[gmatov]

OK, try 2,
Hit n run,

15 PSI is not a lot of pressure. Would you agree to that? Even a wump, as you describe yourself, should be able to hold that pressure in the blowgun with your thumb. Now, if you should be talking about a 3 inch hose, go to pi, 3.14 x times radius squared force. Now we are talking holding back 50 pounds of force, so maybe your self acclaimed weakness comes into play.

Correction: Just did the calculation, at 15 psi exhaust pressure, with a 3 inch pipe, you have 106 pounds of effort pushing your hand off it.
When you hold your hand over your tail pipe, by no means are you holding back hundreds of psi. You have lots of VOLUME, which we have been speaking of, here, but very low pressure.
Edit: this is because of cooling and expansion in the exhaust system, the pressure at the exhaust manifold itself is several hundred PSI.


ie, if you had a hand 144 square inches in area, and a 1 pound (Edit:1 pound per square inch) force against it, you would be holding back 144 pounds of force, can you understand this?

Cheers,

George