Engine Tuning Guide for Beginners - Improve Power and EconomyEngine tuning guide to get the best performance out of your car using aftermarket parts to improve air flow, fuel efficiency and gain power.
When your car left the showroom or forecourt, engineers and mechanics had set it up perfectly for the average driver who wanted an efficient, reliable and economical car. However, a few of us want a little more from our cars and see them as a platform for creating something unique and special through modifications.
These modifications can be as simple or as complicated as your wallet can stand, but a few rules need to be followed first. Before starting any modifications, you must ensure that your car is mechanically sound. There is little point in fitting a carbon fibre wide arch body kit to a rusted chassis or tuning an engine about to die.
If you choose to work on your own (or anybody else's) car, please take care and work safely using good common sense. If something seems unsafe, it probably is, so don't do it.
The scope of this document is aimed at 'bolt-on' modifications that a mechanically minded individual can easily do without specialised tools. This is by no means a complete guide on Honda modifications, and I am by no means responsible for information that may be incorrect or inconsistent. This information is provided for reference only!
Basic engine tuning is all about three simple concepts:
- Getting as much clean, cold air into the cylinders as possible. - Induction
- Burning the fuel at the optimum time, as effectively as possible. - Ignition Timing
- Removing exhaust from the cylinder as efficiently as possible. - Exhaust
Induction
Engine power is directly related to the rate of incoming and outgoing airflow, and many factory intake systems are highly restrictive, thus limiting engine horsepower and torque. Replacing the intake system is one of the most common and easiest upgrades that can be done to a stock engine. It replaces the factory air box with an aftermarket filter and tubing. There is a huge market for air filters, each with different designs, and as always, they have their good and bad points. They range from a replacement panel filter that fits in the factory air box to short ram and cold air intakes; each type has different styles and materials for the filter.
The panel filter can be fitted in only a few minutes. They are a direct replacement for the factory filter and can be made of paper, mesh or foam.
They still suffer from the restrictive piping and boxes that the factory setup uses.
The cone filter is probably the most popular filter, with manufacturers such as K&N and AEM using them in their induction kits. They have a large surface area, allowing more air into the engine.
Pictured here is a blue cotton gauze filter.
The Mushroom filter was designed by HKS.
The Super Mega Flow's unique design combats airflow's propensity to move towards surface areas, which generates turbulence and reduces airflow capacity, typically a weak point of box-type designs. With its vacuum-inducing inner lip, HKS's patented super-funnel design draws air from the filter's outer edge and directs air away from inlet throat surface areas.HKS
Short Ram Intake places a cone or mushroom filter at the end of a short tube inside the engine bay. This can boost performance levels in a vehicle by increasing air volume intake at the expense of increased intake noise. The high air temperature near the engine can reduce performance in some cases, but the increased volume of air often makes up for this.
Cold Air Intakes are similar to short ram, but they use longer pipes to relocate the intake outside of the engine bay (usually in the front bumper or wing. They benefit from colder air, but due to the length of the piping, throttle response is lessened.
After the intake, the next bottleneck is the throttle body. A larger throttle body will help increase the air travel volume to the engine. But remember, bigger may be better, but bigger is not the best. If the throttle body is too large, you will lose the velocity of the intake charge, and the throttle may be over-sensitive. A good size for most naturally aspirated B16s is 62mm. 65mm is good if the IM is modified and some headwork is done. 70mm is for all-out raging fun. Port-matching that the intake plenum be port-matched to the TB is highly recommended for excellent results.
After the throttle body, the air is moved through the intake manifold. This is where the air and fuel are delivered to the cylinders. Air flows like water to the path of least resistance. Straight, rounded passageways allow for a faster flow of air. A square-shaped passageway will allow a greater amount of air to flow. But either of those passageways has to have a bend in it. In that case, the airflow begins to tumble, causing turbulence and restriction. The manifold can be Extrude-Honed, which forces a heavy liquid with a cutting compound in it. The liquid will form passageways to allow ideal flowing conditions without removing too much material. An intake manifold from an Integra Type R bolts directly up to a B16 and offers a mild polish. There are a handful of other companies that make manifolds; basically, you are looking for a larger plenum and straight runners.
Ignition Timing
Once we have air and fuel in the cylinder, it needs to be ignited slightly before the point of maximum compression to allow a short time for the flame front of the burning fuel to expand throughout the mixture so that maximum pressure occurs at the optimum point. If the fuel is ignited too early, the piston cannot effectively transfer the load to the crankshaft or is forced to oppose the crankshaft's motion, causing a massive shock to the bottom end. This can be heard as a metallic 'pinging' sound known as detonation (or pinking or pinging). Changes to the ignition timing should be left to qualified professionals with proper equipment.
However, we can help provide the engine with a strong spark by using quality high-tension leads (HT) and quality spark plugs. There is much controversy as to how much an improvement aftermarket HT leads, such as Nology Hotwires, provide over stock, especially on Honda engines, but one thing that is clear though is that old, worn leads will not be as effective as new leads. They should be replaced along with spark plugs per the manufacturer's specifications.
Another area we can look at is electrical earth. While this will not have a net gain on horsepower, it will help smooth out the engine's running by providing a more stable, high-quality electrical earth. Factory earth leads are stiff iron alloys, usually cheap, and will rust over time. Many grounding kits that use oxygen-free gold cables are available, similar to those used in high-definition audio equipment, which provide very good earthing. Alternatively, you can use an eight-gauge speaker wire and make your own.
Exhaust
After combustion, the engine must eliminate the burnt waste, or exhaust, as efficiently as possible. This is one of the biggest bottlenecks in engines, and it is also the most competitive area in the market, with anyone making different products. The four components in the exhaust system can be looked at.
The most popular exhaust modification is to change the muffler or an 'axle back' system. This has two results: sound and looks. The muffler is the main contributor to the tone of the exhaust, from quiet to raspy, racy to all out loud! They also serve as a visual mod - nobody likes a pea shooter when you can have a 5" exhaust tip. Fitting axle-back systems generally will not have any effect on performance.
The next progression from here is from the 'cat-back', which replaces the exhaust piping from the catalyst at the front of the car and underneath the muffler. This is where you can free up some power lost on the restrictive stock system. Remember, the stock system is designed to be efficient, reliable, economical and, most importantly, quiet.
The third area is the exhaust manifold. This is the collection of pipes that collect the exhaust from each cylinder and combine it into one pipe. There are two ways of doing this: 4-2-1 and 4-1. Again, each has a positive and negative.
4-2-1 manifolds collect exhaust from the 4 cylinders and pair them together forming 2 pipes which then merge into 1 pipe.
This setup is better for low to mid-range power, but not so good for top end.
The 4-1 setup collects exhaust from the 4 cylinders and combines them all at once.
This results in a higher top-end power band, but sacrifices low end.
The final component is the catalyst converter. This device is used to clean up the emissions from the engine, but they do sacrifice a lot of power. When the manufacturer built the car, they were very conscious of the cost of production, so they fit cheap, reliable parts that do the job. Typically, they have around 500-600 cells per square inch. These parts can be replaced with 'high flow' catalysts, costing up to five times more than the factory unit. They will provide less restriction as they have 100-200 cells per square inch (freeing up horsepower) while offering the same emissions cleaning levels.
Conclusion
And it does not end there! Although not in the scope of this page, many more upgrades can be done to your engine - head work, cams, pistons, stroker kits, turbos, superchargers.. the list is endless.
That is not a conclusive list of modifications; I have only covered the most basic intake/manifold/exhaust combinations. There are hundreds of different components to choose from within this, and plenty of reviews on the internet for each product.
