Pneumatic Engine using new large v2 cylinders

[futtigue]

Hello everyone

After fiddling with my LPEs for some time, I have finally managed what I think is a first: a running engine using the large cylinders from the new V2 pneumatics series.

Like many of us, I was very worried once linear actuators appeared that LEGO had given up on the expensive pneumatics.  So I was very happy when they released the V2 system with the Mercedes Arocs set.

Well some time has gone by and I simply have not had the disposable income to grab the set, so I finally stopped making excuses and just ordered some of the new cylinders off of ebay.

After seeing how high the friction was on the cylinder, I immediately set about modifying them.  I drilled the opening slightly larger and added a small amount of finer silicon lube.

I ended up with a very large inline-4 with twin camshafts.  It runs at a very low rpm but with a lot of torque, easily the most powerful LPE among the ones I have built.  Here is the video of me modifying the pistons and running the engine.  

I owe quite a bit to builders like DrDudeNL, LPEPower, NCJanso, and many others!  I started out following their instructions and copying their ideas, until with enough time and practice I came up with tricks and a style of my own.  I am quite proud to show the first large cylinder LPE (...I think.  Let me know if there has been another one forst and I will give credit).

Anyways, let me know of you have any ideas or suggestions for improvement!

[BrickbyBrickTechnic]

Thank you! I have been trying to make an engine with v2 cylinders, since I have no v1 pneumatics. Is there any risk associated with modifying cylinders? How does it affect the cylinders? Thanks again @futtigue ! 

[futtigue]

It is not much different from modifying regular v1 pneumatics.  I was very worried because of the high cost of the large cylinder (especially when I ordered them a while back, as they were even less common) if i messed it up, but also the smaller diameter of the hose inlets.

It seems TLG has gone with that new 'stepped' inlet so as to make it easier to squeeze the hose onto it.  I was nervous that this new reduced diameter would not hold up well to drilling the hole out larger.  Because of this it is very important to make sure you are drilling in straight.

I see some of the pneumatic 'grand masters' out there recommend a drill bit of 1.8mm.  Even though we use the metric system here, twist drills are all still fractional.  So I took a conservative approach, and stepped down (rather than up) to a 1/16th" bit, which is equivalent to a 1.55mm.  This still dramatically increases airflow into the cylinder, but is a bit safer when considering the thinner wall of the end of the inlet.  Avoid using a hand drill, as once the drill checks through the inlet it will drop down into the cylinder and you will begin drilling out the other side.  If you must use a handheld drill, get a drill stop, or do what I did and use a crappy drill press set not to exceed half the depth of the piston.

One of my holes (the second one I show the camera in the video) did not drill straight in, and you can see the lower inlet on the last piston was ovalled out.  This does not seem to affect the operation, and all pistons seem to seal very well still.  When you hold the inlet up to the light, you can see the very thin area on the wide end of the oval (its thin enough as to appear translucent).  I figure, even if this end does break off, there still should be enough of the thicker portion of the inlet left to hold a hose on.  I just kick myself for only ordering 4 cylinders instead of 5, as I would have been very mad if I had to do another order just to replace one I wrecked!

Next I'll be modifying more valves, and hooking it up to a real compressor.  There are also areas where the engine can be improved yet.

Anyways, I hope that helps in the construction of your own engine.  Let me know if you are curious about anything else.

[Alex Ilea]

I also did an LPE  with V2 cylinders and it worked very poor since i didn't MOD them . But it worked :)

[futtigue]

Quote

I also did an LPE  with V2 cylinders and it worked very poor since i didn't MOD them . But it worked :)

That"s awesome.  What layout did it use?  Vee or Inline?  Pushrods or Camshafts?  Do you have any pictures you could post?  I'd like to see how others tackled this problem.

[Alex Ilea]

Inline (don't think V is possible with only 2 non-modded) , crangshafts and no pics (unfortcenetley) . It run at about 10 rpm btw 

[arshiaIQ]

I made a V2 engine using V2 cylinders, wasent difficult and runs at 700-800RPM at 100psi very well. Havent modified cylinders, just injected some oil into the holes using a syringe... They now move EXTREMELY easily... slide like a champ :D

[1gor]

before this conversation goes to extremes...I have one question - in which vehicles do you want to use larger LPE, I have one  with pneumatic cylinders from 8455 set and steal look in what car to use it because LEGO tires with street profile are small...Only 94.3 x 38 (Unimog tire) has a potential (for a city car or similar) to be used with in-line 3 or in-line 4 engine; V8 can be used in muscle car but with what LEGO Tires? 3rd Party tires are often expensive as pneumatic engine...