CorvetteForum - Chevrolet Corvette Forum Discussion - FOUND: Solution That Stops Oil from Being Sucked into the Intake Manifold

CorvetteForum - Chevrolet Corvette Forum Discussion (https://www.corvetteforum.com/forums/)

- C5 Tech (https://www.corvetteforum.com/forums/c5-tech-1/)

- - FOUND: Solution That Stops Oil from Being Sucked into the Intake Manifold (https://www.corvetteforum.com/forums/c5-tech/1836888-found-solution-that-stops-oil-from-being-sucked-into-the-intake-manifold.html)

FOUND: Solution That Stops Oil from Being Sucked into the Intake Manifold

Over the past year as I have done HPDE events, I have been plagued by oil being pulled into my intake manifold through the line from the valley cover and the line from the passenger-side rocker cover.

Last Spring I installed a AMW catch can in the line that leads from the valley cover to the PCV valve. With it installed I would find about 1.5 inches of oil the bottom of the can after one day of track time. I would also find that the line from the passenger-side rocker cover to the throttle body would also be wet with oil, and I would consume approximately one quart of oil during the day.

After reading several forum members recommendations, I put together a package that has completely eliminated any oil from reaching my intake manifold:

1) I purchased a set of Smith Brothers restricted oil flow pushrods.

2) I purchased a second AMW catch can and plumbed it into the line from the passenger-side rocker cover to the throttle body.

The following are pictures of the twin catch can package and the inside of the two catch cans after a HPDE day at Grattan. The catch can to the front of the vehicle is attached to the rocker cover. The catch can closest to the cylinder head is attached to the PCV line.

This is a view from the driver's side of the vehicle. Note the small aluminum bracket that holds the two catch cans together and that the inlet of the catch can from the rocker cover line is higher than the outlet at the rocker cover. I belive this is important in order to avoid the siphoning of oil out of the rocker cover:
http://img.photobucket.com/albums/v5...riversSide.jpg

The next two pictures are views from the passenger-side of the vehicle:

http://img.photobucket.com/albums/v5...RightFront.jpg

http://img.photobucket.com/albums/v5...engersSide.jpg

The final two pictures of a top-view of the catch cans; one with the tops on and the second with the tops off. Notice that the catch can from the rocker cover is COMPLETELY dry and that the can from the PCV line has a small amount of oil in it.

http://img.photobucket.com/albums/v5...ansfromTop.jpg

http://img.photobucket.com/albums/v5...ithoutTops.jpg

With all of the time and money being spent on catch cans and plumbing can someone tell me what harm is being done to the engine if a little bit of oil DOES get in the manifold?

It lowers your octane and keeps you closer to detonation not to mention gunking up your intake tract.

Quote:

Originally Posted by Higgs Boson (Post 1562286706)

It lowers your octane and keeps you closer to detonation not to mention gunking up your intake tract.

:iagree: Plus, these are supposed to be DRY manifolds in the first place.

Plus I dont need anymore carbon on top of my pistons to cause pinging or detonation.

Quote:

Originally Posted by Pumba (Post 1562286163)

Nice job, now remove the catch can from the line between the TB and valve cover and plug the valve cover line and TB line.
Sell the unused catch can and use the money for other mods.:D
Your fresh air being pulled through the cc is from your breather and the line going to the TB is useless.:leaving:

IMO, what's the point of having the PCV at all since you have breathers on there already? Not saying you didn't do nice work, but it seems self-defeating.

With all due respect, I don't see what the second can has to do with anything. I mean, the first can is obviously catching oil, but the second one is not. I don't think you even need the second one, because if it was doing something, you would at least have oil in it. Maybe your new pushrods helped, but the fact that here is not a single drop in the 2nd can means there's no oil going down that route to begin with. Unless I'm missing something, which, according to my wife, happens all the time!:toetap:

Quote:

Originally Posted by MrLeadFoot (Post 1562291109)

Unless I'm missing something, which, according to my wife, happens all the time!:toetap:

uh, are our wives sisters??? :lol:

Quote:

Originally Posted by corvettebob1 (Post 1562287087)

Before I installed the Smith Brothers pushrods and the second catch can I would pull over 1 quart of oil through the rocker cover to throttle body line, with the valve cover breather as you see it.

I suspect that the pushrods are the major change.

why are you even using an oil breather cap?

Quote:

Originally Posted by knowledgefreak (Post 1562295463)

why are you even using an oil breather cap?

I am wondering this as well. You spent all that time with the catch cans, so why equalize to ambient pressure?

I want to know where I can get the oil breather cap. That thing looks pimp.

I think the use of two catch cans was done solely as a troubleshooting aid; and a slick idea IMO :cheers:

with a conventional catch can setup... if there's excessive oil in the canister, you really don't know which side the majority of the oil is coming from.

Quote:

Originally Posted by knowledgefreak (Post 1562295463)

why are you even using an oil breather cap?

Im just guessing here, but i bet that breather is fake :)

I've read of other members that track their cars using restricted pushrods with success. It doesn't sound like you tested the push rods with one catch can. Did you? If not, how do you know one catch can was not sufficient? By the way your post reads, you introduced two unknown variables, instead of one at a time. I'm not picking apart your setup, but I'd like to understand exactly what you did.

Thanks,

by the way, it's a very clean looking install.....nice work

Quote:

Originally Posted by lucky131969 (Post 1562298297)

Yes, I had two variables in this latest track day to analyze.

I had run the car with a the breather cap, a single catch can on the PCV system hose and a Supporting Vendor had plumbed the hose from the rocker cover over the radiator to the front edge of the air bridge, just downstream of the MAF.

That setup pumped the MAF and the VaraRam air filter full of oil, and the single AMW catch can would also have 1.5 to 2.0 inches of oil in it after one day of HPDE laps.

So, I decided to install the Smith Brother oil flow retricting pushrods. In addition, I had noted where several Forum members had added a second catch can. Another Forum member had installed a second catch can at the end of the rocker cover hose and bolted the can low on the passenber-side frame rail without connecting it back to the throttle body. He had also installed the oil flow restricting pushrods. This member stated that he still filled the catch can on the frame rail with oil every track day. The other individuals stated that they were getting oil in both catch cans after every track day.

I decided to see if the pushrods, in addition to a second catch can mounted so that it's inlet was higher than the outlet of the rocker arm cover hose would stop the oil flow to the throttle body.

It did. The combination of components also reduced the oil flowing into the PCV line catch can by over 90%.

I am going to put the standard rocker arm cover oil fill cap back on the passenger-side valve cover and see if the system still keeps the throttle body dry.

Thanks for the info.

what is a "standard rocker arm cover oil fill cap"

Quote:

Originally Posted by knowledgefreak (Post 1562328518)

what is a "standard rocker arm cover oil fill cap"

OEM oil fill cap. His is modified for the breather.