[Induction Concepts]

OK, I would like to mention a few things. Yea, yea, I know some of you will say I'm a competitor, but I don't consider any remote-mount turbo a competitor with what we do. We focus on a totally different type of customer, and end result, with a totally different (exactly opposite practically) design philosophy. I mean yes, a turbo is involved, but that's where the similarities end. We don't even make a twin turbo system for the H2's. We would if there was enough demand, we just haven't seen it yet, so thats beside the point.

I answered a post on here yesterday or the day before, someone asking about one of those air tornado things on ebay for $20. The guy is looking for a performance improvement, he just didn't know any better. We are all ignorant until we learn, and there's certainly nothing wrong with that.

Anyway, I have seen quite a bit of talk here about remote mount turbos and I think there are many things that the general public doesn't know about this type of design. Unless you have a very thorough knowledge of turbo system design, you have no way of knowing these things. But if you're going to lay down your money for something, especially several thousand dollars, wouldn't you want to have all of the facts? I think that if you read these points, you'll see that they are all common-sense items when you understand whats going on. I'm going to explain all of this in simple layman's terms, so regardless of your technical skill level, you will understand and learn.

LasVegas: I'm not trying to insult or disrespect you in any way, everyone has their own preferences, opinions, and goals. its what makes this country great. In fact I applaud you for taking the turbo plunge. I am just trying to provide some information so that people are well informed and can make an educated, purchasing decision, something that is never a bad thing.

But, for the sake of this turbo vs supercharger comparison, there are some things to note that are different on a remote-mount type of setup than with a conventional turbo system.

First, for those of you who know nothing about a turbo, here are some basics. You know those pinwheels you played with as a kid? They have a fan type wheel on one end of a stick. If you blow on it, it spins. OK, now picture one of those, but instead of the stick coming down, having a shaft attached to the center of that wheel, running out the back, away from the wheel. On the other end, is another pinwheel, facing the opposite direction, so they would both be facing out, away from each other. If you blow on one, it also turns the other one because they are joined by that common shaft. A turbo is a lot like this inside. One side is the exhaust or turbine side. The heat/energy from the exhaust coming out of your engine spins one of these wheels, called the turbine wheel. This in turn spins the wheel on the other end of the shaft, the compressor wheel, which sucks air into the turbo inlet. This air is spun around an increasingly smaller passage inside the compressor cover/housing, which compresses the air making positive boost pressure. That may not sound like it could do much, but turbos typically spin at 60,000-120,000 rpms when in their efficiency range, with 90,000-100,000rpms being common, depending on the size of the turbo. Thats fast. At 100,000rpms, thats almost 1700 revolutions per second. This speed is what makes it all happen. This positive boost pressure crams air into the cylinders, thus the term 'forced' induction. Ok, now you know the basics of how a turbo works, I'll get on with the differences I mentioned.

Exhaust Heat/Energy: A turbo is driven off of exhaust heat and energy, as I just explained, this is just the pure physics of a turbo's design. When the turbo is 15 feet away from the exhaust valve, instead of the normal 12-24", there isn't much heat energy left. I mean from 900 degrees to 200 (or less) is a pretty major decrease in temps and energy. You can actually grap the end of a tailpipe with your hand while the engine is running. It is hot, but not hot like grabbing ahold of your header. There is a formula somewhere that calculates the temperature drop for every inch you move away from the heat source. You want a turbo as close as possible to the exhaust valve for this very reason.

Exhaust Distance/Restriction: The more distance you have between the exhaust valve and the the turbine wheel, the more restriction that adds up. This means slower air velocity, slower turbine wheel speed, less boost and more time required to build boost.

This all means that you have to work the turbo much harder, to make the same amount of boost and power at the engine. For instance to get 5psi of boost at the engine, the turbo is having to make say 10psi, maybe more. This effectively cuts the power of the turbo in half. For instance on a turbo that can make say 30psi max, you may only be able to get 15psi out of it, max. So you are only getting half of the power potential of the turbo you paid full price for.

Charged Air Distance/Restriction: Now, on the flipside, the same is true for the charged air. Charged air is the air that is sucked in by the turbo, through the air filter, then compressed by the compressor wheel and sent to the engine, usually also through a front-mounted intercooler. Charged air is also called the cold side.

You are already having to overwork the turbo on the turbine/exhaust side, to get the same amount of boost at the engine, now you have to also push the charged air an EXTRA 15ft back up to the front of the car, then through the intercooler, then into the engine. This is adding more load to the turbo, after all, the compressor wheel is attached to the turbine wheel by a common shaft, so a restriction or 'drag' on one, affects the other. In effect you have restriction or drag on both of them, compounding the situation. So now its not only slow and under-responsive on the turbine/exhaust side of the turbo, but also having to work harder, on the compressor side, to push this compressed air all the way back to the front of the vehicle to get it into the engine. This extra effort, to spin the compressor wheel, in turn makes it harder for the exhaust to turn the turbine wheel, when the exhaust heat/energy is already crippled to begin with.

You know those pinwheels I mentioned above? Ok, imagine blowing on that while holding your finger out and dragging it against the tips of the blades as they are trying to turn...restriction. Restriction is the enemy of a turbo system.

Here's a real world example to put that into perspective. I had a pair of Dynomax Race Bullet mufflers on a turbo car. They are straight through mufflers, no chambers. I like the way flowmasters sound on a hotrod. I knew that chambered mufflers were not a good choice to run on a turbo car, but I really liked the way they sounded much better than the bullets. I thought there would be a small difference, but nothing major. Besides, it wasn't a race car, it was a daily driver, so we weren't trying to eek every last ounce of power out of it. A small loss would be a worthwhile trade off. The sound of a killer exhaust is almost as big of a part of the whole experience as the power is. The car normally made 12psi on pump gas and made it very quickly. I swapped the bullets for the Flowmasters. And these were 3", 2-chamber flowmasters, so definitely not one of the more restrictive versions. I made no other changes. The power went from 12psi to 8psi, that's a 33% difference! I'd call that a little more than a slight loss of power. And, to top it off, it didn't make boost anywhere near as quickly, the car felt doggy. I promptly took the flowmasters right back off and put the bullets back on. Just the added restriction of those two chambers in the mufflers made that big of a difference.

Charged Air Heat:Turbos have efficiency ranges (efficiency islands) where they operate best. When you move them out of this efficiency range, their performance really falls off and can even go into whats called compressor surge when they can't move enough air. When you compress air, heat is generated, its a law of physics. The more you compress it, the more heat it generates. This is why we use intercoolers, to remove this extra heat we put in from compressing the air. But even the best air/air intercoolers will never reach 100% efficiency, so you can never remove all of the heat that was added, usually 70% is considered an excellent air/air intercooler. Now liquid/air intercoolers can achieve 100% efficiency, sometimes even more, but only when ice water is running through the system. This doesn't work in a street driven car because the ice quickly melts. Its the only way to fly for a racecar though. Well now you are having to generate twice the boost at the turbo (more heat) to make half the boost at the engine, because the turbos are so far away, so you have more heat, which means less dense air, which means less of it can fit in the cylinder. It also means you are more prone to detonation, which is very bad...engine-destroying bad. So its not a matter of just cranking up the boost to offset these problems. At a certain point, you will move the turbo outside of its efficiency range and only generate more heat, not more power. For instance on a 60-1 turbo, it makes its maximum power at 24psi. Sure, you can turn it up to 35psi, but it won't make any more power, it will only generate a lot more heat, in effect making less power (less dense air).

Restriction vs Volume:As I mentioned already, the same distance problem on the hot side also affects the charged air side. The further you have to push this air, the more restriction you have. This equates to less air getting into the engine. Think of a garden hose with water pouring out. When you place your thumb over the end, it starts to spray. That would seem like a good thing, but what it is doing is causing a restriction. Yes, it makes the water spray, but it is reducing the amount, or volume, of air coming out of the hose. In an internal combustion engine, its the volume of air that makes power, not the speed of it.

More Air = More Fuel
More Air + More Fuel = More Power

Yes, increasing the speed of the air will increase the volume to a point, but then the pressure goes up and the volume drops off and you've reached a point of diminishing returns. We face a similar challenge with fuel systems and fuel pressure. We can't only increase the pressure, we must increase the volume.

Boost = Restriction: This may be a little more difficult to understand. Boost is a measure of restriction on the air we are forcing into the cylinders. An engine that is more efficient, free-flowing air cleaner, straight shot of air into the throttle body (or carb), larger intake runners, no sharp corners, ported and polished intake, ported and polished heads, cam(s) optimized for the application, oversized valves, headers with large primary tubes and collector, large diameter exhaust, no cats, no sharp bends, straight-through mufflers, etc., will make more power at less boost than say a stock, or less efficient version of that same engine. Its making more power and moving more air, with less boost (restriction). Its simple, the more air (volume) you can cram into the cylinder, the more more fuel you can add, and therefore more power you can make. Here's an example. Lets say you can make 600hp at the tires with 12psi on a stock engine. Forget about the weak factory internals for a second. Now, take the same engine, with the same displacement, but with the improvements listed above, it might make that same 600hp at the tires at 8psi. As a side effect of less boost, you have less heat and are less prone to detonation, so its safer for the engine.

Pressure: Now, think about pressure for a minute, imagine pressurizing a pipe that is 2" in diameter and 2 ft long. Now, imagine having to pressurize that same 2" pipe, but now its 17 ft long. It takes a lot more air to pressurize it. It also takes more time. Again, on a system that is already hurting on exhaust energy and extra drag. The problems compound.

Vacuum/Boost Reference Signal: If you read the instructions for any quality electronic boost controller, they will stress to mount the solenoid as close as possible to the wastegate. This is to keep the vacuum line that sends the vacuum/boost signals between the boost controller and wastegate as short as possible, because these signals are adversely affected by distance. The general rule is to keep them no longer than 2 ft.

Well, when the turbo and wastegate are mounted by the rearend, you're going to have 15ft of vacuum tubing and usually it takes 2 of these vacuum lines running to the wastegate, one to the bottom side of the wastegate and one to the top. You can't just mount the solenoid back by the turbo either, because it has vacuum/boost signals running to and from it (usually 3 or 4), between the wastegate, the intake manifold, and an inside controller with a display or gauge, so that won't solve the problem.

Factory Exhaust: One of the advertised strong points of the remote mount type of turbo is the fact that it uses the factory exhaust system, one of the reasons why its cheaper, and easier. The factory exhaust system is usually anything but optimal for airflow. Thats one of the first modifications that many do, is chunk the whole factory exhaust system for a set of headers, an h/x-pipe, either ditch the cats or replace them with high-flowing versions and new mufflers. Often a larger size of exhaust pipe is also used. The factory exhaust is usually quite small, just large enough for the stock power level. It usually features compression bends instead of mandrel bends. Now, if you replace your entire exhaust system with a larger version of the upgraded pieces I just mentioned, then you've solved these problems...and added an extra $1500 to the cost.

So, a remote mount turbo system is going to:
- Build boost slower
- Generate more heat and restriction in the charged air system
- Make less boost at the engine, compared to the boost the turbo is actually making
- And because of the above, make less power for that particular boost level. Remember, when you're seeing 5psi at the engine, you're actually running probably twice that amount at the turbo. So if the system makes X hp at Y psi, its kind of misleading because that boost level is measured at the engine instead of at the turbo. Otherwise, it would be much less flattering numbers to measure the boost that the turbo is actually making vs the hp at that boost setting. As an example, lets say it makes 350hp at the tires at 5psi. At first glance, that sounds like a decent number. But when you measure that same boost at the turbo, instead of up front at the engine, the turbo may be generating 10-12psi, and 350hp at 10-12psi is far from flattering. 600hp at the tires @ 8-9psi is flattering.

There are several other things about these types of designs that I could mention, but they are typical design and component selection issues that most turbo companies (not us) also do, so they're not relevant to this post on the differences between a remote mount and a conventional turbo system.

Now, the remote-mount type of turbo systems do have their place. If you've just got to have a turbo, and you're looking for the bare-bones, cheapest way to get a turbo, that is it. I believe I saw a remote mount on a website, a year or two ago. A couple of guys trying to figure out the absolute cheapest and easiest way they could build their own home-made turbo system.

A proper turbo system is very difficult to design correctly and it takes a great deal of effort, time and money. In my opinion, a remote mount design is a poor shortcut. Turbos have been around for well over 100 years, like superchargers. Its never been done that way, before now. Was it because no one ever thought of doing it this way, or couldn't figure out how to do it this way? Is it beyond the mental capacity of people like Gale Banks, Corky Bell or John Lingenfelter? Or could it be because of the issues I just mentioned?

I know that SEMA gave out an award for a remote mount type system. I'll reserve my comments and thoughts on that.

Everybody wants a turbo, they just don't want to pay what it costs for a proper system. Like anything that's done right, with top quality parts and components, its expensive. You guys, of all people, should know that you get what you pay for. You drive H2's, you appreciate the 'finer' things in life, you know that cheapest is rarely, if ever, best. If that was the case, you'd all be driving Scions instead. Thats why it has surprised me to see so much talk on here about them...but like I said, you have no way of knowing what hasn't been told to you.

I hope this at least sheds some light on some issues that haven't been mentioned. I hope I don't have to dawn my fire-suit now, but probably will. As I said, I am not trying to disrespect anyone, just point out some facts so that people can make well informed decisions. Like I said, we don't even make a kit for the H2s, so I have nothing to gain by sharing this information. We're all automotive enthusiasts and we get on these forums to learn, teach and share in something that brings us all a lot of enjoyment. Cars are much more to me than just a job, they are a part of me, my life, my heartbeat, my breath.