Quantcast

Stagger 4 engine CAD

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Screenshot 2015-09-10 at 12.27.56.png

Adding and subtracting little bits to add definition and account for bolt load-paths. Redoing parts for more sensible cutouts, and dimensioning again.

Some things are perfect the first time, others :think:

Looking forward to working the studs into a more detailed head layout.

LuPiScreenshot 2015-09-10 at 12.39.27.jpg

Bottom shot, shows a little more what is unfolding.
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Screenshot 2015-09-12 at 14.05.51.png

Reinforced the edges with some simple geometry, concentric arc supporting the boltholes. Cutoff the four corners.

I like how it looks, time for the head for sure.

LuPi
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
cb450-torsion-bars-04.jpg

Hello again,

I can't seem to find an engine forum to join so if you're not a gearhead my apologies.

The drawing above belongs to a Honda cb450 engine. What I've been considering is Torsion bar finger followers. Not both, but as one element. On the axis of the finger follower pivot end there would be a torsion bar which twisted to allow for the rotation of the finger follower, it then untwists to close the valve. Combining the two, finger follower, and axial valve return spring.

It seems like it would work, so if anyone has any reason why it will not, now would be a good time to speak up.

LuPi
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Screenshot 2015-09-20 at 10.51.04.pngThe valvetrain of a bank will generally look like this. A torsion bar is secured in-between the cylinders. The finger follower shafts will side over the torsion bar axially riding in lubricated plain bearings.

The finger followers will function also as return levers, which to my knowledge has never been tried.

How to do that, well, I'm not sure what's best. Several possibilities, it's a matter of managing contact design to minimize wear. Obviously long life and easy replacement are ideal.

LuPi
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
I have a lot of appreciation for the Ducati Desmosdronic valvetrain, but how to fit all that into a small space?

This fits, and it would be nice to continue with what is shown.

LuPi
 

DanielV

Member
Joined
Sep 15, 2015
Messages
14
Location
Haute-Savoie, France
I have a lot of appreciation for the Ducati Desmosdronic valvetrain, but how to fit all that into a small space?

This fits, and it would be nice to continue with what is shown.

LuPi
You may consider a lateral valve train configuration
flatHead.jpg

This allows a very compact cylinder head. Very old design, but still used

D-motor

f12.9-27.jpg
 

Attachments

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
The D motor holds promise,

but I'm interested in moving in the direction I've started. What I've got is about a 9 inch cube, @ 500cc and will breath just fine up to 6,000 rpm. There are ways to make it smaller, lighter and more responsive. Trying to make a compromise of not too technical, and still introduce some new ideas that will work the first time out.

LuPi
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Screenshot 2015-09-29 at 16.59.32.png

Seriously considering this arrangement for the combustion chamber. The 3 smaller circles represent intake valves with a diameter of .3 bore, while the larger one is .4 bore.

The smaller 3/4 circlets represent spark plugs, ignore the imaging error. The exterior of the outer ring is the bore size, all the valves are enclosed in a 5 cm circle, leaving some outer space for squish or something. Total intake area is .27 bore, exhaust is .17, please advise as to what is considered optimum for 4-5,000 rpm.

Thx,

LuPi
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Thx,

Interesting is a good start. Fitting 2 ordinary sized sparks plugs isn't easy, as I learned after some tries. Was able to get everything into 5/6th bore circle so I'm giving me the go ahead to continue with this.

My favorite part is when I get to move on to some other part of a project. It's a great feeling.

LuPi
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Screenshot 2015-10-13 at 16.09.35.png

Working with the CAD software is no longer a giant headache though I'm still far from an actual professional with it.

Looking at it from another perspective, what I have is more like a 4 valve with one double valve, and three singles.

With this line up, the air will flow in at a 45, and then out basically in line to the inflow. Hopefully this will be good for breathing and pipe fitting.

This would have the exhaust pointing toward the V, which is fine for inverted and pusher setups, but maybe not so good for upright pullprop.

LuPi
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Screenshot 2015-10-18 at 17.56.32.png For the first time, valves, seats and inclined planes meet as one.

Still trying to shuffle things around, options are 3-1 opposed slant, 2 by 2 slant, and purely vertical operation.

Showing 3-1 slant with vertical exhaust, and angled intakes. Most symmetric combustion chamber, normal exhaust angle, not the 45 with this one.

Valves are mated revolutionary and not as slides, so I can't check interference like this, maybe in a couple days...

LuPi
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Screenshot 2015-10-20 at 17.27.23.png

All the valves are at a slant :ermm: otherwise at least glad to get a more realistic placement. Looking forward to getting a volume calculation soon.

Goal is 11:1 compression ratio, which would be a 12.5cc Combustion Chamber. Size of valves are 2.5cm exhaust, 1.75cm intakes. Same as before.

I'm not really looking to "tune" this atm, just get it into testing with some best guesses.

LuPi
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,124
Location
Clatsop, Or
Screenshot 2015-10-24 at 20.39.19.png

It's all coming along I suppose. I've not done anything this complex successfully; in terms of surfaces and drawing. The valves are some smaller, no special reason, just wanted to have 1/4 cm clearance between seats, although I have no stats whatsoever about part failures.

Compression ratio, lift, squish, basically it's all on target AFAIK.

LuPi
 
Top