Tuned pipes are probably the most misunderstood pieces of equipment you will find on a nitro RC. Many people just go to their LHS and buy the tuned pipe their RC company supplies and hopes that their RC will go faster and work better. But, there's a whole detailed world of how tuned pipes work that not many people know about. This article is written to show you inside out about tuned pipes and their effectiveness, as well as exhaust headers, fuel tubing lengths, and more.If you don't have the time to read all this jibba jabba, you can just read the bold parts that are the most important deatils....And don't forget to sign my guestbook! There's a link on the bottom of this page.

ALL ABOUT PIPES

Here's a little info on how tuned pipes work. First, you need to know that the engine in your RC is not 100% efficient. This means that not all the fuel you put into it will be turned into power. Some raw fuel will leave the engine unburned. This is when a tuned pipe helps out. What it does is take that exhaust and cram some of it back into the engine to be burned again. This happens by pulsing pressure waves going through the exhaust manifold, into the tuned pipe, bouncing off the end of the pipe (a major thing here), and coming back to the engine. This gives the engine more fuel to burn, allowing it to gain more power and efficency. Not to mention that it also dampens some sound. A nitro engine would be very sluggish, inefficent, and loud if tuned pipes didn't exist.

First, look below at some of the shapes a tuned pipe has. There are names for the shapes on the pipes: the divergent cone, convergent cone, stinger, and belly. The divergent cone is the place where the exhaust enters and the pipe expands. The belly is where the pipe retains the expanded size until it reaches the convergent cone, where the pipe ends with a little angle to it. The stinger is simply the tube where the exhaust comes out.

There's a reason why these pipes have these characteristics and why they're not always similar to other pipes. The different shapes provide a different powerband.The steeper the angle is on the divergent cone, the more low-end, and the smaller belly there is, the more high-end, and vice versa.Take a look at the tuned pipe pictures to get a visual idea of tuned pipes.

This is the Team Associated Pipe. Take a look at the incredibly steep angle and huge belly on that pipe.This pipe has the most low-end you can buy.It comes with the Team Associated RC10GT, and many other go-fast buyers get this pipe as a hop-up. It's popular on off-road trucks where tremendous torque is needed. This pipe also has a hole as a pressure fitting, so just stick your pressure line in it. No pressure fitting. It comes in two different versions: polished and/or colored, and regular.

Here's a Duratrax tuned pipe. See that very gradual divergent cone and tiny belly?This pipe was meant to extract the high-end RPMs out of your engine.But, there's no low-end. This means it'll take a while to get your RC up to speed, but once it's there, it'll be just screaming. .21 pipes are usually shaped like this to tame the engine's massive power for speed. After all, .21s are naturally punchy anyway.

Here's HPI's tuned pipe. As you can see, it has a gradual divergent cone, but a nice-sized belly. This pipe will give you some pretty nice take-off times, and the high-end is good, too. A pipe like this is common on nitro touring cars where you need torque to get out of the corners, but speed to go through the straights. So it's good for mid-sized tracks where you need a bit ofboth low end and high end.

EXCEPTIONAL PIPES

All the pipes you saw above were hallow, but this HPI Dual-Chamber Composite Nylon Pipe is different. It has two chambers in it instead of one big one to have a greater muffling effect. This ability dampens more sound, but stops more power. You can still tell the performance of the pipe by shape, though, it's mostly speed. It's also really cheap because it's molded, not machined. It runs for about $10, and it's hard to beat it for its price.

This is the Paris Turbo Ring Pipe, otherwise known as the ripple pipe from other brands (this pipe is vastly copied). The pipe has a great low-end shape to it. Plus, there are ripples in it that give backpressure in the high RPMs to give it more speed. Think of it like a rally, though. It doesn't master high end or low end, but it gives you a nice amount of each. It comes in black, blue, purple (shown), or chrome.

This is the widely known CVEC pipe. This pipe is very special - it has a spring-loaded piston in it that shapes the pipe as the engine revs. This pipe has 5 tuning adjustments inside it so you can tune it for efficiency or power. It has moving parts, so it is not ROAR legal. Most people buy this pipe because it looks cool with two stingers and it's loud, but the efficiency of the pipe is not anything to be proud of... it's a little lacking on overall power compared to the others.

EXHAUST HEADERS

Headers (also known as manifolds) have their own purpose why they're all different, too. Not just because they're shaped so they'll fit in the RC, but because different shapes and sizes dramatically changes the power output for low or high end, just like tuned pipes. Lots of stock manifolds have sharp right-angle turns and use silicone L pipes. These manifolds are something that you want to stay away from because they take away some of your engine's precious power and efficiency.

Finding the performance of the header you buy visually is simple:the longer header you get, the more torque, and the bigger tube it is, the better it will be in overall performance and efficiency, and vice versa.Touring car drivers usually prefer a shorter exhaust tube and most off-road drivers like long tubes.

Here's a little explanation on why the shapes and sizes of a manifold really matter. Imagine the engine running right now, and imagine the pulses of exhaust coming out of the engine and through the exhaust system in slow-mo. Now, the engine has hit some throttle. A longer manifold will make the exhaust system have more lag for the exhaust pulses to get back to the engine. It has to go through thelongheader, to the pipe and bounce back, through thelongheader again, and back into the engine. Since the tuned pipe gives the engine more fuel to burn, it makes the engine run slightly richer. Since the effect of a tuned pipe is lagged through a long header, the engine runs slightly lean for just a very short time.

However, there are drawbacks to having a long header. After the pulses have gone out of the engine for a while, the pulses even out more and more into steady airflow. Tuned pipes depend on pulsing pressure to work, and the more accented the pulses are, the better it works. With a short header, the pressure has less time to even out, so the pulses are more accented and the tuned pipe works better, and vice versa for a long header. Also, the bigger manifold bore is always better because it's easier for the exhaust to mold it's shape from the engine's exhaust port to the header's port.

This exhaust header is the Associated RC10GT header. As you might have noticed,this header is made for high-end speed.See how the header brings the exhaust straight out from the engine and to the tuned pipe using as little material as possible? That's why. The diameter of the tube is a nice size, too, giving pretty nice performance. This manifold comes with the RC10GT along with that torque pipe. This manifold gives the truck a chance at some speed.

This is Traxxas' exhaust manifold, a mere copy of MIP's 360 exhaust. See how it takes its time to reach the pipe?This header was meant for huge low-end.Unlike most manifolds, this one was designed for the exhaust to exit through the rear, and a special pipe associates it with a stinger at the end of the pipe for rear, not side, exhaust. The stinger pipe setup is also nice because it comes with a rear shock tower to hold the pipe.

HEADER TIPS 'N TRICKS

Keep in mind that you don't need to buy a new header to tune your performance. The coupler that connects the pipe to the header can be spaced out or pushed together to widen or shorten the exhaust travel until it reaches the pipe. Sometimes this requires you to chop off a little bit of your header to acquire more speed, but if it's speed you want, a little machine work is worth it. However, if you want a dramatic change, a new header will do the trick.

Don't let the pipe and the header come in contact, though. When two metal pieces touch on a RC, it glitches for just a split second. But if the pieces are vibrating on and off each other, this will cause your RC to go out of control. An example of metal-to-metal glitching is when you clip on your glow igniter onto your glow plug and you see the servos jerk.

Most headers come with an opening that is smaller than your engine's. Having a small manifold opening will rob your engine's power, so use a Dremel and a cone-shaped grinding tool to increase the size of the opening. This is hard to explain, so look at the picture to the left. See how the opening has been widened to shape itself to the engine's exhaust? Cut your header to this shape for free power. The NJ BigTube manifolds are sold pre-ported.

Some people will find a problem with their tuned pipe falling out of their coupler or manifold. This is a common problem for a lot of people, especially off-road where the pipe gets jostled around. To prevent this problem, flange your pipe and manifold at the ends. You can flange it with some needle-nosed pliers. Grip the last 2mm of the tube and pry it up a little, and do this all round the pipe. It doesn't matter if it looks bad since the coupler or silicone L pipe will cover it.

JUST THE RIGHT FUEL LINES

Fuel and pressure lines are also an important part to your nitro engine. Having the right length of fuel tubing can save an arm and a leg in a race, and may even affect your performance. The nice thing about fuel tubing is you adjust the lines for better performance, not to change your performance for your needs.

First, look at thepressure linefrom your tuned pipe. Usually people leave this line short. However, the pressure coming from the tuned pipe is pulsing, not steady. So, if the pressure line is too short, it can "blow bubbles" in your gas tank and foam up your fuel. Foamy fuel that goes to the engine makes it run lean because it is airandfuel, not just fuel itself. To make the pulses steadier, make your fuel line longer, about eight inches total, because longer lines give the pulses from the tuned pipe a longer time to even out. For less clutter, you can use zip ties to hold the line in a coil, as shown in the HPI pipe picture way up at the top of this article. Having the right length of pressure line will increase performance because it gives a steadier pressure to the engine and does not foam up the fuel. However, if you go too far with the length, you will begin to lose pressure and lose performance. Soaround eight inches is good, but seven or nine is still fine.

Another line that can be fussed with is thefuel line. First, let me get you familiar with the gas tank. The fuel comes from the bottom of the tank so the engine will get every last drop of fuel you put in it. So, when the car's flipped over, all the fuel goes to the top of the tank. The fuel can't get to the fuel line because the fitting is at the bottom. So, the fuel source is cut off. So why does the car still idle for a few seconds? The fuel line still has fuel in it that is still going to the engine. So you can probably understand why longer fuel lines are better - the car will idle longer when flipped over because there's more fuel in the lines. You can still go extreme with this length, too. If your lines are too long you will lose pressure and lose performance. For racing, I'd recommend abouteight inches of fuel line or less.This will allow the car to idle about thirty seconds when flipped over and will not affect performance