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Tiny Inline 4 Cylinder IC

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dieselpilot

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With the cast iron sleeved aluminum pistons I think expansion is going to be a problem. A piston with an aluminum core will have to be loose in a steel bore when cold to avoid seizure when hot. The overall expansion of the piston will probably only be a little less than the aluminum, depending on how thick the sleeve is. You could also see distortion of the piston.

At our scale, runner lengths have very little impact on anything, but maybe Kel's main concern about how cylinders are fed. it's one reason Harley's have that rough idle. In the quest for power I'd be looking at airflow like Lakc mentioned. Combustion chamber shape won't be important at the displacement, compression ratios, and RPM you're talking about. If you really want to develop this design I'd consider building a single cylinder to do testing with. You'll find as breathing improves power will increase beyond the RPM you're running now. HP in little engines is found at high RPM. Even at 1.5cc per cylinder I'd expect HP to peak nearer to 10-12kRPM, or even closer to 20k if it could breath.

BTW, Kel, your TI4 has been giving me the itch to scale either BMW 4 or 6 cylinder and build one.

Greg
 

kustomkb

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It's good to hear you are tearing the performance envelope wide open ;D


I thought I'd share a little assembly video I was able to produce using Kelly's very nice plan package;

[ame]http://www.youtube.com/watch?v=K6wMcQcsRhI&edit=ev&feature=uenh[/ame]


 

kcmillin

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That is a pretty cool video Kevin. Thank you for posting it.

I am still working on the new upgrades. I am thinking about moving the combustion chamber from the top of the block to inside the head. This will allow more angle on the spark plug leaving more room for bigger valves and larger runners. My current runners are .093" holes, I would like to increase these to .141 - .156 or so.

My current compression ratio is 6:1, If I create a quasi-heart shaped combustion chamber I can get it up to 6.7:1. I am not to sure how high we can get with these small engines though. but at 6.7:1 it is still a bit modest.

My main concern now is valve size. I want the largest valves I can fit. The old valves were .156" and are actually more like .135" after the hammering they took on the last few runs. The new design I can fit both valves at .219", but I was also thinking about an asymmetrical design with a larger intake valve. This would create some goofy things with valve placement though.

Kel

Kel
 

agmachado

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KustomKB, I like a lot this video type !

Kel,

My intention is purchase this plans by your web site... I pay with PayPal method and receive the plans in PDF format. That's possible ?

Best Regards,

Alexandre
 

kcmillin

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Alexandre Machado said:
KustomKB, I like a lot this video type !

Kel,

My intention is purchase this plans by your web site... I pay with PayPal method and receive the plans in PDF format. That's possible ?

Best Regards,

Alexandre
Yep, that's exactly how it's done. I can usually deliver it to your e-mail within a few hours.

Kel
 

Lakc

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Muhahahahahaaaa

Yes Igor, we have created yet another horsepower monster ;D
 

agmachado

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kcmillin said:
Yep, that's exactly how it done. I can usually deliver it to your e-mail within a few hours.

Kel
Thank you Kel!

I will arrange and talk to you soon!

Cheers,

Alexandre
 

kcmillin

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I have here a couple designs for the combustion chamber.

Previously the combustion chamber was in the top of the cylinder in the block, and the head was flat.

This design the combustion chamber is milled straight into the head .1", with flat square sides all around. This allows the spark plug to be placed at even more of an angle, making more room for valves.

Your thoughts on these designs, and perhaps a vote?

The bore is .5, and the valves are .219" on all but the C intake, which is .250.

A, B, or C.



Kel

 

kcmillin

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It Lives!!!..............again.

The crank throw journals on the crankshaft were to far gone to fix, but I have managed to fix one of the crankshafts I screwed up before by making the main journals smaller to get them to run true. Well, I could only fix the outer two bearings, I will be leaving the three center main bearing out. Since it was basically like this before, I am not worried.

I have also made a new set of connecting rods as per my drawings, but I added an oil spout out the bottom of the rod journal. This also acts as a stay for the split bushings. The spout actually intersects the bottom bushing half locking it in place and preventing it from spinning. Which is the part of the reason the original bushings were getting destroyed.

I will be adding this spout to the plans and sending them out to the owners in the next few days. There is also a couple things that need fixing which will also be in the update.


I put the engine on the stand without the radiator and ran it for a couple minutes. All seemed good. I will be tearing the bottom end down and cleaning it all up before putting it back together on the stand. Then I will post a new video of the engine running with the new crank and connecting rods.

Now that I have it running again, I can put it aside, (hopefully) and go full bore (Pun intended) into the "High Output TI4".

Kel
 

dieselpilot

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Combustion chamber C would probably make the most power. It really depends on how crowded the valves are. Because they are so close to the wall they are mainly flowing in the areas open to the cylinder. Between A and B, A would make more power because the valves are less shrouded.

Greg
 

Lakc

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Glad to hear you have her back in shape!

As to CC design, big unshrouded valves like Greg mentions will flow the most air, and more air with more fuel = more power. :)

Avoid right angles to airflow and choked intakes, but keep your intake passages skinny enough to keep airflow speed as high as practical, that helps keep the fuel from dropping out. View the head passage for the intake and intake runner as another venturi between the carb output and intake valve.

Try and avoid the square sides of the combustion chamber. You want every fuel molecule mingling with air molecules, and fuel trapped in the corners probably wont burn since they are not surrounded with enough air. Thats one benefit of the hemispherical combustion chamber.
 

kcmillin

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Thanks for the tips guys.

I have made another design, based on C.

I can round out the combustion chamber quite a bit. Though I might need to dome the pistons to get the compression ratio I am after, between 6.5 and 7 to 1

I currently have room for intake runners up to .203" diameter, and the intake valve is .250" or one half the bore size. The exhaust valve is .219" or about 20% smaller than the intake valve.

I have read that you want your intake runners volume to be about 40% of the pistons displacement. Does this seem right?

Kel
 

kustomkb

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I am looking forward to see your next version come to life.

I've been playing with the animator a little more. Here is another video;


[ame]http://www.youtube.com/watch?v=aRrX-_YvXeI&feature=player_profilepage[/ame]


 

kcmillin

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Wow Kevin, that is a pretty cool vid! I love the fly through camera work.

I have nearly settled on a design, I will indeed be increasing the stroke from .5" to .575" or .6". I will need to make solid bronze connecting rods in order to make them smaller so they don't interfere with the block and oil pan.

I will be doing a test combustion chamber. My plan is to smooth out the sharp corners with a rotary tool by hand. I am thinking about making a jig of sorts to help me get them equal. Once I have it made I can find out my compression ratio top a finer degree. My target is 7:1.

Also, one big difference is there will be 4 separate intake runners in the head instead of two into one. This will make things more predictable for the flow of air.

Kel
 

kustomkb

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Thanks Kel. I've learned a lot about the software, modelling from your drawings.

Its been fun too! Now if I could design an engine...
 

Stieglitz

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Hi kcmillin,
Great work,will look forward to the completed engine and plans.
Thanks and Cheers.
 

djalal

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hello sir can you tell me the size of the piston !! because i think very small

djalal.
 
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