Now, I know those of you with an eye for detail will have lots of questions, and I don’t have all the answers, since the brain of the project is Mr Valentine, but I can tell you this:
-meant to be much lighter than any currently available
-modular (in fact, this will mean trying different sections to fine-tune)
-does away with the std. secondary theories by use of other alternative tuning methods (balance bars)
-plans are to have a flexi section and sports cat as well
-silencer will not be repackable and will not need to.
We’re planning to have it fitted and March and will be on the RR when I come back from holidays, mid April.
If everything goes well, I hope this is the one I’ll be using at Croft.
Ah jeez! Left that up from the last debauched session! Interesting you think it’s loud. The rest of the pipework follows a straight route to the rear valance, so there is limited space for a very large silencer + Cat. I have a new design of silencer internals which I hope will be sufficient …we’ll see. The manifold I’m more confident about. Light, easy to fit, good strong mid-range but still allows max top-end (not much to hope for really ) as Uldis said it’s just a teaser, for interest at the mo. The dyno will have its say soon enough.
Can you tell me how the scavenging works as they seemed to be paired up wrong
As they are now wouldn’t the reflection pulses interfere with the gases trying to escape ?
But besides, the beauty of this system is that the middle section can be exchanged to try different configurations as well.
He’s told me he’s making a few more prototypes to try out and see.
Hello Phil. This scavenging business; long believed that on a normal 4cyl firing sequence 1-4-3-2, if you paired cyls 1+4 and 3+2 each pulse would help scavenge the neighbouring cylinder. I too, had read this, took it on board and well, believed it!
Another urban myth to go with the “oh a 4-2-1 manifold will give good mid-range but a 4-1 is best for top-end”. Yeah right!
One day, (are you sitting comfortably )I was building an exhaust for a race bike when another bike of the same type came in to the dyno shop (not mine) for some chassis work. I was intrigued to see a race exhaust on it by a well-known Italian mob and even more intrigued to see that the cylinder pairing was 1+2 and 3+4. Now these guys were well respected so “WTF!”, I said. I finished up, (yup! I had paired 1+4 and 2+3) …SO we ran it up on the dyno …THEN swopped over the other system Hmm, not a dramatically different curve shape-wise but 2bhp more mid-range than mine. But surely with that pairing they would have LOST power/torque everywhere? Was it just a “freak”, a one-off on that particular model? That was 13 years ago and nothing I’ve seen since has convinced me that one cylinder will scavenge its neighbour (to any great effect) just by pairing the primary exhaust pipes. You may have noticed the “balance pipes” (call them what you like - but they balance nothing) boost pipes would be better but that sounds so naff. Now these DO help in a scavenging process of its neighbour. When Uldis saw these he said “I’ve seen those on an Akrapovic (bike) system before but they were in a different place, further down the pipe”. True, but they’re smaller and I believe doing a different job. Mine are big and close to the exhaust port, they do more than one job and I’ve never seen a satisfactory explanation from anyone for what they achieve. I see what they DO power/torque - wise but no-one has conducted a proper science-based test on them.
The only down-side to them is a manufacturing one, they can be a to fit/weld. The combination of a tapered/stepped header plus these erm, “balance pipes” is unbeatable. There, I’ve said it.
mm - that’s about it, Mr Pesky yes. The conventions you speak about are displayed in the manifolds available for your cars at the present time. Long, long, LONG primaries with long, long, LONG secondaries. I’m saying there’s another way.
There’s nothing new in my manifold (not in the bike world anyway). Generally, we’re talking 4 cyl, twin-cam, 16valve engines. I first came across tapered pipes on a works Yamaha exhaust - certainly good for keeping gas speed up as it left the head, vital for torque. You needed the larger dia to increase exhaust volume but putting that size next to head slowed down the gas speed and caused suckback and dilution of the inlet charge, especially with large cam overlap. Do you see tapered/stepped pipes on car exhaust manifolds today - nope! (you do NOW on F1 but Superbikes have had them for years). Manufacturers of manifolds hate the very idea, all that extra work!! Micron (Magnex) get round this by hydroforming a “serpent head” to speed up the flow (it also increases the cross-sectional area - amazing technology) but it’s only appearing on the bike exhausts. The “balance” pipes? Yes, I think they help with scavenging but they also disrupt the returning wave(s). Everything I read about manifolds on the net fixates on these waves! "If you get the length just right, the returning wave will help scavenge the cylinder …blah blah blah… " Yes! At one particular point in the rev range all of the above will come true. SO! You get a whacking big peak where it all chimes in (hopefully near max revs, then the rest of the curve looks like a rollercoaster as the minor harmonics (3rd, 5th etc etc) chime in too (keep up! ) Nah! Get rid of the waves, treat the engine as a pump, keep the pipes as short as possible and The Holy Grail is yours!
PS The Holy Grail - stonking mid-range AND booming top-end.
And another thing!
The manifold isn’t split because it’s easier to try different configurations. The alternator gets in the way of the front cyl pipe and I swung the middle two up in a "ram’s horn " shape to allow an easier turn across the engine for 1+4. This means more TIG welding but heh! I love it! The “ram’s horn” won’t fit through the slot underneath so the top half of the manifold fits over the top and the bottom half …you get the picture.
I admit I do have an alternative design to try but that’s really for the larger capacity engine on the way. Out of curiosty, we will try it on Uldis’ engine though.
Yes! The layout of the secondaries is dictated by the position of the sump and the lack of room between engine/ fairing to keep the primaries together.
When that bike first came out I DID keep everything together down the one side, far better power figs but the erm , large hole in the fairing didn’t go down too well! I believe the sump is being moved on the latest models (this dictated by the race teams). I don’t like secondaries. There is a definite relationship between primary/secondary and if you go with secs you better spend some time getting the length/dia right!
On a more serious note. I will only be involved in the design side, production is in the hands of a very professional outfit down sarf. No prices have been decided yet but of course I’m aware of what’s on the market at the moment and I’ll make sure I’m VERY competitive.
170mm.
More of a restriction on space down near the turn under the sump, aluminium (water?) pipes jut out from the bulkhead side and of course the engine’s on t’other. I will be welding on short pins (with hole + pip-pin) which you slide the heat-shield on to - much better/quicker than trying to line up a bracket and corresponding bolt.
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