Oddball engines and prototypes

[Grumph]

So...with the benefit of 40 years of additional knowledge & experience, how do we deal with one exhaust port closing just as the other opens?

Changing the phasing, or the stroke, might allow one of them to charge the other, but not visa versa. So some extra power, but not double?

Asymmetrical piston motion through linkages has been looked at and rejected for adding too much complication.

That only leaves engines with 3 or more cylinders to provide the pulses.

Old Kwakas and Suzi triples did run OK(ish) with 3 into 1 chambers. Is there more development left here?

Having been the proud owner of a 70's Suzuki Fronte car - 500cc, 3 cylinders - I can state that the short 3 into 1 header arrangement does work to give more torque at low revs. By the time i'd finished with it, it wasn't too bad at high revs either, lol. I liked taking on Mini Coopers with it and in the end was lapping the local circuit as fast as some Lotus Cortinas. A Kart with a roof.

[WilDun]

Having been the proud owner of a 70's Suzuki Fronte car - 500cc, 3 cylinders - I can state that the short 3 into 1 header arrangement does work to give more torque at low revs. By the time i'd finished with it, it wasn't too bad at high revs either, lol. I liked taking on Mini Coopers with it and in the end was lapping the local circuit as fast as some Lotus Cortinas. A Kart with a roof.

I liked those little machines and heard of the 3 conjoined pipes being a huge benefit. I had aspirations of playing with a slightly munted engine I acquired, but family life got in the way (as it does). Think I have seen some You Tube videos on those things performing well - got to have been a helluva lot lighter than the minis?
Got any photos/details etc. on your machine?

There's always a way around a Patent.
This is the legendary 1929 Brough named "Moby Dick". Fastest, privately owned, road legal, motorcycle in the world, in 1931.

Bet John Britten was also inspired by that machine, right from the front suspension, to the rear suspension and the artistic licence employed in the design of the exhaust!

So...with the benefit of 40 years of additional knowledge & experience,...........Asymmetrical piston motion through linkages has been looked at and rejected for adding too much complication.

PURSANG
We all know that asymmetrical piston motion can be achieved by offsetting the crankshaft from the cylinder axis (within reason) and that there are a couple or three linkages which could conceivably be used to this end, - got any idea which ones were tried and rejected?

[Pursang]

PURSANG We all know that asymmetrical piston motion can be achieved by offsetting the crankshaft from the cylinder axis (within reason) and that there are a couple or three linkages which could conceivably be used to this end, - got any idea which ones were tried and rejected?

Back around November last year, in the Bucket Foundry thread, around post#2661. there was a bit of discussion on innovative cranks and linkage systems, for concentric piston motion, asymmetrical timing, etc.

Rejected 'mentally' (or at least no consensus traction), for failing to satisfy the KISS principle.

Cheers, Daryl.

[Grumph]

I liked those little machines and heard of the 3 conjoined pipes being a huge benefit. I had aspirations of playing with a slightly munted engine I acquired, but family life got in the way (as it does). Think I have seen some You Tube videos on those things performing well - got to have been a helluva lot lighter than the minis?
Got any photos/details etc. on your machine?

Kept nothing - got hitched around that time, moved etc etc...Took it to Ruapuna a couple of times and easily got down to 65 sec laps on the old short Ruapuna. At a car/bike day I got talking to some of the car guys asking what times they were doing. Lotus Cortinas were struggling to break 65 sec, LOL.
Great fun full noise in 3rd around the sweeper with the inside front about 6 inches off the ground.

It had a spur gear diff which was a bolted up sandwich of cast iron pieces. The outers had bearing carriers machined into them. The final straw was when it broke both carriers out of the top hat shaped pieces of CI. Sinclair Melbourne (marine engineers in Lyttelton) bronze welded everything up again and I machined it true - then got shot of it...

[Pursang]

2 Stroke triples..I had a Suzuki LJ50 4WD. Amazing little buzzer, It would climb near vertical walls, and when it couldn't climb anymore it wouldn't stall the engine, It just bounced up and down trying to throw itself further onward and upward.

Most performance exhausts for 3cyl two strokes use the standard, tried and proven- 3 individual chambers.



Here is a well developed engine from some company with the experience & resources to fit whatever works best.
(At least until they started fitting 4 strokes instead)



And because this is the oddball engine thread....



Excelsior Triple in a Berkley Sportscar.

Can any of the two stroke simulation programs handle a 3 into 1 pipe design?

Cheers, Daryl

[Pursang]

Can any of the two stroke simulation programs handle a 3 into 1 pipe design?

Especially if it looks something like this?



Cheers, Daryl.

[husaberg]

There's always a way around a Patent.
Attachment 329655

This is the legendary 1929 Brough named "Moby Dick".

Cantilevered rear, Under-slung, braced swingarm,
Multiple linkages, giving variable rate,
High and low speed adjustable dampers.

Fastest, privately owned, road legal, motorcycle in the world, in 1931.

Just STUNNING.

Frits Egli controlled the patents for top braced monoshock swingarm , think Fireblade aad FZR750 etc.

At least up through the 1990's Yamaha and Honda had to pay him for everyone they made.

[ken seeber]

Talking about 3 into1 exhausts, at Orbital when we were first mucking about with a 1.2 litre 3 cyl outboard Suzuki DT85 engine, some of the guys tried various length separate headers. All seemed to work at various speeds, but gave really unacceptable power curve shapes. In the end, and things were getting a tad desperate, I made up a really simple, min volume collector, immediately after the power valves. This exited into a 2” downpipe. Instantly, more power and a really juicy power curve. Not as much peak power as a test single cyl engine with an expansion chamber, but more than any other thing that we tried. Ultimately the “collector” was faced with a full size downward facing catalyst brick, giving a quick catalyst warm up and still good results.

Here is a pic of a later 1.2 litre Orbital made automotive X engine (in my museum, being a bower bird) and the powervalve cover in place. Unfortunately I haven’t got an exhaust to go on, but I’m sure you get the idea.



I’m also sure that Daryl will remember an aftermarket pipe which was around in Oz for the Suzuki GT750. This was called a Bromelich (?). It was a 3 into 1, similar to Daryl’s pic and probably a shitload cheaper than trying to replace the original system if you had gone down the road. Not sure of the performance, but they sounded really sweet.

[Niels Abildgaard]

Hello Ken Seeber

Is air injected two stroke still a candidate for the ultimative clean two stroke and if not why?
Aprilia made a 50 ccm moped with Orbit system.
My dream 100 horsepower,2400 rpm V2 engine needs fuel injection.

[Pursang]

Hi Ken, Yes the 3 into one on Waterbottles (and some 380's & 550's too) was quite common, Way Back When. Undoubtedly saved heaps of weight, bulk & $$$.

It's pretty presumptuous to think that we could come up with a new, improved, better design, than a Japanese motorcycle factory, or a serious research org. like Orbital.
But....everything must improve..or die out.

As far as a SIM goes, I've cobbled together this: 3cyls, 3 pipes.

(I've been stuck inside all day, sitting out XTC Debbie.)

So, in order to use the exhaust pressure of one cylinder (#1), to increase the returning charge volume/pressure of another (#2 or #3), the system might need to be significantly different to the standard process.

a) To put more back into #1, we need to draw more charge out into the header/diffuser.

b) Instead of waiting for the pulse to travel to the baffle & return (with the resulting energy loss) we would like to use the pressure of another exhaust pulse.

c) That pulse will be 120 or 240 degrees before (or after) #1. Does this mean overall pipe length should/could be shorter than standard?

d) There will be lots of overlapping & crossing waves, but like voices across a noisy room, they don't necessarily interfere with each other.
Waves in a pipe are so-called "fixed amplitude" (fixed by the pipe diameter) but the changing dimensions of a chamber mess with that idea.

The whole harmonics of this process makes my head whirl, (feels like a hard drive flat out).
So I'll sit back with a Rum and see what comes up.

Cheers, Daryl.

[ken seeber]

Hello Ken Seeber

Is air injected two stroke still a candidate for the ultimative clean two stroke and if not why?

My dream 100 horsepower,2400 rpm V2 engine needs fuel injection.

Niels, the Orbital air assisted system is still used by Tohatsu and Mercury and now in some military drones where they wanted to use a spark ignited engine, but had to use Jet Fuel A. Single fluids systems seem to need high and higher pressures to achieve adequate atomization, whereas the air assisted system was able to achieve this particular task.
For your dream engine, you have choices, both being to use hardware from either a Merc outboard (air assisted) engine or say a system from a DI jetski/snowmobile (single fluid). I'm sure either way it won't be a simple task in so many ways.

Daryl,
As to your Debbie induced exhaust study, I think you'll need some smart dude like Frits to comment on the design and simulation. Frits where are you ?

[Niels Abildgaard]

Hello Ken

The concept looks like this

http://i.imgur.com/SOqAT4f.jpg

100 hp 2400rpm start and 75 and 2200 cruise and no sneaky environmentalists around (Yet).


and if You were investor: Orbital or E-Tec?

[Frits Overmars]

Daryl, As to your Debbie induced exhaust study, I think you'll need some smart dude like Frits to comment on the design and simulation. Frits where are you ?

I'd like to bite because there may be some good power to be found there, but the subject deserves more time than I can find at the moment.

[Pursang]

.
.
Frits' insights, when available, will be invaluable.

In the meantime, I'll have a bash.

From Kens experience (noted above) + the Yamaha snowmobile, etc. Short header pipes work OK.

Based on the other criteria, here is my first concept (version 1.0).



Headers are shortish and tapered.
Actual dimensions will be adjusted to produce the draw through of sufficient fresh charge to achieve our increased power output goal.
For fuel efficiency, the dimensions must also prevent fresh charge escaping the header cone and getting into the pressure chamber.
It may be that a baffle or dam or a Tesla(ish) pocket or loop could be employed, if needed.

From the sim graph we see that there is a peak pressure rise at #2 exhaust about 15deg before #1TPC & 60deg before #1EPC (#3EP is closed)
The idea is to have this exhaust discharge pressurise the chamber, and push the charge in the #1 diffuser back into Cyl#1 before #1EPC.

The effect is less of a sonic wave reversing at the baffle cone and more of a resonant pressure pulse in the chamber.
As charge volume is returned to the Cylinder, exhaust chamber vol is increased, pressure falls and the system is ready for next exhaust pulse.

Chamber volume, nominal tuned length(s) & average chamber pressure (via stinger bleed off) will need to be refined by experimentation.
(Or, I guess, calculation by Helmholtz wizards)

Package is compact but not super cool looking, better for a snowmobile, scooter, or hidden by a fairing.
Once final dimensions are established it could be cast from aluminum, reducing noise and cost.

And that brings us Back........ to this:

The Villiers Junior De-Luxe had an exhaust chamber just like that!!!

Cheers, Daryl.

[Michael Moore]

My late friend had a 3-1 on his Suzuki (in the USA they were called a Water Buffalo). I think it was a Strader. They were less expensive than 3-3 and made it much easier to have some decent ground clearance.

http://www.oldjapanesebikes.com/GT75...page-A55#pipes

Has photos of various Suzuki exhausts.

IIRC a friend made a 3-1 for a SAAB triple and used very short head pipes, mentioning that he had to carve away metal towards the center of the head from next to the outside exhaust ports for clearance and then contort the center head pipe up and then down in order to get the short lengths he wanted.

cheers,
Michael