ESE's works engine tuner

[wobbly]

I dont remember what that pipe was designed for, Ive done hundreds of them,but it has a 50mm long cylinder duct, and a 35mm long Ex spigot with no venturi - seems odd.
The length at 839 suggests a low Ex port around 83* from a Honda, but ask Neels, as it appears I did it for him??

The header at 41 or so diameter, usually matches the total effective Ex port area, and the duct diameter reduced to 75% of that area increases the velocity as well as the Helmholtz resonant frequency
of the system.

[RomeuPT]

I dont remember what that pipe was designed for, Ive done hundreds of them,but it has a 50mm long cylinder duct, and a 35mm long Ex spigot with no venturi - seems odd.
The length at 839 suggests a low Ex port around 83* from a Honda, but ask Neels, as it appears I did it for him??

The header at 41 or so diameter, usually matches the total effective Ex port area, and the duct diameter reduced to 75% of that area increases the velocity as well as the Helmholtz resonant frequency
of the system.

I thought it was this pipe. Is very identical to A-Kit pipe posted (in lenghts and angles), page 272

Can someone says by experience how much the exhaust cones assembly angles can change between each other to fit a bike, not making U bens etc, how much loss can be in that.

Some of my pipe designs so far:

[wobbly]

Yes that is a Honda pipe designed for the low Exhaust customer type cylinder, but the spigot length has been changed and the venturi removed in the sim print out.
Its not an A kit design, as that is shorter and is used with a 200* port timing.

The angle changes on your pipes look fine - but I hope you didnt just go ahead and weld them together.
EVERY weld on a mild steel pipe should be hammered on a mandrel, and the ones in the header linished with a flap wheel, or simply throw away 2 to 3 Hp.

[2T Institute]

But one thing i did gain that i had never heard of was the wooden Planks the F1 cars run under the tub. if they are worn by a certain amount after the race the car is disqualified. Clever and simple.

That was Ferrari-gate when it leaked out that they had hinged at the rear and fitted strong springs at the front behind the plank that allowed the plank to tilt up and ride the kerbs or not wear as much in corners.

[Ocean1]

EVERY weld on a mild steel pipe should be hammered on a mandrel, and the ones in the header linished with a flap wheel, or simply throw away 2 to 3 Hp.

To make for a smooth transition?

Have you ever tried purge welding them with a TIG?

[speedpro]

EVERY weld on a mild steel pipe should be hammered on a mandrel, and the ones in the header linished with a flap wheel, or simply throw away 2 to 3 Hp.

I dummy my pipes up on the bike to check for fit and layout using masking tape and then remove the first 2 sections and weld them together, then hammer the joint and grind and sand inside so it's all smooth. Then the next section gets welded on and the joint/weld finished and so on. It takes ages.

[wax]

How do you do the last section. At one point when you join them together your not going to be able to get to the weld

[richban]

How do you do the last section. At one point when you join them together your not going to be able to get to the weld

Someone told me if you run argon through the inside of the pipe, its nice and clean on both sides. Does rely on a pression joint of course.

[senso]

How do you do the last section. At one point when you join them together your not going to be able to get to the weld

Start welding the pipe from the tail pipe?
Then your last weld will be the exhaust flange to mate in the cylinder.

About the thermo-couples, I already had the idea that with even exposed tip sensors 1Khz would be way to fast, but I will at being able to read them at 1Khz, and then do some filtering in software, and having that bandwidth allows me to try to sample right when the spark is generated or latter when the exhaust port is open.

[RomeuPT]

Yes that is a Honda pipe designed for the low Exhaust customer type cylinder, but the spigot length has been changed and the venturi removed in the sim print out.
Its not an A kit design, as that is shorter and is used with a 200* port timing.

The angle changes on your pipes look fine - but I hope you didnt just go ahead and weld them together.
EVERY weld on a mild steel pipe should be hammered on a mandrel, and the ones in the header linished with a flap wheel, or simply throw away 2 to 3 Hp.

Really, 2 ou 3 hp in a Race 125? That's still substancial.

That's the reason why the exhaust around here get better after riding some hours?

Some of the top 50cc around here in Portugal have two U bends in the exhaust :S

Regards

[Frits Overmars]

That's the reason why the exhaust around here get better after riding some hours?

Carbon deposits in the pipe may smoothen the flow, but their main effect is to form a thermal insulator layer between exhaust gas and pipe walls, so the exhaust gas will lose less energy to the walls and more of this energy remains available for charging the cylinder.
A second effect is that the exhaust gas remains hotter which influences the speed of sound, hence the pipe's resonance frequency. If the pipe was already rather short, this effect can be negative.

[Flettner]

I insulate my chamber with mud.

[wobbly]

I always start at the header and work along, these sections are easy to hammer and linish with a 25mm flap wheel in a die grinder.
The rear cone is thus the last and I use a length of 19mm Hi Tensile bar with the end radiused, clamped in the vise,to hammer the last joint smooth.
Make very sure the ALL grinding grit is wiped out, when the engine first fires all the shit will end up on the piston face and cause havoc.
I use argon purge inside when making Ti chambers, but its not really the weld thats the issue with mild, its the slightly uneven joint overlaps.
A hammered header radius looks and performs better than the as welded sections do.
Tig is way faster and WAY cheaper than a gas welded pipe, but I still think gas welding looks better if done right.

[F5 Dave]

Hmm, ok lets talk pipe temperature insulation while the topic is up. We used to see lagged pipes, then that went out of fashion, possibly Ti pipe insulated better was postulated, but largely there was talk of the charge being returned to cylinder cooler was better.

Think it could have started with the snowmobiles as they supercool so lagging really helped. As an aside we've seen the lagging to avoid heating the cases.

Clearly there was the overall change in timing of wave. I've lagged & HPC coated my 50 pipe (awaaay back in the day) & all it achieved was rust, maybe 100rpm move & no power change. I HPC coated my 500 pipes (250x2) for convenience (its a roadbike), thinking it would not do squat but keep it looking nice & unrusty but heck did it whap the peak revs up, maybe 1000rpm. Stripped them & went for boring old paint.

[Frits Overmars]

We used to see lagged pipes, then that went out of fashion, possibly Ti pipe insulated better was postulated, but largely there was talk of the charge being returned to cylinder cooler was better.....Think it could have started with the snowmobiles as they supercool so lagging really helped. As an aside we've seen the lagging to avoid heating the cases.

True, true. The part of the exhaust duct where the fresh charge lingers, should remain cool. That is the reason the ultrashort exhaust ducts of obsolete cylinders have been superseded by longer, watercooled ducts. But the rest of the pipe can still be isolated.