MEAN GTO

iTrader: (1)

Hey everyone, I just had a forged LY6 (iron block) built with Wiseco pistons and their GFX rings. It's on a twin turbo setup and I'm noticing a bit of blow-by after 70 miles of driving.

Due to the turbos having just been rebuilt for the new engine, it was suggested to me by the turbo shop that since some signs of debris was found after tearing the turbos down before the rebuild, that since I would be running the turbos on a brand new engine immediately after they were rebuilt, that I run some basic conventional oil and let the car reach operating temperature, then drain that oil out, change the filter, and refill, before taking it out for a driving or raising the RPM. This was in effort to attempt to eliminate the turbos from getting contaminated with debris from the new engine, so I did just that.

After letting the engine reach operating temperature on the first oil fill with some basic (Carquest brand) 5w 20 oil, I drained and refilled with Mobil 1 conventional 5w 20 and took it out for a drive around the area, getting on the throttle here and there. Once I confirmed all seemed to be good with things (no fuel leaks on the new fuel system, oil oil leaks, no exhaust leaks, etc.) etc., aside from some obvious blow-by, I then took it out and did around 70 miles of driving on it. I didn't get to put a lot of load/hard driving on it often during the drive, but I did make sure to get on the throttle several times for a few seconds.

I'm not sure if with around 75 miles now on the engine I should expect the blow-by to have cleared up by now, but I'm honestly getting concerned about it. I ordered some COMP Cams break-in oil a couple of days ago, and was planning on draining the current oil and replacing with the break-in oil and go out and try to drive the car a bit harder for a while, but I'm not sure if now having driven it 75 miles and already having had a few hours on the engine now is too late to bother with break-in oil or not.

I want to try to save this motor before it's too late, because I sure don't have the motivation nor time to tear everything back apart and take the short-block to the builder. What do you guys suggest I do at this point? I have two -10 AN hoses (one running off each valve cover) to a dual-port catch can with a breather on top, and the amount of smoke coming from the break has slowed down a bit since I first fired the engine up, but the dipstick tube has smoke pouring out at a good rate, especially if I pull the dipstick out.

Any solid advise on this would be hugely appreciated. Thanks everyone!

Che70velle

iTrader: (6)

Are you sure it’s smoke venting out, and not steam? Steam is more prudent out of breathers nowadays due to the ethanol in our fuels.
What is your ring gaps? If you don’t know, ask the shop that did the assembly, and report back.

MEAN GTO

iTrader: (1)

Thanks for the response! I guess I'm not genuinely sure if it's smoke or steam, and I feel silly for asking, but how do I actually tell the difference? What's coming out of the breathed and dipstick is definitely quite hot if I recall correctly, so perhaps it's steam? If so, what does that ultimately mean?

As far as ring gap, upper compression rings are .024" and .025" for the lower compression rings. Thanks again!

td1168

iTrader: (2)

Youre worrying too much! Run it and it will clear up! If you're that concerned do a leak down or compression test.

Jontall

^+1 Those piston rings are very hard and they need time to break-in. Keep running conventional oil and it will help to seat the rings. Keep checking/changing the oil and have patients. 5W30 is the thinnest oil that I would run; 5W20 may be too thin and adding to the problem.

MEAN GTO

iTrader: (1)

Thanks for being blunt guys! I was wondering if I was just being too concerned... but I also didn't want to end up with glazed cylinder walls.

I will definitely put in some thicker oil. Since the break-in oil is sitting here, should I just put that stuff in there and try to put some mileage on the car?? Or should I seriously not bother with the break-in oil at this point??

Btw Jontall... I recognize your name. You've been on LS1GTO for quite some time, haven't you? I've been on there since Fall of '04 and pretty sure I've seen you around many years ago when I was active on there

Exidous

iTrader: (11)

You will also experience a LOT more moisture coming out of the PCV system during cold weather. I have to empty the can on my LS1 about once a month in the winter and maybe once a summer.

00pooterSS

iTrader: (40)

You're not running a pcv and running a breather setup, you're gonna see steam/smoke.

Also at this point all you can do is continue to drive it and watch it or pull it out. So drive it man. You've done all the right things. I'd run the current mobil conventional oil in it or change it again with some basic oil and run it to about 500 miles and change again. Just use basic oil and you should be just fine man.

My boat motor (chevy 305) has an open breather system on it, the engine is well broken in and in excellent condition and steams plenty from the breathers.

I prefer pcv systems myself, for several reasons, one of them being what you are describing.