wells01

iTrader: (1)

when figuring static compression ratio, does the distance from the top of the piston to the top ring need to be took into account? Im building a 408 and I thought I was done figuring compression until I read something about this. I used the compression calculator from the csgnetwork.com website which I've
seen its used alot by other people on here.

my specs are
CID-408
Bore-4.030
Stroke-4"
Rod Length-6.125
Head Gasket Bore-4.060
Head Gasket Thinkness-.040
Head Chamber Volume-64cc
Piston Dome Volume-wiseco -3cc flattops
Deck Clearance-0

Using the compression calculator mentioned above I get 12:1 which is what I want, but now I'm unsure.

PREDATOR-Z

My calc gives me 12.09:1 with the info you gave.

wells01

iTrader: (1)

ok, yeah I seen another calculator that asks for the dimension from top of piston to top of first ring, so I would think that would make the compression come out lower if that had to be figured in. The guy that done my machine work figured for me and came up
with the same thing. I guess most dont use that dimension, just makin sure I actually end up with the ratio I want.

RezinTexas

In my calc the area above the top ring was about 2% of the clearance volume. Kinda insignificant, but if you are very detail oriented then it can be considered.



Here is the link to the calculations explained: http://www.scribd.com/doc/145057435/...RAFT-01-Jun-13

427zm

iTrader: (9)

Rezin, this is both awesome and ridiculous all in one. Your signature should always be followed w/ UATD - "Ultimate attention to detail"

SOHCNightmare

This is great. Bookmarked

RezinTexas

using the top ring volume, I get 11.85:1. Without using it, I get 12.08:1. Here are my assumptions for info that you didn't give:
Top Ring Land thickness (T_RL) 0.295"
Top Ring Land diameter (D_RL) 3.971"

thanks man

wells01

iTrader: (1)

yeah im not sure on the above the ring specs. my shortblock is already together and now i have this to think about lol. i may call wiaeco today and see if they can give me the specs.

wells01

iTrader: (1)

just got off the phone with wiseco and the specs are. thickness-.295, dia-3.976, so your right on that. so im not where I thought i was.