inherit explosions physics in principa, fix or work around?

Its me the motor head again, I was working on a Subaru inspired boxer 4 engine, one the promised to be smoother and more powerful than my last flat engine all was going well until I found out that explosion will do work on objects in cross layers, is there anyway around this, could we possible have the physics of explosion only do work on one layer, or have a new explosive designed just for that, I rather not have to convert the engine to a rocket bases one, nor do I want to increase the stroke to try minimize the effect, it won't be the same, anyways thanks for reading.