Interesting oil in intake manifold problem
 

I recently swapped an FC N/A intake manifold onto my GSL-SE block after about 100-150 miles of breakin. There was so much oil in the secondary runners that pulling the upper off drooled oil everywhere, and oil ran out of the engine when I pulled the lower off!

My T2 block did the same thing, and the oil would collect in the T2 manifold's plenum which acted like an oil trap, but I always figured that particular engine had worn oil control rings, which it did.

The S4 N/A engine I put together after that only ran for about 400 highway and competition miles, and didn't have much oil in the runners but it did start to get carbon in there.

The thing that I don't get is that the primary runners, in EVERY instance, are bone dry and clean. If it was an oiling problem, you'd think that it wouldn't be confined to the secondaries.

The T2 and this GSL-SE engines are secondary side bridge ports and I get these to have good drivability by having them idle almost 100% on the secondaries to REDUCE intake vacuum there, and i always thought that vacuum pulling oil up past the oil rings was what caused oil consumption problems in the first place. So I am at a loss!

In any event, high RPM shut throttle results in no exhaust smoke so I am confident that the oil control rings are in good shape. And if it happened in only one engine, I wouldn't think twice about it, but this seems to be a trend across every fuel injected engine I've played with...

Could be a stretch, but the secondary injectors in the second gen NA and TII manifolds is in the runners. If you're premixing, do you think the oil could be accumulating in the runners? This wouldn't make since if you're using just primary injectors like the GSL-SE runs though.

Oh yeah - I've always run two 680cc injectors. My ECU won't control four injectors.

ive noticed that the fuel keeps everything clean.

so a carburated manifold always looks clean, right?

my friend who only drives his FD at WOT, his intake is spotless.

a stock GSL-SE primary runners, are clean, secondary are always yucky.

my theory is that the ping pong intake manifold, ping pongs the unburned crap/fuel/pcv stuff etc etc around at part throttle

so your situation is normal, but like hyper normal.

ive come arcoss this countless times before aswell,all have been either fc/fd turbo motors that ive either built or been working on,i couldnt see a reason to it(all engines had new oil seals) and as its never caused a driveabltiy issue or caused it to smoke i havnt been too worryed about it!!

j9fd3s, this is kinda what I'm thinking, only why isn't it in the primaries too? I mean, okay there is fuel, but there should still be at least something, no?

That does make sense though, that it could be a mainly part throttle problem. I haven't been doing much heavy load driving with the car. Interesting to note that with the aux ports blocked off and the GSL-SE intake, the engine would just barely sit at the secondary opening point at 60mph. When I put the FC intake on I pulled the aux port sleeves out, so we'll see what change THAT all makes.

And on cold start (it's been -5 to 0c lately) it smokes. A lot. I had been thinking that my cold fuel multiplier was too rich, but if it's not set to 180% or so then it runs lean, so it genuinely wants that much fuel. Then I saw the intake manifold and then it started to make sense :)

I guess I'll just live with it and periodically clean it out like I used to.

How is your crankcase ventilation set up?

Missed this.

There really isn't one, or at least it doesn't recirculate into the inlet tract. Currently I just have a hose on the filler neck nipple that dumps off into wherever the hose dangles. Step two (to be implemented next time I see the car) is going to be capping that off and mounting a Mopar style breather in place of the oil filler cap.

Nothing comes out of the hose unless the engine temps get up over boiling, at which point steam comes out.

I used to run a PCV system on my 12As, but I found that the combination of port and EFI really does not work with a PCV system so I go the open air route.