Oddball engines and prototypes

[Pursang]

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Cheers, Daryl.

[husaberg]

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.

Attachment 329667

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.

I do know that for a foul stroke 3 or a twin turbo 2 a log manifold with the turbo opposite one of the ex ports is extremly efficient, as used on Nissian race motors at one time.
they look basically like this

imagine the last bit on the end is not there unil i find a better pic

[MENTAL490]

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.

OMG i remember one of my aunt's had a little brown Suzuki car, i used to call it the bumble bee because is sounded so weird. maybe thats why i fell in love with 2 strokes that and the sweet smell of synthetic 2 stroke oil buring

[Pursang]

I do know that for a foul stroke 3 or a twin turbo 2 a log manifold with the turbo opposite one of the ex ports is extremely efficient, as used on Nissan race motors at one time.

That works on the inlet side too, a simple log can produce better fuel distribution, & Cfm flow, than sweeping manifold designs.
The ultimate log manifold, the Tunnel Ram, flows better than individual throats per port (like Webers), at max power.


The 2Tx3 model is just a very rough illustration of what might possibly happen, in "real life".

The exhaust from #2 looks like it 'chases' the fresh charge back into cyl1, #3 into cyl2 and #1 into cyl3.
The actual rate and volume of the exhaust pulse expansion will be much more dramatic than shown.
It is likely to very quickly fill the entire exhaust chamber.
The return of the fresh charge back into the cylinder should be slower-ish, as shown, it is cooler and has significant mass & inertia.

Producing sufficient pressure rise and maintaining it for 'just' long enough, will be a key element of making this work.
In the layout shown, there might also be a regular expansion chamber effect, particularly between cyl1 & 3.
Only testing will see if this exists and if it helps or hinders the process.

If anyone is looking for a suitable 2-Stroke triple to experiment with, consider the Yamaha Waverunner engine:
1200cc, only 135bhp stock, (later ones have PV's). You might need to drag out that old Norton gearbox, from under the bench.

cheers, Daryl

[husaberg]

That works on the inlet side too, a simple log can produce better fuel distribution, & Cfm flow, than sweeping manifold designs.
The ultimate log manifold, the Tunnel Ram, flows better than individual throats per port (like Webers), at max power.


The 2Tx3 model is just a very rough illustration of what might possibly happen, in "real life".

The exhaust from #2 looks like it 'chases' the fresh charge back into cyl1, #3 into cyl2 and #1 into cyl3.
The actual rate and volume of the exhaust pulse expansion will be much more dramatic than shown.
It is likely to very quickly fill the entire exhaust chamber.
The return of the fresh charge back into the cylinder should be slower-ish, as shown, it is cooler and has significant mass & inertia.

Producing sufficient pressure rise and maintaining it for 'just' long enough, will be a key element of making this work.
In the layout shown, there might also be a regular expansion chamber effect, particularly between cyl1 & 3.
Only testing will see if this exists and if it helps or hinders the process.

If anyone is looking for a suitable 2-Stroke triple to experiment with, consider the Yamaha Waverunner engine:
1200cc, only 135bhp stock, (later ones have PV's). You might need to drag out that old Norton gearbox, from under the bench.

cheers, Daryl

One of my fav authors Julian edgar (even though hes an aussie)wrote about it in Fast fours years ago
he was doing a manifold for some Kei class Daihatsu mira mini van with a big turbo he had the volumes and all
not sure how it would translate to two stroke but still interesting.
I will see if i can dig it up.
he mentions it here
http://blog.autospeed.com/2004/08/29...inwin-for-fun/

[guyhockley]

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?

I haven't worked it out, but I assume this will give asymmetric timing.

[Pursang]

.

First Hiccup.

We want more Power, this is a 'performance' oriented engine.

Say, 9000 rpm. That's 150 cycles per second.

If the exhaust chamber was harmoniously resonating it would be breathing in and out 3 times per cycle.
resonant frequency = 450Hz.

Now some more assumptions:

Header/diffuser pipes:-
mid point diameter? perhaps 35mm?
piston to chamber length? 150mm?

SoS? fair guess.. 550m/s.

Solving Helmholtz @ 450 Hz. (http://www.vk2zay.net/calculators/helmholtz.php)

Volume = 2.5 x 10-4M3
= 250cc (including the volume of the other 2 headers @ about 140cc each)

Conclusion: Just join the 3 pipes together, with a bleed off point.

Seen this before?

Now..just need to find a 1959 Berkeley to put it in:

Perhaps to replace the 3 individual pipes in this one!!

cheers, Daryl

[MENTAL490]

in my 2nd year eng we looked at how tuned pipes work, I knew a little from learning to port and polish as a boy, but it was most interesting, the demo was of a inline 4 cyl car engine, the numbers can be tricky but basically they made each header the same length , the length and size (total volume) was determined by the pressure volume and valocity of the exhaust gasses. After each exhaust there is a point where it goes from positive pressure to a negative (vacuum) for a split second. you want to time it so the vacuum caused by one cly exhausting creates a vacuum in another just before valve close, thus giving you a hand on inlet. Sorry if i confuse anyone im not so good at explaining on paper. ok clear as mud

[Grumph]

Now..just need to find a 1959 Berkeley to put it in:

cheers, Daryl

As I've said before on here in another thread, a mate of mine sidestepped all the calculations and slipped an Ariel square four into his Berkley...

[Pursang]

As I've said before on here in another thread, a mate of mine sidestepped all the calculations and slipped an Ariel square four into his Berkley...

Good choice for the time.

The factory one with the big Enfield twin made the front a bit bulky & ugly

Here's another with a later update - a Honda 4 nice neat fit.

They were a pretty clever idea, front engine & front wheel drive. More potential than a Goggo Dart.

Cheers, Daryl.

[Pursang]

in my 2nd year eng we looked at how tuned pipes work, I knew a little from learning to port and polish as a boy, but it was most interesting, the demo was of a inline 4 cyl car engine, the numbers can be tricky but basically they made each header the same length , the length and size (total volume) was determined by the pressure volume and valocity of the exhaust gasses. After each exhaust there is a point where it goes from positive pressure to a negative (vacuum) for a split second. you want to time it so the vacuum caused by one cly exhausting creates a vacuum in another just before valve close, thus giving you a hand on inlet. Sorry if i confuse anyone im not so good at explaining on paper. ok clear as mud

Here is an inline, 4 cyl, car engine that's been Seriously Tuned. (Ok, it might be half of a v8)



That's a four stroke exhaust working hard and as close to being an expansion chamber as it possibly can.
This one will have a positive return pulse, from the high pressure point at the collector, to shove back some lost charge, before EX valve close.

Cheers, Daryl.

[husaberg]

OW70
I knew the earlier Ow61 was disc induction between the v but not the Ow70 as well


Drawing is OW61

[husaberg]

Someone mentioned BSA somewhere?

Here's a prototype 250cc near horizontal single. Features include 4 radial valves, 2 carbs, 2 exhausts, monoshock rear suspension. 'Management' decided not to put it into production.

It's on display at the National Motorcycle Museum near Birmingham, UK.

Thanks, found it, the suspension was patented by Phil Vincent, and used on his HRD and Vincent bikes.

http://www.voc.uk.com/net/docs/19.16/19-452-49.pdf

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.

Bentley and Draper rear suspension - Irving is rather caustic about the stiffness of that "braced" arm....

The MC1 as told by Hele


I post post the 1936 New Imperial with its underslung braced and catalever with a link suspension in the next post or maybe in the chassis thread.
It was unit construction as well.

[tjbw]

The MC1 as told by Hele


I post post the 1936 New Imperial with its underslung braced and catalever with a link suspension in the next post or maybe in the chassis thread.
It was unit construction as well.

Thanks husa, I enjoyed that. I never heard of a connecting rod with integral bolts before! Did anyone else, apart from Lagonda, make those?

Also, I don't know where is the cantilever in the rear suspension.

[husaberg]

Thanks husa, I enjoyed that. I never heard of a connecting rod with integral bolts before! Did anyone else, apart from Lagonda, make those?

Also, I don't know where is the cantilever in the rear suspension.

No idea re the conrod
This might help with the Suspension
one pivot is under the spring the other has a shiny colver cover the bracing is below the pivot just above the exhaust


BUGGER IT GOOGLE


GEAR PRIMARY DRIVE AS WELL AS UNIT CONSTRUCTION
http://cybermotorcycle.com/gallery/n...937-engine.jpg
Well worth a look through
http://cybermotorcycle.com/