Okay, now that we’ve covered the basics as to what components can be modified, let’s talk specifically about how these parts can be modified and what kind of performance you can expect to get. Again, I would reiterate that I am primarily targeting the turbo community out there simply because that is what I own and know best and the 2.0T is where you are going to get the most bang for the buck. With that said, if someone wanted to do a forced induction (turbo or supercharger) modification to their 3.8, much of the information in this thread will apply to them as well. In many cases, many of the modifications discussed here have been discussed in detail elsewhere. Whenever that is the case, I will provide a link to the detailed thread and will only touch the surface of the modification in question. We will start with the simplest modifications first and work on down to the more complicated ones further down the thread.
Magnuson–Moss Warranty Act
- (Only applies in the United States)
Probably the most frequently asked question with regard to modding is, “Will this modification void my warranty?” The answer to this question is that we are protected by the Magnuson–Moss Warranty Act that was enacted in 1975 to protect consumers from being forced by manufacturers to only purchase from them. With that said, although the manufacturer cannot void an entire warranty because you used an aftermarket replacement part, that does not mean that the manufacturer cannot deny a damage claim if they can reasonably show that the cause of the failure is related to the improper operation or installation of a non-covered part. For instance, say your turbo receives some foreign object damage because something was sucked into the intake and the aftermarket filter did not prevent the object from entering the intake. The manufacturer is not liable for the damage to the turbo due to the failure of the aftermarket filter. If, however, your stereo stops working, the manufacturer cannot reasonably connect the intake filter to the operation of the stereo and the manufacturer is still responsible for honoring their warranty.
The Magnuson–Moss Warranty Act is not a panacea for all things related to warranty repairs, and in many cases a manufacturer may attempt to deny a claim in hopes that you will quietly accept their verdict without pushing legal action. The question that you have to ask yourself, and you have to be honest with yourself when you answer, “Did my modification cause the failure?” If you cannot reasonably rule out your modification, then accept the fact that you may be responsible for the damage and move on. If you cannot connect the failure to the damage… keep pushing. The dealer will escalate the problem to the manufacturer who will evaluate the failure and provide an official verdict as to whether the damage is covered by warranty or not. If you lose the verdict you may have to take legal action to get the manufacturer to honor the claim.
Do I need an intake modification?
All modifications come down to “what are your goals?” You may want to do an intake mod to make room for performance gains or you may simply want to better hear your turbo spooling. Yes, that’s right… an intake modification will make your turbo louder! There is a metal silencer in the stock intake that does a pretty good job masking the sound of the turbo spooling and the associated bypass valve “whoosh” sound when it opens and dumps the charged pressure from your intercooler piping back into the intake. You can get some of that sound without changing your intake by gutting the silencer.
As discussed before, you have essentially two aftermarket choices for intakes. The short ram intake (SRI) is the shortest path to the inlet of the turbo. The disadvantage, if any, is that the filter intake is located in the hot engine bay and some of that hot is going to be sucked into the intake. Many SRI setups come with an air dam that will isolate the filter from the hot engine bay air. Some will provide ducting from the factory ram air intake to bring in fresh cool air from the outside.
A cold air intake (CAI) has longer intake tubing to allow the intake to drop down behind the front bumper to pull in cool air from the front of the car and from underneath the car. The additional length of tubing to reach the front bumper is almost negligible in most setups and the CAI will never pull in hot engine bay air. As discussed before, there is a danger that a CAI that sits very low in the bumper can accidently be submerged in deep water, suck in a large amount of water, and cause the engine to hydrolock. This scenario is not completely unlikely and several owners have destroyed their engines while using CAIs.
There are more examples, but you get the idea. The CAI is really a fair weather intake solution and you should be extremely careful if you have a CAI and operate your car in wet conditions. If you decide you just absolutely have to have a CAI and that no other intake will do, at least take the precaution of installing an air bypass valve and a hydroshield. The air bypass will open if there is a blockage at the filter (water qualifies as a blockage). Keep in mind for you turbo guys that the amount of air that can be sucked in through the bypass valve is limited; thus it would be best if you didn't rev your engines going through a puddle. The hydroshield is a bit of technology that is effective in keeping the filter dry if it is sprayed (not submerged) with water. Keeping your filter dry is important to ensure proper flow. In fact, it works so well, I recommend it for those of you who are running any aftermarket intake (SRI or CAI) to protect your filter from water spray.
Do I need a BOV?
Like with the intake, there are a number of non-performance related reasons for purchasing a BOV. Technically speaking, you do not need a BOV unless your stock BPV is no longer doing the job. If your BPV fails, it will fail open and you will not be able to build boost. Generally speaking, you will hear a fluttering sound during partial throttle or high RPM pushes if your bypass valve is leaking. If you hear a metallic fluttering sound, especially when you let up off the gas, do not drive your car until you determine what the problem is.
Aftermarket BOVs/BPVs can be mounted in the stock BPV location, on the hot side pipe or on the cold side pipe. The mounting location will have no effect on how the BOV works. Some BOVs are designed to use the stock solenoid valve that is controlled by the ECU to open and close others will use any available vacuum source. A quality BOV, regardless of manufacturer will do the job that it needs to do and the choice really comes down to personal preference with regard to how the BOV sounds. Stay away from eBay budget BOVs made in China.
What is a manual boost controller and do I need one?
The turbo’s wastegate is normally controlled by the ECU through the turbo boost solenoid valve located above the power steering module. The purpose of the wastegate is to keep the turbo from overspeeding and surging beyond the programmed pressure as set by the ECU or a manual boost controller.
A manual boost controller bypasses the ECU controlled boost solenoid valve and allows for manual control of the wastegate actuator. The manual boost controller can be manually set to allow boost signal pressure that comes from the compressor section of the turbo to open the wastegate at a manually set pressure. The advantage of the manual boost controller is that you can manually set the boost level without regard to what the ECU is programmed for… this is also a disadvantage if the ECU cannot compensate for the set pressure by adjusting timing and adding fuel to compensate for the additional air. Generally speaking, you should not install or use a manual boost controller unless you have a tune that supports one or you can tune your car using a piggyback device such as CMD or a full plug and play ECU like the Haltech.
A variation of the manual boost controller that adds a level of convenience to the operator is the electronic boost controller that allows the operator to remotely adjust maximum boost levels through a control panel in the cockpit. More sophisticated electronic boost controllers have presets that can adjust pressure based on engine RPM, allowing for a slower spool on the low end to limit the immediate and sudden punch of boost.
What should I look for in an aftermarket intercooler?
There are three things you need to pay attention to when evaluating any aftermarket intercooler:
That’s all fine and good, but I suck at math…
- Size – While you can get an intercooler that will sit in front of your car like a giant aluminum battering ram, bigger is not always better. Keep in mind that the space inside of the intercooler will pressurize to the same pressure as the rest of the charged system… bigger means a larger volume of space that will need to be filled each time the turbo spools and will contribute to a certain amount of lag while in the time it takes to fill it. You want an intercooler that is just large enough to cool the volume of air that you will need to maintain pressure and no more. Most importantly, you need an intercooler that will fit where you want to install it. If it won’t fit, it doesn’t matter how good it is.
- Thermal Performance – This is where the rubber meets the road with regard to the effectiveness of the intercooler. High thermal performance intercoolers contain many tight passages that allows the air to come in contact with as much of the cooling surface as possible. The tradeoff to high thermal performance is a reduction in flow performance. While high thermal performance is desirable, so is getting the air into the intake manifold where it can be used.
- Flow Performance – Flow performance is measured in cubic feet per minute (CFM) which is a measure of how quickly and what volume of air passes through the intercooler. Ideally you want an intercooler that has high flow performance and a low pressure drop from intake to exit, but this parameter must be balanced with the thermal performance to ensure that hot air is not being passed through the intercooler to the intake manifold. The flow performance should match the flow potential of the turbo you have installed.
is there a simple performance metric that can be used to match my intercooler requirement to the proper intercooler? The short answer to this question is: Yes. Most quality intercoolers have a HP rating that you can use to match to your car. For instance the Garrett intercooler core that fits the Genesis Coupe is rated for a maximum of 500HP. This is a very simplified rating system for intercoolers and does not speak directly to thermal or flow performance; rather it simply says that the intercooler will handle flow up to CFM flow rates that are required for the engine to produce 500 HP without restrictions.
The simple way to decide which intercooler to choose is to stick with intercoolers the vast majority of owners are using. Do not assume that if a vendor here sells an intercooler that it will meet your performance needs; rather, seek out members who have a build similar to what you want and check their garage or look over their signatures to see what intercooler core they are using.
What are the advantages of a throttle body spacer?
A throttle body spacer’s main purpose in life is to accelerate the airflow into the intake manifold that in turn aids in better atomization of fuel contributing to a more complete burn in the cylinder. Additionally, the throttle body spacer adds a small amount of volume to the total plenum capacity of the intake manifold that can provide a little more reserve air capacity in high horsepower applications in naturally aspirated engines.
Does it work? On older engine designs throttle body spacers provided a measurable increase in HP and torque because the throttle body worked much like a carburetor in that the fuel was mixed with the air just after the throttle body throat plate. In modern multipoint fuel injection designs it can be debated that the throttle body spacer’s benefit is negligible as the fuel is introduced just prior to entering the cylinder. On direct injected engines the benefit is almost totally negated because the fuel is injected directly into the cylinder.
With all that said, a throttle body is the perfect injection site for a water/meth injection setup. I will not be covering water/meth injection systems in this thread as it is technically not a “bolt-on” modification; rather requires custom tuning along with the hardware installation to make it work. If you want to know more about meth injection, read this thread: https://www.gencoupe.com/2-0t-discuss...injection.html