Blow by

RBB

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Pulled my lower intake manifold to swap intercoolers and install a Gen3 last weekend and I was pretty shocked to see all the oil in there. This is after only one year on a fresh build, everything was spotless when reassembled, and running JLT separators on both sides. The intercooler fins themselves looked pretty clean, but there was a lot of oil in the lower intake manifold.

Any suggestions for keeping more oil out of the intake? Only thing I can think of at this point would be to install a custom vacuum pump.

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96gt02

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The JLT separators are decent but certainly not the best at catching everything, try a bobs or RX can setup if you want something better at catching blowby
 

RBB

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I run the Bob's catch cans. I just did my Gen3 TVS swap and I couldn't see any signs of oil.
I ran a Bob's back in the day before JLT came out with their v2 separator, and didn't notice that it picked up any more oil than the JLT. My passenger can seems to fill up pretty quickly, driver's side is always pretty dry. I run my car harder than most, a lot of 1/4 mile passes, so it may just be the nature of the beast. My buddy has a vacuum setup on his Terminator. Going to take a look at that this weekend and see if we can come up with some ideas for the GT500.
 

merkyworks

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When I did my Gen2R swap I had oil in the lower intake area, not as bad as yours though. Drivers side ran a JLT v2 and have yet to see an oil in it. Passenger side ran a UPR catch can and it would catch a lot of oil blow by but I was still seeing an oil film at the SC PCV tube connection. So I got another UPR catch can and run them in series, setup for the passenger side is now like this.
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So far with this setup I haven't seen any oil at the SC PCV tube connection. Not sure if thats from having two cans in series or cause the oil in the air has more time to drop out cause of the longer travel it must take.

If you could post any pics of your buddies vacuum setup that would be cool to study!
 

69b302

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I ran open filters on the PCV for a while, but could smell motor oil sometimes. Vacuum setup is not really for a street car, so I just live with it, and sometimes change to the filers when I go to the track. The more boost and harder driving, the worse it will be.
 

96gt02

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There is some testing right now going on between the JLT V3 and RX cans on the DOB facebook page, im waiting to see the results on that but I assume to RX will catch a good bit of what the JLT leaves behind.
 

Catmonkey

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I saw a catch can made by Vibrant Performance recently and it looked like it could do a number on containing oil. This thing is 4" o.d. and 8" long. Finding a place to mount it could be a challenge.

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I installed a Bob's separator on the oil scavenging line between the bottom of the intake manifold and the supercharger. Once oil gets in the intake, it has no where to go. Hopefully the separator in the scavenger line helps to trap some of that.

With a built motor, you can expect to have more generous ring gaps and blow by is just going to be a bit more prevalent.
 
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RBB

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I saw a catch can made by Vibrant Performance recently and it looked like it could do a number on containing oil. This thing is 4" o.d. and 8" long. Finding a place to mount it could be a challenge.

View attachment 1563913

I installed a Bob's separator on the oil scavenging line between the bottom of the intake manifold and the supercharger. Once oil gets in the intake, it has no where to go. Hopefully the separator in the scavenger line helps to trap some of that.

With a built motor, you can expect to have more generous ring gaps and blow by is just going to be a bit more prevalent.
I like the idea of installing a separator on the scavenging line. Have you opened up the lower intake manifold since then to see how effective it is?
 

Catmonkey

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It's not quite back on the road, so I've only had idle time on it. I'm hoping to have it wrapped up by the weekend. There are a few things I found that need maintenance and it's easier to do it on the ramps. First order of business is to get the air bags replaced.
 

RedVenom48

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Have you replaced your PCV valve recently? A failed valve could also contribute to oil in the intake tract.

I switch from JLTs on both sides to a single UPR on the passenger side. The drivers can is useless. That hose is the PCV system INTAKE flowing from the intake tube through the engine.

Lets just say it was one of many JLT products I bought and eventually removed from my car. I think the only JLT product still on my car is the catch can for the rear diff.
 

69b302

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The drivers can is useless. That hose is the PCV system INTAKE flowing from the intake tube through the engine.

This is true most of the time, but oil in the intake and on the tb, is due mostly to piston blow by pressurizing the crankcase reversing the normal flow.
 

sleek98

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Man that’s a lot of oil. Like others have said your rings are likely looser than an oem motor so your going to end up with more. Thought about the weld on fittings to the headers and running the line directly into the exhaust?
 

RedVenom48

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This is true most of the time, but oil in the intake and on the tb, is due mostly to piston blow by pressurizing the crankcase reversing the normal flow.
In my experience with the JLT catch cans on both sides, I had less than half a drop of oil collect in nearly 2.5 years of use. Its possible for a periodic reversal of flow, but it would be rare for it to be long enough to allow oil vapor to condense back into liquid.

Plus the passenger (main) catch can is on manifold vacuum and the fresh air intake is ported vacuum. Id say its just the oil vapor spreading throughout the intake tract after engine shutoff. Sleeks onto something with the rings perhaps.
 

RBB

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Man that’s a lot of oil. Like others have said your rings are likely looser than an oem motor so your going to end up with more. Thought about the weld on fittings to the headers and running the line directly into the exhaust?
Yeah, I’d imagine the looser tolerances on the rings are a big culprit. That plus beating the hell out of the car regularly....

Never seen that done with the weld on fittings. Have an example?
 

RBB

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I checked out my buddy's vacuum setup this morning and we're going to try something similar on the GT500. Pretty simple setup....the pump runs on 12v switched, produces about 6in of vacuum, will be trunk mounted, and the hose routing is very simple. We'll get to it in the next few weeks and I'll post pics of the installation. It should be easily replicable by anyone else who wants to give it a shot.
 

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