my 80 regal limited

from this website Silvolite Pistons-BUICK it says 1.808 for the LK9 flat top piston, 1.805 for the dished LN7 with the .160 deep 2.49 diameter dish; assume this piston would be on lower side of compression compared to the flat top; however, the LN7 MPFI engine has a shorter deck and achieve 9.0 CR with the dished piston,LK9 has same deck height as the 3.8L engines, and flat top is 8.45 CR; but this is taken account in having a 2.66 stroke with a long rod (crank is different)

huh.looks like the RWD 3.8 pistons on the next page has 1.805 and same pin diameter offset...looks like for higher compression, you want the LK9 flat top piston and custom rods? the LN7 head volume is approx 11 CC, but this is taken in consideration that the deck is significantly lower on the LN7 than the LK9 engine; and in addition to the longer rod/crank combo with the 2.66 inch stroke to make 3 liters...
 
Easiest thing to do is to contact a piston manufacturer and have them made the way you want. A 11 to 1 compression will give you what you want and you'll be able to have the clearance cut for the valves that you will need. If you use off the shelf pistons you may have some clearance issues and bend a valve.
 
charlief1 said:
Easiest thing to do is to contact a piston manufacturer and have them made the way you want. A 11 to 1 compression will give you what you want and you'll be able to have the clearance cut for the valves that you will need. If you use off the shelf pistons you may have some clearance issues and bend a valve.
Click to expand...

dang i wished the pistons i have would work for him.:mad: those pistons would be just what he needs.
 
well i wish i had that kinda luck atleast im lucky with the rods im gettin from frankenstein
 
i think LK9 flat tops will bring you to the 11ish compression ratio with the conn rod and crank for a 3.4 stroke engine; as its got much much smaller CCs than the LN7's 11CC head space versus the 25CC heads of the earlier engines...?
 
actually, valve clearance shouldnt be an issue really.

particularly if he has an early block.

but its going to depend on his abilitys as an engine builder to get the slugs checked and then flycut if they need it.

theres lots of ol"skool tricks to do this at home.

think you can pull it off?

A.j.
 
wouldnt it depend on if the pistons are forged or hyperteutic ? I mean; maybe can start with the basic LN7 dished 3.0 piston set then cut reliefs for valve and still maintain reasonable comp if its same comp height as older 3.8 (1.805 comp height) ?
 
CamoDeafie said:
wouldnt it depend on if the pistons are forged or hyperteutic ? I mean; maybe can start with the basic LN7 dished 3.0 piston set then cut reliefs for valve and still maintain reasonable comp if its same comp height as older 3.8 (1.805 comp height) ?
Click to expand...

Depends on how thick the piston is. A thin piston will blow through on the cuts.:eek:
 
i guess a way to find out it i need reliefs in the piston is to get one piston install it put the head on make a casting of the combustion chamber and go from there?
 
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