GM LQ4 decoding
Hi guys, a buddy of mine got a LQ4 engine coupled with a NV4500 tranny, he wants to know what the donor vehicle was, the code stamped on the block is:12551364
Any idea to how to decode that? cannot find any help on the net, any help will be greatly apprecciated, thank you.
The LQ4 6.0 was available on the 1999-2007 GMT800 3/4 ton and 1 ton trucks. 1999 and 2000 LQ4's have iron heads, 2001+ have aluminum heads. The only difference between an Lq4 and an LQ9 is the pistons/rods. The LQ9 uses a flat top piston yielding 10:1 compression, the LQ4 uses a dish piston for a 9.4:1 cr. Same cam, heads, crank, block etc etc, PCM tune is also different.
The 2001 C3 and 2002+ Sierra Denali also used a version of the LQ4 which was rated at 325hp@5000rpm/370 lb/ft torque@400rpm. These had a slightly different exhaust, ar intake and PCM tune.
The 1999-2007 LQ4 was rated at 300hp@4400rpm/360 lb/ft torque@4000rpm. These HD trucks featured a dual 3" exhaust from the manifolds back to the dual in/single out muffler. These trucks were detuned via PCM tuining in order to comply with federally mandated noise laws.
The 2002+ LQ4 was rated at 345hp@5200rpm/380 lb/ft torque@4000rpm.
Cant really diciper what vehicle that engine comes from, unless you had the VIN. So its either a 1/2 ton Sierra Denali(C3) or 1/2 ton HD(heavy half) truck or 3/4-1ton HD truck/Suburban.
I am not seeing that block casting number being used after 2002. Because the engine has teh 4500 trans,I'd surmised its from a 1999-2002 3/4 ton ton HD truck as thats teh only vehcile that uses teh LQ4 and the NV4500 trans.
here is the GM info on the trans
Rear wheel drive, five-speed manual transmission
5.7L - 7.4L
Maximum Engine Torque:
Maximum Validated Gross Vehicle Weight:
Aluminum and Cast Iron
Castrol Syn-Torq Synthetic oil
97.1 kg (wet)
Fluid Capacity (Approximate):
Power Take Off:
Yes. One - Both Sides
GMC Sierra and Chevrolet Silverado(2500 HD and 3500 series)
Same for the LQ4 engine
Vortec 6.0L V8
Overhead Valves (2 valves per cylinder)
1 - 8 - 7 - 2 - 6 - 5 - 4 - 3
Bore x Stroke:
101.60 x 92.00 mm
Sequential Fuel Injection
325 @ 5000 rpm (GMC Sierra Denali)
320 @ 5000 rpm (GMC Yukon Denali/Yukon XL Denali)
320 @ 5000 rpm (GMC Yukon XL and Chevrolet Suburban)
315 @ 5000 rpm (HUMMER H2)
300 @ 4400 rpm (2500 HD and 3500 GMC Sierra and Chevrolet Silverado equal to or greater than 8600 lbs. GVW)
290 @ 4400 rpm (Chevrolet Express and GMC Savana 3500 Series)
370 @ 4000 rpm (GMC Sierra Denali)
365 @ 4000 rpm (GMC Yukon Denali/Yukon XL Denali)
360 @ 4000 rpm (GMC Yukon XL/Suburban)
360 @ 4000 rpm (HUMMER H2)
360 @ 4000 rpm (2500 HD and 3500 GMC Sierra and Chevrolet Silverado equal to or greater than 8600 lbs. gvw)
350 @ 4000 rpm (Chevrolet Express and GMC Savana 3500 Series)
Fuel Shut Off:
6000 rpm (With M32 transmission)
Exhaust Gas Recirculation (Chevrolet Express and GMC Savana)
Positive Crankcase Ventilation
GMC Sierra Denali (formerly Sierra C3)
GMC Yukon Denali
GMC Yukon XL Denali and Chevrolet Suburban
GMC Yukon XL 3500 Sierra and Chevrolet Silverado Pickup and Chassis Cab 2500 HD and 3500 GMC Sierra and Chevrolet Silverado
Chevrolet Express and GMC Savana
High Silicon Molybdenum
Cast Nodular Iron
Main Bearing Caps:
Cast Iron with Undercut and Rolled Fillets
Forged Powder Metal
Extended Life Spark Plugs
Extended Life Coolant
Oil Level Sensor
Electronic Throttle Control (All applications except Chevy Express and GMC Savana)
Electronic Throttle Control on H2, including specific off road (low range) throttle progression calibration
that is great, thank you!
So 99% , engine came from a '99-'02 pick up truck, right?
sorry, not just pick up truck, i forgot about the vehicles list you posted...
My buddy just gave me a code he found on the heads: 2352H9632363, not sure if it says something or not...
If the trans thats currently mounted on the engine is the original, the engine by simple deduction, the engine is going to be from a HD pickup truck as thats the only application that used this manual trans. The Duramax and the 8.1 engines came with the Allison Auto and the ZF S6-650 6 speed manual and only the LQ4 came with the NV4500.
From my post, if the LQ4 has iron heads, it a 99-2000 LQ4. If it has aluminum heads I can tell its a 2001-2007 LQ4. But the block casting number you supplied me only runs up to 2004 from what I can tell. So my educated guess is that you have a 2001-2004 LQ4 6.0 engine from a 2001-2004 3/4 ton or 1 ton truck.
the head code you supplied means nothing to me unfortunatley.
Why do you need the exact vehicle the engine came from if I may ask?
Engine has alu heads so must be the newer model mountedn on HD trucks.
OK cool, not a problem. Take care.
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