s346k

iTrader: (4)

ok, so i bought a 2000 LQ4 complete engine. i am looking to use the stock shortblock with an L92 head setup. i remove the factory 317 heads to discover that the pistons are dished? wtf? i thought the loss in compression was from the heads, i was expecting to see flat-top pistons. does anyone know what the factory dish is? and will i be able to see 11:1 compression without flycutting? i figured 11:1 was feasible, but seeing that these pistons are dished has me pondering again. my goals are simple:

1) get as much compression as possible from the L92 head without flycutting
2) run the largest cam i can after determining the above
3) whoop *** on those who oppose 6.0 powa

bluethunder364

iTrader: (5)

If you wanted the stock flat top pistons you needed the LQ9 motor. The LQ4 is rated @325 HP while the LQ9 is 345HP This is the difference between the two. I believe the dished pistons (I have the same combo) are 6.5CC with the valve reliefs. Someone else had posted there set-up and I think by taking a few thous. off and the right head gasket they got 10.0:1 or close to it. If you want 11.0:1 you will need a piston change. I thought about it myself but it is out of my budget for this year

s346k

iTrader: (4)

hrm...thanks man. i seriously doubt i'll be changing the pistons. i guess we'll find out how much compression can be made up in the chamber of the head.

bluethunder364

iTrader: (5)

If you follow some of the magazine write ups on this 6.0 they are making big power for
stock parts. Just keep in mind there is a limit to everything. I plan on using my stock pistons for now, and maybe later as $$$ permits I'll 402 it or something. Plus if you see mostly street duty, hell 11.0:1 is alota compr. for the street. With todays shity gas you would be on the edge. Check Nov. o7 and Dec.07 Hot Rod Magazine for there write-ups, and Carcraft Oct 07

5150mechanic

iTrader: (6)

Went through the same thing,,,, on a budget myself,,,, I kept my eye out for some LS2 take out rod and pistons. Full floating rod and coated flat top pistons plus I had .030 milled off the L92's put me around the 10.75 cr range running a stock LS7 gasket. I think I figured with a .030 cometic should go 11.0 cr. Some saying the L92 head has 70-1 cc. chamber to a 68.5 cc can def. move the numbers around. A set of those just sold off Ebay for something like $130 shipped.

bluethunder364

iTrader: (5)

That was a good plan, I would be happy with the flat tops. So you have the flat tops now plus you did .030 on the L92's ? I plan to order mine (l92's ) this week. The .030 mill will help me for sure with my 6.5CC dish piston. Is the LS7 head gasket form the new LS3 Corvette motor?? Can you share a part # with me? Thanks

s346k

iTrader: (4)

the engine will be in a purpose built "weekend warrior" car. it will be on the street as much as it will be at the track. running the hell out of something is the same - street or strip. i have set a minimum goal of 10.5:1 with the lq4 shortblock. even at that compression, when adding the L92 carbed intake, a healthy cam, and 2 stage plate setup...i'm convinced the motor will make some power. when it blows up i'll buy another shortblock and probably replace the reciprocating assembly at that point and step up the cubes. as of now i want to see what this stock shortblock will take.

5150mechanic

iTrader: (6)

Yes, flat tops from an 2006 vette with .030 milled off the L92's. 12610046 is the part # of the head gaskets SDPC sent me. Def. should check pushrod length, 7.350 should work. I just don't think you can get 10.5 cr. with the dish with out over milling a set of heads and having other fitment issues.

s346k

iTrader: (4)

am i crazy or can the chambers not be welded to achieve a higher cr? there is more than one way to skin a cat.

bluethunder364

iTrader: (5)

Welding the insde of a combustion chamber will most likely screw up the flow characteristics in a big way. 5150 thanks for the information. What do you plan to use for rockers?? I would like to use the stock ones for now again because of cost. According to the chevy book LS/1 LS/6 by Will Handzel the stockers are good to 6500rpm. But I guess that depends on spring pressures and cam profile. Thanks

5150mechanic

iTrader: (6)

No prob, just helping like others have helped me. I'll be using stock rockers for now myself. Ithink unless your runnin nascar or off-shore boats the stock stuff should work fine. How often for how long is that motor gonna hit 7K ? Like you said, the right cam, springs, valves (weight) make the difference. I guess you could weld up a chamber then get it cnc'd$. Let us know how it goes !!!!$$$$$