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Id'ing a LQ4 vs an LQ9

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Old 03-16-2009, 09:58 AM
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Default Id'ing a LQ4 vs an LQ9

I bought an engine out of a junkyard for my turbo build. It is out of an 07 Van. It's a 6.0, but how do I tell if it's an lq4 or lq9 without pulling a head to check the pistons.

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Frank
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Old 03-16-2009, 10:05 AM
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They only fitted LQ9's,

to Cadillac Escallades and GMC Denalis AFAIK.
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Old 03-16-2009, 10:07 AM
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Originally Posted by Sid447 View Post
They only fitted LQ9's,

to Cadillac Escallades and GMC Denalis AFAIK.

Great! Thanks for the quick reply! That's what I was thinking, but I wasn't positive.

Frank
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Old 03-16-2009, 10:09 AM
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Your only a set of pistons away from an LQ9 spec anyway,

They were identical other than that I think (apart from small differences in the tune).
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Old 03-16-2009, 09:41 PM
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correct, vans only had the lq4
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Old 03-16-2009, 10:39 PM
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if you are going FI, you want the lq4 instead of the lq9 because of the lower CR. and it seems to me that you have an lq4.

good luck on you build.
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Old 05-01-2009, 10:52 AM
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Here is an answer to your question one person was right one is aluminum and the other has a cast iron block the one you have has the cast iron block which is better for turbocharging.
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Old 05-01-2009, 11:15 AM
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Originally Posted by turbomanlq4 View Post
Here is an answer to your question one person was right one is aluminum and the other has a cast iron block the one you have has the cast iron block which is better for turbocharging.
negative, no LQ4 or LQ9 was ever built with an aluminum block. The only difference is dished pistons on the LQ4 and the LQ9 i believe has slightly beefier rods. FYI, the LQ9 was also put in the Silverado SS.


Back to the OP though, you definetly have an LQ4 if its from a van.
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Old 05-01-2009, 11:53 AM
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Originally Posted by turbomanlq4 View Post
Here is an answer to your question one person was right one is aluminum and the other has a cast iron block the one you have has the cast iron block which is better for turbocharging.
As adam1803 said, but to add you are thinking of the LS2.

LQ4/LQ9 = Iron Blocks
LS2 = Aluminum Block

All three are 6.0L, and the LQ9 is an iron version of the LS2 but with 317 heads, versus the LS2 and the 243 heads.
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Old 05-01-2009, 01:47 PM
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later (2005) and up lq4's have the same internals as the LQ9 and LS2 sans the pistons. The LS2 internals are identical to the 02 up LQ9's I believe.
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Old 07-10-2009, 03:32 AM
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So if you don't know what the motor came out of, how else can you tell the difference between a LQ4 and LQ9?

I have a 6.0 long block, and I know its an '05 model year because of the casting date on the heads (10/04).

So how else I can I tell without yanking a head to look at the pistons?

Thanks!!!

Last edited by Ford_Assassin; 07-10-2009 at 03:52 AM. Reason: Details.....
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Old 07-10-2009, 03:42 AM
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Originally Posted by Ford_Assassin View Post
So if you don't know what the motor came out of, how else can you tell the difference between a LQ4 and LQ9?
I have a 6.0 long block, and I know its an '05 model year because of the casting date on the heads (10/04).
So how else I can I tell? Thanks!!!
Have a read here:-

http://en.wikipedia.org/wiki/GM_Vortec_engine

LQ4 has dished pistons, LQ9 has flat-top.
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Old 07-10-2009, 03:51 AM
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Originally Posted by Sid447 View Post
Have a read here:-

http://en.wikipedia.org/wiki/GM_Vortec_engine

LQ4 has dished pistons, LQ9 has flat-top.
Thanks dude, but I guess I should of been more specific.....

I don't want to yank off the heads to confirm if it has flat top or dished pistons on a perfectly good long block..

---------------------------------------------------------------------------

Any other way to tell the difference without tearing into the motor?

Thanks again.
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Old 07-10-2009, 07:16 AM
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Is it possible to pull out a plug and use a screw driver or something similar to feel the top of a piston? Maybe a wooden dowel rod?
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Old 07-10-2009, 07:22 AM
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Other than what these guys have already said, there is no way to tell them apart. Pistons are the only difference.
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Old 07-10-2009, 09:24 AM
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I remember seeing a thread on performancetrucks.net that showed how to identify the pistons from the bottom. It had pictures detailing the differences between the two. It wouldn't be a big deal to pull the oil pan and have a look.
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Old 07-10-2009, 10:05 AM
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Originally Posted by 5.3LJimmy View Post
I remember seeing a thread on performancetrucks.net that showed how to identify the pistons from the bottom. It had pictures detailing the differences between the two. It wouldn't be a big deal to pull the oil pan and have a look.
If that were true it would be great since I am swapping out the truck pan for a LS2 Corvette pan anyway.
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Old 07-22-2009, 06:50 PM
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compression test. Find out the stock compression for the lq4 and lq9 and check compression. assuming you have the heads on the block that came on it.
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Old 07-22-2009, 10:36 PM
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Man, that only took about an hour of searching. It appears that the question "What's the difference between LQ4/LQ9?" is as popular on PT.net as "What cam should I get?" on here.
http://www.performancetrucks.net/for...ght=LQ9+piston
If you look at the pictures in this link you can see the obvious difference between the LQ4 and LQ9 pistons. I would say it's no problem to identify them this way from the bottom.

Last edited by 5.3LJimmy; 07-24-2009 at 02:27 PM.
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Old 07-23-2009, 04:01 PM
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Don't mean to hijack this thread but what is the stock compression ratio on the lq4? thanks
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