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2l Catch Can Overflows After 10 Second Run? Help!

wsln33

By wsln33,
in Engines & Forced Induction

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wsln33 Collaborator

wsln33

Posted
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Hi guys,

Really need some answers to this as its not right. My engine is a 26/30, only done about 800kms. Makes good power (450rwkw, 18psi pump). I went racing a month ago and first ever run was an 11.8@137. Didnt do any burnout really and 60ft was 2.5! No oil came out of the 1.8l catch can. Second run it filled up my catch can (1.8l) and oil went everywhere! Difference was I did a good burnout (about 7 seconds). Ran 10.4 as 60ft was 1.7 but didnt seem to want to rev over about 5500. That put an end to the day as oil was everywhere.

Made an overflow for the catch can and after i raced it again it has filled both up, so about 2.5 litres really! Also the car didnt want to rev past 5500

Not too much of a mess so emptied the can and filled it up and went again. Second time ran 10.04@137 and I changed to second (powerglide) before 5500 to not hit .

Catch can setup is that I have two -12 lines coming from the back of the rocker covers (not the top like standard but actually coming out from the back of the rocker covers). These run into the catch can. The catch can did have a return (on my first outing) which was plumbed into the oil drain from the back of the head. This oil drain returns into the top left hand side of the sump if standing in front of the car. For my second outing i blocked off the return as i thought it may have been getting blown up into the catch can.

I do have restrictors in the head but am not sure on there exact size?

Where on earth is all this oil coming from?

Please help

STATUS Grand Master

STATUS

Posted
Posted

hmm does not sound good, if it was fine for the first run i would suspect you may have hurt the engine on the subsequent run. Hard to say without seeing it though.

wsln33 Collaborator

wsln33

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hmm does not sound good, if it was fine for the first run i would suspect you may have hurt the engine on the subsequent run. Hard to say without seeing it though.

I thought it may have been fine on the first run as i didnt do a burnout?

Maybe the 7 second burnout was enough to fill it and then in the run it overfilled?

How does oil get into the head if the rings are stuffed?

And if I dont have the correct restrictors could they push that much oil into the head?

And again, is the rear drain on the head going into the correct side of the sump? Its going into the intake side?

Cartman Rising Star

Cartman

Posted
Posted

have you sorted out why it doesnt want to rev past 5500?

and sounds like the breathers are in a spot which helps fill the catch can.. being at the back of the head if its filling up while your flying downt he strip gravity is goin to force the oil into your breather lines, but still does not sound good

T04GTR Grand Master

T04GTR

Posted
Posted

for a start the fittings on the back not top of the covers are the issue.

your loosing the whole volume of the rocker cover. also it would be a good idea to use your rear fittings as drains and the stock breathers to the catch can.

Cartman Rising Star

Cartman

Posted
Posted
when you did the build did you install oil restrictors?

sounds like its typically pumping its sump up to the rocker covers

read were he has the breathers coming off the cam covers, its not even getting a chance to drain back down the external return cause its getting forced straight out the 2x -12/-10 fittings into the catch can.

r33_racer Grand Master

r33_racer

Posted
Posted

You should have left the return in, but put it on the exhaust side of the sump. The vacuum from the crank rotation will suck the oil from the return. The inlet side is the pressure side, and as such it would have been acting like or trying to act like a crankcase vent. It very well could have been pushing oil up there intermittently, but as pointed out having the rocker cover breathers out back down low will be letting alot of oil out. However, if you had the return back to the sump, it probably wouldnt have mattered.

wsln33 Collaborator

wsln33

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Whats my solution do you think?

Would it be possible to get away with running these two -12 lines and tee them into the return line from the back of the head to the sump? Therefore all that oil will go straight back into the sump? Or is the oil all frothy and full of air and needing to be condensed a bit before returning to the sump? I could then run some lines off these to the catch can so it is still vented?

Just dont want to have to take off the cam covers and bugger around with them thats all.

rad100 Grand Master

rad100

Posted
Posted

so the rb26 rocker covers have two fttings at the top of the head at the back,

1 inlet and outet on the left and one inlet and outlet on the right,

if i took these out and fitted a spedflow fitting to each, connected these to a catch can with a breather this would be fine?

or do i need to plumb one back into the oil return (turbo)?

N1GTR Grand Master

N1GTR

Posted
Posted
Whats my solution do you think?

Would it be possible to get away with running these two -12 lines and tee them into the return line from the back of the head to the sump? Therefore all that oil will go straight back into the sump? Or is the oil all frothy and full of air and needing to be condensed a bit before returning to the sump? I could then run some lines off these to the catch can so it is still vented?

Just dont want to have to take off the cam covers and bugger around with them thats all.

Put them back to standard, add mines baffles, then put it back together. Simple.

The way you have it looks neat, but at allthe expense of oil issues? Not worth it IMO

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