Model Engine Maker
Engines => Your Own Design => Topic started by: Longboy on September 24, 2021, 04:56:15 AM
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A rare configuration in I/C engines is the square four. From the motorcycling world in the form from the British Ariel S/F classic for three decades.......
(https://i.imgur.com/r6TkygH.jpg)
And later in Suzuki GP racing and a Kawasaki street prototype.
(https://i.imgur.com/WVCys4p.jpg)
Going to make this type mine!
(https://i.imgur.com/XfLUytO.png)
staring this weekend! :ThumbsUp:
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Yes - they are interesting engines !!!
But there are also reasons why we don't really see them :
Air cooling => reliabillity problems (Arial)
The Suzuki was a very succesful racer for years, but somebody found out that 'folding' it out to a V-configuration, allowed them to move the carburators from the sides (making it much narrover -> better aero dynamics), better breating -> more power and better lubrication of the crank and conrod bearings.
That said - I'm looking forward to see your unique take on this type :cheers: :popcorn:
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That takes the term 'engine block' literally! Must be a very interesting internal structure, looking forward to seeing it.
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This S/F is a pair of inline twins with a common output shaft right down their center. Starts with these two block pieces.
(https://i.imgur.com/6OTMgaC.jpg)
One inch bore with liners and O-ring head gaskets.
(https://i.imgur.com/IudY56y.jpg)
A relief is milled in at the lower inside corners of the blocks to receive quarter inch aluminum plate verticals to accommodate the crank shaft throws.
(https://i.imgur.com/NPyqE2K.jpg)
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Yes - they are interesting engines !!!
But there are also reasons why we don't really see them :
Air cooling => reliabillity problems (Arial)
The Suzuki was a very succesful racer for years, but somebody found out that 'folding' it out to a V-configuration, allowed them to move the carburators from the sides (making it much narrover -> better aero dynamics), better breating -> more power and better lubrication of the crank and conrod bearings.
That said - I'm looking forward to see your unique take on this type :cheers: :popcorn:
The Danes had a motorcycle with an intersting engine - the Nimbus. An owner told me that the rear cylinder regulated its top speed by gradually tightening up.
I will follow this build with interest. Are you going to show a drawing or solid model of the engine?
AVTUR
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Thanks AVTUR. You will see the development of SQUARE FOUR as it progresses though the postings. No plans or drawings to present. My scratch builds start with the engine block and proceed from that major item.
I'll offer up this "teaser" photo. It only makes sense to me. However, you will be able to match this up upon seeing the completed model! Dave.
(https://i.imgur.com/KB0uF7d.jpg)
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The Danes had a motorcycle with an interesting engine - the Nimbus. An owner told me that the rear cylinder regulated its top speed by gradually tightening up.
I think that he to a degree was mixing - pulling your leg and telling some of the truth in an alternative way.
Both versions of the Nimbus had a 4 cylinder 746cc in-line, along the length axis. This meant that the front cylinder had much better cooling than the rear. They were (and are) very reliable motorcycles - especially when you consider time of birth and production :
"Kakkelovnsrøret" 1919-1928 and "Type C" 1934-1960 ...!
I would be lying if I claimed to be very knowledgeable on Nimbus motorcycles - they where plenty in my youth, and you still see them on the roads - though nowadays mostly in the weekends.
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The S/F will be using the geared crank webs.
(https://i.imgur.com/xJ2wxSf.jpg)
This is my third engine build with this method having opened up some unique design elements transferring the reciprocal to rotary motion. The webs need steel halves to balance out the piston/ rod assembly.
(https://i.imgur.com/1nHYggt.jpg)
The webs are made by the pair in 12L14 steel.
(https://i.imgur.com/NaQLRLD.jpg)
The vertical frame members with their bearing carriers to engine blocks.
(https://i.imgur.com/RuaZGSi.jpg)
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The webs are finished with a 5/16 in. stub shaft. A brass tube spacer on the web side of bearing spaces out to clear the screw heads. On the bearing flange side an aluminum spacer, tapered to ride the inner bearing race. The machine screws will be replaced for the spacer and the bearing carriers with socket heads to get the right angle allen wrench up there as there will be no room for a screw driver.
(https://i.imgur.com/ZC1WBgX.jpg)
The extended stub will have the drive gear, both cylinder banks, meshing with the driven flywheel shaft.
(https://i.imgur.com/GzjKNBY.jpg)
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I always like the square four. Not without it's problems for sure, but an fun and interesting design. I will be interested to see your engine progress.
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Are those plastic gears?
If so, are they just for mock up?
Sid
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Are those plastic gears?
If so, are they just for mock up?
Sid
Thanks Sid. Sourced from the R/C model world, they are plastic and work well.
(https://i.imgur.com/SAKvrQHl.jpg)
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I always like the square four. Not without it's problems for sure, but an fun and interesting design. I will be interested to see your engine progress.
As with V-Twin engines in motorcycling, the lead cylinder shields the cooling air. No longer an issue with many contemporary liquid cooled models . Back in the early days, packaging a liquid cooled solution too expensive and too bulky for vehicle size. The Air cooled V-twins out lived the Ariel, most likely by cost times number of cylinders and the strength of the company's market.
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I always like the square four. Not without it's problems for sure, but an fun and interesting design. I will be interested to see your engine progress.
As with V-Twin engines in motorcycling, the lead cylinder shields the cooling air. No longer an issue with many contemporary liquid cooled models . Back in the early days, packaging a liquid cooled solution too expensive and too bulky for vehicle size. The Air cooled V-twins out lived the Ariel, most likely by cost times number of cylinders and the strength of the company's market.
Conventional V twins could suffer from the front cylinder tightening. Nothing about air cooling, the rear cylinder receives most of the oil thrown up from the crankcase. The British Army had this problem with their BSA V twins in the early and mid 1930s. They never cured the problem. Phil Iving, who probably knew more about V twins in the past, mentions this problem in passing in his book "Motorcycle Engineering". Early JAP engines had the bottom of the rear cylinder baffled to prevent this from happening.
AVTUR
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Round stock for the cylinder heads on these rectangular bocks.
(https://i.imgur.com/36q5CYN.jpg)
Combustion chambers are bored to 3/8 in. depth. With the pistons rising to 1/4 in. below the block deck that gives easy turnover compression to hand start with 3 -4 in. diameter flywheels. The larger diameter cut in the bottom of cyl. head is the seat for the cyl. liner.
(https://i.imgur.com/PaEHgga.jpg)
Heads need a butt fit to each other over the cylinder liners.
(https://i.imgur.com/gMaWoul.jpg)
Plain top surface with some broad horizontal finning. Cooling will be subsidized with some fin overlays to the upper block surfaces.
(https://i.imgur.com/1nEnJCI.jpg)
From the crank webs to the cylinder head, a major sub assembly takes shape.
(https://i.imgur.com/lsFoMvr.jpg?1)
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The lower end of SQUARE FOUR. Looks like the start of a donkey cart or pull toy. Bearing end plates set the spacing between the vertical plates.
(https://i.imgur.com/Enuk0EM.jpg)
Trying out a set of 1Mod 20T helical cut bevel gears over straight cut bevels used on the SIDE SHAFTER engine. Checking the three gear fit before bearing carrier install in the end plates. I like them though not sure if better here than using the straight cut versions.
(https://i.imgur.com/QzG5xWW.jpg)
The flywheel end will have a pair of R1810RR shaft bearings with the nose end having one bearing. Between the gear and inside bearing goes another brass tube spacer to set the gear lash with minimum thrust movement of shaft after the end plate receives its bearing carrier.
(https://i.imgur.com/kSKJXl0.jpg)
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Looks like the start of a donkey cart or pull toy.
Or a BattleBot! And I love those siamesed cylinders. :ThumbsUp:
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Conventional V twins could suffer from the front cylinder tightening. Nothing about air cooling, the rear cylinder receives most of the oil thrown up from the crankcase.
AVTUR
[/quote]
That is two reasons that kill engines. Over heat and under lubed. Most air cooled issues seem to be at stop and go rush hour traffic conditions @ 90F/30C and higher temps that have a chance at recovery when you can get rolling. Got to move that air as well as spray those cylinders with oil! .....Dave.
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On the nose end plate backside go the ign. points.
(https://i.imgur.com/jncCJoR.jpg)
A slot milled into the end of the vertical plate for the insulated connection to coil.
(https://i.imgur.com/7de3urc.jpg)
Lead for the condenser and a quick connect spade goes under the screw nut for the 6 volts.
(https://i.imgur.com/2PCWTdS.jpg)
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Interesting configuration for the Crank etc. - will it be a 'Waste Fire' Ignition ?
Per
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LOL I recognize those gears! Keep it coming Longboy....this is an interesting build for sure!
Dave
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The cyl. heads overhangs the outboard side of the block.
(https://i.imgur.com/lsFoMvr.jpg?1)
On the low side of block, a shallow cut mill run up its length for the lifter bar.
(https://i.imgur.com/Ipy3orK.jpg)
Installed, the pushrod will pass through the head to the exhaust valve only rocker arm on top.
(https://i.imgur.com/nOJ8qlp.jpg)
Completed Lifter bar with camshaft attached.
(https://i.imgur.com/4uJgWG8.jpg)
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The cam drive......belt or geared?
(https://i.imgur.com/GkskadE.jpg)
Drive cogs are seven inches apart. Gonna need a belt longer than my shoe laces and three idlers in this scale. Going to do gear drive in seven gears from the cam sprocket for a more compact arrangement.
Transfer shafts off the sprocket shaft through vertical plates to the cams. All shafts here brass bushed. All gears .5 Mod/ 24T
(https://i.imgur.com/s1hrLTw.jpg)
Shaft support bushing bolted under heads intersecting the cam drive with the final gear pair.
(https://i.imgur.com/7NwjpSU.jpg)
(https://i.imgur.com/KaQC1Do.jpg)
And the shaft disappears to the back of engine to drive another item!
(https://i.imgur.com/xIp1ACw.jpg)
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Tail end of this shaft drives the distributer. Using a 3/4in. inner dia. PVC end cap with #8 brass screws for the wire leads. Extended length brass bushing pressed into aluminum body for the dist. shaft to rotate in.
(https://i.imgur.com/qANnZRE.jpg?1)
Easy placement upon a pair of 1/4in. rounds on the shaft end plate, the body sits high on the engine.
(https://i.imgur.com/5DuEzqt.jpg)
Will not need too much flywheel back set from it's bearing carrier to clear the distributor gear set.
(https://i.imgur.com/BOiV1cN.jpg)
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I'm enjoying following along on this build. Very clever approach to fabbing a distributor! :ThumbsUp: :popcorn:
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Using collet locker to join flywheel to their shafts pretty exclusively over the years. A three bolt retainer squares up the flywheel to its shaft for a true run. I use Delrin collets slit on one side spaced out with a brass or aluminum tube over shaft to a length that extends the collet past the shaft end about an eighth to 3/16th inch.
To free the flywheel from its shaft for service you need a release mechanism. Unlikely one could tap at the flywheel with a mallet to drive the flywheel back off the collet and not damage the engine.
(https://i.imgur.com/avygFiT.jpg)
A couple of 8-32 machine screws are threaded into the end plates at a spacing equal to the through holes around the flywheel. Flat washers on the screws push the flywheel off the collet that bottoms upon the brass spacer behind then.
(https://i.imgur.com/mVkGNOR.jpg)
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Sometimes the price of parts one uses building models hits me the wrong way. Gives you a chance to find substitutes for these particular items......or an opportunity to develop your own.
(https://i.imgur.com/OpKjLJp.png)
The top of the electrode diameter on a CM-6 sparkplug.
(https://i.imgur.com/uCwdeC0.jpg)
I take a 3/8in brass round for the wire terminals. Offset in the lathe chuck for a thin/ thick side and tap drill for an 8-32 set screw. Finish drilling with an "A" or 15/64 in. drill to the depth of the top of electrode to where it meets the ceramic, around .230 in. Tap the 8-32 threads to the end of the length of terminal then.
(https://i.imgur.com/4DfDYZ7.jpg)
The thick side at the threaded top side of terminal is cross drilled the diameter of the wire insulation. Tucked into the hole and the set screw locks in the stripped end copper wire.
(https://i.imgur.com/x7kdaQV.jpg)
Finished length of these terminals is under 5/8th inch and do not overwhelm the small size of these plugs. I think when I do these again, I will thru drill and tap the 8-32's and start the set screw from the top side!
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Atmospheric intake valves seem to be winning in my designs. Even more so integrating into SQUARE FOUR being to the inboard of the cylinder heads. Space being at a premium here for another cam drive.
(https://i.imgur.com/4xX8Gq8.jpg)
Pair of aluminum flat stock pieces (from a previous model shown) sandwich the valve guides sealed by O-rings between as well as the mounting to the heads with a brass tubing between these valve blocks and head.
(https://i.imgur.com/xidMjAw.jpg)
(https://i.imgur.com/YscwyWF.jpg)
Long machine screws adjacent to the ports hold the blocks to the heads. With the intake plumbing in place, there is no room for a screw driver or Allen key to mount them to the heads. To get a grip on the screws, I straight knurl across 5/16th threaded rod. Drill and tap 6-32. Cut to a short length and thread up to the head of the machine screws with epoxy to lock them on. Now I can tighten down with my index fingers! :ThumbsUp: I use the same type finger nuts setting rocker arm clearance too.
I'm going to need some short 90 deg. elbows right out from the carburetor port side from here. I can make them.....or see what my friendly ACE Hardware store has to use.........
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From RAINBIRD Irrigation Systems, I find some 90 deg elbows that fit in nice to the valve blocks the inch and three-eights distance between them. They are the right kind of rigid plastic for use here.
(https://i.imgur.com/TyJq7Zn.jpg)
Just cut off the barb and press fit into the port up to their flange. Aim them to the front of engine.
(https://i.imgur.com/N8YLAPr.jpg)
Cut up some pieces of vinyl tubing to bring up to the intake manifold. Vinyl pretty heat sensitive so most likely substitute silicon tubing for the job.
(https://i.imgur.com/xzRia0c.jpg)
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Intake manifold here of some black plasticky stuff is drilled for the plenum.
(https://i.imgur.com/heZEnZk.jpg)
Bolts onto the lower valve block pieces with a couple of spacers. An O.S. carb will feed the engine.
(https://i.imgur.com/Q5wWBPA.jpg)
(https://i.imgur.com/0nXEBms.jpg)
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Natural metal or black satin? I like contrast with dark deep color.
(https://i.imgur.com/68RoSIj.jpg)
For radiators, the upper part of engine blocks get the fin cladding bolted on each side.
(https://i.imgur.com/jDBA3fL.jpg?1)
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My vote would be the black satin. :ThumbsUp:
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The black satin certainly does make the brass pop! :ThumbsUp:
Kim
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Yes! The black with the brass looks great.
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Square four engines being a pair of 180 deg. crank twins, its cylinders in unison rise and fall diagonally.
(https://i.imgur.com/OwhjRJK.jpg)
The firing order is 1-2-3-4. Though I built the engine numbering the cylinders starting with the front left, the distributor with its gear drive rotates counter clockwise. The #1 cyl. is now the front right. This allowed for a symmetrical layout of the spark plug wiring from the cap.
(https://i.imgur.com/ZU0PSdA.jpg)
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A 72T belt takes care of the cam drive. With sprockets instead of gears for the cams, that belt would have had around 400T.
(https://i.imgur.com/lYEpGJK.jpg)
More cylinders need more fuel capacity and up front I was able to have twin on board vertical fuel tanks totaling about 2 OZ. SQUARE FOUR idles along for over 20 minutes per fueling.
(https://i.imgur.com/Lm7Yqku.jpg)
Copper tanks and mufflers, the red metal along with white and yellow metal.....my kind of jewelry!
Longboy's SQUARE FOUR concluding this week! :cartwheel:
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Welcome to my introduction of my new engine, Longboy's "SQUARE FOUR" Model Gas Engine! :popcorn:
(https://i.imgur.com/CsZfSTA.jpg)
Only found in the motorcycling world per my research, the Square Four found its way as a production motorcycle (Ariel), a racing motorcycle (Suzuki) and a production proposal motorcycle (Kawasaki). Now in a Google/ YouTube search on the web......as an obscure model engine, as are its full sized examples.
(https://i.imgur.com/HBIPLvH.jpg)
SQUARE FOUR was started second week of November. (2020)
(https://i.imgur.com/m3e6dB0.jpg)
Completed first week of March.
(https://i.imgur.com/LodvH0d.jpg)
Very smooth performer. (see teaser photo for above photo early in postings)
(https://i.imgur.com/Rvmwj63.jpg)
20 minute run time per tank full.
(https://i.imgur.com/4q1NPGD.jpg)
Geared twin cams.
(https://i.imgur.com/BKm1qSU.jpg)
And geared crankshaft to central flywheel.
(https://i.imgur.com/OKuJxMd.jpg)
See it run! Thanks, From LONGBOY ENGINE, Dave.
https://www.youtube.com/watch?v=lpLHSQOZKtI
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I've been following along and I wasn't sure how it was going to fit together. Now that it's running, I can see that there was a lot of real engineering involved in figuring out all the events involved in making it run.
Congratulations on making something that is a departure from what most have done. I really like the way it looks running.
Thank You for posting,
ShopShoe
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Another easy starter and fine runner from you :ThumbsUp:
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That's a very neat engine, it's great to see how well it runs! Very nicely designed and built. Congratulations! :ThumbsUp: :cheers:
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That's a really interesting engine! It has a lot of fascinating motion to watch - way more than most IC engines. And it runs great!
Kim
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I've been following along and I wasn't sure how it was going to fit together. Now that it's running, I can see that there was a lot of real engineering involved in figuring out all the events involved in making it run....................Thanks for posting,
ShopShoe
An unusual engine created in an uncanny way. In my early days building Stirlings, with their many configurations possible in joining their two cylinders, has helped me with a few of my gas engine designs coming together. The S/F engine is my free standing, open crank design of a rare configuration. Not a career machinist who works from plans and print and no CAD but have an idea of "what goes where" as the build progresses. Along with the pleasure of bringing some eye catching design, technique and creativity to the forum, :thinking: maybe the definition of "scratch build', means others looking at the work take their caps off saying, "what/how"? :headscratch:
Dave.
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Excellent :praise2: :praise2: My brother in law has an Ariel square four as well as a CBX and a couple of 1950s Ariel singles.