Compression ratio
 

Does altitude have any effect on compression ratio?
I'm at 5200 feet.

"Volksrod70" > wrote in message
m...
> Does altitude have any effect on compression ratio?

It lowers compression, but the ratio is the same. :)

On Fri, 5 Nov 2004 21:18:42 -0600, "jjs" > wrote:

>"Volksrod70" > wrote in message
om...
>> Does altitude have any effect on compression ratio?
>
>It lowers compression, but the ratio is the same. :)
>

Hmm... Good answer as long as you mean increased altitude (all else
being equal) means decreased compression. Or... at least I agree
with you, so you're probably wrong. :-) I think Tim is starting up a
support group for people who get unnerved by having Chris and I agree
with them, so you may need to talk to him for comforting. As always,
I'm ever so glad I could help. :-D

--

Always carry a flagon of whiskey in case of snakebite,
and furthermore always carry a small snake.
- W.C. Fields

"Shaggie" > wrote in message
...
>
> I think Tim is starting up a
> support group for people who get unnerved by having Chris and I agree
> with them, so you may need to talk to him for comforting. As always,
> I'm ever so glad I could help. :-D
>
>


..................There's a strict age limit.

jjs wrote:
> "Volksrod70" > wrote in message
> m...
>
>>Does altitude have any effect on compression ratio?
>
>
> It lowers compression, but the ratio is the same. :)

At elevation, the pressure in the combustion chamber will be lower at
BDC /and/ TDC; this because you start out with less dense air: at one
mile elevation, air density is only 85.5% of sea level density, so
presumably when the piston is at TDC, the compressed version is 14.5%
less pressure than it would be at sea level.

The compression ratio does not change: If you have an 8:1 compression
ratio at sea level, it remains 8:1 in Denver. The swept volume of the
piston does not change, nor does the the volume of the combustion chamber.

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westphalia: "Mellow Yellow (The Electrical Banana)"
KG6RCR
-=-=-
When asked *why* he was dragging a lobster through the the Bois de Boulogne
on a length of pink(?) ribbon, Nerval replied "it does not bark and it
knows the secrets of the sea." The same goes for a good cat except that, I
fancy, it knows everything.
-- Jane Skinner
------------------------------------

Multiply the sea level compression reading by the FACTOR to see
what it would be at the ALTITUDE. Multiply the altitude compression
reading by the INVERSE to see what it will be at sea level.


ALTITUDE FACTOR INVERSE
1000ft .9711 1.0298
2000ft .9428 1.0607
3000ft .9151 1.0928
4000ft .8881 1.1260
5000ft .8617 1.1604
6000ft .8359 1.1963
7000ft .8106 1.2336
8000ft .7860 1.2723


examples
Compression in psi at sea level = 125 What would the reading be at 7000
foot elevation? 125 x .8106 = 101.325

Compression in psi at 7000 foot elevation = 115 psi. What would the
compression reading be at sea level? 115 x 1.2336 = 141.864.


"Volksrod70" > wrote in message
m...
> Does altitude have any effect on compression ratio?
> I'm at 5200 feet.