How many of you guys with strokers builds are experiencing excessive crankcase pressure build up. 402-427, even 383. I have a cathedral headed 418 , 11:5:1 compression,N/A, -10an hose in each valve cover and -6an hose from valley cover all going to a big vented catch can and still have my dipstick getting pushed up during a pull. just wanna see what others have done to help alleviate the issue. vacuum pumps ? more breathers put in ?

 

Hello Boback,

You're not alone, for the most part.. Also, someone like Chev70elle may have some more insight on smoke from the vents aside from myself. I believe he's running an oil cooler.

I will say - I have a 427 recently back from the machine shop, so keeping in mind this is a "fresh...refresh" with everything re-clearance'd (albeit, for big turbo power) There is lots of smoke from my single breather setup. There was before the machine shop, and even more so after the machine shop. I'm not running a catch-can, *YET*. My PCV system consists of nothing more than:

Driver Side Fixed Orifice
Crossover to Passenger side Valve cover
Going out to atmosphere through a single Oil Fill Cap Filter.

Now granted, I never had an issue with my dipstick popping out - so you may have more blowby than I do. From the perspective of the general poster here in LS1tech and the online community, the amount of blowby coming from my engine in the form of smoke, would be an absolute cause for alarm, I have no doubt.

However, after dealing with these issues personally and slowly learning over time, and the fact that it's a fresh re-build, I'm going to go ahead and say that most of the online community tend to exaggerate the "situation" and tell you that your engine is about to blow.

If a machine shop knows that you are going to be adding forced induction, they will purposely make bigger tolerances, and probably instruct you to use thicker oil... more space between a ring and its' wall = more blow by.

Now, pushing up a dipstick is plenty of blowby, but... does anyone here know what's considered truly too much? Genuine question.

Just thinking out loud.

Thanks,
Andy

Edit:

I do also plan on adding a vacuum pump in the near future.

 

hello andy , Thanks for your feedback. My engine is also a fresh rebuild (900) miles so far. clearances and ring gap all set tight from machine shop. It doesn't smoke, more like vapor i would say during a pull. engines runs great and pulls good . just pushes dipstick out. before i rebuilt the engine( all same parts just new pistons and cylinder bore) it would push dipstick,shoot oil out and smoke out of catch can all the time. now no oil just dipstick pushing up.

 

I just have a breather on the passenger side valve cover and no issues here.

Are you getting a lot of oil in the catch can?

 

i wouldn't say alot of oil but i drained it last night. First time draining it since rebuild. 900 miles, a dyno session after 500 miles and alot of street pulls. enough oil to fill up a mobil 1 quart cap.

 

If theres not a lot of oil in the catch can, it doesn’t really sound like a blowby issue. Are you sure all the hoses are routed correctly and there aren’t any kinks?

 

I’m running a single -10 from my pass side valve cover to a vented catch can, and my vented valley cover vents over as well. No pvc. That’s the only venting I’m doing, and have no problems. What oil pump are you running?

 

All 10an and -6an Hoses. No kinks

I’m running the Melling 10295 pump.

 

You running an oil scraper by chance? Deserves attention for sure. It’s either gonna push the stick up or push the rear main out.

 

Gen3 block? How big is the bore? What piston/ring package? What kind of rpm?

 

running a chevrolet performance windage tray. It's an gen 4 ls3 block , 4.080 bore manley standard tension ring pack 1.5/1.5/3mm

 

Piston to wall clearance? Ring gaps?

 

I honestly don't know. I have to find my sheet from the machine shop. I told him go on the minimum spec of the piston to wall and min on the ring gap set for naturally aspirated.

 

Post the info. Those two sets of numbers are critical for keeping rings together and square on the cylinder wall, or as square as possible. Forged pistons? Is the filter on the catch can clean? Try taking the filter off the can and make a pull.

 

Mighty Mouse 'wild' road-race setup!











Works fantastic. Also have a clean side Mishimoto:









-Don

 

Can’t find my build sheet and machine shop can’t remember so I don’t know what the piston to wall or rings gaps are. Forged Manley -4cc pistons, standard tension rings. Doesn’t smoke, compression is around 200-205 each cylinder.

hammdo nice setup. What size is your engine ?

 

Forged and Stroked LSA 416 - built by GPI - for road course work ;o)

lots of torque/power. Ported LSA blower, GMPP CNC heads, 2.45 upper, 18% lower, e85, meth, 102 NW, 5" CAI, etc...

build’s on camaro5.com

-Don

 

Nice, those lsa’s are fun.
Well I guess my crankcase pressure was worse than I thought , I just blew out my rear main seal smh.

 

Ouch!

-Don

 

Damn, that got bad quick...