Author Topic: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.  (Read 1139 times)

Offline Longboy

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LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« on: September 24, 2021, 04:56:15 AM »
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.......


And later in Suzuki GP racing and a Kawasaki street prototype.


Going to make this type mine!


staring this weekend!   :ThumbsUp:
Wadda you mean, "It don't run"???

Offline Admiral_dk

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #1 on: September 24, 2021, 11:39:20 AM »
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:

Offline crueby

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #2 on: September 24, 2021, 12:17:50 PM »
That takes the term 'engine block' literally! Must be a very interesting internal structure, looking forward to seeing it.

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #3 on: September 25, 2021, 06:29:32 AM »
This S/F is a pair of inline twins with a common output shaft right down their center. Starts with these two block pieces.


One inch bore with liners and O-ring head gaskets.


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.
Wadda you mean, "It don't run"???

Offline AVTUR

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #4 on: September 25, 2021, 12:24:40 PM »
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
There is no such thing as a stupid question.

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #5 on: September 25, 2021, 05:32:35 PM »
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.

Wadda you mean, "It don't run"???

Offline Admiral_dk

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #6 on: September 26, 2021, 10:22:06 PM »
Quote
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.

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #7 on: September 27, 2021, 05:55:54 PM »
The S/F will be using the geared crank webs.



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.



The webs are made by the pair in 12L14 steel.



The vertical frame members with their bearing carriers to engine blocks.

Wadda you mean, "It don't run"???

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #8 on: September 29, 2021, 10:36:42 PM »
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.



The extended stub will have the drive gear, both cylinder banks, meshing with the driven flywheel shaft.



Wadda you mean, "It don't run"???

Offline propforward

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #9 on: September 30, 2021, 05:53:12 PM »
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.
Stuart

Offline sid pileski

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #10 on: September 30, 2021, 08:12:54 PM »
Are those plastic gears?
If so, are they just for mock up?

Sid

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #11 on: October 01, 2021, 05:54:13 AM »
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.
« Last Edit: October 01, 2021, 06:12:02 AM by Longboy »
Wadda you mean, "It don't run"???

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #12 on: October 01, 2021, 06:10:53 AM »
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.
Wadda you mean, "It don't run"???

Offline AVTUR

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #13 on: October 01, 2021, 05:21:40 PM »
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
There is no such thing as a stupid question.

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #14 on: October 01, 2021, 08:30:40 PM »
Round stock for the cylinder heads on these rectangular bocks.



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.



Heads need a butt fit to each other over the cylinder liners.






Plain top surface with some broad horizontal finning. Cooling will be subsidized with some fin overlays to the upper block surfaces.



From the crank webs to the cylinder head, a major sub assembly takes shape.

Wadda you mean, "It don't run"???