Hawk Talk

Ariel Red Hunter · 02-13-2017, 10:48 AM

Although I started this about high-end horsepower, upping the compression ratio adds power all the way up the scale. There is more than one way to up compression ratios, two rather obvious ways, and one not so obvious. The most obvious way might be to lower the head as compared to the piston at TDC. Either by milling the head or by turning a few thousandths off of the bottom of the cylinder. I would do the latter, because 1] No chance of weakening the head/cylinder joint, 2] Easy to adjust compression ratios by various shims between the bottom of the barrel and the engine cases. Then the not-so-obvious way mentioned above, which is for you that have TIG welders lurking in the garage, which is to add metal inside the combustion chamber to reduce the cc's of the combustion chamber, as compared to the swept volume of the piston. Even better when adding metal, is to add squish bands to the equation. Squish bands cause more turbulance in the mixture. This causes the mixture to burn faster, leaving more time for the expansion of the gases of combustion, and thus add more pressure on the piston. I don't know whether the younger set can think in steam engine terms, like some people of my age can, But if you can, it really simplifies the grasping of the concept. Imagine a steam locomotive of the turn of the last century, running about 250 lbs of steam pressure, and a temperature of 275 degrees f. Now look at the 1950's engine, running steam at 600 degrees, and 300 lbs pressure. The 600 degree steam is what is causing the great increase in power over the engine of 50 years earlier. Because 600 degree steam expands much more than 275 degree steam. So, too the air in the cylinder expands more than an engine of lower compression. And because of the added turbulance, all of the fuel is consumed earlier, leaving more time for expansion of the exhaust gases. So it is really quite similar to a steam engine, in that the goal is to get as much push out of these expanding gases as is possible. One engine is classed as internal combustion, and the other is external combustion, but expanding hot gases do the work in both cases.

02-13-2017, 10:48 AM	#11
Ariel Red Hunter Join Date: Jun 2016 Location: akwesasne, NY-13655 Posts: 2,220	High compression Although I started this about high-end horsepower, upping the compression ratio adds power all the way up the scale. There is more than one way to up compression ratios, two rather obvious ways, and one not so obvious. The most obvious way might be to lower the head as compared to the piston at TDC. Either by milling the head or by turning a few thousandths off of the bottom of the cylinder. I would do the latter, because 1] No chance of weakening the head/cylinder joint, 2] Easy to adjust compression ratios by various shims between the bottom of the barrel and the engine cases. Then the not-so-obvious way mentioned above, which is for you that have TIG welders lurking in the garage, which is to add metal inside the combustion chamber to reduce the cc's of the combustion chamber, as compared to the swept volume of the piston. Even better when adding metal, is to add squish bands to the equation. Squish bands cause more turbulance in the mixture. This causes the mixture to burn faster, leaving more time for the expansion of the gases of combustion, and thus add more pressure on the piston. I don't know whether the younger set can think in steam engine terms, like some people of my age can, But if you can, it really simplifies the grasping of the concept. Imagine a steam locomotive of the turn of the last century, running about 250 lbs of steam pressure, and a temperature of 275 degrees f. Now look at the 1950's engine, running steam at 600 degrees, and 300 lbs pressure. The 600 degree steam is what is causing the great increase in power over the engine of 50 years earlier. Because 600 degree steam expands much more than 275 degree steam. So, too the air in the cylinder expands more than an engine of lower compression. And because of the added turbulance, all of the fuel is consumed earlier, leaving more time for expansion of the exhaust gases. So it is really quite similar to a steam engine, in that the goal is to get as much push out of these expanding gases as is possible. One engine is classed as internal combustion, and the other is external combustion, but expanding hot gases do the work in both cases.
	1