domed piston 2002+ 3.0L

[evanesce69]

Does anyone have any hard numbers onthe size of the dome, either in cc or cu in?

I'm having some trouble finding that little tidbit of information...

 

[fixizin]

Very hush-hush... seriously, you'll probably have to dip one in a graduated beaker of water, and check the displacement that way... don't look at me, I have neither beaker nor piston available.

Also, where's the thread establishing which post-2K 3.0 Vulcans have these domed pistons?... suddenly I feel inadequate with my 19th Century flat pistons, lol...

PS: Do you have some combustion chamber sim models you can plug detailed data into?

 

[evanesce69]

just my noodle and trusty TI-83 plus.

my strong point is theoretical math and systems, it isnt that far removed to figure compression

 

[evanesce69]

OKAY.... some numbers that I crunched last night....

Bore - 3.5
Stroke - 3.14
Non EtOH head - 49cc
EtOH head - 47cc
Nominal gasket thickness - 0.065"


So here goes:
Area of bore = pi R^2 or 3.1415(3.5 / 2)^2 = 9.62
Volume of cylinder = area * height or 9.62 * 3.14 = 30.21 in^3 per cylinder

The volume the head gasket provides is a similar calculation
Area of bore * compressed height of gasket or 9.62 * .065 = .625 in^3

Now we just convert the CC of the head to in^3, we simply multiply by a factor of 0.061
49 cc * .061 in^3 / cc = 2.989 in^3

So total volume of the combustion space at BDC is cylinder volume + gasket volume + chamber volume
30.21 in^3 + .625 in^3 + 2.989 in^3 = 33.824 in^3

Total volume of chamber at TDC is just the gasket volume and chamber volume, (assuming zero deck height)
0.625 in^3 + 2.867 in^3 = 3.614 in^3

Compression ratio is volume at BDC over volume at TDC
33.824 in^3 / 3.614 in^3 = 9.35:1, or the compression of stock engine

Substituting the smaller chamber heads gives
47cc *.061 in^3 / cc = 2.867 in^3
33.702 in^3 / 3.492 in^3 = 9.65:1

ASSUMING the dome on the piston is between 5 and 7cc
5cc * .061 in^3 / cc = .300 in^3 min
7cc * .061 in^3 / cc = .427 in^3 max

The volume of the dome is subtracted from both the BDC and TDC volumes
33.402 in^3 / 3.192 in^3 = 10.46
33.275 in^3 / 3.065 in^3 = 10.85

The combination's:
49cc head and stock piston : 9.35:1
47cc head and stock piston : 9.65:1
49cc head and dome piston : 10.46:1
47cc head and dome piston : 10.85:1

I have options to play with, and with the high octane of E85, I could easily run 10.5-11 compression

That is all dependent on the my assumption of the dome size.....

 

[evanesce69]

Just for you fixizin!

http://www.enginebuildermag.com/Article/2179/rebuilding_the_ford_30l_v6.aspx

 

[evanesce69]

i found some information about the dome. seem meager to me but here it is

1.966" x .032"

Very small, only 1.6 cc

this will put a serious wrench in my plans......



CRAPPERS

 

[fixizin]

Now, now... this is no time to be timid... think about...

BRAZING ON YOUR OWN DOMES! Yeah baby, YEAH!

True, the consequences of dome-separation would be catastrophic, but what is that when PROGRESS against Big Auto and Big Oil is at stake?

 

[triumphrider-1]

You could just get some aftermarket pistons to bump the compression to 12:1 (I think they make them...). If not you could always have some made, that what we do with our race bikes.

 

[evanesce69]

point me to those 12:1's

i'll be all over that like stink on you know what???

 

[triumphrider-1]

After poking around some websites I could not find a kit for our awesome 3.0L motors. However, I did send a couple companies an e-mail inquiring about them possibly makingsome custom pistons. Will let you know what they say.


Edit:
Are you going to use your current block or a different one?

Edit again:
Ross Pistons makes custom domed pistons for, what looks to be, any Ford 6 cyinder:
http://www.rosspistons.com/uploads/6_cylinder_custom_f_m.pdf
May want to give them a call to see about different compression ratios avalible and pricing.