Now what?

With the broken piston removed it appeared all the engine technically needed was one new piston. The problem is that LQ9 engines are a lot more rare than their LQ4 counterparts and the pistons and rods are the difference between the two. So it could be a challenge to find a replacement piston to drop in. On top of that replacing the engine in the FRC is so much more work than my other cars I wanted to be sure whatever I put in was going to be reliable.

So the next thought was to get a set of Summit Pro LS Forged pistons. But I decided against that due to supply chain delays for parts, the time it would take a machine shop to balance the rotating assembly, and the expense for forged parts that I’m not sure is warranted at this power level and use case.

Next idea is to use an engine I have already. The L96, LS2, and 427 all need to gone through which present the same issue as above. The LM7, LQ4, and 98 LS1 all have gen iii connecting rods which would be at risk of bending at the power levels the FRC is making.

That left me with the 2004 GTO LS1 that I rebuilt last fall. I disassembled it, cleaned everything I could, had a machine shop clean all the larger stuff and install new cam bearings. I installed new main and rod bearings and replaced all gaskets. I checked the gap on all the compression rings (they were all > 0.30) so the engine was boost ready. At the same time I installed a SS2 cam, new oil pump, PAC1218 springs, and upgrade the rocker trunions with a BTR kit. Two more benefits of this engine is it is nearly identical the the LQ9 as far as the tune is concerned as well as being 80-100lbs lighter which would help get the front of the car off the ground a little bit more.

The drawback to this engine is I already had it installed in the IROC with f-body windage tray, oil pickup tube, oil pan, and accessories. I had to pull that engine out anyway to install a aftermarket clutch master cylinder among other things so I was only facing time and a few drops of RTV to swap out the parts.

Derek helped Charlotte and I move the IROC out of the back corner and pull off the hood. The next day I pulled the trans then engine out of the IROC.