So in the coming weeks I'm planning on buying an LQ4 or LQ9 for my swap. So far I've heard good things from LQ4s and LQ9s when used for FI applications except that the according to some the rods are weak and according to others it's just the rod bolts that are weak. So all of you with personal experience with LQ4s and LQ9s what are their weaknesses? Which parts should I swap out for stronger parts?

 

When I bought my LQ9 I just swap everything from my ls1 into it. So I wouldn't be so sure about what parts are weak but ones u put it 2gether ur not going 2 regreat it awesome motors.

 

Yeah but for now I'm planning on just buying a used longtblock. I'm going to overkill the drivetrain though cause I want to beef it up before I go FI, but I want a few more info on some basic stuff I should worry about when it comes to LQ9s.

 

so why would you go with an engine that has higher compression when it's best to go with lower compression to avoid detonation and run higher boost? LQ4 and LQ9 are identical except the pistons, the LQ9 is the higher compression engine, for N/A i'd say go LQ9 if you want bigger cubes and no F/I but if it's F/I you'd want LQ4 and some 6.0 heads . . . or forge a 347 throw on some P&P 243's with a twin screw and watch peoples mouths drop lol

 

I totally forgot to put that on the thread sorry. Yeah I want to know what the weakness are on both cause depending which one I find for a good price I'll buy. Hopefully an LQ4 since the lower compression would help more for the FI setup. I've read that LQ4 and LQ9s are basically the same except for the higher compression flat pistons on the LQ9 so I was thinking if I can't find an LQ4 I can just go an LQ9 and switch to lower compression pistons or trade them with someone with an LQ4 who wants higher compression for a N/a nitrous setup.

 

For my FI build I'm using an LM7 5.3, dished pistons and boost friendly, then I'm going to slowly build a forged 347 out of my old LS1 block.

 

Are you looking to build an engine or run the stock motor? If you want to build do what I did. Forged 370. Mines a LQ4 block, stock crank, callies rods, weisco pistons and its built for boost. Do it right the first time and just build it.

 

I'm going to run it stock for a while then next summer when I get the cash the bottom end will be forged and I'll turbocharge it. But while the motor is out I want to replace, if I need to, any parts that might be common to fail in these engines. It's my dd which I use to go to college so I can't have it down for too long. During Xmas holidays, which is like almost a month and a half here, it's getting a stock 6.0, a level 3 4L80e from monster, a PST driveshaft, and a 12bolt or ford 9". I want to get the drivetrain beefed up before I build the motor up.

 

It depends on the year of the LQ4. They did not get the LS2 rods until 2004. All LQ9s have them. They didn't get coated pistons until 2003. You're best off with a 2004+ LQ4.

 

Thank you that's the type of info I was looking for.

 

hmmm... not sure of the weaknesses. But I have an 02 LQ4 that's been running strong and I've enjoyed it very much. Very stout motors...