Post by Sabertooth on Oct 30, 2018 13:21:09 GMT -5
So you've decided you want to mod your car to make more power, but don't know what direction to go in. That's fine! Everyone with a modded car has been there. To make more power, an engine needs more fuel and oxygen. It's a simple concept, but harder to implement. One method is to physically force more oxygen into the system through a "forced induction" system, such as nitrous, turbocharging, or supercharging. These are all possible, however not good beginner mods as they require custom fabrication and background knowledge to make them work.
The easier way for a beginner is to find a way to make the engine flow air more efficiently in and out of it. Engines are air pumps, and the more efficiently it can pump air the more power you get as well. The colder the air going into the engine, the more densely packed the oxygen is as well. There are some easy mods that help with this and they make for easy first mods for beginners.
1: Throttle body bypass
On the car's throttle body, you'll find a coolant hose going in and out. This heats the throttle body, which in turn warms the air going in. As discussed previously, warmer air has less oxygen by volume, so it causes a reduction in power. It's not a huge amount, but everything adds up. You can modify this line by disconnecting it from the throttle body and connecting the 2 hoses with a 3/8" barbed coupler, picked up cheap at a local hardware store in the plumbing department (check with the NPT fittings)
2: Cold air intake
This does what the name suggests, and is a modified intake system to take in cold air from outside of the car's engine bay. They also come with a cone filter, which may outflow the stock airbox. Installing a cold air intake also has the added bonus of a nice induction sound. You'll really hear it when MIVEC comes on, and I've never heard of someone being upset by the sound change. It's great
3: Underdrive pulley
While not a "power adder", an underdrive pulley reduces the load on the engine by removing some rotating mass from the accessory belt system, driven by the crankshaft. RRE makes an underdrive pulley for the GS that has been shown to add 5-6 horsepower at the wheels. It drops the weight from 3.9lbs on the stock pulley to 0.58lbs. This is probably the best $:horsepower mod you will find
4: Custom exhaust
An aftermarket exhaust system can be made to flow better than the stock system. I'm sure you've heard of people putting on "too big" of an exhaust and "not having enough backpressure". Well, I want to end that myth. Backpressure is the enemy, but too big will hurt power. Why? An exhaust system works by preserving the velocity of each puff of exhaust gas out of the engine. This way, the exhaust puffs will actually help by drawing the next one out the pipe, reducing the resistance.
What size is right? Well, that depends on the power level you're making, or plan to. Typically a bolt on GS will only need a 2.25"-2.5" exhaust, even the stock 2 1/8" isn't going to cause you much grief. But remember, the larger your piping, the higher in the rev range you'll be making peak torque. That's good for horsepower, to a point (it's no good if peak horsepower comes on 500rpm past your redline!). For a street car, try to be more on the reasonable side and go smaller rather than larger. It will save you drivability issues, and can make for a more torquey fun car. You know best to what you want, but unless you're doing a forced induction system, avoid larger than 2.5" on your GS.
Generally, it's cheaper to have an exhaust shop build you something custom rather than buy an online bolt on. Most people I've spoken to ended up in the $200-$350 area. You also have the added bonus of knowing it fits! Some people have had issues with material tolerances being too large on pre-fabricated designs, and have had to modify them to fit.
When picking a muffler, you'll have a couple of choices generally. A straight through muffler design with packed material around a perforated pipe as sound deadening, or a system with baffles in a chamber to resonate the sound and quiet it down. What you choose is down to your power and sound goals. A straight through design flows more, and will allow for more high end power. However, that is at a cost of a large volume difference. On a daily driven car, I'd avoid straight through designs especially if you removed catalytic converters (but who am I to stop you). With a baffle design performance muffler, you'll definitely still hear your exhaust, and it will have a cleaner less choppy sound to it with minimum power losses at bolt on power levels (it matters much more on a 1000hp drag car, for example)
5: Header
An exhaust header it the first part of your exhaust that connects to the engine. It's where you pull your exhaust scavenging from initially, and can have a huge impact on power. Aftermarket ones typically will have no catalytic converters in them. Check with your local laws and regulations to see if this is allowed, and make your decision. Removing them will also result in a cat efficiency code, which can be fixed either through tuning or use of O2 spacers.
If you're going this route, there are 2 major options. The long tube header off of eBay, by DNA Motoring, or the RRE short tube header. The DNA Motoring one in theory can make more power, but there are a few catches on this. The build quality is low (people have complained of burned through welds), the material is thin, the stainless rusts easily, the header is too low to the ground and scrapes often, and the design is wrong. Yes, it's wrong. It doesn't have an O2 bung on runner #1 (far left), so must be modified to be used without risking damage to your engine.
The RRE header is built better, and will give you more mid RPM range power, which is generally more friendly to use and what you'll be using in a street driven car (low-mid). The downside is they are getting harder to source, as the company is in California and does not readily make them anymore (feel free to email them though!)
Aftermarket headers can add noticeable power to the car, but don't expect them to drop your 1/4 mile time by a half second. Everything adds up though.
6: Throttle body
This one is debatable, and I haven't seen any dyno evidence to prove or disprove it. HOWEVER, the Eclipse GT throttle body can bolt on to our intake manifold. It will increase the size of the throttle body, allowing for potentially more airflow at a given velocity. On cars that are limited by the flow of the throttle body, adding size here as well as matching the size to the intake manifold can yield respectable increases in power. If doing this, a tune is definitely required.
7: A tune
A tune is what's needed to make the car run at its best. This will bring all your mods together, and is a staple of any build. Even on a stock car you'll see improvements in fuel economy and power. It literally pays for itself. Tuning on this platform can be done over the internet by a company called Fastworks when using the stock ECU, or you can use piggyback systems such as the AEm FI/C, or a standalone ECU.
For a beginner, I would suggest going the Fastworks route as it doesn't require any modifications to the wiring. All you need are a Tactrix Openport 2.0 cable, a laptop, and an internet connection.
I hope this guide helps someone out there, have fun modding
The easier way for a beginner is to find a way to make the engine flow air more efficiently in and out of it. Engines are air pumps, and the more efficiently it can pump air the more power you get as well. The colder the air going into the engine, the more densely packed the oxygen is as well. There are some easy mods that help with this and they make for easy first mods for beginners.
1: Throttle body bypass
On the car's throttle body, you'll find a coolant hose going in and out. This heats the throttle body, which in turn warms the air going in. As discussed previously, warmer air has less oxygen by volume, so it causes a reduction in power. It's not a huge amount, but everything adds up. You can modify this line by disconnecting it from the throttle body and connecting the 2 hoses with a 3/8" barbed coupler, picked up cheap at a local hardware store in the plumbing department (check with the NPT fittings)
2: Cold air intake
This does what the name suggests, and is a modified intake system to take in cold air from outside of the car's engine bay. They also come with a cone filter, which may outflow the stock airbox. Installing a cold air intake also has the added bonus of a nice induction sound. You'll really hear it when MIVEC comes on, and I've never heard of someone being upset by the sound change. It's great
3: Underdrive pulley
While not a "power adder", an underdrive pulley reduces the load on the engine by removing some rotating mass from the accessory belt system, driven by the crankshaft. RRE makes an underdrive pulley for the GS that has been shown to add 5-6 horsepower at the wheels. It drops the weight from 3.9lbs on the stock pulley to 0.58lbs. This is probably the best $:horsepower mod you will find
4: Custom exhaust
An aftermarket exhaust system can be made to flow better than the stock system. I'm sure you've heard of people putting on "too big" of an exhaust and "not having enough backpressure". Well, I want to end that myth. Backpressure is the enemy, but too big will hurt power. Why? An exhaust system works by preserving the velocity of each puff of exhaust gas out of the engine. This way, the exhaust puffs will actually help by drawing the next one out the pipe, reducing the resistance.
What size is right? Well, that depends on the power level you're making, or plan to. Typically a bolt on GS will only need a 2.25"-2.5" exhaust, even the stock 2 1/8" isn't going to cause you much grief. But remember, the larger your piping, the higher in the rev range you'll be making peak torque. That's good for horsepower, to a point (it's no good if peak horsepower comes on 500rpm past your redline!). For a street car, try to be more on the reasonable side and go smaller rather than larger. It will save you drivability issues, and can make for a more torquey fun car. You know best to what you want, but unless you're doing a forced induction system, avoid larger than 2.5" on your GS.
Generally, it's cheaper to have an exhaust shop build you something custom rather than buy an online bolt on. Most people I've spoken to ended up in the $200-$350 area. You also have the added bonus of knowing it fits! Some people have had issues with material tolerances being too large on pre-fabricated designs, and have had to modify them to fit.
When picking a muffler, you'll have a couple of choices generally. A straight through muffler design with packed material around a perforated pipe as sound deadening, or a system with baffles in a chamber to resonate the sound and quiet it down. What you choose is down to your power and sound goals. A straight through design flows more, and will allow for more high end power. However, that is at a cost of a large volume difference. On a daily driven car, I'd avoid straight through designs especially if you removed catalytic converters (but who am I to stop you). With a baffle design performance muffler, you'll definitely still hear your exhaust, and it will have a cleaner less choppy sound to it with minimum power losses at bolt on power levels (it matters much more on a 1000hp drag car, for example)
5: Header
An exhaust header it the first part of your exhaust that connects to the engine. It's where you pull your exhaust scavenging from initially, and can have a huge impact on power. Aftermarket ones typically will have no catalytic converters in them. Check with your local laws and regulations to see if this is allowed, and make your decision. Removing them will also result in a cat efficiency code, which can be fixed either through tuning or use of O2 spacers.
If you're going this route, there are 2 major options. The long tube header off of eBay, by DNA Motoring, or the RRE short tube header. The DNA Motoring one in theory can make more power, but there are a few catches on this. The build quality is low (people have complained of burned through welds), the material is thin, the stainless rusts easily, the header is too low to the ground and scrapes often, and the design is wrong. Yes, it's wrong. It doesn't have an O2 bung on runner #1 (far left), so must be modified to be used without risking damage to your engine.
The RRE header is built better, and will give you more mid RPM range power, which is generally more friendly to use and what you'll be using in a street driven car (low-mid). The downside is they are getting harder to source, as the company is in California and does not readily make them anymore (feel free to email them though!)
Aftermarket headers can add noticeable power to the car, but don't expect them to drop your 1/4 mile time by a half second. Everything adds up though.
6: Throttle body
This one is debatable, and I haven't seen any dyno evidence to prove or disprove it. HOWEVER, the Eclipse GT throttle body can bolt on to our intake manifold. It will increase the size of the throttle body, allowing for potentially more airflow at a given velocity. On cars that are limited by the flow of the throttle body, adding size here as well as matching the size to the intake manifold can yield respectable increases in power. If doing this, a tune is definitely required.
7: A tune
A tune is what's needed to make the car run at its best. This will bring all your mods together, and is a staple of any build. Even on a stock car you'll see improvements in fuel economy and power. It literally pays for itself. Tuning on this platform can be done over the internet by a company called Fastworks when using the stock ECU, or you can use piggyback systems such as the AEm FI/C, or a standalone ECU.
For a beginner, I would suggest going the Fastworks route as it doesn't require any modifications to the wiring. All you need are a Tactrix Openport 2.0 cable, a laptop, and an internet connection.
I hope this guide helps someone out there, have fun modding
