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I have just opened up a 2006 LQ4 and it has two valve reliefs cut into the pistons facing each other. The numbers 9805-R078 are also stamped in the face of the pistons. Does anyone have any idea why and what the reliefs are for situated as they are? Is this really an LQ4 6.0 litre engine?
Thanks,
Peter
So the valve reliefs are on top of one another? Usually they are diagonal so that which ever side a piston is on, the valve relief is in the correct spot. So what do you mean facing each other? Sounds more like an LQ9. Are the pistons flat or dished? Maybe an aftermarket piston.
The reliefs are horizontal and the right one is a dome and the left one is a cup. The pistons are dished and the engine had never been opened up. Do LQ9 engines have pistons like this?
Thanks,
Peter
LQ4 engines are supposed to have a dish in them but a stock one should not have any valve reliefs cut in it. LQ9 motors have a flat top piston with no valve reliefs either. I am not sure why the valve reliefs would be cut like that. If you could post a picture of it I think it would help out a lot.
You say it has never been apart before? I have been into a few lq4's and 9's and never saw any cuts on the pistons. Like stated above, lq9 will be flat top, and lq4 will have a small dish.
My big block chevy has valve reliefs like that, although the valves are canted, not wedge like on an LS. I'm afraid someone put those in there. I've never seen a factory motor with reliefs like that. Actually the one (towards the exhaust port side) is worthless and ineffective.
l96 pistons in a 3rd Gen. ...you are not the first one in there buddy!
Actually he probably is, the last of the LQ4s, 2006 and 2007 typically have Gen4 rotating assemblies with a 24x crank reluctor. I have had 3 of them opened up and they were all the same. They have the beefier factory rods that are brushed for floating piston pins like the LQ9 as well. The LQ4 that is in my brothers 1987 G20 van was in an 70K mile late 2006 build cab and chassis 1-ton and it has a complete Gen4 rotating assembly. This is well known with people that actually know the 6.0L engines.
l96 pistons in a 3rd Gen. ...you are not the first one in there buddy!
Originally Posted by Fast355
Actually he probably is, the last of the LQ4s, 2006 and 2007 typically have Gen4 rotating assemblies with a 24x crank reluctor. I have had 3 of them opened up and they were all the same. They have the beefier factory rods that are brushed for floating piston pins like the LQ9 as well. The LQ4 that is in my brothers 1987 G20 van was in an 70K mile late 2006 build cab and chassis 1-ton and it has a complete Gen4 rotating assembly. This is well known with people that actually know the 6.0L engines.
You didn't have to wait for 2010 L96 to get valve reliefs.
I call these LY6 pistons which had them standard 2007 , but I have opened open 2006 LQ4 that have had them too. Some did some didn't, supposed they have been in 2005 also.
Oh and also the L76 truck engine had the valve reliefs also.. But the L76 Cars had flat tops .iirc the reason GM started using it was in preparation for Gen lV with afm and vvt .How accurate that is I not sure ?
hey there, been a while since this thread has had any additions. I have an lq4 that was pulled out of a 2007 silverado classic. No DOD/AFM. Appears to be Gen 4 rotating assembly, and the pistons also have the fly-cuts!
03-08-2011, 10:24 PM
LQ4 with fly cut pistons? 
