If you're looking to squeeze more strength out of your engine, messing around with twin cam camshafts will be usually one of the first big steps on the list. It's a single of those adjustments that bridges the gap between fundamental bolt-ons and full-blown engine rebuilds. While a cold air intake or the cat-back exhaust might give you the nice sound plus a tiny little bit of Pep, swapping out the cameras is where you actually start to feel a real difference in how the particular car—or bike—moves via the gears.
The whole concept of "twin cam" or Double Over Mind Cam (DOHC) setups has been about for a long time, but it's still the precious metal standard for high-revving performance. By having two separate shafts—one with regard to the intake regulators and one with regard to the exhaust valves—engineers (and backyard mechanics) have way more control over how the particular engine breathes. Plus as we all know, an engine is basically simply a giant air mattress pump. The better this breathes, the more power much more.
Why Two Cams Are Much better than 1
In an old-school single cam setup, one shaft offers to do all the heavy lifting. It's trying to time period the intake plus exhaust perfectly, yet since everything is on one stay, there's only so much you can do with the geometry. When you shift to twin cam camshafts , you decouple those two procedures. This allows regarding much more aggressive valve timing.
Because a person have two devoted shafts, you can optimize the intake side to pull within as much air-fuel mixture as feasible while establishing the exhaust side to scavenge those invested gases efficiently. This also reduces the of the valvetrain because you don't need long, heavy pushrods to achieve from the particular block to the head. Less weight means the engine can spin faster without having the valves "floating, " which is what you want when you're chasing high-RPM horsepower.
Understanding Lift and Timeframe
When a person start shopping intended for twin cam camshafts , you're going to see a lots of quantities thrown around—mostly raise and duration. If you aren't a spec-sheet nerd, this can get confusing quick.
Lift is pretty very much what it sounds like: how higher the cam lobe pushes the control device open. The increased the lift, the particular more space there is certainly for air in order to rush in. But you can't just proceed for that biggest lift possible, or your valves might determine to possess a chaotic meeting with your own pistons.
Duration is how long the valve stays open. This is definitely measured in degrees of crankshaft rotator. A "long duration" cam keeps the valves open much longer, which is perfect for top-end power because it gives the engine more time to gulp air at high speeds. However, it usually makes the engine run such as crap at low speeds. That shaky, loopy idle people love? That's generally the result of high-duration cams having a wide range of "overlap, " where both the particular intake and exhaust valves are open at the exact same time.
Road vs. Track: Getting the Sweet Place
One of the biggest mistakes I see individuals make is purchasing the most intense twin cam camshafts they could discover because they would like that race-car audio. Honestly, unless you're actually racing, "stage 3" or "race-spec" cams can create a street vehicle miserable to push.
If you're sitting in a reddish colored light and your vehicle is bucking plus trying to stall because the cams are too aggressive with regard to a low idle, the novelty would wear off pretty fast. For a day-to-day driver, you generally want something tagged as "Stage 1" or a "Street/Strip" profile. These provide you with a nice bump within the mid-range and top-end without sacrificing all your low-end torque.
You have to keep in mind that whenever you obtain power at 7, 000 RPM, you're almost always shedding it at two, 000 RPM. In case you spend most associated with your time cruising on the highway or even stuck in traffic, you want the cam profile that keeps the power exactly where you actually utilize it.
The Popular "Twin Cam" Harley Context
It's hard to talk about twin cam camshafts without mentioning Harley-Davidson. For a couple of decades, the "Twin Cam" engine was the heart of the H-D lineup. Within that world, replacing cams is almost a rite of passage.
The stock cams in those bikes are often designed to fulfill strict noise and emission standards, which usually means they're fairly choked up. Simply by dropping in a set of aftermarket twin cam camshafts , you may completely transform a touring bike. It's not only about velocity; it's about exactly where the torque strikes. For a large bike, you desire a "torque cam" that helps a person pass a semi-truck on the highway without having in order to downshift three occasions.
Don't Forget about the Supporting Solid
You can't just slap some high-performance twin cam camshafts into a stock head plus call it the day—well, you can , but you might regret it. When a person increase the lift and the speed at which those valves are moving, the stock valve suspension systems may not be able to keep up.
If a spring isn't strong enough to the valve shut before the cam lobe comes back about, you obtain valve drift. At best, the motor loses power and misfires. At most severe, the valve remains open too longer, the piston hits it, as well as your engine becomes a very expensive paperweight.
Anytime you're upgrading cameras, it's a smart idea to appear at: * Stronger device springs: To handle the particular extra lift and RPM. * Adjustable cam gears: So you may fine-tune the timing where exactly you would like it. * New lifters or followers: Because placing old, worn parts on a brand-new cam is just requesting trouble. * The solid tune: This is the huge one. Your ECU needs to know that the breathing characteristics of the motor have changed, or even it'll struggle along with fueling.
The particular Sound of Achievement
Let's become real for the second: part associated with the reason we love twin cam camshafts could be the way they create an engine audio. There's nothing very like the "chop" of a cammed engine. That rhythmic, slightly uneven lope at idle tells everyone within a block that there's something serious below the hood.
That audio is the consequence of exhaust gases pressing back into the intake manifold during the overlap period. While it's technically "inefficient" at reduced RPM, it's music to an enthusiast's ears. It provides the machine a personality— a sort of mechanical heartbeat that sounds like it's just irritation to get on to the open road.
Installation: The Weekend Project?
If you're helpful with a wrench tool, you can definitely install twin cam camshafts your self, but it's not really a job you want to hurry. Timing is everything. If you're off by even the tooth on the time belt or chain, you're taking a look at the bad time.
Most people discover that the toughest part isn't actually swapping the shafts; it's getting in order to them. You possess to tear lower an excellent chunk of the the top of engine, move cooling lines, and maybe still pull the rad depending on just how cramped your motor bay is. But once you get these covers off plus see the valvetrain laid out, it's a pretty fulfilling project. Just make sure you use lots of assembly lube. Starting a dry cam for the particular first time is a great way to ruin your investment decision in about five seconds.
Conclusions
At the particular end of the particular day, upgrading in order to performance twin cam camshafts is usually one of the particular most rewarding points you can perform for your vehicle. It's a "mechanical" upgrade in the world that's becoming increasingly dominated by software tweaks plus electric motors. There's something special approximately changing the physical timing of an internal combustion engine in order to make it shout.
Whether or not you're looking regarding more torque in order to pull a truck, more high-end power for the monitor, or simply that basic cammed-out idle at the local car meet, the correct fixed of cams can get you there. Just do your research, don't go too overboard with the specs, and make certain you've got the particular supporting parts to handle the new-found power. Your engine will be glad for it—usually by roaring every period you hit the gas.