Imola high pipes tuned length assistance?

[Aussiess]

Hi,
I have a set of Imola High pipe headers, for fitment to my Bosch-squarecase engine. This engine has had some improvement made and is currently running in my race bike with individual NCR headers /pipes (with some grounding issues). I have a replicated 76 SS frame.
As I have these Imola headers (large bore for a race engine), I have decided Id like to fit them , but want to ensure best performance from them.
I will have to make up a set of "meggas" for them, and will use the same 60mm exhaust opening on a reverse cone style mega, but this is my question- Can anyone advise if there is a tuned length (from the head to end of exhaust), that provides optimum performance.
I did read a very interesting article on a race engine build and the author referenced 33 inches as the length (measured around the outside of the bends).-Was on another Ducati website. This would make some sense to me, as each pipe should I think be the same tuned length.
Im hoping that someone out there has been through this over the years with your bevel and can assist me.
My engine has ported heads, larger valves (42 /36), has stroked crank +6,mm and runs Imola cams. I run Malossi 42mm carbs etc
Appreciate any help and maybe images that anyone can offer me.
Many thanks
regards
Grant

[Zanetti]

I'm in the same boat re designing and building an exhaust for my Mille Alchemy, never been able to find any info regarding the dimensions of the actual megaphone part
but there are a few sites which will give primary header length and diameter.
http://www.mez.co.uk/mezporting/exhaust_length.html
http://dairally.net/daihard/chas/MiscCa ... iPipes.htm

Another method of determining if the header lengths are the same is to measure the volume by filling with water assuming you have nice constant section mandrel bends.

If you do find info re megaphone dimensions / design I'm sure a few other people would be interested, they were all the rage in the 1930's~1960's for big single brit race bikes

[Aussiess]

Thanks for the links, good info ( if you can input the values), I am hoping that just maybe there is someone out there that has done this with high Imola pipes, as they were a very popular race pipe. We shall see.
I will post anything I find though.
Regards
Grant

[machten]

Grant,

This one is Spaggiari's 72 Imola bike owned at the time by a mate of mine:

viewtopic.php?f=29&t=2924

If I could get some better side on photos from the owner of the time, would that help?

EDIT: In fact, IIRC the owner of the time told me that Phil Aynsley came over way back then and took a bunch of photos of it. If that's the case, then Phil more than likely has the best photos of it.

Kev

[Aussiess]

Kev,
That would be great as I can scale off that no worries. You have my details via Aussie forum too.
Look forward to any info
Grant

[Lumpy]

There is the old Phil Irving book Tuning for speed that has a chapter on header length specifications

[Ray O'Donohue]

There were a lot of the high pipe sets sold;they were easy to get,and dirt cheap,via Berliner/Leoni. Mine are long since sold,but somebody's bound to have a set for measurement purposes.

[machten]

A friend has some "Imola" high pipes on his 75 750 SS that were from back in the day, but they aren't the same as the Imola race bike pipes. They're sort of "road legal" for the time and have some (small) baffling. I think Grant is asking about the race pipes. I'll see if I can get some photos, but of course they will have been set up for a genuine 750 Imola and consequently not tuned for a 900 (which I think Grant is racing).

Kev

[Aussiess]

I am indeed Kevin, but at present any images help!
I am sure I will get someone who can pass on some wisdom!
Regards
Grant

[Ray O'Donohue]

I'm also now thinking my race pipes had Ducati part #'s.(?) These were the high pipes with open megaphones.

[machten]

Here's the 75 750 SS with high pipes. They are standard SS Contis on the headers...







btw...This thing barks like a dog and goes like stink...and the extra clearance down below can be handy if you're feeling brave!

Kev

[Aussiess]

Thanks Kev, thi is getting me closer to what Im seeking. So, the standard contis fitted without issue? Do they mount to the shock mount bolt?
I will be fitting possibly my pipes(megas) from the NCR pipes I think, will just check the lengths are the same.
The headers are a larger bore than my current pipes, and I will be interested to see how this affects the power spread. I think I read, larger bore means a movement in the power curve to higher revs? A little less low down.

I will go back and check that, but as I will be replacing pistons with 90mm, I may not really notice this incrental change so much, will be lost in the upgrade power delivery.
Anyway, thank you for those images.

regards
Grant

[machten]

Hi Grant,

Sorry for the delay in response, I only got hold of my mate tonight over an ale...

So, the standard contis fitted without issue? Do they mount to the shock mount bolt?

On the 75 SS, yes and yes. (one other piece of advice from personal experience...be careful reaching over from the RHS when setting idle on the rear carb with high pipes....kinda hot around there!)

George confirmed that Phil Aynsley took a whole bunch of photos of the 72 Imola circa 1979 and has the best photos. George took measurements of the pipes but reckons he won't find them until he moves - they are somewhere, but doesn't know where.

Sorry i can't be of more help.

Kev