pdbq

iTrader: (7)

I see the factory compression ratio for an LQ9 HO motor (with flat top pistons) used in trucks such as the Silverado SS is 10:1. So how much compression will I gain from putting on stock 853 heads? If this will be under 11:1 compression, how much milling would it take to get there, assuming I'm using a standard thickness head gasket? If I decide to mill down the heads to achieve 11:1 compression, would I have to flycut the pistons for PTV clearance?

edit: cam of choice will be a torquer 2 cam with stock 1.7 rockers...

theguyulove2hate

iTrader: (5)

Just get the head you have on there milled. You have 317's on there, the 317's are a better form of the 243's (ls6/ls2). The 853's are LS1 heads and flow no where near the 317/243's. I just dropped an LQ9 in my Camaro and i am going to use CNC'd 243 heads.

pdbq

iTrader: (7)

I bought the block with the 99-00 iron heads. I've heard those heads are not good at all for any performance application. Motor started its life as an LQ4, but I'm rebuilding using the LQ9 specs, with the addition of the 853s and a T2 cam.

12secSS

iTrader: (30)

If you do not already have the heads, go get some 243s. They can be purchased for $400. Thos 853 are pretty much useless unless you port them.

pdbq

iTrader: (7)

What would the compression ratio be with the 243s vs the 853s on my 6.0L with the LQ9 flat top pistons?

oange ss

iTrader: (50)

using GM MLS gasket @.060

243 = 11:1

853 = 10.6:1