flyinbluess

right now i have a twin turbo ls1 on 8lbs of boost.... added about 200hp....
not sure the stock 5.7 can take much more than 8lbs...... so i was thinking of building an lq engine....... i know the lq4 has less compression....... if u are leaving the short block stock is the lq4 better since it has lower compression ? other than compression ratio...... is there any advantage to using the lq9 over the lq4 ? cause i can get a complete LQ4 so much cheaper.
and......... how much boost can the stock lq 4 or 9 take ?
thanks for the help.

Vcious04

iTrader: (16)

I bought a complete 80k mile junkyard LQ4 for $800 and plan on testing it's limits witha front mount single 76 turbo (MPT76, Q-Trim, 72AR charge, 1.00AR Exhaust). Other than a new timing chain, blower cam (mild, 224/234, 567/577 115), LS6 oil pump, chromoly pushrods, 918 springs and retainers, it is internally stock with stock manifolds. Other parts I am using is LS6 intake, BBK throttle body, motortron 60lb injectors, racetronix fuel pump kit, cobalt map sensor.

I plan on echieving 600-650rwhp on 8lbs and 750-800rwhp (with meth) on 14lbs. If I blow it up, just gives me reason to beef it up. We shall see!

To answer your question on block difference's, I believe they are indentical, just different rods (lq9 better rods) and pistons (ie compression).

98Z28CobraKiller

iTrader: (17)

Do a search for specifics but the older LQ4's had a different crank flange in the rear which means the stock auto wont work or something.

flyinbluess

Well..... I can pick up a turnkey 60k LQ4 for 700 or a 40k LQ9 for 1000 but I wanna leave the bottom end alone....isn't th 10.5 compression to much for the aps tt kit at 10 to 12 psi ? All I will do to motor is head work and mild turbo cam

LsxCody

iTrader: (3)

The early lq4s had a different crank also had cast iron heads. I would get the lq4. With a spot on tune I don't think anybody has found a limit on how much is too much

JAX04

iTrader: (17)

if i were using a 4l60e which year lq4 would i want to use?

deadhorse66

iTrader: (2)

99 and some 2000s had a longer crank flange to make it work with the 4L80 without making changes to the bellhousing. Later ones use a spacer to back the flexplate out toward the torque converter, and use standard GenIII dimensions.

kalypso123

useful thread... was searching for these answers and glad I found this.

does the LS1 and LQ4/9 have the same mounting points - for the motor mounts?

xXxSilveradoxXx

iTrader: (5)

Sounds exactly like the engine I'm putting into my 02 Silverado!

2000+ (The LQ4s with the short crank flange)

Yes

stock48

iTrader: (17)

If the LQ4 is 05 up I would go go with it, but if not go with the LQ9 and run good fuel at high boost. The rods are the week link on the 04 down LQ4's, and will bend and fail well before the piston if the tune is right. LQ9's have the better rods.

98Z28CobraKiller

iTrader: (17)

17 psi

JAX04

iTrader: (17)

and you made xxxHP with that 17 psi? just curious

stock48

iTrader: (17)

My 4950LB Z71 4x4 with a stock bottom end 01 LQ4 went 10.65@127MPH 16psi 5000' elv, tried to run 16psi at lower elv went 10.59@124 hurt then snapped two rods on the next run. When I pulled it apart every rod was bent, and pistons were .020''~.100" in the hole. Pistons were still intact, even #7. Here is one of the rods that was untouched by debris

JAX04

iTrader: (17)

so i guess the answer is (for me anywayz), LQ4 then. lol. i dont think i need to run more then 12 psi to make my goals, so ill go with the LQ4 this winter i do my build.

trnsfmr99

iTrader: (1)

This sounds like my setup that's under construction too
Its within a couple of days to completion. Looking forward to 600, nothing more than 650rwhp with that setup. Sounds like we have everything to accomplish that goal

JAX04

iTrader: (17)

True, but dont the lq4s have the better pistons?

want1ls1

If its any help , I have a stock 5.3 180k motor out of the junk yard. I put the motor in my 94 s10, 2 speed glide , s476 turbo 20 psi, 60# injectors , super safe tune , hp tunners 3 bar tune, motor is bone stock except for a 98 ls1 intake. it runs fine and has taken my truck down the track 10.1 @ 136 . I guess my point is these ls motors are strong as hell and i too have a 6.0 ready to go in once the little 5.3 pops. 00 6.0 afr 225mpi turbo cam , apr head studs .. <- i hope the new set up will take me in the low 9's

Vcious04

iTrader: (16)

Nice! It sounds extremely good, it's actually at the tuner shop as we speak get dialed in. Will be making the 1st dyno pulls this saturday if all goes well. I'll keep ya'll posted!

I was very pleased how it turned out. Cranked up on the 1st attempt. All good as of now. Hopefully it will make some power!

xXxSilveradoxXx

iTrader: (5)

Oh you gotta keep me posted! You should post up a video too!

jfg455

iTrader: (5)

We have a 4400lbs C1500 pick up w/5.3 T70 15psi and meth goes 11.9 @ 121 Totally stock except z06 cam and springs. Use a 2001 up LQ4 as they have alum heads and short crank. The blocks have been over 1700 hp, the crank is good to 900-1000, stock rotating asm will make 750ish with meth or race gas but you really have to watch the tune. Even a 50 degree day or night can be enough to lean it out a little and melt a piston. We cracked a piston with the 5.3 due to low fuel level in the tank on a lauch. Uncoverd the fuel pick up for a second and that was it! JMHO