86Tri-z

I have prc 62 cc heads with the mls .052 head gaskets. I blew a hose in the middle of summer In Phoenix and over heated my car. Car still runs fine just uses a little coolant I plan on pulling the heads here in the next few weeks and was thinking about using the ws6 store head gaskets that are .045 or .046 compressed thickness can’t remember which. The bottom end is stock 98. Looking for a rough estimate on what the compression will be.

G Atsma

Summit has a compression calculator. You just enter bore, stroke, chamber volume, deck clearance, gasket thickness, and # of cylinders.

86Tri-z

I did not know they had that thanks.

G Atsma

Yeah, out of all the ones they have, I play with the cam timing calculator and compression ones the most. Pretty handy!

86Tri-z

was very handy after putting it in there would put it at 10.85:1, only problem is ws6 store says it’s .045 before it’s clamped down so it could be closer to 11

86Tri-z

actually I take that back on their site says compressed thickness is .045-.046 but a thread on here a tech from their site wrote that is before it’s clamped down so I don’t know which one it is

G Atsma

I would believe WS6Store. They have a good rep here, and they are the source. Trust them....

86Tri-z

alright appreciate the help

BFK86

iTrader: (1)

I'm assuming it's the original LS1? if it's anything like mine the pistons were .007" out of the hole which you have to account for. Using the summit compression calculator it should be at about 11.2:1 compression with those heads and the .045" gaskets.

86Tri-z

did I do something wrong because I get 10.85:1

this isn’t the summit one tried a couple different ones

86Tri-z

I get 10.82 on summit I’m guessing the deck clearance because I haven’t pulled the heads off

LS1Formulation

iTrader: (13)

Your deck clearance should be a negative value if the piston is out of the hole.

86Tri-z

it’s the stock 98 flat tops I might have the heads off today.

LS1Formulation

iTrader: (13)

Generally on stock LS1 engines, the piston comes out of the hole by anywhere from .006-.009. My '98 was .006 out when I built it. And I myself have never seen an LS of any kind with pistons below deck from the factory.

86Tri-z

ok cool I just put that in wrong. I just put it in as -.006 got the 11.2:1. That should still be pump gas safe I’ll have to re check ptv clearance. Do you think I should get my custom tune re done with the extra compression. It was tuned for the.052 gaskets but tuned for phoenix. I live 100 miles north with way higher elevation so the car already runs way richer here.

grinder11

iTrader: (1)

If you're using a MLS head gasket they don't move much, if at all. I use a micrometer to measure thickness before install to ensure I'm installing what I spec'd. All the MLS gaskets I've seen are stainless steel with an ultra thin coating of Viton. There's not much to compress. It's been my experience that my .052" thick gasket stays at .052", maybe to .051". Steel won't compress in this application. Older style, non MLS gaskets will compress somewhat.

86Tri-z

Is there a reason why prc is blocking off the rear coolant crossovers? I think this is why I lost the head gasket when I blew a hose.

86Tri-z

think I’m going to re use the same style gaskets I don’t want to get the car re tuned again. Gotta drive the car across the country this year when I move anyway. I plan to build an engine when I get to my new house.

86Tri-z

I get about.006-.007 out of the hole

LS1Formulation

iTrader: (13)

Good to go then. I see no issues running 11.0-11.5:1 on pump gas with a decent sized cam. The piston being out of the hole actually helps with quench and mixture motion, which helps your engine have a higher detonation threshold. With a .045 gasket, you're sitting around a .038-.039 quench area. I like to shoot for around .035 myself, but I'd have no problem being a few thou over that.