my 80 regal limited

[CamoDeafie]

depending on the piston and crank combo; somewhere from 10-11 to 12s

 

[dr_frankenstein]

depending on the piston and crank combo; somewhere from 10-11 to 12s

you have the compression height measurements for them?

A.j.

 

[CamoDeafie]

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...

 

[futten]

i was kinda hoping for a much simpler answer

 

[charlief1]

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.

 

[mat231v6]

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.

dang i wished the pistons i have would work for him. those pistons would be just what he needs.

 

[futten]

well i wish i had that kinda luck atleast im lucky with the rods im gettin from frankenstein

 

[CamoDeafie]

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...?

 

[charlief1]

But he won't have the clearance for the valves Stephen. He's looking at a lift close to .500.

 

[CamoDeafie]

oo sh!t. then the LN7 with the shallow dish would be his best option?

 

[charlief1]

For what he wants he'll need custom made. Not an option here.

 

[futten]

as ive said befor i really apprichiate the advice from you guys

 

[dr_frankenstein]

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.

 

[futten]

what tricks?

 

[CamoDeafie]

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) ?

 

[futten]

that sounds like a pretty good idea what you guys say?

 

[charlief1]

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) ?

Depends on how thick the piston is. A thin piston will blow through on the cuts.

 

[futten]

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?

 

[futten]

took some new pics of the rust on the car today to many to post so go on the album and check it out but i will share these with you

those blobs arent welds they are SILICONE!

my car pictures by futten - Photobucket

 

[mat231v6]

took some new pics of the rust on the car today to many to post so go on the album and check it out but i will share these with you

those blobs arent welds they are SILICONE!

my car pictures by futten - Photobucket

looks like you have alot of work. dont worry i had almost as much rust when i did my car.