Automotive Breath:
...The groove alone provides benefits not found with increased compression. I have done this before, groove an engine with out increasing the compression and the performance improves.
Crocket
...appears that the benefit the groove provides seems to out weigh the negative effect on performance that the DECREASE in compression resulting from the grooving operation (increased chamber volume) would usually net.
Earlier I posted pictures of SBC AFR heads; I have been running these heads for about five or six years in my Camaros.
I first had them on a flat top 355 that resulted in 10:1 compression. The performance was OK but not what I expected from a quality head, ¼ mile time in the high 11’s at 115 mph.(no grooves)
Later I swapped to a set of mini dome pistons that brought the compression near 11:1, performance improved, times in the low 11’s at 119. (no grooves)
After reading about Somender Singh I found his email address and asked him how to groove the AFR heads, the pictures are the result. One groove in each combustion chamber lowered the compression slightly, each groove measures 1cc. The result is something I have never seen before, an engine that struggled to idle before the modification at 1100 RPM now idles at 800 RPM cold. Fuel consumption is down, the plugs and oil run clean and the engine runs stronger than ever. High 10’s at over 122mph in my 67 and 10.65 at 124 in my lighter 68.
Over one year later I have grooved more than 15 sets of heads and have been contacted by numerous people from around the world. Still most people think it’s some kind of scam and don’t give it a second thought. I spent much of my time grooving more heads and figuring out what is happening inside of my engine.
To understand what’s happening it’s best to think of the negative effects of compression and squish. We know the benefits of the two but what about the negative effects. When air/fuel is compressed and pressures are rising due to the approaching flame front bad things can begin to happen. Fuel starts to separate from the air as it is squished tighter in between the piston and the head, under the right temperature and pressure it can explode uncontrollably. The solution has been lower compression or higher octane fuel.
When thinking about the effect of the grooves I read some one comparing it to the grooves on a tire. Run a slick tire on a dry surface and everything is OK. Add water and it gets caught between the tire and the road. The solution is to add grooves to let the water out.
So what does this do to my engine? The piston is coming up to the cylinder head and the flame is quickly approaching. With out grooves some of the air/fuel mixture is trapped in the squish area and goes unburned and is pushed past the rings (or explodes if conditions are right) Add grooves and the air fuel mixture is routed into the approaching flame front.
