Best pipe setup for performance?

It could be several things.
What I see from the Daytona dyno sheets I have seen is that the high mount systems tend to make better low end torque (a couple more ft-lb from cruise rpm and lower), but the short low mount systems make a bit more top end. It is a trade off. If you don't ride at low rpm around town much, you don't miss a couple of ft-lb at low rpm.

The exhaust pulses don't know length, they only reverse when the pipe changes to a bigger diameter, or when they hit open air (or the perforated tubing in the silencer). So the pulse tuning for each set up is different.

On a flowbench, a tube doesn't see much restriction (other than wall friction from length) from bending it until it starts nearing 90 degrees. The closer you get to 90*, the more restriction you get. Beyond 90*, it continues to escalate.

Clear as mud, right?

With no other changes other than collector length, and free flowing silencers/mufflers, shortening the collector length rocks the rpm where peak torque occurs to slightly higher rpm point. Maybe a couple of hundred rpm higher.

If the silencer has as much or more flow as the engine needs, torque doesn't fall off rapidly, and more power is produced. IF the silencer doesn't flow enough, torque falls of rapidly, and the potential power is lost.

Peak power occurs where torque starts falling off more rapidly than rpm is gaining.

REMEMBER THIS: You can not measure power. You can only calculate it from measured torque.

Torque causes acceleration. Power is how much torque you have at a given rpm.

Now the water is even muddier.

Let's see if I can get this across better. You seem to have a good grasp on basic wave theory - this helps. Bear with me, I am not a great teacher.

"Is the effect on torque in relationship to the collector a factor of flow or exhaust pulse?"
It is a combination of cam events, velocity, pulse tuning, and flow - in combination with temp, and a whole lot of lesser factors.

Pipe inside diameter determines area and thus velocity - or where the peaks occur.
Pipe length alters when the waves are reflected back to the cylinder(s) and can be used to rock the peak torque and power points by several hundred rpm or to fill in dips in the curves.

Exhaust pulses reflect both ways in the exhaust flow, and act as both positive and negative waves. They occur in the primary and secondary (collector) pipes and travel between the cylinder and the silencers. So there are lots of waves occuring in the exhaust that change with rpm and throttle opening. Making even more complex waves.

Pulse tuning and scavanging are VERY important to how an engine performs - MUCH more than double amplitude due to the dynamic nature of the engine. But it is a trade off if you need to perform over a wide rpm range. You take what you can get - without robbing too much from other rpm zones by causing negative wave tuning.

This is a bit overly simplified, so bear with me if you already know this.

When the cam opens the exhaust valve, the high cylinder pressure gets a chance to blow out into the exhaust. Think of it as an elongated egg of pressure that travels to the end of the primary header pipe. When it meets a bigger volume opening in the collector, a suction wave forms that acts like a sound wave. This suction wave travels back to the exhaust valve and (if it is still open) into the cylinder. It helps to pull fresh air and fuel into the cylinder and out to the exhaust. This is called scavenging and it helps power - a lot. Think of this like a scavanger hunt where everyone is trying to collect the same things - fuel and air.

It happens again at the end of the collector.

At some rpm points, the suction wave will travel back up the header and meet a closed or closing valve. At these parts in the rpm band, the suction wave can do nothing, or even hurt flow if it reaches the valve at the wrong time. (This is where a cross-over between pipes can help at lower rpm)

In reality, the suction wave reflects back and forth in the header tubing several times, and causes both positive and negative reflection waves. The temperatures and pressures in the header alter the speed at which these waves travel - the tubing length and diameter plays a part in when they occur - based on cam timing and engine flow.

Cam timing (when and how long the valves are open, and how much the intake timing overlaps the exhaust timing) is the heart of the engine.

A four-stroke engine rotates twice (306 degrees times 2) before all cylinders get a chance to fire. That means that the exhaust pulses in a three-cylinder engine are 240 degrees apart. If the exhaust is designed correctly, a group of three cylinders are far enough apart, the suction from one cylinder can help scavange the other two cylinders. It happens in all milti-cylinder engines, but groups of three (240 degrees apart) work together best (3,6,9,12-cylinder engines).





All of this also occurs in the intake, but to a lesser degree.


Have I made things worse?

HarriS said:

At least they are not too long for a low revving 1050. You have to keep in mind that the fashion with stubby pipes started with 16000rpm 600s. even 1000cc sportbikes have pretty long midpipes and undertail mufflers.

Click to expand...

Exactly!
[Bells ringing, alarms going off, confetti falling from the sky, beautiful women weeping in joy]


Premier - I don't have enough information to make a determination one way or the other. The ONLY low mount 1050 dyno sheet I have seen is for a Zard full system with and without PCIII tuning. It is very hard to compare it to other dyno graphs due to different testing conditions and dyno variations.

However, it looks a bit low on torque below 3500 rpm compared to other graphs - but that doesn't mean much.

When Avi8or Dynos his Zard full system we MAY learn more. It may even open up new and different questions. Since he doesn't have a baseline dyno graph to compare it to.

On silencer length: The exhaust gases and waves see a silencer's perforated tubing as a wide cone shape - almost like an opening to the outside air, but not exactly. So silencer length is not much of a factor other than being better at absorbing sound.



One thing to ALWAYS keep in mind. A Speed Triple is a naked 'street fighter' not a sport bike.
It uses a wide torque band to 'battle' on the streets. The recent Bike magazine engine shootout shows why this engine is so good on the streets. It performs better than lighter bikes making a lot more power due to have such a wide torque band and decent gearing.

Triumph did their homework, and build 'street fighters' better than anyone else. To me, doing anything that alters the character of the engine and bike should be a crime. Making these characteristics more pronounced is what I have been doing with my bike. If I wanted a hypersports bike, I would own another one.

I really like my Speed Triple. Best bike I have ever owned - it does so much, SO well.

Optimum? No.

See it really depends on where you want torque. What is optimum for one rider or riding condition is not optimum for another.

For Avi8or, who lives on a small island with bad roads, and spend a lot of time in stop and go trafic, high rpm power is of little value. He needs a few more ft-lb available down low.

For Triple Rider who lives near the wide open spaces of Utah, and spends more time above cruising speeds, a couple more ft-lb below 3500 rpm will not me missed. But a couple more ft-lb at 7500 rpm will definately be more exciting.

For guys that ride the canyons, the Tail of the Dragon, or on tight tracks, a couple more ft-lb throughout the entire powerband would be very nice.

The problem is knowing what you actually need, not what you think you want.

I have built, helped build, or modified engines for guys that told me what they wanted. But after looking at how they actually used these engines, I did something, or suggested something, different than what they said they wanted, but actually matched the way the engines would be used. In several cases, the guys have said this was the fastest engine they have ever owned - when in fact, they had more peak power before... and more AVERAGE power (where they needed it) after.

Clear as mud?