aaronc7's C5 Z06 Build

[aaronc7]

Shit's running well. About 1500 miles on the new bottom end. Made 440hp/415tq on a dynocom dyno.

[KiwiFlavor]

You can eat off that engine bay.

[aaronc7]

I did have a few issues on the new motor. After around 500 miles on the motor I started driving it a little harder/high rpms etc. Dipstick popped out-- I knew something was up from oil apparently hitting the headers and causing some smoke--scary.

I had a track event a few weeks out, so I was wanting to quickly figure out a fix or determine is something more serious was up/cancel the event/hotel reservation etc.

Did a complete compression test and all cylinders were +/- 2-3psi, so that checked out. I did a leakdown on a few cylinders that had the valves closed was something around 3% leakdown. You can't reach the crank pulley/turn the engine over by hand, so it's kinda a pain to do a leakdown. And compression was good so I felt pretty good.

Called the builder and he recommended running some large -10 or -12 AN line off the driver side valve cover into a VTA can and removing the pcv system functionality. Seemed a little "old school mentality" to me, but it was clear I probably just needed more venting. Also worth noting to me was how loose the dipstick was. I can't think of any reason why it wouldn't have been like that pre-rebuild, but it was so loose, basically zero resistance to pull it out of the tube. Obviously my idea of a solution wasn't "strap down dipstick down", but I did go ahead and replace the O ring, which snugged it up quite a bit (like any other normal car's dipstick).

Track deadline quickly approaching I decided to get one of those oil fill one-way breather filters. Lots of venting capacity under load and would close in vacuum, keep stock pcv system in place. Went to the dyno with this setup and it made 440whp/415tq as noted above. Under WOT, some smoke fumes out of the breather, but nothing i'd consider abnormal. Less than my turbo miata had lol. Did some sustained high rpm constant speed stuff (not sure what rpm), and in this case a good amount of fumes were coming out, but no liquid oils and dipstick stayed in place.

At this point I figured I was good to go, but at the track event it turned out that it was not. I got oil puking out of the breather filter and same smoke/headers scenario, so i called it quits. I don't think we got it high enough sustained rpm on the dyno to run into this issue, because i was able to duplicate the problem on the street after the track event. The rpm threshold seemed to be around 5500, running it at that rpm for over a second or so, and problems/smoke would arise.

Went back to the drawing board. On the early LS1s theres a valvecover vent on the driver side. Mine has a plastic/rubber plug, but all VC baffling still in place. Bought a pretty legit catch can setup from a ls1 vendor, it maintains stock pcv system, but the can is well baffled and has a one way breather as well for maximum venting under load. I went all out and got -12AN (3/4”) hoses and fittings. I lucked out and the 3/4” plastic barbs fits perfectly in the valvecover with no epoxy or anything to hold it in place. Long term plan is -12AN alum bung welded on, but it’s totally functional as is.

I haven’t been back on the track, but I can hold high rpms for an extended time, no oily crap or smoke. In fact I don’t feel any oily residue or anything on the outlet of the can. It’s hard to say, but probably working better from a combination of 1.) better venting location (oil fill area has zero baffling) 2.) much larger line 3.) proper can that is filtering out any crap that does make its way out. Next track event not until March, so going to just continue to drive the car once in a while as able.

[Pu Manchu]

6 month bump.