Author Topic: V3 90 deg 'Jota' Engine big bore  (Read 3371 times)

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
V3 90 deg 'Jota' Engine big bore
« on: December 22, 2019, 09:32:14 PM »
Hello there,

What should you do, when you have ideas and make some sketches the last couple of months?
I will start on make a 3d model of a new engine. And later on build it.

A multi cylinder of higher rpm range. More kind of a 'sport' engine.

I do like three, six and even twelve cylinder engines of there sound an simplicity/engine balance. But something different.
But what about a V3 engine? I only know a couple two stroke bikes that use this engine geometry (Honda NS500).


I was thinking of the next thing.

- 3 cylinder 90 degree bank angle
- 180 degree crankshaft. Where cylinder 1 and 3 are on 180 degree, and cylinder 2 shares the crank journal with cylinder 1. (so it is more a mix of a 180 deg twin and 90 deg V twin engine)
- Big bore B/S ratio around 1.4-1.5
- 3 or 4 valve design per cylinder
- Overhead camshaft while cylinder 1 and 3 shares the intake and exhaust camshafts(cam rollers are shifted 180 degrees)
- Split connecting rods with one piece crankshaft, two smaller bearings on each side, a larger bearing in the middle
- Thinking of 2 split crankcase
- Addition, two primary balance shafts for compensate the piston motion of cylinder 2
- Water-cooled
- Larger cam durations than my one cylinder, higher static compression ratio to 1:8-9

Firing order 1-3-2
1 [180 °] 3 [270 °] 2 [270 °]


Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #1 on: December 23, 2019, 01:18:16 AM »

A rough principle of the bottom block of the V3 engine. Reused some parts and had to modded dimensions.

Offline Art K

  • Full Member
  • ****
  • Posts: 1674
  • Madison, Wisconsin USA
Re: V3 90 deg 'Jota' Engine big bore
« Reply #2 on: December 23, 2019, 03:37:29 AM »
Alex,
That sounds complicated, I'm glad you are visualizing how to make this work & not me.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Admiral_dk

  • Full Member
  • *****
  • Posts: 2808
  • Søften - Denmark
Re: V3 90 deg 'Jota' Engine big bore
« Reply #3 on: December 23, 2019, 11:49:24 AM »
Hi Alex

The Laverda Jota was a straight 3 cylinder Four Stroke 1000cc with a 180 degree crank for the first six years 1976-1982 and later with a 120 degree crank - is this the one the title refers to ?

Real V3 motorcycles where : 1955 DKW 350, 1968 Suzuki RP68, 1982-1984 Honda NS5000/NSR500, 1983-1984 Honda MVX250F and 1985-1987 Honda NS400R.

A related layout was the W3 engine, although this placed all three cylinders in the same plane, but none of them in the same bank. This was used for the 1905–1915 four-stroke Anzani engine, which was used in motorcycle and aircraft applications.

I have tried to construct something similar to your ideas in Alibre a few years ago, but was never satisfied with the result ....

Best wishes

Per
« Last Edit: December 23, 2019, 01:40:37 PM by Admiral_dk »

Offline tghs

  • Full Member
  • ****
  • Posts: 508
Re: V3 90 deg 'Jota' Engine big bore
« Reply #4 on: December 23, 2019, 12:35:09 PM »
having road a few bikes, laverda jotas were a bit on the thumpy side at lower rpms, but fast and powerful once up to speed, great open road bike.. when BMW K100's came out (4cylinder inline)fast, even power with a harmonic buzz at certain rpms, I thought the electronic gear indicator was one of those "why?" things.. a few years later when the K75 came out (3 cylinder with a counter rotating counter balanced shaft) it was needed as the motor was as smooth as an electric motor,, best triple ever made 
what the @#&% over

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #5 on: December 23, 2019, 01:44:00 PM »
Yes indeed Per, this engine is refers to the Laverda Jota straight 3 engine. But then a V3 Jota. Seen that Laverda is not doing business anymore, they could not blame me for use the same name  ;)
The Laverda is known to me. For example, my father rode a 3C Jota from the 80s to around the 00s. I myself can no longer remember that he was still driving it. But funny fact, our current dog and former cat was also called Jota.
But an old neighbour here drove the same bike weekly in the warmer days. And you could tell by the typical sound whether he started it or came back from driving it.

After some looking on Youtube I saw a late 3 radial and early W3 engine. Here the guys are not scared, some fresh burned fuel after breakfast is a good way to start the day.

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #6 on: December 23, 2019, 04:23:01 PM »
I was looking for a site that sells CI piston rings. I can remember that I have visited a site that was suggested on this forum before. But can't remember the name :-[
I could remember that they also had rings for a 45 mm bore. And they sold more ready-made attributes for model engine construction.
Thanks!

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 5504
  • Switzerland
Re: V3 90 deg 'Jota' Engine big bore
« Reply #7 on: January 01, 2020, 08:31:36 AM »
That's an interesting design concept and another interesting balance calculation  :ThumbsUp:  :ThumbsUp:

At 45mm bore maybe a moped or garden tools supplier can help with piston rings.
Best regards

Roger

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #8 on: January 01, 2020, 03:38:12 PM »
For crank design I was thinking of rotation balance in the mid section web between cylinder 1 and 3. Cylinder 1 and 2 shared the same crank journal and so the extra length and +- 1/2 part of the weight of the connecting rod of the cylinder 2 should be compensate in the mid section web of the crankshaft(like you balance an one cylinder engine). And would be great to add two primary balance shafts in line of cylinder 2, that rotate the speed of the crankshaft to compensate the 'missing' 4th cylinder. So basically it should vibrate like a four-in-line engine. Would be fun to design and build for sure!

Thanks Roger I would look around for a related piston size of used mopeds.

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #9 on: November 28, 2021, 01:43:11 AM »
Should I give this project a designing Go? Designing this engine in my head for almost 2 years. Lockdown project.

Extreme big bore, 50 mm 25 mm stroke. 3 Valves operating dohc or even desmo (?) :LittleDevil: Result 150cc

Going for 150cc fuel injection kit (tunable) or right for nitro setup?
Good tuneable carbs? Let me know.
Any ideas are welcome.

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 5504
  • Switzerland
Re: V3 90 deg 'Jota' Engine big bore
« Reply #10 on: November 28, 2021, 07:19:21 AM »
Would you choose 1 carb/injector per cylinder or use a manifold and single carb?
Best regards

Roger

Offline Admiral_dk

  • Full Member
  • *****
  • Posts: 2808
  • Søften - Denmark
Re: V3 90 deg 'Jota' Engine big bore
« Reply #11 on: November 28, 2021, 10:58:29 AM »
Quote
Should I give this project a designing Go?

Well, honestly - there is only one person that can answer that question .... yourself  ;)

But I will certainly be following your progress if you choose to do so - and I'm sure so will others.

Per

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #12 on: November 28, 2021, 11:14:32 AM »
Roger,

Both options are possible, but maybe 1 carb or injector would be easier to find a motorcycle type one or to combine throttle linkage. Things that I have to sort out.

Per,

Indeed! I think this would be a nice and challenge project. I saw a video about rotary valve for even V8 or bmw i6 engines, give me fruits to think about.


t=1063s

I'm curious what the transmission looks like of the V8 driving the rotary valves.

Already found 50mm pistons (GY6 big bore (could go bigger to, could be buy and fit or get the ring set and make some delicious ones on the lathe!


Someone known with software like EngMod4T here?
https://vannik.co.za/EngMod4T.htm
« Last Edit: November 28, 2021, 11:24:58 AM by AlexS »

Offline AVTUR

  • Full Member
  • ****
  • Posts: 204
  • West of England
Re: V3 90 deg 'Jota' Engine big bore
« Reply #13 on: November 28, 2021, 11:53:51 AM »
AlexS

In your first posting you said you were going to do a solid model of the engine first. Have you done so? It could answer quite a few questions particularly if it is too complex. You could try sleeve valves!

Years ago I used to park next to a Jota in the bike sheds at work. The biggest bike there and was ridden by a 5 1/2 foot lady.

AVTUR
There is no such thing as a stupid question.

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #14 on: November 28, 2021, 04:26:13 PM »
Avtur,

I only have the model shown in picture in post nr 9. So the whole engine has to be designed!

Cool idea of the sleeve valves, are these systems also running on high speed engines?

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 5504
  • Switzerland
Re: V3 90 deg 'Jota' Engine big bore
« Reply #15 on: November 28, 2021, 05:13:18 PM »
Sleeve valves were (are?)used in aircraft engines.
Best regards

Roger

Offline Art K

  • Full Member
  • ****
  • Posts: 1674
  • Madison, Wisconsin USA
Re: V3 90 deg 'Jota' Engine big bore
« Reply #16 on: November 29, 2021, 01:25:21 AM »
Alex,
Not to help you jump down the rabbit hole, but the sleeve valve engine is an interest of mine. There are two types of sleeve valve engines. The Knight uses a system with two cranks each operating sleeves they each have ports in them opening at intake and exhaust. Willy's in the US and Daimler in Britain are probably the most famous to use the system. The single sleeve Burt-McCollum design uses a crankshaft to drive the sleeve. This gives the sleeve an eliptical path opening the ports as it moves. It's best known for its use in Bristol Hercules and Centaurus aircraft engines. But It was also used in the Scottish auto Argyll and also Barr and Stroud motorcycle engines. I would suggest saving the sleeve valve for a different engine and do the V3 with conventional valves.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #17 on: November 29, 2021, 06:17:48 PM »
Thanks for the info guys.

It would be great for a test engine or single cylinder one. Would be nice experiment to build. But agree with you Art, it takes more challenge to fit in a V engine, and to get a good cylindricity of the sleeves (for my beginner skill and lathe).
But does someone here build a sleeve model before?
« Last Edit: November 29, 2021, 07:49:26 PM by AlexS »

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #18 on: November 29, 2021, 07:48:39 PM »
Tonight played with putting info in a simulator. Would like to run the simulations tomorrow and make some changes on geometry of valve/port and cam system.

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #19 on: November 30, 2021, 09:02:46 PM »
First digital testrun are done!  :atcomputer:

1st picture shows power curve of a 1 cylinder test engine. Changed some spec of the valves, cams and last manifold diameter of the intake. This should also be done for intake diameter before throttle valve (simulated for each cylinder) and for exhaust manifold and pipe (straight pipe for now).

2nd picture the power curve of the start model and latest changed model of the 3 cylinder (simulated as inline 3).
I am not really interested to get every hp out of it or in the horse numbers, but more that I am in the right direction to get a breathing and powerful high rpm engine ;)

For comparison, Dirtbike Honda CRF150R: 23,5 hp @12500 RPM 14.10 Nm @ 11000 RPM [66.0 mm bore x 43.7 mm stroke].
« Last Edit: November 30, 2021, 09:07:37 PM by AlexS »

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #20 on: December 01, 2021, 09:05:12 PM »
Today played around with EngMod4t and Solidworks model.

Simulation:

Intake/Exhaust valves 20mm both 6mm lift 250 deg duration with 40 deg overlap.
Intake and exhaust manifold and even for runner/pipe 20 mm diameter. Intake runner length 50+50 mm between valves-carb-atmosphere.


Added bigend split bearings for the split connecting rod. Changed some dimensions of the crank. Last thing added a idea of outside cylinder to liner.

Should be the "stickout"of the pistons to bad when the crank runs bdc swap? I could enlarger the liners, but the bottom side of the connecting rod hit the other liner in the V setup. More than the half of the piston skirt still hit the liner .

Offline Admiral_dk

  • Full Member
  • *****
  • Posts: 2808
  • Søften - Denmark
Re: V3 90 deg 'Jota' Engine big bore
« Reply #21 on: December 01, 2021, 09:52:56 PM »
In my opinion you need to have the liners go a lot further down ....
Don't get me wrong - it will not prevent it from running as is, but it has a lot to do with wear and reliability ....

Also - the bigger the diameter to piston length ratio is - the higher demand on tight tolerances + full support on the total length of the travel. On the opposite end of that ratio, you can have the piston sticking far out without too many consequences ....

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #22 on: December 02, 2021, 10:03:24 AM »
Yes agree, playing around with dimensions of the connecting rod this is now 57.5 mm center-center big end to small end witch is now quit large for the stroke of 25! Or make the liners for Cyl 1 and 2 A-symmetrical.

Offline AVTUR

  • Full Member
  • ****
  • Posts: 204
  • West of England
Re: V3 90 deg 'Jota' Engine big bore
« Reply #23 on: December 02, 2021, 11:18:15 AM »
Apologies for mentioning sleeve valves. The problem is that they don't scale. You are stuck with the same maximum engine speed whatever the engine size.

I will not metion the subject again on this thread.

I liked your valve calculations. I remember do them by hand at tech about 55 years ago.

AVTUR
There is no such thing as a stupid question.

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #24 on: December 03, 2021, 09:42:25 AM »
You don't have to apologies Avtur, I am always open for ideas. However, I am not really familiar with sleeve valves myself.

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #25 on: December 08, 2021, 07:43:03 PM »
For bottom part of the engine, changed connecting rod center-center dimension to 75 mm and lifted the cylinders a couple of mm.

Was thinking about making valve guides/cages out of grey cast iron. Valve seat, guide and sliding surface for cam followers in-one.

The surfaces of the valve guides and cam follower should be reamed H7. I am not sure if the material should fit to the job to get good sliding and surface finish.


Last picture a shoot of a very very raw design, things grew (+-14 kg).
« Last Edit: December 08, 2021, 08:00:16 PM by AlexS »

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #26 on: December 13, 2021, 07:55:33 PM »
A quick view of designing the Jota. Our dog is also called Jota even as a kitten years ago! Named of the motorcycle of my dad had years ago, Laverda.

So last weekend spend modelling of cylinder head parts. :) Local supplier sells cast iron for same price as bronze for valve guides. So think that fits job better also to have soft valve seats run in easier.

Dual overhead cam. Idea is to make it modular as possible. There should be a transmission axle and combined balance shaft between the cylinders to connect every cylinder head to crankshaft. 4 belts seems a lot, have to look how it would fit, but less issues with distancing of pulleys. There is enough space in above the V shape.
Exhaust and intake camshafts connected by a pair of spur wheels.

Shims under the cam followers to adjust valve clearance. I have thought about what is useful to fix the valve spring assembly. Valve stem is now 5mm and what about give it a little bit of M5 thread, making or weld a nut so you can fix it. Valve spring (15mm 2.5 thread) stiffness 37 N/mm to match oscillating mass of around 50 gram each valve assembly.

Needle bearings for camshaft and even for big end connecting rods (could run 12k rpm for big end). Camshaft axial fixated with shaft collar and spur wheels.

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 5504
  • Switzerland
Re: V3 90 deg 'Jota' Engine big bore
« Reply #27 on: December 13, 2021, 08:41:34 PM »
The valve gear seems rather tall, the max. valve lift only needs to be 1/4 of the valve diameter.

Valve cages can give sealing problems, especially with different thermal expansion. unless you are looking at serious use seats directly in the head will work.

Certainly an interesting design  :)  :ThumbsUp: Have you looked at ports and manifolds yet?
Best regards

Roger

Offline Art K

  • Full Member
  • ****
  • Posts: 1674
  • Madison, Wisconsin USA
Re: V3 90 deg 'Jota' Engine big bore
« Reply #28 on: December 14, 2021, 02:59:32 AM »
Alex,
Just out of curiosity what is the angle between firing. The twin part of your engine would fire 180 degrees apart. Like an old John Deere B is a parallel twin fires 180 apart then 540 degrees before firing again. Is the 3rd cylinder such that it offsets that 540 deg. of no power stroke?
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #29 on: December 14, 2021, 07:08:57 PM »
Roger,

Yes the cams are quit large, 6mm lift while the valves are 20mm 5mm can also  :thinking:
I was thinking of press the two aluminium head part together, bore it to 19.5 mm and the ream it to 20H7 +21/0. Then turn valve cages with press fit p6 +48/+35 tolerance. Not sure if it seals good enough, maybe you have a idea?

Valve cages can give sealing problems, especially with different thermal expansion. unless you are looking at serious use seats directly in the head will work.

What do you mean by this sentence?


So far thinking of ports and manifold: Option A, to bore for intake 18mm or 16mm for each intake valve. Boring at an angle of 45 deg (viewing from horizontal orientation). And then mill both holes to a straight slot to meet the manifold or mill a v-shape hole in the manifold to combine both runners. I realise now that when you do this, you go straight trough the mounting holes cylinder studs.

Another option B is to mill both intake runners at right angles to the valve cages. But bore it with some angle so the centre of the runners meet each other in the head as one hole (Viewing from vertical orientation, face where manifold would be mounted). Doing both in angle directions would be difficult. Maybe with some angle fixture to mount the head on (mill can only twist the Z-axis).


Art,

Yes! The angle between firing between the twin part (cylinder 1 and 3) firing 180 degrees apart. 180-270-270 So first you have cylinder 1 bang, after 180 degree cylinder 3 bang, then after 270 degree cylinder 2 bang, 270 degree further cylinder 1 bang and then everything repeat. V-twin and inline twin combined.
I think this should give a nice sound. Other option is (cyl.1)90(cyl.2)-90(cyl.3)540 and so on. Or (cyl.1)90(cyl.2)-450(cyl.3)180. Or (cyl.1)450(cyl.2)-90(cyl.3)180.

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 5504
  • Switzerland
Re: V3 90 deg 'Jota' Engine big bore
« Reply #30 on: December 14, 2021, 07:19:52 PM »
'Valve cages can give sealing problems, especially with different thermal expansion. unless you are looking at serious use seats directly in the head will work.'

If the, probably aluminium, cylinder head expands more than the bronze or cast iron cages you will get leakage problems. Unless you are intending to use this engine for power production or racing valve seats cut directly in the aluminium head with separate bronze or cast iron valve guides will work well. If you make the cylinder head section from cast iron it may weigh more but you can have the seats and valve guides cut directly in it which may allow you to reduce the dimensions and the weight.

Every engine design is a set of compromises  ::)  :wine1: 
Best regards

Roger

Offline AlexS

  • Full Member
  • ****
  • Posts: 207
Re: V3 90 deg 'Jota' Engine big bore
« Reply #31 on: December 14, 2021, 07:43:56 PM »
ah yes the heads would be out of aluminium. mmm okay seperate valve seat/guides.

Lets try a calculator. delta 300 deg C

Material: Aluminum 20.000mm
Change in Length (ΔL): 0.1332mm
Final Length (L + ΔL): 20.1332mm

Material: Bronze Round 20.000 mm
Change in Length (ΔL): 0.108
Final Length (L + ΔL): 20.108

Material: Bronze 20.050 s6 tolerance
Change in Length (ΔL): 0.10827
Final Length (L + ΔL): 20.15827


Agree there should be a leak path of when there is not enough  press fit tolerance.

Every engine design is a set of compromises  ::)  :wine1: 

Agree! And that is the fun and tough bit of designing. Several ways of doing stuff.
Like the idea to use cast iron heads, only not sure how to turn seat valve in my mill :noidea:


Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 5504
  • Switzerland
Re: V3 90 deg 'Jota' Engine big bore
« Reply #32 on: December 14, 2021, 09:05:24 PM »
I made a simple cutter for the valve seats. As they are somewhat recessed in this design turning or milling was difficult.
Best regards

Roger