What are camshafts for performance cars? Should you replace yours? Find out other information in our comprehensive guide to high-performance cams.
If you do not are driving a vehicle powered by rotary it is likely that camshafts impact the performance of your car. You may be driving with one or perhaps four, but regardless of the amount, they’re an essential part of the engine’s performance.
Camshafts are an extremely complex topic that could be the realm of physics at the top if you go in depth, but at a minimum they’re probably the most misunderstood aspect of UK tuning, which leads to a number of common and beautiful big mistakes when selecting camshafts that will fit your particular engine.
This article should provide you with an understanding of the performance car camshafts, as well as what’s right for the engine you have.
How do you define car camshafts, and what are they used for?
In the most fundamental sense the camshafts are cylindrical rods made of steel in piston engines , with the lobes sticking out of the rods. They are responsible for opening and close the exhaust and inlet valves in the correct amount at the appropriate time.
The quantity and length of time and the point at which valves are opened by the cams are crucial in determining the amount of horsepower and torque the engine produces as well as the exact rev range that it develops this, and whether the engine can operate at all. As you could think of, with proper adjustments, a camshaft swap could dramatically improve the performance. But, a misstep could result in disastrous results not just in terms of the performance but also for reliability too.
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Why should I need high-performance car camshafts?
Whatever you decide to do be careful not to immediately switch cams now, since changing cams is not always a good idea! It is important to ensure that it will benefit the performance of your vehicle before doing because we’ve witnessed some cam swaps that have lost a lot of power. The thing about camshafts designed for performance vehicles is that they usually remove performance some point in the rev range in order to bring it to another. And when you add forced induction to the mix, things can become more complicated.
Don’t believe for a second that the more powerful cam you choose, the more powerful your car will run, even if it has more peak power numbers, because this isn’t always the situation. From the beginning, the cams in a car are typically quite light and are generally designed to ensure economics as well as reliability and, the most important thing, driving. That means that there’s every chance to improve however with a low specification engine and turbocharged engines in particular These standard cams could typically be the best option overall.
The number and the location of the camshafts
It’s not a huge impact on performance, however, the different engines come with different positions for cams and also different amounts. The majority of modern engines come with four valves on each cylinder and typically, they come with separate cams for the exhaust and inlet valves. Therefore, twin cams on straight engines and quad cams for flat and V engines.
A lot of older engines had two valves per cylinder as well as one cam operates each. These engines are becoming more rare, but they are made today, including the amazing LS engines that are found in VXR8s, Corvettes and many more. They LS engines, like some older models, include the camshaft in the block, however most engines have camshafts in the highest point of the engines located within the head.
To make things more confusing to make things more complicated, certain engines – typically from Honda include only one cam that controls all 16 valves. Likewise, there are also engines (a couple of old Ford and Fiat units , in particular) that have twin cams, but just eight valves. Some engines contain five or three valves per the cylinder, as well. However, overall the majority of engines have or have a single cam with the cylinder has two valves or twin cams that have four valves per one cylinder.
What is the right amount? Performance car camshafts guide
This is a common issue when it comes to cam swaps, because it is true that the benefits a cam can provide in one part in the range of revs, usually eliminates in another. Based on how well its performance to rest of the engine specs and the engine’s spec, it may provide more than it subtracts and produce less than what it takes away. It doesn’t matter if it’s forced or N/A induction, using too large a cam without the other components of the engine equipped to produce the same power at the same rpm usually results in a tiny boost in horsepower with massive loss of power at lower speeds. Overall, the car will be slow.
The very wild cams tend to result in a smaller powerband regardless of the specs racing cars typically sporting a powerband that is approximately 2000rpm, which is right in the middle on the speed range. It’s not just that this makes the car difficult to drive on the roads however, if your gearing is in order, you may actually lose a bit of the powerband each time you switch one gear. This would result in a slow acceleration regardless of what the highest power level is.
The cams are usually referred to as “Fast road” or “Race specs, and that is not without reason. While it may offer a bit more top horsepower but a race cam not the most enjoyable on the road and could cause you to be more slow overall.
What type of camshaft is appropriate for my vehicle?
Cams help get air into and out of your engine. However, depending on the way in which your engine gets its air will determine what kind of cams is best for you. Each engine is unique – and so are the opinions of people about what’s too wild , and it is essential to conduct study into the impact of various cams for your particular engine prior to making a final choice. After you’ve been warned, here’s an overview of the basics…
Without air being forced in to your vehicle there is no choice other than to use quite wild cams and, in the end, have lower and higher rpm powerband when you want more power. How far you’d like to go is entirely up to you, but generally up to 280-290 degrees cams provide a significant power boost and support modifications, but still suitable for driving on the road.
The engines, as they are out of the box, have much more gentle cams than those normally aspirated because they have air forced in, which means they don’t need to sacrifice that much power in the low down by making use of particular wild cams. To maximize gains while maintaining driveability and a low time duration cams would be the recommended method to go with which is why they’re often called ‘Turbo Cams’. Long-duration cams suffer from an advantage over turbo engines due to the lower down power loss that you experience for all engines is typically caused by an inefficient turbo spool therefore you must be aware of when you’re going to take your turbo cams.
With a typical four valves per engine, you will typically get around 200bhp per litre of pump fuel, with relatively light cams with a duration of around 260 that make the car responsive and tractable at a low. For race turbo engines operating at with high boosts, we’ve witnessed approximately 400bhp/litre with similar mild cams. This doesn’t mean that wilder cams don’t work in the case of creating an engine designed for full performance or for top speed, the super-long duration cams like an N/A engine will give you the power you need at a less boost, but at the cost of plenty of torque and lower power.
Another trick used by turbo engines is the use of unicams, in which the inlet cam has like 265 in duration and an exhaust cam has a standard or inlet is 285 in duration, but the exhaust has a lower 265. As we was mentioned earlier in the equal the cams subsection, can be a smart method to increase performance by let the turbo pump into more air, without losing any lower down power.
The issue of overlap is debatable in turbo vehicles as it is a subject that can be based on the preferences of the tuner as well as the specifications for the engine. Although overlap results in the air/fuel mix remaining burned when it is released into the turbo and could help the spool, if an engine is more backpressured than boost pressure, the effect is usually reversed and the performance decreases with no gains at all.
Supercharged engines behave in a similar way to turbo engines in terms of the cam selection, excluding one aspect that is overlap. Except for a handful of maximum-effort applications that only use high-rpm the overlap is not a factor for a supercharged engine , aside of reducing the performance in certain parts or even all in the range of revs.
The reason is that compressed inlet air, as well as the fuel that goes together, will simply be thrown away from the exhaust, which would increase the exhaust temperatures, emissions along with back pressure and the system is wasting huge amounts of energy simultaneously.
Due to the fact that VTEC engines utilize one cam profile for low-rpm use , and another one for high speed, wild cams are not as problematic for driving in a VTEC-equipped car , just as they would be with other engine. However, Honda fit wild cams as standard on their high performance VTEC engines, such as the EP3 and the FN2 Civic Type Rs, and generally speaking the idea of making them higher would make the car impossible to drive. On milder VTEC engines, this offers the chance to boost the top-end power without affecting the driving experience.