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Head Lift Engine Damage, Turbo VQ

Off Topic Discussion

If it's not really about tuning or wiring. Then it belongs in here.

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So, I recently had some issues with head lift on my VQ35DE powered Infiniti G35. I’m running a GT35R single turbo with a built motor (Wiseco turbo pistons, Brian Crower rods, and ARP 2000 head studs) and a ProEFI computer with flex fuel/E85. I was planning on adding stronger head studs and gaskets (ARP L19 head studs and HKS head gaskets) and putting the heads back together, easy peasy… or not.

After I pulled the heads, I noticed some damage on the heads, block, and pistons.

1. Heads: there was some scoring outlining the combustion chamber, you can see in the pics below, the machine shop stated that we’d need to weld and resurface the heads.

2. Block: here I noticed the continuation of the above head damage, there was some slight scoring at the inner ridge on cylinder wall, the machine shop said that it shouldn’t be an issue.

3. Piston: so, 1 out of 6 pistons had some alarming damage. Cylinder 1 had a potential crack forming at the top/ring land region, the remaining pistons just had some slight pitting. I’m thinking I’ll just replace that single piston.

Now a “quick” head gasket & head stud has escalated to a full rebuild now.

Just some background, I’ve got nearly 30k miles on this engine, the last 12k miles on E85 almost exclusively. I lifted the heads after a few high boost pulls (approximately 600whp), I ended up driving the car another 4k miles after that, just lowered the boost down to spring pressure. The car ran perfectly, never overheated, etc. I just pulled the heads to really just swap out the head studs and head gaskets, didn’t think it’d have to come to this.

Seems like the engine was seeing some heavy detonation, I’m thinking when I’d lift the heads I’d foul the plugs and that’s when most of this damage must’ve occurred… Any thoughts or input?

Attached Files

For sure looks like knock erosion! Have you checked the bottom end yet?

Is the damage confined to just that 1 cylinder?

I'm going to pull the block this weekend.

The rest of the cylinders had some damage, but this cylinder (#1) had the most damage. The remaining pistons had some pitting, no cracks though.

Thoughts on what could have caused this damage?

Are you still running the returnless system or did you change to a return system with your fuel?

The pitting will be from detonation, with it being worse on one front cylinder I would look towards a lack of fuel delivery, the fact that there is pitting on all the tune would need investigated also

Yeah, I'm running a CJM return fuel system, DeatschWerks 1000cc injectors, a Walbro 485 fuel pump, and E85 for fuel (ProEFI flex fuel system); the car made roughly 600whp.

Detonation can result in the head lifting due to the pressure spiking that goes hand in hand with knock. I've noticed that our N/A Z has massive fuel distribution differences from bank to bank. Investigation has suggested that this may be due to faulty pulsation dampers as these have been known to fail. A good friend of mine in the UK who is s a Z specialist mentioned they've had huge trouble with return style fuel systems if they didn't include pulsation dampers. Might be off track but worth considering.

I'd be very careful about the detonation damage visible on the edge of the bore. You will want to clean this up as it could prompt further issues once you have the engine back together. I'd also get the machinist to check both the head and block surface to ensure they haven't gone soft - If this is the case they are unfortunately scrap :(

Best to get another block and take some timing out, are you deaf?