Frequently Asked Questions
This page is dedicated to help people understand more indepth how and why certain modifications work. I will be explaining the in's and out's of power adders (forced induction and Nitrous Oxide). I hope that these explinations give you a better understanding of how and why these modifications work.
If a part says for "off-road" use only, does that mean that I can't use it on my car?
What is the difference between supercharging and turbocharging
What does intercooling mean?
How does intercooling work?
Which intercooling method should you choose?
How does nitrous oxide work and is it dangerous for my car?
How does a "Wet" Nitrous system differ from a "Dry" Nitrous System?
How much does a nitrous system cost?
How much does it cost to refill your nitrous bottle?
If a part says for "off-road" use only, does that mean that I can't use it on my car?
The reason why you see this phrase on parts such as the y-pipe, only has to deal with the fact of getting that product certified. If you pay the extra money to get a certification for your product and do more tests you can make your aftermarket part "legal" for street use. The main reason why this part isn't for street use is that the company making the part doesn't know if they will get their money back from the parts that they make so they don't spend the extra time and money getting the part certified. No reason to use the extra time and money if you don't know that you will get your initial investment back out of it. That is something that they would do after they see that there is a demand for the product.
You can still use these "for offroad use only" parts and a lot of people actually do this. That is just something that is said b/c that part hasn't met certification or the research that would qualify it for legal street use. 95% of the time parts labled as "for off-road use only" are still infact good part and will meet all emissions requirements. However, the time and money to put the part through certification processes and to make it a legal modification have not been undertaken. Go to the top
What is the difference between supercharging and turbocharging?
Turbocharging is a way of making free power. What happens is you use the exhaust gases that your car creates to spin turbines in the turbo to create boost. You are therefore using the energy that your car creates to make free horsepower. A downside to turbocharging is "turbo lag" which is the difference in time from when you push down the gas until the turbo spools up and starts making boost. This can be cured by changing the type of turbocharger you have with a more efficient one that has a less lag time.
Supercharging works differently as the supercharger uses a belt drive off of your crankshaft pulley to run the supercharger to create boost. You can think of a supercharger as an air pump that uses power to make power. You will make boost at different RPM based upon what type of supercharger you have. There are 3 different kinds: The Lysholm (twin-screw), the roots, and the centrifical. The twin-screw supercharger will start making boost right from idle all the way up to redline. The roots supercharger of old are remembered as the kind that top-fuel dragsters use which typically stick up out of the hood with the visible row of butterfly valves. The present roots superchargers are characterized by a supercharger package that takes up considerably less space and has a self contained oiling system. Finally, there is the centrifical supercharger. These superchargers can either have self contained oiling systems or they can draw the oil from your oil pan for lubrication. Centrifical supercharger have a linear boost curve which means that you make more boost the higher up in RPM you go. Typically you start to make boost above 3,000 RPM all the way up to redline, but there are ways to get boost to come on earlier. Use of an smaller supercharger pulley will produce more boost at lower RPM's than it would with its stock pulley but it might also cause more wear and tear on the internals of the supercharger. Going with smaller supercharger pulley usually voids your warranty on your supercharger so investigate any other ways to get more power before taking this route.
Typically turbochargers are more difficult to install because of the extra tubing and are more expensive than superchargers in overall cost. With this added cost you do have some advantages. A good thing about turbochargers is that you get the same amount of power running a turbocharger at lower boost levels than you would running a supercharger a higher boost levels. The reason behind this is that you are using the spent exhaust gases to power your turbocharger while superchargers are powered by running off a belt from the crankshaft pulley. This is why superchargers seem to "come on" at a certain RPM. Taking this into consideration you can get more power out of less boost on a turbocharger than you would a supercharger. Factor in that you would more than likely have an intercooler installed with your turbocharger and you have cooler, more densly packed air going into the engine than you ever could get with a supercharger. Turbochargers are usually silent running which mean that you will hear little more than a "Whoosh!" coming out of the Blow Off Valve during shifts. This is good because people don't know that you are running a turbocharger because they don't hear anything abnormal when your car is at idle. A large intercooler in the front grill usually tip people off that your car has more power than they can see. Go to the top
What does intercooling mean?
Intercooling is the practice of cooling down the air coming into the engine before it gets to the intake manifold. Generally, you will find that for every 10 degrees Fahrenheit that charge-air temperature is reduced, you will gain one horsepower. If the charge-air temperature is reduced from 500 to 200 degrees Fahrenheit, a temperature change of 300 degrees will yield 30 horsepower. This gain is achieved because as air cools it becomes more densely packed with oxygen and takes up less space. The denser the charge, the greater the concentration of oxygen molecules per cubic centimeter. Having air that is dense with oxygen molecules in the combustion chambers will allow for more air to be packed in the chambers and will allow for more horsepower to be produced compared to air that has less oxygen molecules.
To achieve maximum horsepower, the temperature of the charge-air entering the engine requires close attention. The benefits of reducing charge-air temperature besides the gain of more horsepower is also the increase in the detonation threshold. In optimal combustion, the air/fuel mixture begin a controlled burn at the spark plug and graduate outwards through the end-gas, thereby driving the piston through its stroke in the cylinder. Detonation deviates from this process by beginning its burn as any controlled burn would, but instead ignites the end-gases uncontrollably. Leading to an increase in peak and mean cylinder pressures of up to 1500 psi, doubling normal peak combustion pressure. This deviation is referred to as detonation. End-gas temperature directly determines the onset of detonation, based on the temperature of the charge-air entering the cylinder.
Intercooling is essentially a win/win situation. Not only do you dramatically increase horsepower, but you also eliminate the likelihood of detonation. It can be implimented on both supercharged and turbocharged applications. Go to the top
How does intercooling work?
An intercooler transfers heat from the incoming charge air to the air molecules outside of the cooler just like any heat exchanger (EX oil cooler, radiator, etc). When hot charge air enters the intercooler, there exists a change in temperature between the charge air (incoming air) and the air outside of the intercooler core. The heat energy will want to dissipate from an area of high heat energy concentration to an area of low heat energy concentration, using the aluminum on the intercooler as a transfer medium. The extent to which heat energy will dissipate depends on the internal and external temperatures. The coolest that the charge can possibly become will equal the average of the temperature within and outside the intercooler.
Some factors that effect intercooling are pressure drop, charge-side cooling and often times the plumbing design that delivers the charge to the engine.
If the pressure entering the intercooler is 10 psi and the pressure exiting is 8 psi, then you have a change of 2 psi of pressure drop. The heat produced from turbo/supercharging comes mostly from the compression of air entering the turbo/supercharger. As air is compressed it creates heat and has a tendency to want to expand to equalize with the temperature of the outside environment. Pressure drop (expanding the air), cools the charge that is entering the intercooler.
So lets put this in an example. While your turbo/supercharger is pushing 10 psi, your plenum only sees 6 psi of intercooled boost. This can be good and bad in some cases. It is good in the sense that you are creating more horsepower per lb of boost because you have a denser amount of air coming into your engine than if you didn't have a intercooler on your car. Remember more dense = more power. On the other hand it can be bad if you have your heart set on running 10lbs of boost. In this case you would have to spin your turbo/supercharger many more thousands of RPMS in order to reach your desired boost level. High RPMs means more heat produced which tend to kill turbo/superchargers if they are not built to run at RPM's that high. If more heat is produced you will have lower horsepower and you will increase the likelihood of detonation.
Charge-side cooling refers to the efficiency of your intercooler to equalize the temperature within and outside your intercooler. If charge air were 200F and the cooling media is 100F, 50% charge side efficiency should result in air at a temperature of 150F leaving the intercooler.
The plumbing design of the intercooler also effects how efficient the intercooler will be in delivering the boost. The sharper the angles that boost must travel the greater the increase in pressure drop. The quickest path is always the straightest path (the path with the least amount of bends), with distance travelled coming in close second. Case in point, end tank design on intercoolers must take care not to hinder the flow of charge-air.
In choosing an intercooler you must weigh these factors and arrive at a compromise of a heat exchanger with minimal pressure drop while maximizing charge-side cooling. Go to the top
Which intercooling method should you choose?
You must take into consideration weight, convenience, and application. You may choose one or all three types of intercooling methods to satisfy your application and budget.
1) Air/air intercooling- uses a heat exchanger with air passing through the core as the cooling medium. This is an excellent method for overall convenience given that you have ample airflow through the core. However, this method will never attain a charge-air temperature equal to the ambient air temperature unless another medium is used in conjunction with the air passing through the core. Good examples are injecting nitrous oxide, methanol and/or water through spray bars on the intercooler.
2) Air/liquid intercooling- uses a heat exchanger with liquid passing through the core as the cooling medium. This method requires more attention to detail because you must have an external reservoir and pump to move the fluid across the core. To use this method reliably you need to have another smaller heat exchanger where air can pass thorugh it to cool the medium as it leaves the main core on its way back to the external tank. This method has the flexibility to manipulate and vary the liquids used to cool the charge. This is one of the only methods that can attain ambient air temperature. Given that ice water is used in the tank and that the ice water temperature is colder than ambient, the resulting equalized temperature should equal the ambient environmental temperature. However you have to consider the fact that ice will melt over time and diminish in its ability to reach cooler temperatures as the water gets heated.
3) Water/liquid injection- Injecting liquid directly into the charge path entering the engine allows for heat to be transferred directly into the medium (water) injected in the tract. Water makes for an excellent intercooler since it has higher specific latent heat transfer properties. The concept of injecting water into the internal combustion engine has been around for over 50 years.
When we apply heat energy to water its molecules begin to expand. At 100�C the water begins to evaporate and a large amount of heat energy is consumed in sustaining the process. So what? Water is the perfect liquid for regulating excess heat under certain engine-operating conditions. Its biggest contribution is inside the combustion chamber where under excessive loading, pre-ignition and detonation can otherwise occur. Most of the heat inside your engine is transferred to the cylinder wall. The solution: use water injection to alleviate the heat build up. Go to the top
How does Nitrous Oxide work and is it dangerous for my car?
Nitrous Oxide injection provides additional oxygen by 2 methods. The first (and lesser effect) is by cooling the intake charge. Since Nitrous Oxide is stored in the bottle in liquid form (and usually at about 1000 PSI), when it is released into the intake, it expands into a gas. The effects of this it that you will experience a drop in temperature, which will cause the density of air to rise. A typical nitrous system will drop the intake temp by about 60-80 degrees.
The second effect is the break down of Nitrous Oxide in the combustion chamber. When Nitrous Oxide is heated to 572 degrees Fahrenheit it breaks down and releases the oxygen into the mixture, allowing extra fuel to be burnt.
There is a third effect to nitrous injection- The nitrogen released during the breakdown process helps to buffer (dampen) the increased cylinder pressures created, which leads to a more efficient burn of the oxygen/fuel mixture
Using Nitrous Oxide in your car will not harm it or lessen the life of your engine if installed and operated properly. Before you start using nitrous you will want to make sure that your engine is in good running order and passes a thorough examination. If your engine has been checked over and it is in good running condition you can proceed with installation a nitrous kit on your car. I would highly recommend that you have an experienced speed shop or professional install and tune your nitrous system if you do not possess the skills necessary to do so. Don't overestimate your ability and be honest with yourself, remember that you will be driving your car with this nitrous system on it. As a bare minimum you should expect to run colder spark plugs and 93 octane gas.
Some myths have been created by people that were inexperienced in installation or operation of their nitrous oxide system. The main reasons that a Nitrous Oxide system can destroy reliability in an engine is lack of professional installation by the user or using a nitrous jetting to get extra horsepower while not upgrading the weakest links in their cars. The higher amount of horsepower you choose to add to your car by a bigger nitrous jet will put more strain on your engine unless it is properly upgraded. The more horsepower you put into your car the more you should be looking for a weak link to show up. With more nitrous being injected into your engine you should at least consider upgrading the following components: upgraded engine internals, as well as additional fuel supplied by a bigger fuel rail, fuel injectors, and fuel pump. These are some but not all of the "weak links" that are not up to the task of supporting higher levels of horsepower. Go to the top
How does a "Wet" Nitrous system differ from a "Dry" Nitrous System?
The "Wet" system injects both nitrous and fuel into each of the intake manifold runners to ensure an even nitrous/fuel distribution. The "Dry" system injects nitrous right before your Mass Airflow Meter and might result in an uneven distribution of nitrous into each cylinder.
The advantage of a wet nitrous injection system is that it evenly distributes nitrous and fuel into your intake manifold. Depending on your application, you might be able to hide it under your intake manifold for that "stealth" installation. A downside is that this kit will cost more for as a whole and for installation.
Some advantages of a dry nitrous injection systems is that it requires no plumbing for the additional fuel delivery and fuel does not flow through the entire intake manifold. Lastly, as the nitrous pressure in the bottle fluctuates the amount of fuel delivered will fluctuate in the same amount (since the system is using the nitrous pressure against the regulator to boost the fuel). A downside is that your intake manifold might not get an even distribution of nitrous into each of your cylinders, which would cause a "lean" condition. Running lean (running low on fuel) in your cylinders is the reason why people ruin engines, blow heat gaskets, burn pistons, or destroy cylinder heads. This is the reason why nitrous oxide use has got such a bad reputation from some of its users. Another downside is that your engine is getting fooled into supplying more fuel to your mixture when it sees more oxygen is being produced by the nitrous oxide breaking down. Your engine could run lean if your fuel system can't support the amount of fuel that is required to properly support the amount of nitrous that is being used. Go to the top
How much does a nitrous system cost?
They start out around $400 and can go up in price from there. The price of your kit will increase depending on what type of system you get and what additional equipment you get with your kit. Additional equipment would include a nitrous bottle warmer, a remote nitrous bottle opener, a nitrous bottle pressure gauge, a micro-throttle switch, a progressive nitrous controller, and a blowdown tube if the actual bottle is inside the passenger compartment. Go to the top
How much does it cost to refill your nitrous bottle?
For a 10lb bottle it can cost anywhere from $30 to $40 per refill depending on where you get it filled. Go to the top
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