Well, it took a few weeks but UPS brought me a cool package today. It was my new Mini Madness Air/H20 intercooler. About 3 hours later I started installing it in my buddy’s garage (my x-wife took all my tools). The install was fairly easy but I did install it my own way. The kit was very complete and all I need to buy was some Anit-Freeze, Water Wetter, and distilled water (25% WW, 25, Anit, and 50% water). The whole install took about 4 hours and now that I have done it once I know I could do it in 2 hours.

After driving the car for about half hour, I soon became very impressed. I was breaking the tires loose and the needle was racing faster than ever to 7500rpm. Even my friend was like, “damn this things pulls!” He said he would finally be nervous to race it against his BMW M Coupe. The BIGGEST surprise was when I opened the hood to check the intercooler for leaks; I noticed the outlet side (driver side) horn was cool to the touch. Almost as if the car was off for an hour. I couldn’t believe it! I have had 3 different intercoolers, but the 4th was the winner. I’m a true believer in this “Air to Water” thing. it is perfect for my aggressive street driving. Every other intercooler I have owned ran super hot and even the outlet side was just barely cooler than the intake side. I was never able to get my other intercoolers to run as cool as the air/water even when I was misting or spraying water on the outside. Of course the Air/water is twice as much as most Air/Air intercoolers but you do get what you pay for.

My only concern is that with my OEM intercooler I was hitting 17.5 psi of boost and now with the Mini Madness air/h2o I’m only hitting 15.5 to 16psi. I’m not sure why this is happening because the core of the air/water is a STOCK intercooler wrapped in metal so the water can flow over and below it. I will have to check the rubber boots to make sure there are no air leaks.

Now is it time to hit the dyno and get a new tune. I wonder what mod is next

M

 

Actually, the drop in boost, coupled with the increase in performance, is testament to how well the intercooler is working. Since you're cooling the air more effectively now, the cooler air is taking up less volume, thus producing less pressure. The performance increase tells you that the total *mass* of air being fed into the engine is larger now, which is the important part.

 

If your air to air's were hot on the drivers side your hood seals were probably not sealing. I run hard with the Alta classic and its cool on that side, hotter than hell on the passenger side. Although to check it you gotta be quick to get out of the car .Your air/h2o is the way to go for a cold charge ,if you can handle the added cost and complexity .

 

If that is the case, is it safe for him to run a smaller pulley?

 

You need to be more specific with that question...A small pulley is safe to begin with...depending on what RPM range you like to run at.

Yes it will help keep the IAT's lower, however you still run the risk of over reving the SC...However no one know's when we are actually over-reving the SC....I've tried to search for this but with no success...

 

That sounds fun but, as of now I have a 17% and spinning to 7500rpm. In about a week I'm going to have my car retuned and will up the limter to 7850 because even now I'm making power on the way to 7500rpm.

 

Maybe now you can keep up with that R56 in AZ?

 

 

 

Mario, glad to see you are happy... and finally have proper cooling... as you know... it's a killer not to... especially since we like to drive hard! LOL

congrats! I look forward to seeing what your car makes on the Dyno!

 

 

Thanks buddy, I'm very happy now. I would love to get the new Fireballed work of art Intake Manifold. I wil be at Fireballed later today for their BBQ.

I was wondering what you thought about the 1.5lbs of boost I'm missing even though it is the same OEM intercooler, just the MM one is wrapped?

 

Ouch!

ScottRiqui's explanation seems sound to me. Moving to a smaller pulley seems ideal now!

 

ScottiRiqui seems to have it right... at least that's what I think as well...


I would stay away from a smaller pulley though.... 17% is more than enough...

there is always the intake manifold... knowing Hubie and Brian... it will be spot on and make for a great power upgrade

 

POST OF THE YEAR.

 

lol.....ok. that was funny.

I hope the new tune and stuff work out though, cause you will need it when I am done.

 

It was early in the morning when I made my first post, so I could have been clearer. Here's attempt two:

Bottom Line Up Front: "Boost is only proportional to power IF you keep the temperature constant".


The power that the engine can produce is largely determined by how much fuel and air you can feed the engine, while keeping the air/fuel ratio within a certain desirable range. Additional fuel, combined with an appropriate amount of additional air, gives more power.

The thing is, the air/fuel ratio is the ratio of the MASS of air to the MASS of fuel, NOT the volume of air or fuel. For instance, an A/F ratio of 14.7:1 means that you're providing the engine with 14.7 pounds of air for every pound of fuel. (I know that "pounds" is actually a measure of weight, not mass, but that's the drawback of the "English system" of weights and measures - the actual English measurement of mass is the "slug", but no one knows what a "slug" is, so I'll just use "pounds", since they're directly proportional to slugs).

The general behaviour of gases is governed by the equation PV = nRT, where P is pressure, V is volume, n is the mass of the gas, and T is temperature. R is a numerical constant, so we can discard it and just say "PV is proportional to nT". Likewise, the volume in your intake system is constant , so we can discard V and just go with "P is proportional to nT".

So, if you raise the temperature, but keep n (the mass of air) constant, the pressure (boost) will increase, even though you won't get any more power (because the mass of air is staying the same). This is what would happen if you were to heat up your intercooler with a heat gun or a torch - the boost reading would increase, but the engine power wouldn't increase, since the total mass of air is still the same. (In reality, the boost would go up *and* the mass of air would go down, causing an overall loss of power).

Likewise, it's possible to both *lower* temperature and *increase* the mass of the air without the pressure changing at all. But you'll still get more power because the mass of the air has increased.

In your case, you've lowered the temperature of the air more than you've increased the mass of the air, so your overall boost reading is lower, even though you've still drastically increased the mass of air going through the engine (hence your noticeable power increases).

If you were to fill your intercooler reservoir with ice water, you'd probably notice an even bigger "loss" in boost, but since the lower temperature would increase the density of the air, you'd be feeding an even larger mass of air into the engine, and would see even bigger power gains.

Your "loss" of boost might point to a restriction somewhere in your intake or exhaust tract that's become the "weak link in the chain", now that you're doing such a great job of cooling the incoming air. This might be the time for a new intake manifold, freer-flowing intake/cylinder head /exhaust, or a larger throttle body. (I know you've already made some, if not all, of those mods to your car - I'm speaking in the general case here).

 

SLUG:


sorry couldnt resist.... thanks for the GREAT post.... always nice to read quality stuff... WOO HOO! That is something I forgot to point out in my disscussions about pressure drop and ICs... especially since it has been made out to be "evil" LOL...

 

Nice! If you could somehow make that post into a cocktail you could make a spoon stand up in it!

Tuls: thats a weird lookin slug man.

ScottRiqui: so you're saying that you could run on like 8 psi and still make more power than if you were running at 16psi w/ air that has less mass? Is there a point where you would be running such a low boost that it would become inefficient, just like overspinning the S/C (hot air)???

 

Exactly - although going from 8psig to 16psig while keeping the temperature constant is a tall order, because of the way positive-displacement superchargers work (they heat the air pretty drastically as the boost increases).

But using more "normal" numbers, here's an example. Let's say that you're currently maxing out at 10 psig of boost. You install a super-whamodyne, highly-efficient intercooler. Your power will increase, but the boost readings may drop to 7-8psig. So now you fit a smaller pulley to increase the boost back up to 10psig. This will increase the power even more (assuming your intercooler is still within its capacity and can still effectively dissipate the additional heat). So now you're back up to your "original" boost reading of 10 psig, but you're making a LOT more power.

But like I said above, there's a point of diminishing returns. With a PD supercharger, you reach a point where spinning it faster only heats the air, without increasing the density of the air much at all. At that point, you could cool the intercooler with liquid nitrogen and it wouldn't matter - the supercharger isn't going to be able to push any more mass through itself. Your only option (without going with nitrous, changing the compression ratio, etcetera) is to go with a larger/more efficient supercharger, or switch to a turbo.

 

Great slug picture - I can't work a physics problem involving "slugs" without getting a similar mental picture.

The other thing I love is when people get all bent out of shape about the pressure drop *across* the intercooler (comparing the boost readings at the intercooler inlet to the intercooler outlet). They act as if any pressure drop across the intercooler is a bad thing, when in reality, if the intercooler inlet and outlet are the same size, and you *don't* get a pressure drop across the intercooler, it means the intercooler isn't working!
With a properly-functioning intercooler, the hot air coming into the inlet gets cooled down in the intercooler, causing it to contract (like a balloon on a winter day), causing it to not press as hard on the walls of the intercooler, giving a lower boost pressure at the outlet. That's what an intercooler is *supposed* to do.

In fact, the ultimate example of an intercooler would be a steam condenser. Hot steam under pressure comes in one end, gets cooled in the condenser, and comes out the other end as liquid water. The steam pressure at the inlet might have been 100 psig, but the gas pressure at the outlet will be zero, since all of the steam has been condensed into water.

 

Its nice to have read about I/C pressure drops from a scientific point of view, not just the usual PRESSURE DROP!?!?!

(now bows repeatedly)

 

ahhh this is nice... I think you understand this far better than I... LOL I can not articulate it as well... I just know what works... and why... LOL... never the less... thank you!

 

Thanks - I tried to keep it simple, but sometimes when you have a complex, interesting question like MarioKart's, you can only go so far with analogies and you have to at least dip your toe into the physics governing the phenomena.

And my post *was* overly-simplified, believe it or not. The interactions in a "real world" engine can get pretty complex. For example, spinning the supercharger faster both increases the mass of air flowing through it *and* increases the temperature of the air, so it's hard to tell how much of the resulting boost increase is coming from the increased air mass and how much is coming from the increased temperature.

Likewise, the pressure drop across an intercooler comes from both the decrease in temperature *and* from restriction to airflow. As you push more and more air through the intercooler in a given amount of time, the cooling becomes less effective, while the pressure drop from the restriction becomes larger and larger. So it can be hard to tell how much of the pressure drop comes from the temperature decrease, and how much comes from the flow restriction. That's why intercooler efficiency is measured by taking both pressure *and* temperature readings at the inlet and the outlet.

 

Seems like you've nailed the point that you can't just bolt on mods and have more power. In a way, the way an engine works is just a beautiful thing. BTW, the cocktail remark was a compliment! (post was loaded w/ info...just in case you misunderstood).