Algodoo

Nice work.

My pc is about 3 years old with a dual core prossecor and it still lags xD if i wait long enough i can see its workings... pretty cool though

I've got an hectacore at 4 GHz and 20% sim time when it spawns fuel xD
You should use For(10, (x)=>{ spawn script }) instead of putting a bunch of scene.addCircles, and then you modify the 10 for the times you want the script to be executed

Nice valve lifting mechanism! Good job!

And while we are on the subject, My PC runs at around 70% -80% sim time with a dual core Sandy bridge CPU.
@The Linkage, correct me if I am wrong but I didn't think Algodoo was multi-threaded? so having 2 cores or even 12 cores won't make any difference will it?

You can use Threading.numThreads = (number of THREADS, not cores) to use the experimental multithreading thingy. it crashes with water, nothing else
As far as I know, intel i3s have 2 cores and 4 threads, i5s have 4 and 4, and i7s have from 2 to 4 cores, and 4 or 8 threads.
To count the threads on your processor you can go to Task manager and count the green graphs
For example, my FX-6300 works awesome with multithreaded apps and x64, but is slightly crappy at single thread (most single thread apps use two threads on mine, maybe it has three cores?)

Anyways, I always write a lot for stupid things I think it's more of my videocard than my processor, because Algodoo only can make it work at 30%
Most say that dual-cores are the best for Algodoo. Not single cores, I've tested that xD

Well coming back to the engine after some off-topic crap
I think you can put some polygon where the intake valve is so that only the smoke collides with it and it doesn't stay there, and you would have more speed (and lag) because the intake would work better if more balls enter on each stroke