LSX oil drain back question.

[Cubic_Cleveland]

We are using a GM LSX block in a build for a customer. It's a street strip deal, using a wet sump (Melling 10295 pump) with more of a focus on street driving. The block only has two ½" holes in the centre of the valley for oil return from the heads one at the front and one at the back.

I'm happy to run vent lines from the crank case to a catch can/rocker covers to relieve crank case pressure, but what are people doing for oil return? I don't think basically one ½" oil return towards the back of the block is enough...

[Cubic_Cleveland]

Forgot to add the block casting # 19212322. We've thought about slotting the rear oil drain, but hoping there's a better solution.

[Cubic_Cleveland]

Looks like slotting the oil return is the go? Either that, or everybody's using the stock blocks in street builds like we do

[induction apprentice]

Ive got a new gm lsx on my build table. You have me very curious now. I won't be able to respond until probably monday morning by the time I get a look at it and back home. but I will have a close personal look and see what I can come up with?

[Cubic_Cleveland]

Ive got a new gm lsx on my build table. You have me very curious now. I won't be able to respond until probably monday morning by the time I get a look at it and back home. but I will have a close personal look and see what I can come up with?

Thanks, doesn't seem to be much info about this out there. It's an older block (purchased in 2010 I believe), so maybe things have changed?

[induction apprentice]

So no. nothing has changed. Two half inch holes one front one rear. Also a large vent hole at the front of the valley for crank case pressure equalization. That's it.

There is plenty of material to oval the hole as you suggested. But I don't believe you will have any trouble with it. I was thinking about the worst case senario being un restricted lifters and pushrods with spring oilers in the covers etc. Would still be ok unless road racing or in a boat at sustained rpms for long periods. Other than that. the only time it might be in question is under acceleration were you are on the rear drain only. So if it only see's short blasts of full acceleration for 20 secconds or less at a time. The small amount of accumulation would be insignificant. At least that's what I think. Mine is a pro street deal N/A. I'm going to put my trust in G.M. engineering and leave them just the way they are.

[pamotorman]

the corvette owners manual tells the owner to run 1 quart over full when doing track days. I don't believe it is the return holes in the block as it is the oil being held up in the rocker covers by the "G" forces in the turns

[Cubic_Cleveland]

So no. nothing has changed. Two half inch holes one front one rear. Also a large vent hole at the front of the valley for crank case pressure equalization. That's it.

There is plenty of material to oval the hole as you suggested. But I don't believe you will have any trouble with it. I was thinking about the worst case senario being un restricted lifters and pushrods with spring oilers in the covers etc. Would still be ok unless road racing or in a boat at sustained rpms for long periods. Other than that. the only time it might be in question is under acceleration were you are on the rear drain only. So if it only see's short blasts of full acceleration for 20 secconds or less at a time. The small amount of accumulation would be insignificant. At least that's what I think. Mine is a pro street deal N/A. I'm going to put my trust in G.M. engineering and leave them just the way they are.

Thanks for looking. I think we'll enlarge the holes, and also tidy up the lifter area to help the oil drain out of there quicker. Compared to a stock block there's a lot of oil being held in the lifter "sections".

[induction apprentice]

yes the lifter area does trap a few ounces for sure. Looks like there is room to tidy that up a little. Opening the drains a little surely wont hurt anything other than a slight windage change. I don't want to remove any metal there because it is a critical strength area. But if your staying 55 mm. then probably a non issue.

[induction apprentice]

the corvette owners manual tells the owner to run 1 quart over full when doing track days. I don't believe it is the return holes in the block as it is the oil being held up in the rocker covers by the "G" forces in the turns

good thinking. but the LSX block is compleatly stand alone in oiling to other LS blocks and so th drain dynamics are also unique to that block.

[Cubic_Cleveland]

yes the lifter area does trap a few ounces for sure. Looks like there is room to tidy that up a little. Opening the drains a little surely wont hurt anything other than a slight windage change. I don't want to remove any metal there because it is a critical strength area. But if your staying 55 mm. then probably a non issue.

Yep staying 55mm. I think the lsx block is overkill for what he wants to do, build plenty of stock blocks around his power level, can even do it for a little while with stock pistons and rods!!

[jed]

We have several LSX blocks in the shop the casting numbers i am getting are
19260089 for the standard deck and 19260090 for the tall deck.
I would definitely enlarge the drain back holes. The LSX are notorious for
Spinning number 2 and 4 main bearings. Could be the pan is being sucked
Dry because of all the oil being held up top.

[cjperformance]

Id prefer external oil returns over increasing windage and oil airation.
External drains also usually overcome most corner G' related oil hang up in the cylinder heads.

[RW TECH]

The LSX are notorious for
Spinning number 2 and 4 main bearings.

That's a crank issue. Oil aeration & starvation would result in rod bearing failure first.

[RW TECH]

We are using a GM LSX block in a build for a customer. It's a street strip deal, using a wet sump (Melling 10295 pump) with more of a focus on street driving. The block only has two ½" holes in the centre of the valley for oil return from the heads one at the front and one at the back.

I'm happy to run vent lines from the crank case to a catch can/rocker covers to relieve crank case pressure, but what are people doing for oil return? I don't think basically one ½" oil return towards the back of the block is enough...

There are a LOT of these blocks in Mastercraft boats & I'm fairly certain they do not have trick drain-back systems. Same with supercharged COPO engines.

Why do you think you need more than the 2 holes?