[Elarson]

Burning nitro has proven to be very abusive on main bearings; due to the long duration combustion cycle that puts a lot of heat into the mains. The #2 bearing dies first and then takes #1 and #3 with it. We're already feeding oil into the IA2 "turbo oil feed hole" that connects to #1 bearing. So the theory is that #2 sees the lowest pressure since most of the oil comes into the gallery from the back of the block.

Here's a few pictures of our new idea, to add oil directly to the front of the left side gallery. Track testing will confirm or deny the validity of this concept. We drilled and tapped a 1/4" NPT thread straight down into the gallery. Then a 1/4" pipe nipple comes out a PCV grommet in the valley cover. We'll feed it with a -8 hose directly from the dry sump pump.

The IA2 block had plenty of meat to do this. I don't know if other blocks can be done this way.

Eric

[slowbird]

Originally Posted by Elarson

Burning nitro has proven to be very abusive on main bearings; due to the long duration combustion cycle that puts a lot of heat into the mains. The #2 bearing dies first and then takes #1 and #3 with it. We're already feeding oil into the IA2 "turbo oil feed hole" that connects to #1 bearing. So the theory is that #2 sees the lowest pressure since most of the oil comes into the gallery from the back of the block.

Here's a few pictures of our new idea, to add oil directly to the front of the left side gallery. Track testing will confirm or deny the validity of this concept. We drilled and tapped a 1/4" NPT thread straight down into the gallery. Then a 1/4" pipe nipple comes out a PCV grommet in the valley cover. We'll feed it with a -8 hose directly from the dry sump pump.

The IA2 block had plenty of meat to do this. I don't know if other blocks can be done this way.

Eric

Cool, we did this to our street 400 a while ago. Fed it from the back and front. Worked good but we didn't come close to the stresses you'll see.

[J.C.you]

have you considered the firing order contributing to the problem?

[Elarson]

We've pondered the firing order....even put the crank in v-blocks and rotated slowly while envisioning power pulses. We keep deciding that the #3 main takes the most abuse from firing order, since it is the only one that gets 4 sequential hits (4-3-6-5).

Do you have any thoughts to add? We're having to look at all ideas and take nothing for granted.

Eric

[bignate]

My dad's old Lincoln v-12 (1936 Model K) has the main oil feeds in the main caps I always thought this was kinda neat. It may help keep an oil film on the main cap.

Nate

[J.C.you]

What order seems to the norm in fuel circles?

[Elarson]

I don't know about the big show cars, but I believe the nostalgia hemi's have the same firing order as Pontiac.

Eric

[J.C.you]

googled this....

http://youtube.com/watch?v=jxyEtC6G5U4

[Tom McQueen]

Were running a pressure line from the top rear port (directly from the pump) to the turbo feed hole in the front main. This same line feed's both turbo's. Pump is a Titan, so plenty of volume. The cam is a 4/7 swap.

[BruceWilkie]

The LS motors are dual swap...(actually same order as 351w ford,,, just ford numbering system is different)... GM supposedly tested and decided there was benefit in how it loaded the crank(cant recall where exactly I sourced that though. Think it was an engine masters article.)... Ford cylinder bank arrangement is same as our Pontiacs.

I still feel sending all the oil to the mains first and lifters last has merit...

If your mod, a dual swap cam, and/or priority feed doesnt fully cure the problem(which IMO they will help mask the issue but not cure it) then I would go where no one has gone and SEMI Float the offending bearing(s). (same total clearance but two cushion areas vs one.) Oil flowing on both sides of bearing = more cooling of the bearing.

[J.C.you]

Something else in that clip was interesting, they repositioned the blower so there would be more equal fuel distribution, then went to the different firing order.

[RA462]

I have had these pictures saved on my computer just because I thought they were interesting. Not my engine. Just another way to do the same thing. Cool idea.

[Elarson]

One of our crewmembers is an Oldsmobile guy. He tells me that "Oldsmobiles have the same problems but at a lower power level". One of the Olds engine builders plugs all of the lifter feed holes (from the gallery). Then he runs a separate feed under the valley cover with (16) individual small tubes and restrictors to feed the lifters.....totally separate from the main bearing oil.

Eric

[Elarson]

Originally Posted by RA462

I have had these pictures saved on my computer just because I thought they were interesting. Not my engine. Just another way to do the same thing. Cool idea.

We considered something similar but the built-up area of the IA2 block would have interfered with the tube nut. This looks like a good approach for a stock block. I'm glad we coaxed these pix off your computer. They'll inspire somebody.

Eric

[Tom Vaught]

Originally Posted by RA462

I have had these pictures saved on my computer just because I thought they were interesting. Not my engine. Just another way to do the same thing. Cool idea.

Yep, Local Michigan Guy made that mod several years ago. Kind of like the Turbo Oiling deal but flowing a LOT more oil. Your deal might work really well Eric.

Tom V.

[455-4+1]

Our previous (long past) oiling issues centered around #2 main as well.??? (different loads by a long shot but interesting the same) Assume you are running a front and back plate and not using block mounts of any sort ??

An external dual feed Peterson pump was a big help in being able to dial up more volume via a pulley change. We decided to monitor the pressure at the front via a similar (albeit smaller) tapping and came out the front of the block bulkhead. We also restricted the crossover to the far side lifter gallery at the #1 main.

Next step was to feed the front directly from the HP6 size filter pressure side. It became apparent soon afterwards that this was pretty common practice on endurance style boat engines over here

First photo was when we ran a Moon cover prior to going to BOP plate and belt drive seen in later pic where the flexible line comes out the front

[Tom Vaught]

Looks like I was mistaken, mate. Earlier photo matches your deal.

The other guys install was very similar and quite a few years ago.

Tom Vaught

[BILTIT]

Hmmm, now i am wondering if i should be looking at this mod for my boat. Its not an endurance style boat but it still sees alot more load compared to a car engine.

6000rpm=70mph (18% overdriven prop), 12:1 455. Stock oiling system, stock rods.

[Half-Inch Stud]

Nor sure if Firing Order is the substantial concern with Pressure on Main Bearings; me reason is the oil is not compressible, so only the rotational rate should matter; no load to full load on the film. If I'm nearly correct, then the matter of additional heat vs additional load in within 20% of no load for same rotational rate.

Shear: so perhaps flow of cool oil is the dominant matter. Oil cooler needs snuff to be up to snuff. Snuff like a fan blowing thru it.

[Tom Vaught]

We did some Main and Rod Bearing testing at one time on a rig:
Different clearances, different oiling strategies, different bearing materials.

One thing that became immediately apparent was the large increase in heat generated at the bearing shell from rpm increases. All of this testing did not have the additional influence of cylinder firing impulses so it resembles a main condition more so vs a rod bearing condition. Firm believer in carrying away as much heat as possible with high oil flow rates.

Tom V.