LQ9 build questions

[askkmb]

Hey,
I'm building a daily driver street truck with a LQ9 and I have the L92 heads and have seen some of you combining that and I have some questions:
1- Do you use the lq9 cam or the l92 cam???
2- Which injectors would you prefer???
3- Or would the l92 injectors even work with the lq9 computer???
Please, anyone.

[jiveass]

l92 cam wont work as it is not the early 3 bolt cam, and also is ground for variable valve timing. so i would stick with the lq9 cam or a mild aftermarket cam. you will need to use the l92 or an ls3 intake for those heads also..

gen4 intakes are machined for smaller-diameter fuel injectors, which require a different electrical connector than used on early LS motors. you will need pigtail adapter for your harnesses. The L76 intake comes with 40 lb injectors... the LQ9 had 29 lb injectors. so a tune is a must.

[SMWS6TA]

one more very important thing to check on is the reductor wheel.

With an 03 you most likely have a 24x setup for the PCM. Any block found after 04' you have a higher chance of them being 58x


Some options in dealing with this:

1) you will need to find a >04 LQ9 that has 24x setup on the crank. You can quickly tell what the block has by the color of the sensor on the block. 24x is black while 58x is grey.
2) invest in a 58x converter to be able to work with your PCM.
3) new wire harness adn PCM setup for 58x
4) break motor down and replace the 58x wheel for a 24x wheel on the crank.


First 2 are best case while the last 2 are most expensive.


Going with the LS3 style heads and intake will give lots of flow and with the right cam very good HP. With it being for a truck you may want more torque then HP for towing and hauling.

With cams and heads you need to check for PTV (Piston to valve) clearances, in this case a custom grind might find you better results.

[jiveass]

yea i forgot about the reluctor...they retained the 24x wheel up to 2006 and the early split year 07s i believe had them as well...like scott said, check the color of the crank sensor. black sensor is what you need.

[SMWS6TA]

You also have another option:

LQ4 and LQ9's share the same blocks and crank. Only major difference is the pistons. LQ9's have a flat tap piston while the LQ4's have a dish piston. Because of this the LQ9's have a higher compression then LQ4's.


I have a LQ4 short block that I'm going to do my 6L build.

Last night I scored used (only have 32K miles) LS2 pistons for $100. Getting these pistons will up my compression a lot.


You can also get LQ9 pistons for about $48 and can swap them. The connecting rod length for the LS2/LQ4LQ9 are the same and so is the crank. This makes them interchangeable. Only on the LS2's will you most likely need to get rods because of the way they are held on to the piston.


FirebirdJones is the guy I've been going to for any LQ4/9 6.0L questions I have. he has been very helpful and knowledgeable in this area You can pm him and I'm sure he'll give much more details and the how/why's that I've glossed over or haven't touch on.