Mustang and Ford Performance Forums banner
1 - 2 of 2 Posts

· Registered
1 Posts
Discussion Starter · #1 ·
I am trying to decide if I need (or should) use 0.010" thickened head gaskets. I realize removing material from the block and heads increases the compression ratio, but it will also retard the timing at least several degrees since it changes the physical relationship between timing chains / crankshaft and camshafts. Additionally, it seems recommended to avoid thicker headgaskets if possible because it increases probability of headgasket failure.

If possible I'm trying to keep stock or better compression ratio. It might be a toss up between losing some compression at the cost of keeping the timing close to stock..
I am trying to calculate the compression ratio using the oversized pistons that I have installed. I've seen videos of people measuring the volume of a liquid that fills the cylinder head and piston to upper deck to accurately determine combustion volume. Should I do this or am I overthinking things?

I've tried some online calculators but cant seem to get consistent results between any of them. If anyone is familiar with this and could help me with the calculation or point me in the right direction, it would be greatly appreciated!

Specs as follows:

5.4 3V out of a 2009 F150 Platinum. (I realize this is a mustang forum, but I'm getting 0 help from the F150 forums on anything technical. So figured I'd give this forum a shot.)

Block decked -0.010"
cylinder heads resurfaced -0.005 (at most -0.010", have no data)
cylinder bored from 3.55 to 3.571 (+0.020")

Stock compression ratio: 9.8:1

Bore: 3.571" (stock 3.55)
Stroke: 4.160" (stock 4.170)
Rod Length: 6.658"
Headgasket Bore: 3.640"
Headgasket thickness: 0.036" ? (Or 0.046 if I use 0.010"+ Thickened)
Deck Height: 0.120" (to be confirmed shortly)
Piston head vol: +11.80 CC (piston spec)
1 - 2 of 2 Posts