Iron block LQ4 vs. LS2

[Jay37]

I recently picked up a '99 2500 HD pick-up. It had 350,000 miles! ran and drove with original driveline, this truck had a very hard life, yet the engine still looks great. Very impressed. Has anybody out there ran the LQ4 in a perfomance app? How expensive does the gen3 LQ4 to Gen4 LS2 swap get with computer and sensor changes? The reason I ask is because I would like to build the 6.6 LQ4 then swap out short blocks with the LS2 to avoid having the car laid up for who nows how long. I paid 500 for the HD truck got a LQ4, 4l80, and 350 back in scrap weight. It seems impossible to find a good deal on a LS2 block?
Thanks in advance for any help

[Blackbird WS6]

if im not mistaken Ron aka HI-PO is running the LQ4...not 100% sure

[ls1camino]

The difference between the Gen III and Gen IV motors are as follows:

- Valley Cover...LS6 style with the PCV in the cover. Other changes include the Oil Pressure Sensor being integrated into the cover just like the PCV. The thing here is that the valley cover matches the Gen IV block, so an LS1 or LS6 Valley Cover should be used in your application.
- Knock Sensors...these were moved from the Valley Cover to the side of the block. Because you'll be keeping the Gen III Valley Cover, you don't have to worry about this.
- Timing Cover...camshaft sensor was moved from the rear of the engine to the front. You'll also need the electrical extension.
- Cam Timing Gear...has provision for the camshaft sensor being moved to the front.

Everything else should swap right over.

[Jay37]

Thanks!

More questions,

Do all of the LS2s have a 58x reluctor wheel? If they do what would need to be done to get the factory computer to work with the gen3s 24x wheel? I am assuming that knock sensors would operate on the same frequency?

[shady milkman]

there are conversion kits to run a gen III to a gen IV

[ls1camino]

Thanks!

More questions,

Do all of the LS2s have a 58x reluctor wheel? If they do what would need to be done to get the factory computer to work with the gen3s 24x wheel? I am assuming that knock sensors would operate on the same frequency?

I THINK there is an electrical converter out there that will plug in between the sensor and the computer...if not, you'll need to get the correct reluctor wheel pressed onto your new crank.

there are conversion kits to run a gen III to a gen IV

It sounds like he wants to put the LQ4 into his GTO which has a Gen IV LS2, so he already has the parts, he just wants to know what he needs to swap it over.

Taking that into consideration, you won't need the extension for the cam sensor.

[shady milkman]

I THINK there is an electrical converter out there that will plug in between the sensor and the computer...if not, you'll need to get the correct reluctor wheel pressed onto your new crank.



It sounds like he wants to put the LQ4 into his GTO which has a Gen IV LS2, so he already has the parts, he just wants to know what he needs to swap it over.

Taking that into consideration, you won't need the extension for the cam sensor.

good call.

[Jay37]

I talked to performance wiring. according to them, all the gtos have a 24x wheel.