JimMueller

iTrader: (9)

Just curious where the oil is pooling at high G's, and if there was any sort of modifications which can be made to the drainback system to alleviate the issue in the stock heads, as well as wondering if aftermarket heads would have resolved the drainback issue (assuming the problem is in the heads)?

Momentum

The dry sump system really won't eliminate the pooling which occurs in high speed sweepers. But it will eliminate the oil pump from running dry which is the real issue. No cheap solution if you're determined to go fast at the road track.

DietCoke

iTrader: (18)

Restricted pushrods are a start

JimMueller

iTrader: (9)

I'm looking at new heads down the road and was hoping that aftermarket castings might have addressed the drain back issue. So far I've found these suggestions:

- Drill the lifter trays OR switch to link bar lifters
- Oil restricted pushrods (would a .040 orifice be adequate?)
- open up all drains in the heads and/or use external drain
- baffle can only control oil which is in the pan, and there's not enough there because it doesn't drain effectively

KCS

iTrader: (20)

On the Ls3 heads, the drain back passages are already bigger than the cathedral port heads.

I think the BEST solution is to block the drainbacks completely and run them externally or to a scavenge stage in the dry sump. The easiest solution is probably just an Accusump.

Crf450r420

iTrader: (1)

If it's in corners only then the oil is likely holding on the outside of the head since the drain backs are at the inner head bolts. Never seen it or anything, but if you really want to fix it on a budget you could tap the head below the valve cover rail and run some lines externally to the pan. There isn't a lot of room there, but may you could do enough and it would certainly be cheap. Maybe it will start a budget trend. LOL

KCS

iTrader: (20)

There is a long lost thread somewhere in the cavernous archives of LS1Tech where someone had already tried this. I think they used the three threaded holes above the header (one is used for the dipstick tube), drilled them out larger and ran some AN lines down to the oil pan.

studderin

iTrader: (28)

I grind out the casting around the head bolt holes. Into a upsidedown tear trop shape, from the machined round hole to get the socket on them. You can grind a drain back slot pretty far following coolant passange. That will drain oil out of then heads alot faster then letting it pool up to a height that it runs back thu these holes when they are round machined. Also the lifter tray drill mod helps.you can do extremal passages back to the pan too. also helps that oil not to dumping right on the cam and crank,

Mark200

G forces aside, I have read that the reciprocating nature of the engine (crankshaft I suppose) tends to pressurize the right side of the engine internally at high RPM, making it more difficult for the oil to drain back out of the head on that side. Theorized solutions are varied, ranging trying to control the windage at the crank, to external drain lines from the head to the pan (supposed to either be above or below the oil level in the pan, forget which), to various valve cover venting schemes (seems the pressure on the right side of the engine leads to a slight negative pressure (vacuum) on the left side; IIRC some venting looked in that direction).

This is a pretty exotic area and I'm not sure anyone knows exactly what is going on or exactly why. Google will probably turn up some links.