Mordeth

Hello,

I have a 2007 Z06 w/ LS7 that is road raced. I am getting ready to pull the motor during the off-season. Current mods are: Lingenfelter Gt19 Cam (going to yank it out), oem heads milled 30 thou and ported. NW 102mm TB, Mamo ported MSD intake, Haltech 108 CAI, LG 1 7/8 headers, gutted cats, MM catch can, Lingenfelter expanded dry sump tank w/ AVIAID tank insert, Improved racing oil pan baffle, PAC1209X springs (new), Moldstar 90 guides and new intake and exhaust valves (heads just refreshed). Motor is N/A and currently putting down around 580rwhp SAE and 520 lb-ft torque. 95% track (road course) and 5% street. Various other suspension/brake/aero mods.

I have been combating crank case pressurization and oil leaks (pushing oil). I did a leak down and found 50% leakage in cylinders 5 + 7. Car was on a pretty safe tune, but I think I had pre-ignition on the track. Maybe I got a tank of bad gas (93 octane). I put my borescope down the spark plug holes and found this (attached pics). I don't see any cracks/damage to the cylinder liner and don't see any chunking of the pistons themselves.

My plans are to pull the motor, inspect the extent of the damage and rebuild. Assuming my cylinder walls and block are good, here are my plans. I am interested in any constructive feedback/suggestions.

- Install Mahle -3cc forged 4032 aluminum slugs (4.13" bore, 4" stroke, 6.067" rod length). I will bore 5 over and hone the cylinder walls (to 4.13") to accept the new pistons. Current bore is 4.125" (stock)
- Inspect and re-use stock titanium rods and crank. I will replace the rod bolts with ARP
- line hone block and install ARP Main studs
- Rebalance entire rotating assembly to accommodate new pistons
- Install 6 rib IW harmonic balancer
- Install Texas Speed cam custom spec'd by Pat G. 230/244 .651"/.651" 112LSA+2 camshaft ground in 8620 chrome moly.
- Install Johnson 2126LSR Slow Leak Down Race-Style Lifters With Axle Oiling
- Inspect/replace oem rockers with oem rockers
- Measure/replace pushrods
- Install Katech C5R timing chain
- Install Improved racing crank scraper
- Install Improved Racing oil cooler
- Install Dewitts radiator
- Install Katech Red oil pump
- Remove catch can and install GZ Motorsports Vacuum pump from passenger VC
- Static compression will be 12:1 and DCR should be around 9:1.
- Plan to run race gas and/or Boostane. Car will be tuned for 93. Will only use the concentrate to mitigate pre-ignition/detonation. I don't need more power and am at the limit of the power I can produce for the race class I run in.

How does this look? Really looking for constructive feedback from those that know this motor and the components I am considering. I am still up in the air over whether I should go 2318 aluminum or 4032 and whether I should install the GZ pump or just stick with my catch can from the valley plate. If I go 2318 aluminum I would go Diamond pistons, as they will accept my rods which I am not replacing and have the valve relief I desire.

Thanks in advance for any suggestions!

nhra686

The vacuum pump will fix the crankcase pressure problem and help keep oil out of your combustion chambers so your pistons don't look like they do now. with that much compression, you need to control the oil into your combustion chambers as it is an octane killer. Give me a call and I'll help you get a system speced out.

pantera_efi

iTrader: (1)

Hi Mordeth, my customers race long races. (BAJA 1000)

I would add :
DLC piston pin coating.
CHE "rebuild" OEM Rockers, just send to CHE. ($200.00)
Bob Weight REPORT ?
Over Balance @ 2%, may SAVE balance costs with new LIGHTER pistons/pins.
State Oil Filter size ?
Modify Oil Pan for FLOW INCREASE, I will show how to due.
My Oil Filter Magnet, internal.

Lance

Mordeth

Thanks Bill and Lance. Much appreciated.