SilverXJ wrote:
I still don't understand KB's logic in putting the piston so far down in the hole.
jsawduste wrote:Did you talk to Panetta at Diamond ? For whatever reason his quote was far different then what you were given.
A longer rod wouldn't be a bad idea. say add .015-.018 to it and then have enough left over to flatten the deck. I need to look up what my Eagles were in length. I know they were longer the 4.0`s but I don`t recall how much.
And yes the Scats are 6.123/5 in length.
I thought the logic was the KB pistons were "teamed" with the Eagle rods to give a zero deck out of the box. Eagle rods had/are 6.150".
jeepxj3 wrote:I still don't understand KB's logic in putting the piston so far down in the hole.
I just checked and it appeals the deck of the 944s is the same as a stock piston at .0215 down the hole correct?
I see stock pin height at 1.601" and the 944s at 1.353 + 0.248 in rod length difference = 1.601" The other stock pistons are sitting further in the hole. Why doesn't the compression ratio calculator account to pin height and rod length? It has rod length in there but without pin height it does not seem it is doing much. I guess you have to adjust the deck height to account for the pin height?
The IC944 pistons paired with 4.0L rods and a 258 crank are 0.027" down the hole at TDC. Like Chris, I don't understand that logic either but I think there's an explanation. If you go to KB's site, they quote a deck height of 9.433" instead of the standard 9.453" for the 4.0L block so I guess KB expect you to mill 0.020" from the block deck (leaving a deck clearance of 0.007" and a CR of 9.6:1).
Stock 4.0 pistons (1.601") with 4.0L rods and a 4.0 crank are 0.022" down the hole at TDC.
When using the CR calculator you enter deck clearance to account for the pin height.
I6FAN wrote:I thought the logic was the KB pistons were "teamed" with the Eagle rods to give a zero deck out of the box. Eagle rods had/are 6.150".
If only! The problem is that the IC944 pistons have press fit pins (diameter 0.928") and were designed specifically for the 4.0L rods in a stroker, whereas the Eagle rods were designed for pistons with full-floating pins (diameter 0.912") thus making the IC944 pistons incompatible.
To achieve zero deck clearance in a standard unmilled 4.0L block with a standard stroke 258 crank, the total length of rod + piston needs to be ~7.505".
Therefore the piston will need to have a pin height of 1.380" when coupled with a 4.0L rod (6.125") or a pin height of 1.355" when coupled with an Eagle forged rod (6.150").
The IC944/945 piston would have been ideal together with the Eagle rod if the two were compatible but since they aren't, you'd need to specify custom pistons. I've calculated the required piston dish volume based on a zero deck clearance, 57cc combustion chambers, and a 9cc head gasket volume (0.043" thick HG) to achieve the following compression ratios in a 4.6L stroker:
sly-jeeper wrote:does anyone have a good chart or enough experience for quench, static compression,and dynamic compression related to octane at sea level
i know there are lots of 'rules of thumb' but im looking for someone with real experience with the stroker and what it likes...
mine is square motor 3.895
OEM renix 89 cam... retarded owner=retarded cam(hopefully being changed in a few weeks)
pistons dished to 20cc
4.2 rods
0 deck
degreed, balanced.
forget ign timing.
carb... (i know)..
running KB/SILVOLITE 20cc pistons w/coated skirts
if i run 87 or even old gas-it pings.
one time I ran out and had old 87 gas in it-almost couldnt drive home.
seriously.
I run 91 exclusivly.
dig around in my started threads-you can see my build and what its in.
