbox can get high while idling in heavy stop-start traffic.

As others have said, the stock IC works very well, and I've never seen measurements showing a horizontal flow IC to do better overall. There's temperature drop across the IC and pressure drop across it also--a search over the hundreds of posts on this topic will reveal good discussion on the relative merits of these two elements.

I think I've posted this before, so it could be found by searching, but in the end I believe a consensus would emerge around the following points:
1. use a good CAI and there are lots to choose from.
2. use the stock IC with an Alta or similar diverter rather then the stock cover.
3. get a bigger scoop.
4. clean your IC regularly, maybe once a year, as oil accumulates inside. You could use an OCC also.

Other than this, stop worrying and avoid trying to out perform cars with more HP in heavy traffic...

 

While it isn't a "Fire and forget" cooling mod, There are some kits around that tap into the rear washer tank/pump and spray water onto the IC from the outside. While it definately isn't a true Water/Meth system, It is quite cheap and pretty effective. I believe some Alta IC diverters include the necessary parts. Then basically when you get into a situation where you want to cool off the Ic, just flip the rear washer and watch the temp drop. But you can't run washer fluid in that tank anymore.

 

I wonder how much this actually helps. Considering the Intercooler is going to be its hottest when compressed air is running through it (only under acceleration) During that time you should have the theoretical fastest moving air passing through it and therefore doing the most amount of cooling.
I'm not quite sure I understand the point of the additional water/meth at that point.

 

While this doesn't prove anything, the same concept is in practice. I don't have any numbers on it, so I will defend the principle. But i will yeild that It is not the best set-up.

Put your hand in front of a fan, and note how cool it feels.

Now, pour rubbing alcohol on it, and put it in front of the same fan.


The water/meth spray on the outside of the IC would just amplify the cooling power of the air flowing through it. It is not nearly as effective as true water/meth systems, but it is a ton cheaper.

 

The SC does get Very hot to the touch.....by spraying something on the outside of the IC, yoyu are employing, in most cases, what a could be referred to as Phase changing spray (evaporating) spray....
Liquid CO2 is great.....but you must buy the system, and get the tanks refilled at special places (fire-extinguisher supply houses mostly).
Using a water/methanol, like windshield-washer fluid will be better than straight water, at minimal extra cost...and the tank/lines will not freeze, or require modification (beyond re-routing the line).
Since the IC get so hot when the car is not moving, a good bang for the buck mod (if you don't mind loosing the rear washer/wiper) is doing the re-route as described.....heck, it is free if you already have done a rear wiper delete!
You will make steam.....the IC does get that hot....it will not suddenly be as cold as on a winter day, like the CO2, but the refill is pretty cheap....sorry for you CA folks...your washer fluid has less Menthol in it due to VOC rules......
Just be sure if you live in an area that get VERY cold, you don't use washer fluid that contains AMMONIA!! When I was in AK, many places sold this, since the methanol stuff does not work well in winter.....but it is FLAMMABLE!!!

 

Thanks all -- and especially Phil for providing the "abstract" of numerous previous posts on this subject. (NAM could really stand a proper index; there's too much material for the search function to really be useful at this point.)

If I were to do anything, I'd lean towards a CAI and possibly a DDM diverter (for $145 that's not too much of an outlay for the latter); $90 for a M7 APD doesn't sound too bad, either -- it finishes off the engine bay nicely at the very least. Still I'm not seeing anything to move these up on my priority list at all....

I had toyed with the idea of an M7 Ram scoop -- nothing too extreme aesthetically -- but at this point I'm leaning to staying stock.

One last theory question:

Would there be any downside to more efficient airflow through a) a CAI, b) the IC, and/or c) the radiator? My sense is that in general that an engine that "breathes" easier is a happier engine....

 

Hey, a fellow engineer, admittedly I am only student starting my 3rd year though.

If it hasnt been said specifically, the biggest reason for doing this in my opinion is actually when you are at stop lights and idling. It's not uncommon to see intake temps over 120f after idling for a little bit. All this does is get those numbers back in check (sub 100) without having to move. So I would agree in saying that the benefit under full boost at something like highway speed is probably modest at best. At low speeds (like AutoX) it should be more helpful.

 

Why do you need to get those numbers sub 100 before moving? Your going to have to wait for the SC to spool up anyways, by that point your already moving. Even if your launching, your not gaining a whole lot by trying to get your temp low. Furthermore, if you are spraying any liquid on the CAC that may boil away, I would be concerned with mineral deposits on the Aluminum and having an adverse effect there.
V/R

 

The big reason is just to make sure the car doesnt start dialing back the timing. As soon as that happens your power starts to go kaput.

Sub 100 is an arbitrary point, I dont know how hot the intake charge has to get before the ECU pulls back timing, and whether that pull back is going to based on a map that specifies a certain number of degrees of advance/retard at a given temperature or based on a conditional like a knock sensor. It's likely a combination of both, the fairly basic ECU I have worked with is capable of doing that.

Marginal gains for a marginal price.

You do raise a good point about the mineral deposits on the cooler. I think it has been discussed somewhere but I dont know what the conclusion was.

 

Mineral buildups would be the main reason why you use distilled water.

 

here we go again!

Look, all the stuff about what to do a lights and the like for street driving is pointless. You're not going to pull timing at part throttle because IATs. It's only at WOT and higher revs that you'll run into problems.

Normally, the DFIC design would be dumb, because you'd want the cooling air to flow through the thinnest dimension of the IC. But on the R53, the cooling airflow is so compramized that the flow geometry of the DFIC and the like may help BUT

Like Dr Phil pointed out, there is TONS that goes into the creation of a good IC. Most of the aftermarket ones have much higher thermal mass, and much less efficient internal flow paths. This means that they have some inhearnet design shortcomings do get over before they have a chance to really benefit the engine.

They also couple to other things. Depending on how the core is made, they typically trade between pressure drop and thermal efficiency. But there's a caveat here. If you have ways to deal with IATs like water injection, an IC with extruded tubes will serve you better because of the lower pressure drop. IF you don't have other ways to deal with it, then you want something with higher terbulator fin density at the price of a higher pressure delta.

While these things seem simple, they are far from simple devices when considered in the entire intake system.

For all but those who race, doing something to keep air from leaking around whatever IC you are running is a good thing. Other than that, don't worry about it, as there are so many other things you can do to increase performance at a lower cost than ICs.

The only exception to this for the MINIs is the new (OK, not so new) turbo motors that have an undersized front mount IC in a non-ideal location. Spending a bit of money here will make a difference, as will making sure that air doesn't go around the IC.

Waaayyyyy back when, I did a bunch of testing on top mount ICs for the R53. I wrote it all up. If you want to read it, click here.

Matt

 

the way our cars run the engine, the computer controls mixture via the T-MAP sensor (on R53s) and some other stuff. During closed loop operation (not wide open throttle, or WOT), it's going to do what it wants to do to keep the A/F ratio where it's programmed to be. At WOT, it's still going to do what it wants to do based on manifold pressure, RPM and load, so you're not going to do much with A/F ratios with intakes.

not leaking air around the IC is a good thing.

This has nothing to do with the engine breating. This has to do with cooling system capacity. If you're running your car hard a lot, it may make some difference, but really the car is designed with a thermostat and two speed fan. While in concept it's a nice thing, I'm not sure how much it does for cars not driven in anger. IT can't hurt though, and may help.

Don't worry about the A/F ratios. For me, I'd say these mostly are bling. But that's not a bad thing. Really, it depends on what you use your car for. If it's a commuter car and you don't really push the car hard, keep the money in your wallet. If you do want improved performance from your car, I'd put my money elsewhere. If you have a blown Tritec, get a pulley.

Sure, and improve intake will give a bit of bang for the buck, but they aren't cheap. They change the sound of the intake for sure, and a lot of people value that.
Huge difference? No. Some difference? Yes.

Anyway, I'm just a lowly physicist. I run a Hot Air Intake (K&N on the TB) not because of higher HP, but improved throttle response. I have a GP intercooler with a thermal dispersant coating on it. I don't have an APD, but I did run a bunch of ICs. You want your car to scream? Here's the recipe:

Pulley. Save your money for a head job. If you really want power, get a header and a real exhaust. Tune the sucker.

19mm rear bar and camber plates so it will handle. Get good tires, and lighter wheels.

Get driver training at high performance driving events. Improved driving skills will make every car you drive better, stuff you bolt onto your car will only improve that car.

Anyway, this is contrary to what lots say and do. So be it, I'm OK with that. If you are really going to use your car competitively, then going further than this may make sense. The stock MINI is more capable than most can actually use (other than the crappy stock tires and near verticle front wheels). But it really is easier to add stuff to the car than to really learn how to drive the car well.

Also, if you're really curious about what to do to make a car perform better, get some of the classic books on the subject. I've done some reviews in the review section, as have some others. Our car is just a car, and handling dynamics and improving how power is produced is far from new science. While "lean burn" "stratified charge" and some other stuff is now doable with computer control (like direct injection and variable valve timing), these are variations on themes that have been around for decades.


Hope this helps,

Matt

ps, if you do want to read some of the articles I did for MC Squared, you can find them here. -M-

 

^^Here Here. Smartest thing I've read on a forum in a long time. I wanted to say a lot of what you said, but I didn't want to sound like I was on a soap box.

 

Awesome, Matt; very succinct! Thanks very much -- the thread discussion was getting very interesting, but also *way* over my head.

 

Agree! Dr Obnxs +1

 

Boy, is this thread timely. I came home last night and unboxed the new Alta IC with diverter and spray I purchased for $299 (significant saving). I found this discussion after the box was opened. Matt and Phil give compelling arguments to return the unit for a refund, which I now believe would be a no-brainer if I had laid out $799 retail bucks. But, I also read Matt's 2006 article on IC mods, which states in part "For just street driving, there are better ways to spend you money than an aftermarket IC, but if you’ve done all the easy modifications, don’t let me talk you out of the purchase. But I, for one, don’t put it near the top of the mod list, unless you can get one used, for a
significant discount off of retail." Prophetic.
The discussion is pretty clear that the diverter is a "must have," which would cost a hundred and a half by itself, so deduct that from $299 and the IC has just gotten really inexpensive. The real downside of keeping the IC is apparently that I will lose the hood scoop (so what's left, a gaping hole with a raw edge?) that sounds aesthetically unpleasing, which I could live with for a significant (5 hp) performance gain.

So, on a cost-benefit basis, is it worth it to keep the IC or should I ship it back? (PS- I have an '03 JCW with more mods than shown in my signature.)

 

I personally don't think anyone would argue that for the 150~ you paid for it, that it isn't worth it. If they were all that price I don't think this topic would even exist. At that price it'd probably be one of the first mods, and definately the easiest install.

I also think for that price, you could sell it in the marketplace and remake the money you spent on it, instead of going through returns.

 

Unless you are tracking the car, or you have made modifications beyond a Stage I MINI (which includes 15% pulley, CAI, exhaust, and tune), an aftermarket intercooler is really not going to help. Reference this post on five intercooler tests: https://www.northamericanmotoring.co...tercooler+test. The only intercooler I would consider is the GP model, and they are hard to come by. The stock intercooler is a good design because it cools down very quickly after it heat soaks.

I do have the M7 extreme scoop, and that I do believe helps because of the overall increased airflow being diverted to blow by the intercooler. Another option is to buy one of the spray diverter kits to go along with the stock IC. The good doctor recommended going to Cradin (http://www.cradin.com/) to get a thermal coating. The cost is $75. I just got my stock IC back from my old '02 MCS. I should have it installed by the end of the weekend.