I've heard as low as 48cc and as high as like 56cc, and values in the middle... anybody ever measure the volume of the combustion chamber in the head?



15.9 @ 86.7mph
http://www.exileracing.com

Mods List:
http://highlander.dsmpower.com/sig.htm

sorry i am somewhat confused. combustion chamber in the head? there is only one combustion chamber that I know of, between the piston and the where the valves and spark plug poke through the head, is that what you are talking about?
_________
96 talon esi-t
san clemente, ca



turbo8u> you suck
Uberingram> i know
turbo8u> oh

SaberKhan> Someone needs to snatch that GST of yours up and give you your Cavalier back.

You mean like how much area is there when the piston reaches the peak of compression cycle?

because.. would that vary depending on piston compression ratio?

With the piston at TDC, is that what you are looking for? If so, then that is called the "quench" area. Sorry, not sure what it is though...

Piston is irrelavant for the volume of the head. It's somethingyou see a lot listed on V-8 heads, companies like Trick Flow reduce the volume in the head to bump compression. But that's not important.

How you measure the head's cc is with the head off, get a piece of clear plastic/plexiglass, with a small hole in the middle. Use something like vasaline to seal the plexiglass to the head, then take a burett and fill the head's combustion area/dome/quench area. Then take the reading on the burett and you have the head cc.

What seems to be the most prevailant number floating around is 52cc.

So Mike, How would this information be beneficial.



Nick
97RS

turbo8u> shut your SUCK
ZAO684: NIPPLE warning...maybe>?

It can be used to figure out compression ratios. If you know know stock cc, and you have a milled head and measure the cc of your head you can figure out your new compression ration. It it needed by piston manufacturers to make custom pistons. Doing head swaps between motors it can be usefull... The information has it's uses.

Yes it does, seeing as we dont have it I think its even more important. The method you posted is How I was told to do it and how I would do it. I think You can buy it at a school or lab shop?

Originally posted by Michael_97RS
I've heard as low as 48cc and as high as like 56cc, and values in the middle... anybody ever measure the volume of the combustion chamber in the head? 15.9 @ 86.7mph http://www.exileracing.com Mods List: http://highlander.dsmpower.com/sig.htm

I've been lurching for the last couple weeks and came across this post.

Christ you guys are killing me.

I'll post the numbers

Stock Combustion chamber volume is: 51.797 rounded off to the nearest one-thousandth and some more interesting numbers:

9.6:1 51.797cc
10:1 49.224cc
10.5:1 46.313cc
11:1 43.693cc
11.5:1 41.322cc
12:1 39.167cc
12:2 38.359cc
12.5:1 37.2cc

You could plot a graph to show some other accuracies in case you're off a mm or two.
Yes increasing or decreasing head volume will change the compression ratio and chamber fill. Fuel can't be compressed but air can be. Decreasing the head volume means that the air has even less room to move around in, thus increasing the compression. The trick is raising compression just enough to allow sufficient timing decrease, since more compression is better than more timing. I know for a fact that 12.2 is possible on shitty MTBE 91 octane gas here in Sunny Southern Cali (well no longer sunny but rather smokey)

Anyway, this should help a bit.

Take care Mike, sorry for the trouble...

If it helps any, I made a compression ratio spreadsheet. It has one view that calculates what gasket thicknesses and/or mill depths are required to go from one CR to another. It has another view that lets you calculate what CR would be achieved by changing the gasket thickness and/or mill depths. You may find it usefull - http://www.users.fast.net/~metaljim/garage/CRCalculator.xls


95 Eclipse RS : 5 speed
15.901 @ 88.34mph
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

If the info I found is correct the PT Cruiser has a 50cc head, so if doing a swap and you slap our head on, you will have even lower compression, and that engine is already listed as 9.4:1.

Josiah you are alive.

Jim, I have to take a close look at yoru spreadsheet when I'm off work. Does it take into account the shape of the head, and the fact that it's not round for combustion area as you go up?



15.9 @ 86.7mph
http://www.exileracing.com

Mods List:
http://highlander.dsmpower.com/sig.htm

Originally posted by Skrilla
I've been lurching for the last couple weeks and came across this post.

Welcome back Jo.