On your web site you state:

[FONT=Arial][FONT=Arial][FONT=Arial][FONT=Arial][FONT=Arial][SIZE=2]Intake-
CAI's are dubious at best: they might work on a rolling road "pull" but that does not translate well to the real world (read the dyno warnings!). Use a K&N flat panel.
Silicone air tubes collapse under pressure -- don't use them.

Could you all go into more specifics why a K&N flat panel is preferred over a CAI?
Are there any benefits to opening up a larger hole between the cowl area and the stock intake box?

Thanks
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I haven't seen any good data on real world benefits with the CAIs. In general, I find vendors claims to be higher than what I can determine, and a lot of items may go into that mix. I'll be testing the HAI vs Stock to see how much air density is improved pre-SC. But it's quite another thing to get all that extra air into power...

Matt

 

For what it's worth, I did some testing with a pda dyno tool on a flat panel vs green twister cai vs pipercross cone filter and the flat panel turned in the best numbers. I did 0-60 runs with each, threw out the high an low and averaged the results.

Not good for actual hp measurement, but OK for comparison purposes.

 

MTH listed power figures are from STOCK MINIs

Just so you know

 

Quickly, because I am traveling, CAI are not really “cold air inductions.” Until recently most didn’t even have a top. That allowed for hot air to enter the intake – the exact opposite of what the intercooler is trying to overcome. The stock air box is designed to work with pressure – “CAI’s” reduce pressure due to their size. All they do in the real world is make noise.
They seem to work on a dyno because on cheap dynos all you have is a fan to blow on the snorkel and it is easier to suck air in through the enlarged cowling hole. But this is not how it works in the real world. To really test an engine you need wind tunnel like conditions (to pressurize the air box). Most manufacturers test in with real world conditions. Bank’s Engineering is a good source of knowledge. (Our tow truck uses one their systems.)
A K&N flat panel works fine because the bottle neck on the Mini is the small exhaust valves and not really any where on the intake side. A header and/or exhaust system works well. You can open up the hole in the cowling a little but you must make sure that you seal it to the back panel. You don't want to suck in hot engine bay air.
I have seen with my own eyes (through a camera lens) silicone intakes collapse. That is why the stock air tube from the air box to the TB has those ribs – they add rigidity.
This was composed quickly but I hope you can make sense of it.

 

There is so little open area into the stock box that it runs under vacuum at WOT and higher RPMs. If the silicon hose is collapsing, it has to have less pressure inside. So much for the box working via pressure....

Some CAIs seal against the hood more than others, and this is true. But it's not just air temp that matters, it's pressure as well, because you're just chasing molecular density.

If an air-box to TB hose is collapsing, then one better open up the flow into the air-box for sure! Either by opening up the back, or improving flow through the front.

While some designs (HAI, K&N Typhoon, AGS) will suck hot air when at a stand still, when really moving there's more air flowing through the engine compartment so it's not that hot of an aircharge. Some with the AGS and HAI have opened the hole in the front of the car to improve flow (but you can't do this with the K&N, it uses the stock funnel, and adds some ductwork to direct the cooler air towards the filter).

If the restriction is the filter, then opening up the holes to the stock air-box won't be a big win.

Just some things to think about....

Matt

 

What do you guys think of these filters?





Or the:
http://www.bmcairfilters.com/VisDetail.asp?ID=201

Is it better then the K&N Typhoon. Pippercross open filter?

 

When you talk about the silicon hoses are you referring to the hose like that supplied by Alta?
If you are referring to the Alta and it is collapsing is this causing a problem, is it restricting air flow?

Alta if this is true, collapsing of the silicon tube, what do you have to say?

I have one of those noise makers and if it is just making noise then is just assume remove it and put back the stock air box and I want my money back for the person that convinced me that it was the way to go – I originally didn’t want to have the additional noise but was assured that along with the noise I was getting more

 

When you talk about the silicon hoses are you referring to the hose like that supplied by Alta?
If you are referring to the Alta and it is collapsing is this causing a problem, is it restricting air flow?

Alta if this is true, collapsing of the silicon tube, what do you have to say?

I have one of those noise makers and if it is just making noise then I just assume remove it and put back the stock air box and I want my money back form the person that convinced me that it was the way to go – I originally didn’t want to have the additional noise but was assured that along with the noise I was getting more

 

I just wish I could get a clear definitive answer with graphs to show if the stock box has more density and air flow over traditional CAI's and HAI's. Right now, I have my stock box back in, but my butt dyno cant seem to tell which is better???? can someone give a good answer with proof???

 

I was interested in more information from MTH about their views concerning the CAI intakes for the MINI mainly because they are a tuner that doesn't sell a CAI. I don't fully trust the views of a tuner who says their product is the best because they are trying real hard to sell it. I tend to trust the views of tuners who are not trying to sell CAIs.

This is not the first time that I have been told by a tuner that the CAIs are just not worth the money. I have also been told by my local tuner shop, who was running a special on a "not to be named" CAI at the time, that the CAIs were not worth the money and my money would be better spent on a rear swaybar or some better tires.

 

Andy (I think) did some testing and found that the stock airbox was running with a bit of vacuum. This isn't good. So what's an aftermarket filter/intake supposed to do?

1) Get more air to the TB. This is done by removing restrictions. If you look at the stock airbox, the cross sectional area of the TB is larger than the tube to the airbox plus the hole into the cowl, so there's room for improvement there.

2) Reduce pressure drop across the filter by increasing flow efficiency or filter surface area.

3) The sound is a bonus (if you like it).

4) Bling factor.

The last two don't increase car speed, but have value to some.

The right way to test the efficacy of the intakes is to look at pre-SC air pressure and temp, and compare molecular density. I haven't seen a lot (any?) data that does this.

Matt

 

SO if the CAI is sooo bad can someone explain why my MPG also jumped up more than 5 mpg overnight, in which case it was worth the oney cause it has already paid for itself? Also take a look at the MINI challenge cars, they are all changing intakes, and in the Unmodified NAMMC there are long silicone hoses being used on winning cars; why have they chosen not to use just a panel filter?

If the goal is to get the most pressurized air into the head (even the MTH site seems to agree with this) then CAIs and HAIs would serve there purpose if even in reducing pressure they could supply porptionally more air, and the lower the temperature the less pressure needed to reach the same quantity of air. Ideally the goal is to get the most pressurized cold air into the engine, there are several methods of doing this, and some are better than others, I don't think the other products out there are all BS as is claimed, but lets allow MTH to make thier case.

 

Yes, these are good things to ponder concerning trying to out design the Mini/BMW engineers. From over 10 years of experience with MOTEC on my Porsche/Fabcar I have gained some insight.

Concerning the Mini, the bottleneck is the small exhaust valves -- you need to scavenge the air. At WOT and high RPM most all systems run a vacuum -- CAI or not. That is why the tube running from the air box to TB has the supporting ridges. But to get to that point it runs under pressure just as designed by the manufacturer.

Pretty much all that matters is air temperature when making power and that is why HAI's or CAI's without tops don't work. Typhone's and AGS can only mix the ambient temperature with the engine bay temperature -- it's definitional.

By enlarging the hole in the back of the box and sealing to the back wall helps because at WOT and high RPM's vacuum is created -- it allows more air in. (But as I was quickly trying saying above, this does not work at low RPM's -- that is why it is best to keep it under pressure by using the stock box.)

Yes, there are compromises Mini made with the stock box which can be improved but it is not the place to start. First, do a pulley, change the software, improve the exhaust, the heads, then worry about the intake (the box, TB, etc.).

 

that there is no point at which this tube is running under pressure. The motor is sucking air in, that has to go by the condutance restrictions of the pre-airbox tubing, and the restriction of the filter.

And yes, the biggest restriction is the exhaust valves, but even then, getting higher air densities at the intake valves is a good thing, even if not all the benefic can be achieved due to the exhaust valve constriction.

Most don't start with a head because it's expensive, and not an easy mod to do. Most start with the CAI because it's cheap and easy. While the pulley is the best mod, it takes more work and some specialized tools to put it on, so many don't start there.

There are other constrictions that can be worked on as well, like the stock header.... And this will help with breathing, even without doing the exhaust ports... Sure it would do more with the head work....

The implication in your post about the optimal designs done by Mini/BMW is funny because then you go to bash the design of the exhaust valves/ports on the head. If their design is so perfect, then it wouldn't need any work! Also, the factory designers are working on a different set of optimization priorities than the driving enthusiast, so even if they did their job perfectly, theres little or no guarantee that it would be the best for the performance driver. Most notably they choke airflow to reduce intake noise for the average buyer.

Matt

 

dmh;

In reference to silicon tube collapse, does that refer to the Alta silicon tube to the CAI??

 

If your asking me I'm not sure about Alta but if they are silicone it might be a good idea to check it out.

 

That is an impressive MPG gain in percentage terms!

I have spent my life looking at silly things people do to good cars and motorcycles in effort to out-engineer the engineers. But I have yet to see the privateers beat the factory. (I spent 5 years as a factory racer for Yamaha raced a few times in IMSA in the late ‘80s.)

You must be referring to the US version of the Mini Challenge. Research what the semi-pro teams run in Europe and repost. What you see in the US are a few “tuners” with their products and no serious racers or race teams. See what happens when the winner goes to Europe in the fall.

Air is forced into the snorkel which leads to the air box. Excerpt for WOT and high RPM’s there is plenty of air available – the box is pressurized. I suggest using a JCW box or enlarging the cowling hole as long as you seal it up to the rear wall. The main idea is to get the coolest air into the engine – it is why the Mini has an intercooler. (Not all forced induction engines do.) To feed the engine warmer air than needed is simply counterproductive. But they do make noise and influence what is referred to as the “butt dyno.”

 

The box is pressurized and not the tube. (I don’t think I said the tube was pressurized but if I did I wrote incorrectly.)

Forcing in more air is not always a good idea if you cannot get it out the other end.

If people do a modification based on if it is cheap and easy – well, what more needs to be said.

I never bashed anyone or company – your implication is enlightening, though. The engineers choose an optimal design. Optimal and perfect are two different things. I never said the air box couldn’t be improved; I actually said the opposite. But using a "filter on a stick" is not the way to do it. Noise and air flow are not necessarily connected.

You seem to be taking my writing out of context and misconstruing it for an unnamed reason.

 

Not at all. You say the factory does the best work. I am just pointing out that their constrains and optimization matrix isn't universal. Case in point. Rear control arms. They are heavy, prone to breakage, and are not adjustable. While this may meet the needs of most buyers who don't modify thier cars, (except for the breakage part), it sure doesn't meet the needs of the handling enthusiast. But it meets the price/performance goals of the factory.

There are lots of examples of how the factory optimization matirx differs all over the place. Pulley diameter is another. Windshields are a third (I'm on my third, far from optimal).

Now I'll have to mount up data logging stuff to really see what the pressure in the stock airbox is and that it's not too good (I think this has already been done, but a few years ago....)

I'm a data driven guy, with no axe to grind other than looking for sound numbers.

Also, it's not just air temp that determines performance, it's air density. If you have too little air, it doesn't matter how cold it is, you just can't burn enough gas to create power. It's when you really stuff the cylinders and start to run into the limit of the knock sensor induced timing retard that temp takes a more important role.....

And really, if the holes improve the box, why won't a filter with larger surface area, and removing the rear baffle help even more? Then it seems that the actual benefit would be a trade off between more airflow into the motor, and some as yet unquantified mixture of some warmer air....

Some things about engines are pretty simple. Your upper limit to power is based on the number of molecules of gas that you can burn. You can't get any more than that. So you burn more molecules, you have the potential to make more power.

Matt

 

this one is Randy sharing the "secret of the holes" from 2002.

This post is from macncheese sharing initial results from the HAI and it's benefits, pointing out that he did better because he got so much more air in that it overcame some of the temp difference. It's from Jan 2003.

Also, with an IC running about 60% or more efficiency at any road speed of concern, the temp increase at the engine is less than half of the temp increase at the filter....

Matt

 

This is turning into a he said/she said. However, the posts are still active and my writing can be verified.
I never said the factory does the best work.
Yes, air density is important (and is influenced by temperature) but air temperature is easier to alter (with the likes of a GRS IC and a proper air box).
You do not have to do anything! Are you trying to out-engineer-the-engineers?
If you want to exploit the benefits of hot air by utilizing a “filter on a stick” I’m not going to stop anyone. I do, however, suggest searching for the truth. Interested parties should go outside of this forum and research (in an appropriate place with appropriate materials) the subject and then decide for themselves.
Mr. Randy Webb first learned the Swiss cheesed air box trick when he was a young boy working at the shop that I used to race out of in the early '90s: Promotion Motorsports. Small world, huh?
One last note concerning CAI’s: Even those that claim to seal against the hood do not seal very well once the car is in motion because even with polyurethane engine bushings the engines sways quite a bit.

 

Please do post pictures... To me this seems like a nasty speculative unwarranted and practically impossible rumour.

The Alta silicone tube from the CAI to the throttle body is quite thick. 'Cooler air' than in the engine compartment comes in through the louver on the drivers side, enters the intake, travels through the tube, and down into the throttle body.

How can an open air intake generate so much force that it can cause a very thick silicone tube to collapse, without vacuuming the the foam filter into the throttle body?

And *IF* it did collapse, you would lose air to the engine, essentially choking the **** out of it, no? I think this would be blatantly obvious if there were any sort of truth behind it, and it would be known throughout the community... And with a company like Alta, I highly doubt they would sell a product with that type of potential defect.

 

I never mentioned Alta but is Alta more sophisticated than Ford engineering and its new GT40? Want more proof of collapsing air tubes: I was pm'ed that the Speed Channel's latest episode of Sports Car Revolution showed on video the air tube collapsing. Interesting, huh? That is why the Mini’s has ridges and most others are hard plastic!
I am new and am astounded by the amount of disinformation while I search around. People modify the strangest things – the air box (by using a filter-on-a-stick) and larger injectors come to mind as well as a fascination with coilovers but not corner balancing. My integrity is sound.[FONT=&quot][/FONT]

 

but it's not all without merrit.

The ECU is reporting duty cycles that are longer than the duration of a single cam rotation at WOT and redline. I didn't look at the injector pulse with a scope yet, but that allone brings the injector capacity into question.

And the intake debate will never end. some quote up to 8 HP improvement, but other tests show much, much lower, to the point of statistical insignificance.

Fact is, these little buggars (Minis) are a real pain to dyno. They are so sensitive to airflow that most dyno rooms have some serious compramises like you alluded to in earlier posts.

I use a G-Tech for relative improvement measurements, along with other data logging hardware and software. I have yet to document a HP improvement that matches vendor claims. I think a lot of it has to do with dynamic (on the road) vs static (on a dyno) testing, but it's just a hunch as I don't have a dyno, nor will I pay for the time to check for sure.

But I gotta agree, if you go coil-over, you should corner balance. FWIW, my Mini was very, very close to corner balanced when I set the ride height with a ruler in my driveway, prior to the corner balance/allignement. I dont have the numbers in front of me, but I was shocked how lucky I'd been.

Matt