Why I chose my supercharger kit

[kthxbye]

Disclaimer

I am not here to say that any one kit is better than another, so please keep the negative comments to yourself. To be honest I really like all of the kits that are available for our cars, and I appreciate the time each tuner has invested into developing their kits


Purpose of this Thread

I recently placed an order for an Active Autowerke Stage II kit, in doing so I did a great deal of independent research and came to a few conclusions that led me to go with the AA kit. To clarify I do not have the kit yet, but I just wanted to share some of my observations that led me to the kit. Info specific to the AA kit does not seem to be very well documented here, so I figured I'd give it a whirl. I intend to continue these threads as I receive the kit, the install proceeds, and I get road time with my kit. Feel free to agree, disagree, or disregard anything I say - again these are my personal opinions and conclusions.


Cooling

Superchargers increase intake by compressing air above atmospheric pressure, without creating a vacuum. This forces more air into the engine, providing a "boost." With the additional air in the boost, more fuel can be added to the charge, and the power of the engine is increased. A by-product of this compressed air is heat, often substantially raising the temperature of the air.

In a nutshell I think we can all agree that heat plays two primary roles in a supercharged car: 1) it reduces performance and 2) it increases wear on components - both things none of us want.

The kits available for our cars each approach cooling slightly differently, but at a surface level you have air-to-air cooling VS: air-to-water cooling. Quite honestly neither is truly better than the other, but when looking a specific applications a particular design can give one an advantage.

Air-to-Water - This setup functions similarly to a radiator, air flows through the intercooler with cool water running through it. As the air passes through, heat is transferred from the air to the water, thus providing a cooling of the air. These setups generally take up less space in the engine bay and allow one to be a little more flexible with placement. In addition, the radiator effect with water tends to provide slightly better cooling than just air alone.

Just like the saying, "what goes up, must come down" - there is a downside to air-to-water cooling. Water holds a higher "specific heat" than air, this means two things 1) it requires more energy for water to increase its temperature than air & 2) Once the water is warm, it will take more energy (time) for it to cool down again.

In theory this means that when running a SC kit that utilizes air-to-water cooling for an extended period of heavy use you risk a loss in performance, but more realistically you risk longer downtimes. However, in theory again, this setup should provide superior cooling during short burst, like 1/4 mile runs - just not back to back runs.

Air-to Air - This method of cooling is slightly more straight forward and requires fewer parts - in my book a simpler design to reach the same end result is generally better. The ambient air travels into the intercooler and transfers its heat to the intercooler, which then disperses it the atmosphere. The intercooler is filled with a series of channels, fins, and louvers to increase its surface area and maximize contact with the ambient air to ensure maximum cooling.

One draw back of the air-to-air system is the need for a larger intercooler, which is almost always placed in the front center of a car's front bumper. Back to specific heat, air has a lower specific heat than water - this means that it requires less energy (time) for air lose the heat its absorbed - allowing for more consistent cooling, even with extended us.

Obviously the major drawback with air-to-air in comparison to air-to-water is the fact that it can't possibly cool the air as efficiently - at least initially, but over time it can match and then exceed the cooling ability of an air-to-water setup that loses its ability to cool as efficiently over time.

The Active Autowereke kit specficically address this variance in cooling ability of the two approaches by adding a methanol kit to their stage II air-to-air cooling system. Contrary to what many believe, the AA kit does not use meth as it is traditionally used in forced induction setups - Active only uses the meth to aid in the cooling of intercooler air. The kit is not tuned for the use of meth and it is safe, it would be insane to use meth in any other way on such a high compression motor. So basically in the AA kit meth is used solely as a cooler not an octane booster.

With all that said, in theory an air-to-air setup will provide the most consistent cooling, regardless of the level of usage. Specific to the Active Autowerke kit, this consistent cooling can reach levels equal to or above that of traditional air-to-water methods with the addition of methanol cooling - and the AA design allows you to maintain that cooling over long periods of time/use. Again in theory, air-to-air setups seem ideal for road courses and the specifically AA kit seems like a great all around solution that combines the best of both.

Oil System

Just like cooling there are two approaches to supplying the supercharger kit with oil, each comes with its associated pros & cons.

Integrated Oil System - In this type of system the engine oil supply is shared with the supercharger. Minimizes maintenance and in theory increases durability of the supercharger. When you change your engine oil, you change the supercharger oil.

The downside I see with this is that sure your supercharger is supplied oil by your engine and is working with your car, but should something go wrong you risk impacting your engine's oil supply. Repairing an S65 motor is generally most expensive than any supercharger kit.

Independent Oil System - This approach utilizes a separate oil cooler and oil system dedicated to the supercharger. Although this require an extra maintenance step, this further isolates the supercharger from the motor and the way I see it reduces one more risk of motor complications.


As you can see I do truly see value in all the kits available. Some are newer and some have been available for years, some are owned by the masses and others by a select few - I take all that with a grain of salt. It is clear that each tuner invested a lot of time, money, and expertise into developing their kits and I am sure I'd be happy with any choice I made. Hopefully this post was helpful to some, I look to continue these post as I learn about the AA kit first hand.

What I would take from this if you are in the market for a supercharger is that there are more questions to ask and more to consider when choosing your kit. It goes far beyond who has the most kits or who has the best reliability track record. Our opinions are skewed by looking only at forums, because a good portion of the owners of these kits are not even active on M3Post. From what I gather you really can't go wrong with any kit in terms of reliability, so ask the right questions and choose the kit that is best for you.

[schnell325]

I think you will enjoy it.

Nice write up.

[Mbauer]

Originally Posted by kthxbye

[I]Disclaimer

Obviously the major drawback to air-to-air in comparison to air-to-water is the fact that is can't possibly cool the air as efficiently - initially, but over time it can match and then exceed the cooling ability of an air-to-water setup that decreases its cooling ability with continuous use.

Sorry my man, but I disagree with this statement. Most Air to Air Intercoolers struggle to remove even 70% of boost heat. Air only has 10% of the thermal conductivity of water. Under the right circumstance Air makes a great Insulator.

Only air-water, or air-refrigerant intercoolers can reach 100% thermal efficiency or greater. I could not find an exact number, but correct amount of meth injection with an air to air intercooler could get you around 85% thermal effieciency I would guess.

[jlh335i]

^ regardless of the rhetoric, the issue is more so about heat soak, not thermal efficiency

[akh23456]

nice man congrats on the kit...you will love the boosted life.

[pbonsalb]

My understanding is that the term intercooler is correct. The compressed air is cooled in between the turbo or supercharger and the engine. Vortech coined the term aftercooler for whatever reason -- probably to differentiate its water to air intercooler from the much more common air to air intercoolers twenty years ago.

I, too, have studied the available supercharger systems. I have also ownd and modified supercharged and turbocharged BMWs, with air to air intercoolers and air to water intercoolers. While there are theoretical arguments that can be made to say one aspect of one kit is better than one aspect of another kit, I am much more practical. They all work pretty well. None have been proven in this application to have much advantage over the other in any respect, whether air to air or water to air intercooling, gear drive or planetary ball drive supercharger, self contained or engine oil, etc. To me, the most important consideration is the tuning -- which maker has blown up the fewest engines per number of kits sold.

[kthxbye]

Originally Posted by Mbauer

Sorry my man, but I disagree with this statement. Most Air to Air Intercoolers struggle to remove even 70% of boost heat. Air only has 10% of the thermal conductivity of water. Under the right circumstance Air makes a great Insulator.

Only air-water, or air-refrigerant intercoolers can reach 100% thermal efficiency or greater. I could not find an exact number, but correct amount of meth injection with an air to air intercooler could get you around 85% thermal effieciency I would guess.

Originally Posted by jlh335i

^ regardless of the rhetoric, the issue is more so about heat soak, not thermal efficiency

You are both correct in a sense, and that is what I was trying to get across. I got carried away writing last night, so it may not have been written clearly.

From the independent research I've done, I've learned that air has 1/4 the thermal conductivity of water. But - water has a higher specific heat, so once it does heat up it will take nearly 8 times as long for it to cool down. An air-to-air setup, in theory, can offer consistent cooling over time.

Air to air setups address the thermal conductivity issue by incorporating larger intercoolers that feed more air through a series of channels and flaps that increases the contact time with the hot air and allows for a cooling that is much closer to what is offered by the smaller air-to-water intercoolers.

What pushed me to the AA kit over other air-to-air kits was the fact that it uses methanol injection as one additional stage to cool the air even further. It is almost like the best of both worlds.

Originally Posted by pbonsalb

They all work pretty well. None have been proven in this application to have much advantage over the other in any respect, whether air to air or water to air intercooling, gear drive or planetary ball drive supercharger, self contained or engine oil, etc. To me, the most important consideration is the tuning -- which maker has blown up the fewest engines per number of kits sold.

I agree with the what most of what you say, we've reached a point where what is offered is fairly safe. Your last sentence I'd take with a grain of salt, that often involves tuning beyond the supercharger manufacturers specs. Also what you hear on a forum is not necessarily the full story - there are plenty of kits out there owned by members who just aren't on the forums. I'd go out on a limb and say that close to half of the kits from any given manufacturer are owned by individuals who are not regularly active on the forums

Originally Posted by schnell325

I think you will enjoy it.

Nice write up.

Originally Posted by akh23456

nice man congrats on the kit...you will love the boosted life.

Thank you guys, I can't wait. It should be a good time

[pbonsalb]

An air to water intercooled supercharger system can use methanol injection as an additional cooling aid just like air to air intercooled supercharger system. I have used meth injection with both forms of intercooling.

In another forum, there is a thread on AA's meth injection system failing and hydrolocking the engine. My view is that a good meth system like an Aquamist, is reliable enough. I have used one for over ten years. Unfortunately, with a centrifugal supercharger, there is no way to tie the meth injection into the tune with a failsafe that will drop boost or ignition timing or rpm limit, at least not on the stock ECU. Therefore, I would not "tune" for the meth and AA states that it does not do so. I would only tune for meth on a $10k to $20k engine if it had multiport meth injection and a failsafe.

[kthxbye]

Originally Posted by pbonsalb

An air to water intercooled supercharger system can use methanol injection as an additional cooling aid just like air to air intercooled supercharger system. I have used meth injection with both forms of intercooling.

In another forum, there is a thread on AA's meth injection system failing and hydrolocking the engine. My view is that a good meth system like an Aquamist, is reliable enough. I have used one for over ten years. Unfortunately, with a centrifugal supercharger, there is no way to tie the meth injection into the tune with a failsafe that will drop boost or ignition timing or rpm limit, at least not on the stock ECU. Therefore, I would not "tune" for the meth and AA states that it does not do so. I would only tune for meth on a $10k to $20k engine if it had multiport meth injection and a failsafe.

I saw that thread as well, there will always be one off cases with any kit. And with products like these, there will always be those who tinker around trying to squeeze out more performance - when that happens you can't really blame the kit.

You are correct about AA not tuning for the meth, in other words the kit does not rely on it. Because they are simply using it for cooling and not octane boosting it is a nice little addition that lets you reach, and in situations, exceed the cooling of an air-to-liquid system without sacrifices the long-term usability and consistency or air-to-air.

Active's car that took 1st in its category for One Lap of America is a great testament to that. The event traveled the country racing track to track over a week, a consistent theme was heat soak degrading performance across all platforms on air-to-liquid systems

[Mbauer]

Originally Posted by kthxbye

Active's car that took 1st in its category for One Lap of America is a great testament to that. The event traveled the country racing track to track over a week, a consistent theme was heat soak degrading performance across all platforms on air-to-liquid systems

You keep saying that all these cars using air-water intercoolers are heat soaking. They only heat soak if the size is not engineered correctly for the application. A correct size air to water intercooler will out preform a air to air intercooler always.

[kthxbye]

Originally Posted by Mbauer

You keep saying that all these cars using air-water intercoolers are heat soaking. They only heat soak if the size is not engineered correctly for the application. A correct size air to water intercooler will out preform a air to air intercooler always.

Again my conclusions were based off of the observations I've made. At some point the water will heat up and lose its ability to efficiently cool. When that happens the down time with water is up to 8 times of what it would take an a-to-a setup. Ive seen the a-to-w kits expert experience a greater loss of performance than a-to-a (specifically the AA kit, i cant speak for others) kits on hot days

Perfect example is One Lap of America, the M3s running a-to-w experienced a decrease in performance as the laps went on.

[dnotorious]

Interesting read, thanks for the post. I learnt alot; I like the style u presented the information with (i.e with pro's & con's) and importantly educating us about supercharging our beasts with various kits

[kthxbye]

Originally Posted by dnotorious

Interesting read, thanks for the post. I learnt alot; I like the style u presented the information with (i.e with pro's & con's) and importantly educating us about supercharging our beasts with various kits

Exactly, I'm glad you got the point. I am not here to point fingers or justify my purchase, I just want to share information i gathered regarding supercharging to empower those who are on the edge to ask the right questions and ultimately make the dive. I don't care what kit choose, just have fun and enjoy your purchase!

With that said, I can't wait for some boost

[Mbauer]

Originally Posted by kthxbye

Again my conclusions were based off of the observations I've made. At some point the water will heat up and lose its ability to efficiently cool. When that happens the down time with water is up to 8 times of what it would take an a-to-a setup. Ive seen the a-to-w kits expert experience a greater loss of performance than a-to-a (specifically the AA kit, i cant speak for others) kits on hot days

Perfect example is One Lap of America, the M3s running a-to-w experienced a decrease in performance as the laps went on.

I know you are stating based on what you "saw" but you did not log any IAT temps and you are drawing your own conclusions without actual facts, so your just speculating.

I know your just trying to explain why you chose your kit, which there is nothing wrong with that. I'm actually pumped for you cause I know you will enjoy it. Its just disappointing when people try and blur the science of how these things work to try and rationalize their view of a product being "better" more or less.

Theres a bad ass book on amazon.... HERE
Ive read the entire thing multiple times because my brain is energized by engineering like a kid on Christmas day. Its filled with case studies, mathematical formulas ect... sorry if I'm getting nerdy. Anyways, it explains everything your talking about and how efficient they are. I was even quoting it in my response. I highly suggest you read it, not just you but anyone that wants to own a supercharged vehicle. Theres plenty of things being left off the table on this forum that a lot of these kits dint even address. The answer isant always MORE boost or Meth!

Lets see some pics of that thing when it shows up!

[m33]

A little deep but good write up , bottom line is this is an unsafe world and so is the environment against our cars but at this point all we can do is create a good comfortable safety margin for the cars as far as heat goes and all the available kits out there address this,some better than others but to each his own.

And please don't say amount of kits don't matter when it does cause when company A sells 1k kits with 0 issue track record that says something PERIOD ! Means its a good safe purchase.

Great efforts none theless .

Cheers

[crabman]

Originally Posted by kthxbye

Again my conclusions were based off of the observations I've made. At some point the water will heat up and lose its ability to efficiently cool. When that happens the down time with water is up to 8 times of what it would take an a-to-a setup. Ive seen the a-to-w kits expert experience a greater loss of performance than a-to-a (specifically the AA kit, i cant speak for others) kits on hot days

Perfect example is One Lap of America, the M3s running a-to-w experienced a decrease in performance as the laps went on.

You are just making excuses here for choosing what you want. It makes no difference what the cooling medium is, any cooling system simply has so much capacity. Whether its air to air or air to water makes no difference whatsoever. Exceed that capacity and the system will lose its ability to keep up with the heat load. This is true whether it be air to air or air to water. Physics works as the saying goes.

You say you like the less to go wrong approach and its a strong point in the air to air choice and then turn around and say you area also going to run meth which puts your simplicity advantage out the window and further say can "reach levels equal to or above that of traditional air-to-water methods". Yet you can equally well run meth with water cooling. Again it just sounds like making excuses for purchasing what you want.

As far as intercooler or aftercooler we are talking about aftercooling and aftercoolers. Where turbochargers are run in stages the first stage compressor feeds the inlet of the second stage compressor that further compresses the charge air. To keep temps in check a cooler is positioned between the first and second stage compressors. This is the intercooler. The cooler positioned after the final compressor stage is the aftercooler and as its name implies comes after the final stage air compression and from there air is fed into the engine.

[cavisboung]

the issue is more so about heat soak

[kthxbye]

Originally Posted by m33

A little deep but good write up , bottom line is this is an unsafe world and so is the environment against our cars but at this point all we can do is create a good comfortable safety margin for the cars as far as heat goes and all the available kits out there address this,some better than others but to each his own.

And please don't say amount of kits don't matter when it does cause when company A sells 1k kits with 0 issue track record that says something PERIOD ! Means its a good safe purchase.

Great efforts none theless .

Cheers

Not saying that the number of kits sold doesn't matter, surely it does. But take what you read here with a grain of salt, every manufacturer has a whole slew of customers who are not active or not even on the forums.

It just like saying every M3 owner must be on here, it simply will never happen.

[Verify]

Great post! Hope its everything you want it to be.

Ignore the people that live with hate in their heart and want to discredit any decisions you made.

I just ask you post some high resolution pics and video when its done.

[kthxbye]

Originally Posted by Baggy_M

Great post! Hope its everything you want it to be.

Ignore the people that live with hate in their heart and want to discredit any decisions you made.

I just ask you post some high resolution pics and video when its done.

Thank you Baggy, I certainly will. I plan to document every stage of the build

Went I built up my Z06 I didn't take the time to document the build. Now that I've sold it, I wish I had some more pictures to hang on to.

[tma1c]

Nice write up and clarifications.

[erm324]

Personally I think the blower is too small on the AA kit and youll be leaving a significant amount of untapped power on the table by running it, my buddy Akash is running a nice AA setup with a larger HKS blower and picked up some great gains you should see what hes running and do the same.