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Discussion Starter #1 (Edited)
Know Thy Oil Pan!! Parts I & II

A lot of questions have arisen concerning Oil System Pressures and Engine Oil Fill, especially when tracking the car. Many questions have arisen because of the factory recommendations to over fill 1Qt if tracking the car and some confusion on what to do after the race with the extra volume. Some have seen low system pressure especially when tracking the car when hot and entering the pits find system pressures at 25PSI when idling hot.

Some research into these concerns reveals all is well and many concerns can be relieved. A great source is Chris Enders book "LS1/LS6 Performance" by HP Books.

Historically there were problems with LS1 engine development. The nature of the long skirted engine block and 6 bolt mains initially and effectively caused the block to be 4 enclosed Bays on the bottom end. This caused aeration> reduced oil flow >and ultimate main bearing starvation. The good news was the block was engineered and cast as BOTH a Priority Main and Priority CAM system. Chevy solved these initial problems recasting the block with cutout reliefs along the lateral wall of the block to allow oil flow around the mains and adding a windage tray. In addition Lo Flow main bearings are utilized.

After the above problems were solved the racing community had a number of engines "grenade" at speed on high banked turns caused by hydrolocking of oil underneath Cyl 7 & 8 blowing out the sides of the cylinder case. The Z06/LS6 case was upgraded with lower cylinder wall windows and an upgraded PCV system. In addition the Corvette pan being shallower than an F Body was engineered with baffles, compartmentalized and built in reservoirs added. So the major development problems have been solved but many owners are still confused over the 1 Qt. overfill mandate. Let's look at the major componants of the paan to understand it all.

1. Windage Tray - Actually is not a tray as seen on earlier Chevy SB & BB's. Most picture a piece of flat sheet metal bolted to the bottom of the crank. Such is not the case. The LS6 windage tray is bolted to the mains but is actually a 3 sided box. It is open in the front and covers the rear 3 mains. It has strategically placed drainage slots and incorporates a crank wiper. The box completely empties under braking. Consider it the attic of a house.

2. Baffle - This is the upper part of the pan, consider it the upstairs, second story of a house. The baffle actually has a number of baffels and shelves which collect the oil draining from the windage tray and crank. It is a cast aluminum structural member of the block. It houses bosses for the filter, oil temp and pressure probes. The internal baffles direct the flow of oil to the down sloping rear of the baffle and a shelve prevents the oil from reentering the front of the baffle, instead directing the flow to the lower pan.

3. Pan - This is the part you see when looking at the bottom of the car. The pan is actually "split level". The center section being deep (you could consider this the basement of the house). This pan is also baffled and heavily compartmentalized forcing all the oil to the center of the pan using extensive internal windows. The center of the pan is the actual sump. The oil pickup is an oval screened pickup which sits deep in this "basement" and is aligned with the axis of the crank (front to rear) to enhance pick up in all racing conditions. When you fill to the factory 6.5 QT's the basement is filled, only.

The upper part of the split level bottom pan is 2 built in wings or reservoirs which fill partially when the extra Qt is added. These can be considered the 1st floor of the house. They drain to the center part of the pan or sump. They give the bottom of the pan it's odd shape. There is no way any oil in these reservoirs could migrate up to the baffle and further still past the windage "Box"

As you can see it is not necessary to drain off the 1 Qt overfill when your done racing.

I will continue with Part II as a reply to this post.
 

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That's good info! But why wouldn't you just always put 7.5 qts. in the pan if that were the case?
 

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I think the theory is that with high cornering G's, a lot of the oil gets deposited on the block, caps, etc.., this keeps the oil away from the pickup. Over filling keeps the level around the pickup at a safe level.

Under normal use, the oil would accumulate and actually overfill the crank, partially submerging the crank in oil and resulting in HP loss.

These baffles are also the reason the front end of the car must be lower than the rear when draining, otherwise a lot of oil will sit in these baffles.
 

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Discussion Starter #4
PART II

Oil Pump - The oil pump is a gerator, crank mounted unit external to the oil pan. There are currently no aftermarket units. The pump is a good unit but has some limitations. These flow limitations can be minimized by actually porting the pump as we do cylinder heads. Agostino and MTI sell ported pumps and will port yours. It is however a simple process and you can port it yourself as show in Chris Enders book "LS1/LS6 Performance". The pump can also be reshimmed to produce additional PSI.

In short the LS6 pan is the closest thing you can get to a dry sump system. There are now appearing in the market place some aftermarket sheetmetal pans. Canton and Moroso market some. I think. These are meant to upgrade the F Body pans but IMHO they can't come close to the Corvette/Z06/LS6.

There may be ways to help the stock system. Besides porting and shimming the stock pump you could completely dissasemble the stock pan and mildly polish and deburr the internal pan casting and then probably have it coated by Swain for oil drainage.

I also think that running Mobil 1 15W50 in hot racing conditions is beneficial. I have found the heavier weight oil to keep the hot idle
PSI at 40-45 rather that 25 or below(!) and the hot running PSI in the 60's. In hot weather all temps are just slightly cooler with the heavier weight.

In addition, running an engine oil cooler is definetly beneficial. Either a front mounted air/oil an integrated air/oil or a water oil unit is great if you track the car.

The ultimate pan for the Z06 is of course a dry sump. KaTech has a cast 2 stage dry sump pan and a billet 4 stage pan. These are only recommended for dedicated race cars but will net out an additional 15-20 HP.
 

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Discussion Starter #5 (Edited)
There is no way oil can accumulate in the upper baffle near the windage tray, even with the 1 Qt overfill. In fact now many Chevy Dealers are dropping in 7 Qt. oil changes as SOP.

Correct, since the pan has so many levels, compartments, baffles and shelves is why it is important to have a reasonably long drain period and have a forward "rake". It may explain why some have noted different and seemingly confusing fill levels after oil change or have suddenly and mysteriously lost 1/2 Qt after racing, even when checking an hour later. Thinking that they had a ring problem or valley seal problem; relieved only when the 1/2 Qt reappear the next day before start up..
 

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DJWorm, THANK YOU, THANK YOU, THANK YOU for that explanation. You are putting my mind at ease. This is something I have been concerned about. I do remember a GM Racing person saying at last year's Fest that driving to and from the track with the extra oil was OK but you explained why.

Thank you.
 

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Good info. Can anyone describe how far up the dipstick 7.0 quarts would equate to?

Thanks,
 

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Re: know thy oil pan

Question: If I'm mounting the engine backwards in a v-drive boat, do they design an oil pan thats different or can the LS6 oil pan be modded?

Im told the trap doors would be facing the wrong way for my application
 

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Discussion Starter #15
I am not well versed in marine applications but a reversed (backward) mounted engine in any vehicle would inhibit adequate drainage of the windage tray, pan baffle and defeat the engineered shelves and steps in the pan drainage system.

It might be better to use an aftermarket dry sump system in a reverse mounted marine application.
 

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Good write up!

He speaks the truth.

I heard the same info a few years ago from a well-known auto mechanc who advised me to just run the extra quart and not worry about it.

BTW, as stated above, my dealer usually does 7 quart refills on my Z.

I believe a 7 quart fill results in a dipstick reading about 3/16 inch above MAX.

:usa:
 
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