I decided to put the double cam into retirement and will pursue the pushrod road. The first design is instantly better than the double cam setup. (which i was trying to perfect for the past 2 weeks, without any significant improovement). I have to experiment with the opening times, but it's definetly going to be a winner.
I ran the engine again, and it made 1660 rpms effortlessly. The key? I provided timing gears on the back too, thus preventing torsion in the crank and cam to affect performance. It proved to be a huge success. Now i only have to make the switches to align properly...
I upgraded the engine to a double cam setup and voila, promptly got 440rpms more. For now i'm running the engine completly unlubed. If i optimize it a bit further i think i can make it to 1600 rpms. I wonder how an inline 4 would go..... (insert manical evil scientist laughter here...) :)
Not much to say really. Details will follow when the engine is fully understood. Here are some pics. Enjoy the video untill then.
So i did it. It struck me a few days ago, and i got rid of the double cam setup, and the complicated tubing and everything, and went for this. I liked how the camshaft turns so easily, and i like the simplicity. This engine ran effortlessly to 1040 rpms on the absolute first try. The version on these pics is a slightly modified version which should run a coupple of rpms more.
The reason i went for this is more power and a much smaller size. I think i succeeded in both, and also, the engine is more responsive. And another good thing, i need only 1 chain, and no chain tensioners. Just like it should be.
This is the final version of the engine, that will go into the Challenger. Despite my best efforts, i couldn't make it run even as fast as the 4 cylinder. It runs only 1060 rpms on the normal chain setting. For now, i'll stop engine development alltogether and concentrate on the body of the car. I may resume experimenting with the engine in the fall, when/if i get more ideas what to do. Right now my mind is blank. I don't know what else to try. In this setting, the engine runs the best of all of what i tried. And i tried a lot.
As you can see, i also abandoned the idea of a central intake, because i just couldn't fit it. Everything is just too tight.
So, after a lot of struggles with the camshaft setups and experiments with flat mounted switches, i finally found a setup that works. The engine runs only 1360 rpms. But it delivers them smoothly, which is what counts. As you can see on the pics, cylinders 1 and 3 have different timings than cylinders 2 and 4. I found through experimentation that this works best. Also, the intake manifold is mounted on top of the switches, so that i can use a central intake for the V8.
So, the HEMI is not one of the fastest engines i've ever built, but it sure is the most powerfull one. I will put its power to the test tomorrow. So far the engine produces 1020 very smooth and powerfull rpms. I'm very sad though that it doesn't go any faster, despite everything running extremly smooth and easy and the engine being extremly stiff. It's like a solid block.
Why HEMI? The original engine has hemispherical combustion chambers. Well... in lego we don't have combustion chambers, but the switches have a bionicle ball joint attached to them, and thus, the name HEMI is fully justified :)
I started development of the engine. I think this is the best V engine block i've made to date. It is 2 studs longer than the engine from the mustang. It has no valve system yet, but that will soon change. I'll keep you posted.
So... congratulations to Ivan who broke the 2000 RPM barrier.
Enjoy the video of his engine in his brickshelf: Link