Exhaust Balance line

[pooh]

I’m having a custom exhaust built for my 900ie my question is what benefit is there for having the two exhausts linked and if not what effect would it have? Due to the routing of the exhausts a link pipe may be awkward.

Pooh

[Mr Gazza]

This is a very interesting question and one I also will need to ask when the time comes to make a custom exhaust for my 750ie engine.
I think it is more important to get the exhausts of each cylinder balanced on an ie engine than a carburated one. I don't know if it is possible to adjust the mixture of the individual cylinders separately with injectors, especially with the simple early 900ie ECU? Whereas this is perfectly possible with carbs.

I think it would be important to get both pipe lengths exactly the same if no balance pipe could be used, I think that connecting the pipes compensates for different lengths to some extent and allows each cylinder to have the same back pressure and flow characteristics, but unfortunately I only know enough about this to be dangerous!!

[pooh]

Gazza
From what I am being told by BSD in Peterborough it is possible to tune individual cylinders on the IAW 15M ECU without needing a Power Commander so I’m not sure.

Pooh

[Darren69]

Most tuned exhausts for Ducati use a tangential manifold of some sort, which improves the gas flow and boosts midrange by around 10% which is where you want it. As Gazza indicated it is to do with matched or balanced header lengths and controlling back pressure pulses. As I understand it the way the tangential manifold works is by using this to get the gases out more efficientily, in effect like a vacuum would do.

http://www.madasl.co.uk/products.php

https://www.ducati-kaemna.com/tangen...uschwinge.html

[Mr Gazza]

Originally Posted by pooh

Gazza
From what I am being told by BSD in Peterborough it is possible to tune individual cylinders on the IAW 15M ECU without needing a Power Commander so I’m not sure.

Pooh

That's reassuring to know, although I believe that the IAW 15M is rather crude and has quite large adjustment increments, but I've never messed with mine. Come to think of it, it would be rather poor if you could not adjust one cylinder individually.
I do happen to have a power Commander in the cupboard if I do need to go that route, but it has no instructions and as far as I can remember doesn't appear to differentiate cylinders, but I'm sure there must be more to it than just a button for the mixture?

As Darren said, if the pipes are linked properly, one pulse helps the other out and so forth, but I have heard that some folks have used individual pipes with no ill effects.. Quite a clever trick to get them both the same length though!

[Zimbo]

I recall that playing about with exhaust options on a 620ie Desmodue race bike some years ago with a power commander tuning each cylinder individually on the dyno, when the exhaust crossover "crucifix"was modified to separate exhaust flow from individual cylinders to individual exhausts, a noticeable drop in torque was observed.

[Darren69]

Originally Posted by Zimbo

I recall that playing about with exhaust options on a 620ie Desmodue race bike some years ago with a power commander tuning each cylinder individually on the dyno, when the exhaust crossover "crucifix"was modified to separate exhaust flow from individual cylinders to individual exhausts, a noticeable drop in torque was observed.

Yea, that figures and with that setup you might as well run an SV650 engine with drag pipes, as you've lost any subtle advantage the Desmo system, with it's much more accurate valve control would give you.

I might be wrong but I don't even think the PCIII has a separate map for each cylinder, there maybe an offset value which can be changed however. An efficient exhaust design that works with the Desmo system is more important and 2 crude straight through or 2 into 1 won't work as well I don't think.

I 'm assuming that Termi did a hell of a lot of the development work going back to Roche's 851 factory bike in early Superbike days, which allowed him to beat Honda V4's and bagged him the world title back then.

[350TSS]

Originally Posted by Darren69

Yea, that figures and with that setup you might as well run an SV650 engine with drag pipes, as you've lost any subtle advantage the Desmo system, with it's much more accurate valve control would give you.

I might be wrong but I don't even think the PCIII has a separate map for each cylinder, there maybe an offset value which can be changed however. An efficient exhaust design that works with the Desmo system is more important and 2 crude straight through or 2 into 1 won't work as well I don't think.

I 'm assuming that Termi did a hell of a lot of the development work going back to Roche's 851 factory bike in early Superbike days, which allowed him to beat Honda V4's and bagged him the world title back then.

The extra 100+ ccs also helped a bit

[bigredduke]

My apologies if this is a stupid question but, would a 2 into 1 exhaust system achieve the same effect ?

[pooh]

Bigredduke
My thoughts exactly as long as the tube after the joint is big enough for the gas flow and am I wrong in thinking the latest Monsters have a two into one system.

Pooh

[slob]

2 into 1 are likely to be more restrictive at the silencer, maybe a worthwile trade off to save quite a few kg. new monsters are 2-1-2 but the cat is hugely restrictive ( and heavy as well as expensive) anyway, as is any exhaust valve when shut

[bigredduke]

This is the middle section pipe for the 1100 Evo which connects the two header pipes to the silencer.

https://www.amazon.com/Ducati-Monste.../dp/B06XTWHVR7

[Kato]

When building exhausts the first thing to understand is the camshaft profile it will dictate pipe dia & length as a rule the bigger diameter the higher up the rev range you move the power, reaching a point where you cant rev high enough to get into the powerband

http://www.ukmonster.co.uk/monster/s...hlight=exhaust

Read this thread for a bit of theory

[pooh]

Kato
thats the stuff the guy building the exhaust for me was babling about, as I design pipework systems based on pressure drop and gas velocity I understood most of it but i do not have to worry about pulse frequency so your reply made a lot of sense. He has suggested fitting a balance pipe prior to the end cans but basically there will be two separate exhaust systems but he is going to match the pipe volume as matching the length is not an option due to the bikes design. there is no option to make the rear cylinder exhaust the same length as the front cylinder so he is going to increase the size of the front collector to balance it. Hopefully it should work better than what I have which is a cobbled together 999 system with Mivv end cans which works really well considering, 87BHP and 89Nm at the back wheel and very rideable.

Pooh

[Darren69]

The exhaust tuning using the exhaust pulses is described more eloquently by Kato in a previous thread below and I suspect that is what he Tangential manifold takes advantage of?

However the 2-1-2 system employed by the 999 Testastretta bikes seemed to work just as well and is much easier to replicate. Although I believe this may have been more of an effort to reduce the noise as much as anything and as such they used stupidly big 70mm pipes!

This reflecting, negative pulse energy is the basis of wave action tuning. The basic idea is to time the negative wave pulse reflection to coincide with the period of overlap - this low pressure helps to pull in a fresh intake charge as the intake valve is opening and helps to remove the residual exhaust gases before the exhaust valve closes (scavenging). Typically this phenomenon is controlled by the length of the primary header pipe.