View Full Version : "spagetti" exhaust system

10-02-2013, 11:12 AM
Default "Spaghetti" exhaust system
Greetings all,
Mark Lumb (MADasl Ltd... 8madasl@googlemail.com) has knocked up a system for my 851 (to be followed buy a system for my SL) The stainless tube is of a finer gauge than previous systems and the welding is of a high quality, and held together with springs on the expansion joints. We are going to try an experiment here in that the current fitted system has two pipes of exactly the same length to the end cans not interconnected by "balance pipes" The idea is to , next week, do a dyno run with the old standard header/can arrangement to get a base line set of results, fit the new system, do another dyno run to see what improvement is made and then fit a system with balance pipes to see what (if any) further improvements have happened. Obviously The necessary mixture/mapping will be done to optimize each new system. On finding the best set of results will determine the final design.
I would be interested if any one out there has any experience of running systems without balance pipes a'la existing spaghetti systems ?? I understand that later 748's did not use a balance pipe system.
Any comments or thoughts would be most welcome. These new systems will be as good as anything out there and very competitively priced.
Thanks for reading,
with appologies for posting under "reply to thread" subject Immobilisers

brad black
10-03-2013, 10:32 AM
my thoughts:

the std 40mm headers are too small anyway, 45mm works better. so using a 40mm system as a base line is a bit like hotting up a Harley. it's an easy mark. start with a suitably modified st4 45mm header set and decent mufflers.

and tune the std header combo to start with too, so your baseline is not jut what the factory put out, but the best it can be. depending what eprom you're running, if you start taking out spark advance on only the new exhausts you'll make a false top end gain. the 008/009 eproms will cost you 2 -3 hp due to too much high rpm wot spark advance alone.

use the same mufflers for all tests too. the local megacycle monster ones that I used on my 888 gave a noticeable midrange increase compared to the staintunes I had run previously. they can make a real difference, and you need to be scientific about this to get good results.

every engine, 2 or 4v from paso onwards has had a collecter in the headers excepting the sport classic range and the 749/999. the sport classics seemed to really hurt for power with the std headers.

a non collected pipe per cylinder will probably make a bit more in the midrange. it should make less at the top end. see the third graph: http://www.bikeboy.org/s4rexhaust.html or even the first two, and remember that's compared to a box collector, not a good one.

maybe a larger diameter will give a lessened top end loss, but it may also lead to a less linear torque curve/give greater variation between tuning peaks and troughs.

the spaghetti term comes from the two pipes connecting the main headers. on the termi systems at least they are not balance pipes. they exit from the main header at a shallow angle allowing full flow into them and enter the other cylinder's main header at a similar angle to again allow full flow out.

I have seen photos of an akra so called spaghetti system which seems to have right angle exit/entry style balance pipes between the headers. I'd call that a misinterpretation of the idea/theory, and would expect it to not work. that's what the s4r in the above graph had.

I've seen std headers modified like it too, by people who just don't understand what the idea is. pour water into a vertical tube with a hole drilled into the side and see how much comes out the hole. then replace the hole with a nice tapered y piece and see how much comes out of each y leg. the pipes are allowing each cylinder to see each muffler.

to my mind, this one is marginal: http://www.ducati.ms/forums/attachments/supersport/36493d1220552225-spaghetti-style-header-dscn9081.jpg

needs to be more like this: http://i292.photobucket.com/albums/mm21/JonTravisKing/Ducati%202005%20Monster%201000s/SpaghettiHeader1.jpg?t=1305661314

if there was a better system for them than the termi spag then termi would have made it. the system wasn't developed for a model that didn't do anything. it was an ongoing development of a world championship contender with a clear goal, and I see not a great deal of point trying to reinvent it as such. not trying to be a know all smart arse, but i'd be surprised if there was an overall gain to be had over it. or a great gain of any sort to be had over an original farne/sp or modified to suit st4 header set.

altho I'm always happy to be surprised.

10-03-2013, 01:15 PM
Hi Brad!

After your great disgression on exhaust systems, I have a question for you to see if, according to your experience, I can get a decent result from this combo.

I'm intending to fit into my 851 an ST4S engine with 996 heads (not "droop") with SPS camshafts. As it's a bigger capacity engine and flow more gas into the cylinders due to the higher lift camshafts, I'm going to fit a SilMotor spaguetti sytem which I think is quite similar to that of Termi.
In my mind, it may be a balanced combination but I have no experience in this area, so, although I'm expecting to get some 120-125 CV out of it, one never knows....
Of course, as I'am retaining the whole electric system and ECU from an S4R (As I think it's at least a 996 map a good point to start with), I'll fit a RapidBike ECU to try to get the best power. Of course it will be tuned by a competent RB retailer.

Thank you in advide for your kind answer!

10-03-2013, 02:43 PM
Hi Pat,
All of the spaghetti systems for the 888's had balance pipes, that's why they were named "Spaghetti" or "Nest of Vipers"... For obvious reasons. ;)

The full 50mm system that I run on my own 851/916 has both headers exactly the same length, but the two balance pipes join to the system at (as close to damn it) right angles and it works pretty well.
My system was supplied by Gio-Ca-Moto the forerunner to Ducati Performance, it was built by F1 Thunderball Racing in Italy for Ducati.
The balance pipes fitted to the factory race kit exhaust system for the 750/900 Bevels and the systems fitted by NCR to their race bikes all had the balance pipes fitted at 90 degrees.
As did the factory race systems fitted to the "Pukka"Thruxton Bonnevilles, Norton Commando's and Moto Guzzi V twin Endurance Racing bikes..
I think this is why the early 888 Spaghetti systems made by "Skorpion" later to become Akropovic had the balance pipes fitted in this way...It was the thinking of the day.
I've always thought that the fitting of equal length headers/full systems aided top end performance/Hi revs and the addition of balance pipes improved mid range power.
Also that the adding of balance pipes fooled the system into thinking it was a lot bigger than it actually is, which improved the extraction, the angle that these pipes were added on didn't make much of a difference to outright performance.
By the time that the factory were fitting full Termi' Spaghetti systems they were chasing the last 1 or 2 rwbhp, this hunt also led to twin engine breather outlets and larger catch tanks/breather boxes under the seat.
The exhaust systems fitted to the 748/916's owe more to fashion than function and shouldn't be considered as an improvement over the race systems fitted to the last 888/926's.

Steve R

10-03-2013, 02:47 PM
many thanks for those most interesting thoughts. Most of what you say makes perfect sense to me. I shall ponder them with Mark. I think he will be most interested. I must admit I agree that if they could have been made better Termi would have done so, I mean even world beating Honda Moto GP bikes use Termi's.
Thanks again for all the links as well.

10-03-2013, 04:07 PM
World beating Honda GP bikes might now use Termi's, but the Termi's fitted to the 888/926's were originally designed by the boys at Acropovic...
But Termi' are now owned by Ducati. ;)
The badge on the system has more to do with who pays the most, than actually who designed it.

The factory GP D16's have systems made and badged by Termi', but they were designed by a guy who lives just outside of Tavistock in Devon, (he's a friend of a mate of mine, who's one of the top boys in cylinder head tuning) a freelance exhaust system designer for the F1 car racing teams.
He had some very interesting ideas when we talked about my little self tuning project for my 851.
This guy can design and put the power almost where ever you want it, given the spec of the motor it's wanted for.
It truly is an art form, but in terms of cost waaaay beyond anything we'd need for our 851/888's.

Steve R

brad black
10-03-2013, 08:41 PM
my comments may have been mistaken a little.

my point was, whoever designed the spag system used on the factory race bikes was doing so in an environment of continuous development to win a world championship, so you would expect that what they came up with should be pretty good.

my experience with the h style cross overs is that they don't work, but that may be just based on the ones I've tried. I had a guy with a guzzi tonti frame racer email me some graphs and he had run his with similar sized h style system and a staintune x system and the result was similar. maybe it needed more cam, etc, to make more top end to need a system like that, but the exhaust alone didn't seem to change it much.

plus the 2v vs 4v rpm range thing would come into play. it seems that 7,500 or 8,000 rpm is where design requirements change and that's probably consistant with the engines of back in the day maxing out.

the guy who made a mv500 replica that is owned locally built both 4 pipe megaphone and 4-1 systems for it. it only runs with the 4 straight megas as it's all about the look, but with 880cc or so it makes 100hp with the 4 - 4 and 115 with the 4-1.

do you have a photo of yours steve? it obviously works. I felt Roberts lack of top end was probably header design based, based on my experience. a photo of his header is about half way down here: http://www.ducati851and888.com/showthread.php?4883-Guess-my-HP-and-torque-game/page2

i'd like to compare a suitably modified st4 header set to a termi spag and any other power making system, but opportunity just doesn't present itself.

10-04-2013, 04:42 AM
Here you go Brad try this link...


Here's the graph for my 851/916cc motor, T1 cams at 107/107, 35/30 valves in 916SP heads, flat top ST4 pistons, (valve pockets opened out) 0.9mm squish and single greens in bored to 54mm TB's, with the fuel pressure at 4 bar.
Pretty mild tune really.


Steve R

brad black
10-04-2013, 10:00 AM
the system on the first page? hard to see the connection pipes, but they look to enter and exit at 90 degrees. i'd expect that to not work, so clearly i'm wrong. how big is it?

10-04-2013, 01:07 PM
Yes that's the one Brad, it's a full 50mm system from front to back.
As you can see from the dyno sheet for my bike it works quite well, no trace of a hole in the curves anywhere.
Chris Steedman/CJS mapped it using a 916 Strada chip as a base, after he found the JHP chip I was using as a baseline was encrypted.
He was surprised that it was only 916cc's.

I'm 100% sure that the later style Termi' Spaghetti systems work even better, so if I was going to copy a system that would be the one I'd choose*.
(That's basically what Jasper did, John Hackett lent him a "Pukka" Corse system to copy.)
I'm with you on not trying to reinvent the wheel, it's always better to stand on the shoulders of giants in my book.

*There were several Termi' Spag' systems as I now use tuned motors, (purely for myself) I'd go for the "Daytona" which I think (?) was a full 50mm system.
I've only ever seen one of these, (apart from some for sale on the web) the late Rob Barksfield found/bought one, but never got around to fitting it to his tuned ST4S engined 888.
Rob's 996cc motor didn't quite equal my 916cc motor for power despite the extra capacity, bigger valves, ported heads, special "Arrow" con rods and genuine Termi' Spaghetti system, all be it a smaller bore (possibly 45mm opening out to 50mm) Corse one.

Steve R

10-17-2013, 04:43 PM
Mark has done the final dyno run on the spaghetti exhaust system and to my non technical understanding,the results are impressive :
Standard 1992 851, 17800 miles, Termi straight thru cans, Shell v power fuel,
1. Standard stock exhaust system : 81.28 RWBHP, Torque 50.97 ...about what you would expect (?)
2. Straight through pipes, (no balance pipes) 84.45 RWBHP, Torque 52.93
3. with balance pipes, 87.90 RWBHP, Torque 53.56
I make that an increase in RWBHP of 6.62 (8.16%)..I recon that's a decent result and represents good value for money at approx 500. looks good to as well as being added value.
The really interesting and unexpected surprise was the bulge and flattening upwards of the torque curve between 4000 to 6000 rpm. To my untrained eye the line is very "fat" and linear. (probably not explaining this very well) but to quote Mark, "this should be a rocket ship for a stock 851"...and we still have to optimize the fueling and the ignition.
I would be most interested in the experts opinion on these results. I have the Dyno traces if anyone is interested but have had a little trouble putting them on as an attachment. Remember I am an old person not very good with com put toors..
Lookin' good ...the Superlight is next up for the treatment.....:-)

brad black
10-18-2013, 07:50 PM
dyno charts and photos please.

10-19-2013, 03:31 AM
+1 on that, I'd like to see the graphs and system.

Steve R

10-19-2013, 04:55 PM
Yeah.. wilko but cant access them until Mon/Tue but I will post them.

10-20-2013, 05:45 AM
Dyno traces as promised


I hope this has worked... not very good on computres

Cant acess pipes to get photos untill thursday..Mark is away and they
are in his worksop.
Willpost on Thur,

10-24-2013, 04:43 AM
Brad, Mr R... any thoughts on those dyno graphs ?. I would welcome your expert opinion
Photos to follow.
Thanks very much,