Technical Write-Ups

I/H/E (Intake, Headers, Exhaust) Write Up

DC Sports Ceramic Header

I wrote the following write-up when I was 17. It was originally posted on solsociety.com (click source link for original post).

I did this write up by accident. I meant it as a reply to a poster’s question and went WAY too into detail, so I figured I would give it it’s own topic and call it a write up. It’s just a compilation of the knowledge that I have obtained over my countless hours of research and my slight amount of experience.

WARNING!: Some things in this write up are opinions, and are intended that way. Please don’t feel offended by these opinions.

I’m a novice, but my god have I done my research. I had the car a full year before I could drive it, so all I did was research and learn about it. If you want, you can listen to me, but everyone likes something a little different. I am just sharing a little of my knowledge in hopes that you’ll get something out of it. Anyway, you might be looking into what I am doing, if you want a little more power and a ride that will be a lot more fun.

Update: To see actual dyno test yielded performance gains, check out our related article.

Intake

AEM Short Ram Intake

I would start with an intake. It’s probably the most common upgrade done to a Honda, or most cars for that matter, and is what most novice’s, ricers, wannabe’s, and even experienced users do first. An intake is the main part of the engine that intakes or inducts air into the intake manifold, and therefore the engine. The faster and easier that an engine can suck in air, the more efficient it will be. It’s not just about speed though. An engine burns oxygen and uses its energy to create a pressured movement. The more oxygen an engine can recieve, the better (as long as it can get enough fuel to create a good mixture). So, the oxygen density in the air is very important. Cooler air can hold more oxygen molecules because in cooler air the molecules are closer together, therefore being more dense with oxygen. So, the cooler the air, the better… to a point of course.

There are many different companies out there making intakes, each with their own promises of amazing results. I personally chose AEM (Advanced Engine Management), because of their proven dyno tests, good build quality, and competitive pricing. But, to each his own. Next thing to decide is whether you want a Cold Air Intake (CAI) or Short Ram Intake (SRI). Each have their own advantages and disadvantages.

Here’s the breakdown, a Short Ram Intake will give you a much nicer sound than stock, a little more power, and a better throttle response for about $100. On the other hand, a Cold Air Intake will give you a little bit more power than a Short Ram Intake because they take in the cooler air away from the engine bay, but will sound a little quieter (mostly) and will cost you about $300. The problem with CAI’s is that they are lower to the ground and can suck up water easier if you run over a puddle or something, destroying your engine due to waterlock. But if you live in a dry environment, who cares. I personally went with the SRI, because of cost effectiveness and I live in New England, haha (lots of rain and snow).

Headers

DC Sports Ceramic Header

The next place that most people would look to upgrade is their Exhaust Manifold, or Headers. Performance aftermarket headers are a popular upgrade, because they offer a much higher quality than a stock exhaust manifold. Most car’s exhaust manifolds are designed in a way that can be made cheaply (using cast iron and bent or flat piping) instead of designed for performance, because of the steep price difference that the manufacturer can make them for. Lower build costs equals higher profits, or at least a lower price tag on an economic car. Aftermarket headers are designed with performance in mind, using rounded, mandrel bent, often stainless steel piping. These offer a much higher flow and a design that usually allows the exhaust gasses to escape the engine much more quickly and efficiently. Headers are generally expensive, because of their complicated bends and custom fitments, and of course their higher quality materials. Although, with headers its hard to go wrong.

The things that come into importance here are: material, design, and build quality. You can get headers anywhere from $50(EBay)-$500. You’re gonna want stainless steel, because of their superior strength and resistance to rust. It’s easy to tell a cheap pair of headers (EBay) from an expensive pair, because the cheaply made stainless steel will change color more rapidly. All stainless steel headers will change color over time, its the nature of the metal (when in contact with a high heat, they change hue), and may turn into a purplish-orangish hue, but cheaply made Headers tend to do it more rapidly. Also, some headers have what is called a ceramic coating, which is a coating over the stainless steel that makes the metal more resistant to heat, therefore slowing the coloring process and actually creating a smoother path for high heated exhaust gasses.

A Header’s design is also very important. Headers with equal size bends are more efficient, because they allow the exhaust gasses to exit the cylinders more evenly. Most headers for a 4-Cylinder are either 4-1 design or 4-2-1 and can be two pieces (with flanges) or one solid piece. 4-2-1 designs generally add a stronger mid to high power gain, while 4-1 designs usually focus on the higher RPM’s only. Difference between the One or Two piece are simply fitment. A one piece will obviously have more ground clearance due to it not having a flange, while a two piece is usually easier to install and remove because of its ability to be broken down into two pieces. Although, a high quality built two piece header should have plenty of ground clearance.

Lastly, there is build quality. Better welds means a more solid design that will hold up longer and create a more even flow. Better made flanges and port matching will increase the strength and performance of the header. Finally, whether it is CARB exempt (meaning basically emissions legal) or not may be important to some and not to others. Many companies make a good header. Just choose wisely. I chose the Holley AirMass Pro-Racing Headers. They are a 4-2-1 two piece stainless steel header with ceramic coating and are CARB exempt. I got my Headers for only $97 (regularly $350) because the place I bought them from was having a clearance sale, haha.

Exhaust

Stainless Steel Mandrel Bent Exhaust

Next, most honda enthusiasts would look towards an exhaust system. A quality made exhaust system will give a car a more sporty sound and will increase power if made correctly. Most people would look towards buying a quality cat-back exhaust. A cat-back exhaust is an exhaust system that starts from the pipe after the Catalytic Converter (we’ll get more into that later) and continues all the way until the back of the car. A header back starts from the headers and goes all the way back, and finally an axle-back will start from the rear axle and go to the back (usually a muffler and the pipe that extends from the exhaust flange over the rear axle).

A cat-back exhaust is the choice that will give you the most power for the price, and is also the most commonly mass-produced. Your exhaust system sits under your car, which is subjected to many types of weather conditions, so stainless steel is basically a must. The exhaust system is all about the flow. The more efficiently the exhaust gasses from your car can escape, the better. This is where we get into pipe bend types. Pipes are bent using 3 common methods (more may exist). The first two, crush bending and rippled bending are an easier, cheaper way to bend pipes, but they create inconsistencies in the pipe shape and diameter that will hurt the exhausts efficieny and flow. Mandrel bending is a process of bending a pipe that keeps the original pipe diameter consistent throughout the pipe, creating a much better flowing exhaust pipe. If you can afford it, get mandrel bent pipes.

Pipe diameter is where most people get confused. Do I get a 2″ pipe or a 3″? Well, it depends on your build. An engine will operate more efficiently if the exhaust gases expell more quickly, because it limits back-pressure. Back-pressure is an affect that happens when exhaust gasses either bounce due to inconsistencies in flow, or when the exhaust gasses create a bottle-neck, in other words the engine is create exhaust gasses faster than they can escape. The less back-pressure you have, the faster the gasses can escape and the less resistance your valves and cylinders will feel. Although, too little back-pressure, and the engine will actually lose efficiency, because of the free movement that they are not necessarily designed for, and because the loss of pressure that causes the exhaust gasses to expell at a higher velocity. So, its all about the balance. Create as little back-pressure as possible without knocking your engine out of efficiency. A N/A (Naturally Aspirated, meaning that it takes in oxygen by vaccum only, unlike a turbo or nitrous injection) engine such as our Del Sol’s needs to have some back pressure to operate efficiently. A 2.25″ diameter exhaust pipe will be the most efficient if Mandrel Bent, because it offers a good flow without loosing too much back-pressure and without the exhaust gasses loosing velocity. If you can’t afford a Mandrel Bent pipe, than you may want a 2.5″ exhaust, because the crushed pipe will loose its diameter in its bends. Although, if you are using FI (Forced Induction, means that the engine recieves oxygen in a forced manner such as a Turbocharger or Nitrous Injection, and is the opposite of Naturally Aspirated) you may want a larger pipe, somewhere near 3″ in diameter, because of the increased exhaust gasses that the engine will be creating.

When it comes to choosing a muffler, a higher flow (usually a straight pipe surrounded by sound deading material) is usually the better choice, but remember that the higher the flow, usually the louder the exhaust. Resonators, are a secondary muffler that is usually part of an exhaust system. They are usually higher flow than a muffler but does less for reduction of volume.

Finally, there is the Catalytic Converter. This is a part of the exhaust that “cleans” the exhaust gasses by reducing the amount of carbon monoxide in the gas. It acts as a catalyst, breaking down the chemicals in the gasses without breaking itself down. In fact, Catalytic Converts (cats for short) usually only need replacement because of the extreme heat that may possibly destroy the catalyst, or the rust that the steel will inevitably form. A Cat, along with your car’s computer and OBD (On Board Diagnostics), is what basically reduces emissions that your car creates. Being that a registered US car requires emissions testing, it is kind of a requirement, haha. The problem that a Catalytic converter creates for performance, is that it acts as a major bottleneck or blockage in the flow of your exhaust gasses.

High Flow Catalytic Converters are Catalytic Converters that have a build that uses a higher flow, therefore reducing the bottleneck and increasing performance while still being effective. These are an expensive upgrade and is most often a hit or miss. The $20-$30 High Flow cats sold on EBay are not really Catalytic Converters at all, but are resonators that are made to pass a visual inspection by a police officer. The problem with these pipes, is that they aren’t really cats, therefore you no longer have something that is reducing the emissions of your engine. So, not only will you not pass the Emissions Test, but you will also be hurting the environment. But for a temporary switch before a race to get an extra horsepower boost, why not? Keep in mind though, a Catalytic Converter not only reduces emissions, but also reduces the exhaust volume and raspy tone. Keep that in mind if you decide to ditch your cat for just a straight pipe.

Many import performance companies offer a cat-back exhaust that is custom made and tuned for the Del Sol and its different engines, but like I said, it all depends on the engines build. If you are willing to wait a month, I should be finished with my exhaust build by the end of October, in which I will be doing a write up of.

Conclusion

There are many engine modifications that are possible, it all comes down to imagination, practicallity, and money. This series of modifications: Intake, Headers, and Exhaust (also known as I/H/E) is of the most popular to novice and light tuners everywhere. Everything from a lightened flywheel to a turbo set-up to even port and polishing is possible, but for many this combination of upgrades is the most practical, simple, and cost effective. The ease of these upgrades also relies on the fact that they can be done in steps, instead of having your engine ripped apart until you have all of the necessary parts and so forth. So, you’re possibilities are endless, but a good I/H/E setup can also be a great backbone for an even more involved engine upgrade.