[Elarson]

Originally Posted by dammen8

OH my goodness that pic is big... sorry about that

Chad

Do you have a picture of the bearing shell that goes with that block? Studying the block and bearing as a system may yield some understanding.

Eric

[RAIV-Z]

Originally Posted by Elarson

Do you have a picture of the bearing shell that goes with that block? Studying the block and bearing as a system may yield some understanding.

Eric

Here is a picture of an LSx main bearing set.

[Tom Vaught]

I just had a thought, based on a blurb I read about the LS-X engine oiling system.

First a bit of Chevy Traditional Small Block/Big Block oiling strategy.

As many will know the Non LS-X Chevy Blocks have an oil feed passage running down the center of the valley area of the block.

Oil goes from that Horizontal passage to individual drilled passages that go through the center of the camshaft bore and then on to the main bearings. A machined groove it located around each camshaft bearing bore and behind the camshaft bearing shell.

A Camshaft Bearing is pressed into the bore sealing the groove edges to the block and also (with a drilled hole) will feed the camshaft journals.

So basically the feed oil to the main bearings has to do a "European Roundabout" to get to the main bearings to feed them oil. Not the best design for oiling vs a Priority Main Oiling" scheme.

So now if we look at the LS-X engine it uses a new "Priority Main Oiling" scheme.

Oil comes from a main feed passage and the main bearings get the oil first followed by the camshaft bearings.

So

Question #1: If we look at the LS-X bearing shell, is the Main Feed Passage at the 60 degree opening in the bearing?

Question #2: Is the upper normal oil feed top location NOW the feed passage for the Camshaft Bearing?

Question # 3: For our Pontiac block we already had communication to the camshaft bearing shell with the way the block drilling is done under the main bearing, what advantage would there be to copy the LS-X oiling strategy to get Priority Main Oiling to the Mains when we already had that?

Tom Vaught

[BruceWilkie]

We dont exactly have priority main oiling...

http://www.pontiacsafari.com/55/Shop...ubrication.pdf page 4 (Other than newer blocks not having the intermittant oil feed passages to the heads the oil system is the same since 1955.)

Here is a thought... block all the lifter feeds to driver side lifters... relocate lifter feeds to opposite side of lifter bore... plumb lines from passenger galley to newly located driver side lifter feeds....
Yep alot of work....

What it does... forces oil to the mains first... reduces top end oil flow (possibly in half)... 16 lifters being fed from 1 passage vs 2. The passage from #1 main to driver side galley can now be restricted if further top end oil reduction is needed.
If oil passage to driver side galley is .25" diameter then feeding all 16 lifters from that galley would equal same metering area as 16 lifter restrictors at .0625" diameter. Restrict galley feed to .125" and you get same area as 16 restrictors at .03125"


We get by fairly well putting 16 lifter restrictions in.... The Butler/Quillen Pro-Mod does ok without this priority main modification but does have a rather robust oil pump system...

However bleeding off supply to mains from 8 lifters, is still less oil getting to mains than you could have, if you fed the driver side lifters last by plumbing from the passenger galley.
You could probably block the normal cam feeds and force even more oil to the mains... that would require even more plumbing from the passenger side lifter galley.

[goatracer]

Originally Posted by RAIV-Z

We’d still like to know what benefit the grooved main saddle provides. If the main bearings in my engine looked like new, I most likely wouldn’t have questioned this modification.

On page #3, post# 44, 07/2011 Lynn posted a pic of your block which showed the grooved mains. Did you question Lynn about this mod 3yrs ago at the start of this build? I understand the bearings look like sh@t, just curious what the explaination was?

[RAIV-Z]

Originally Posted by goatracer

On page #3, post# 44, 07/2011 Lynn posted a pic of your block which showed the grooved mains. Did you question Lynn about this mod 3yrs ago at the start of this build? I understand the bearings look like sh@t, just curious what the explaination was?

No it wasn’t questioned, that was the first IA-II main saddle I had seen. This modification is also not specifically called out under machine shop labor charges.

Any idea why the bearing oil groove would have tooling marks on them?

[67'7F6'Bird]

Can we Assume McCarty and BES did nothing to help resolve the problems with the heads and the overall build and assembly of this engine since you have hired a new machine shop to repair the mistakes and "HACK JOB" work that McCarty and BES made? And now have to pay for machine work, parts and labor on this Brand New Engine?

[Tom Vaught]

On the question of the extra machining on the block for the "Dual Feed Bearing" strategy. I spoke with my Block expert and also with another oil passage expert and they said that they think that the mod is a valid mod for a couple of reasons.

1) They felt that the oil channel in the upper bearing shell was not wide enough to support high rpm rod oiling to the rods with the factory single oil feed hole scheme.
By adding the second feed hole you added a lot more oil to the bearing shell/crankshaft therefore adding a lot more needed oil to the rod bearings when needed at 8000-9000+ rpm.

2) The oil groove in the upper main is only about .130" wide at the lowest portion of the groove so that would support what my associates are thinking. The bearing material is cut back slightly to about .189" at the actual bearing surface. Ed, are your bearings widened at all in the upper groove area?

3) Adding the second oil feed hole would definitely add more oil to the crank rod feed passage as it went by the second hole.

Tom Vaught

Sounds like a good mod to me now that I understand it.

[65nss4spdGTO]

I thought this motor was a street style turbo engine and would never see 8000 RPM to 9000 RPM???

What were the clearances on the mains?

Calvin Hill
Hill Performance
708-250-7420

[RAIV-Z]

Originally Posted by 65nss4spdGTO

I thought this motor was a street style turbo engine and would never see 8000 RPM to 9000 RPM???

What were the clearances on the mains?

Calvin Hill
Hill Performance
708-250-7420

1600HP Pump Gas design goal. Run better gas turn up the boost and make more power. Street, like in drag week.
Main End Play: .0055
Main clearance: .0030

Expected RPM to achieve this was under 8000, the number used by Turbonetics was 7000.

[RAIV-Z]

Originally Posted by Tom Vaught

On the question of the extra machining on the block for the "Dual Feed Bearing" strategy. I spoke with my Block expert and also with another oil passage expert and they said that they think that the mod is a valid mod for a couple of reasons.

1) They felt that the oil channel in the upper bearing shell was not wide enough to support high rpm rod oiling to the rods with the factory single oil feed hole scheme.
By adding the second feed hole you added a lot more oil to the bearing shell/crankshaft therefore adding a lot more needed oil to the rod bearings when needed at 8000-9000+ rpm.

2) The oil groove in the upper main is only about .130" wide at the lowest portion of the groove so that would support what my associates are thinking. The bearing material is cut back slightly to about .189" at the actual bearing surface. Ed, are your bearings widened at all in the upper groove area?

3) Adding the second oil feed hole would definitely add more oil to the crank rod feed passage as it went by the second hole.

Tom Vaught

Sounds like a good mod to me now that I understand it.

Yes, the rear edge of the oil grooves in the upper bearings are chamfered.

[pontsd]

Tom,
After thinking about this would another possible benefit be the extra oil and grove pulling some of the heat out of the bearing ?

Still looks a bit strange in this application but the turbos add more heat to the oil I would think?

[Tom Vaught]

You can only pull the heat out of the bearing if you have proper oil flow clearances that allow the very hot oil to escape the bearing shell area. Possibly the extra oil feed passage allows removing extra heat at the main bearing and still supply proper oil flow to the rod bearings (and remove heat there too).

A Fluids Engineer (named Tom T) and I build a oil shell bearing rig one time for some bearing analysis work. Basically we rotated the rod journal without adding the reciprocating motion to the system. We were checking bearing speed vs oil pressure vs load on the rod.

We could load the rod with a pressure piston as the rod did not move (except in a vertical motion) and we could simulate actual rod loads.

We could control the actual pressure and flow to the bearings precisely.

We could monitor the bearing surface temperature as well as the oil discharge temperature leaking past the rod journal

And we could change the crank journal bearing speed.

So we finger-printed a bunch of different bearing designs, bearing clearances, oil flow rates, oil viscosity, and bearing speeds and loads.

In simple terms, for a small amount of bearing speed increase (say 500 rpm) the oil temperature and bearing temperatures go up dramatically every 500 rpm.

So cooling the bearing with proper oil flow is what makes the bearing survive

ps As far as the turbos adding heat to the oil, that is true. Vortech Superchargers add very little extra heat (only a .040" oil flow passage, (Like one extra lifter bore flow passage). But compared to Bearing Heat it is a very small addition.

When you fill the water jackets of a factory block (with fliier) you remove water cooling surface area so the water temp goes down but you increase the oil temp because the heat now has to be removed by the oil contact with the block surfaces. So the oil temp goes up. Doing this on a street engine causes the oil to now have to work even harder to remove heat at the bearings. So in reality at some point you really need an efficient oil cooling device to lower the oil temperature from the engine.

Tom Vaught

[RAIV-Z]

After resolving some of the issues with the original build, the RA-V is coming back together. Should be complete in about a week, waiting on a few new parts.

Slightly used parts from this historic build "fiasco" might be put up for sale to help finance the repair costs.

It's now dry decked and double o-ringed.

[Jeff Kinsler]

looks good!

[Tom Vaught]

So how tall are the "O"-rings protruding from the block deck and the head deck surfaces?

How thick of a Head Gasket (Assume Copper) are you using?

Tom Vaught

[LiL Jack]

Originally Posted by Jeff Kinsler

looks good!

Shew, I thought you were going to say: BESTTFMF.

[mjm421]

Originally Posted by LiL Jack

Shew, I thought you were going to say: BESTTFMF.

Hard to believe this came out of his shop!

[Tom Vaught]

Originally Posted by mjm421

Hard to believe this came out of his shop!

X 1,000,000

Tom Vaught

[RAIV-Z]

Originally Posted by Tom Vaught

So how tall are the "O"-rings protruding from the block deck and the head deck surfaces?

How thick of a Head Gasket (Assume Copper) are you using?

Tom Vaught

The SCE copper head haskets are .080, stainless wire diameter is .041. I'll get the actual protrusion measurements when I drop of the valve springs.

Notes from SCE:
If you go with double o-rings they should not be stacked unless you use a thicker head gasket. Since copper (like a liquid) does not compress, rather it is displaced, the gasket does not like more than 25% of the cross section impinging at any one spot. Over 25% of cross section you risk cutting the gasket. I suggest off-setting the o-rings so as to deform the head gasket into an ”S” shape between the rings. Off-setting in this fashion will most likely require that the o-rings in either the head or block are in a ‘figure 8’ pattern but you will have to do the layout on the actual deck surfaces to be sure.