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Excessive oil consumption (sbc)?

8K views 22 replies 9 participants last post by  LJM97Z 
#1 ·
This is a fairly fresh .030" 406, there is no blow-by, plugs are good & clean, no leaks, but it'll go through about a quart in 150 miles, I'm running baffled VCs with PCV on one & a breather on the other, any ideas?
 
#3 ·
No smoke at all, pipes are clean, no soot, intake rails are dry, the only sign i see is oil on the threads of plugs, wondering if its the rings, but there no blow-by what so ever, has me puzzled. VC gaskets are those blue rubber/tin units, its all dry around that area.
 
#8 · (Edited)
Never use forged "racing" pistons that use 1/16" top and second rings in engine that is driven daily. . The 1/16" rings are low tension rings to be used on low silicon forged pistons in high RPM racing engines. The 1/16" rings have poor oil control at low RPM. Always use forged pistons that use 5/64" top and second rings. Those type pistons set up at .002" - .0035" clearance and utilize oil return slots instead of return holes in the oil ring lands.

If one insist on using 1/16" low tension rings, a block plate should be used when honing the bores. The 1/16" low tension rings require perfectly round cylinder bores and the ends should not be file fitted. File fitting makes rings progressively egg shaped. Select the 1/16" low tension rings using a bore light and use only the rings from several sets that fit the bores as is. In drag racing engines using thin low tension rings, block filler such as "Hard Blok" should be considered.

Automakers today are using low tension metric rings in new cars to improve gas milage.
 
#10 ·
Are you serious ?? I have built alot of street and strip engines over the years with 1/16 ring packs and never had any issues with oil control.

The 1/16" low tension rings require perfectly round cylinder bores and the ends should not be file fitted. File fitting makes rings progressively egg shaped.
WTH are you talking about I have used file fit rings in just about every engine I have built with zero problems.

I am a believer in torque plate honing and using a good hone and the proper stones to do the job correctly. Alot of shops are using substandard hones to hone they just don't work.

I am careful on my choice of oil control ring anf their tension.

If you are having to fill a block your using the wrong block.

Where did you ever come up with this false imformation ???????
 
#11 ·
Low silicon forged pistons that use 5/64" top and second rings need .002" - .0035" clearance due to a more controlled expansion rate. They are made of 4032 or VMS-75 forged 11% silicon/aluminum alloy with 5/64" top and second rings. Speed Pro L2256F for example

High silicon forged racing pistons that use 1/16" top and second rings need .006"- .010" clearance due to their higher expansion rate. Made of 2618 forged 2% silicon/aluminium alloy with 1/16" top and second rings.

The 4032 or VMS-75 high 11% silicon aluminum forgings are more suitable for street and strip use whereas the 2618 2% silicon aluminum forgings are better for boosted and racing engines. If used in a daily driver, low silicon pistons that use 1/16" top and second will have problems with oil control at low RPM or when not at the proper operating temperature. .
 
#17 · (Edited)
Filing the end gaps of the top ring has everything to do with egg shaping the ring by opening the end gap, especially with low tension 1/16" (or 1.2mm) rings. Rings should fit the bore perfectly round!

Some ring manufacturers tried to address the problem when they introduced "gap-less" top rings. However, low tension and gap-less rings will experience ring flutter at higher RPM and substantial power loss especially when accompanied by standard tension second rings. In order to avoid ring flutter, some racing engine builders use 2-ring pistons. That is gas ported pistons with low tension compression rings and a standard oil scraper rings.

Filing the ring ends reduces radial tension and move the ring away from the cylinder wall. That has been known for decades. The pistons that use low tension rings should have gas ports in the top ring land.

For a so called "racing engine builder"...you don't know very much. Probably claimer engines.
 
#18 ·
I build alot of championship engines and I think your blowing smoke, Ring manufactures are not that stupid and your not that smart, My leak down tests are under under 1.5% and have not had zero blowby issues. And 35 plus years building engines I think you are full of shyyt dreaming this stuff up :nono:

The guys at Total Seal I am sure can educate you on rings and how they work.

I don't build claimer engines, But build alot of Circle track eingines along with street and strip plus I have some winning blower engines. I machine all my blocks with a HAAS 4-axis CNC machining center and blue print block for a living and also build performance engines.

Here is a little bit of what we do.Blue Printing A Block - Chevelle Tech


Whats your claim to fame ?????????
 
#20 ·
LJM97Z,
Do you see any blow-by from the valve cover pcv valve hole with the pcv valve removed from the valve cover, the valve removed from the hose, and the hose plugged on a warmed-up/hot engine?
What type of baffles are in the cover? Stock or aftermarket?
Is the pcv valve sticking open?
If there is still no blow-by with the valve out of the cover, and no leaks, the oil must be getting into the cylinders,and burned IMO.
I would suspect the bottom of the intake gasket is not sealing correctly, and sucking oil onto the head ports(been there), especially if the block/heads have been decked.(head ports will be lower that intake ports)
There should be some blow-by even if only just a small amount if the engine is hot(especially with the pcv valve removed to be certain that its not sucking out the blow-by). If theres no blow-by that would re-enforce the suspicion that the intake gasket is sucking in some of the blow-by as well as oil. Just my opinion.
If the block was decked, some would say to mill the intake the appropriate amount,(can find specs on internet) others say to mill the head intake mating surface so that the intake can be used on another stock deck engine.
For those interested:
"The MAHLE Motorsports Power Pak kit is our high volume shelf stock program developed for high performance enthusiasts and sportsman class racers. The Power Pak pistons are predominately made from 4032 aluminum alloy to allow for tighter cylinder to wall clearances, and improved temperature stability. Some applications require 2618 alloy including the Power Pak Plus category. Each kit is complete with a set of high performance rings, containing a low drag 1.5mm, 1.5mm, 3.0mm set or 1/16’, 1/16”, 3/16” high performance Ring Pak standard with big block kits."
I bought a set for a 383 sbc w/6" rods(pn SBC125040F05) and they don't need an oil ring support rail as the pin hole doesn't intersect the ring groove. They came with a set of "File to Fit", "Standard Tension"(not to be confused with low drag), 1.5mm rings, and spec'ed for 0.0025"min.-0.0033max. piston to bore clearance.
ssmonty
 
#21 ·
LJM97Z,
Do you see any blow-by from the valve cover pcv valve hole with the pcv valve removed from the valve cover, the valve removed from the hose, and the hose plugged on a warmed-up/hot engine?
What type of baffles are in the cover? Stock or aftermarket?
Is the pcv valve sticking open?
If there is still no blow-by with the valve out of the cover, and no leaks, the oil must be getting into the cylinders,and burned IMO.
I would suspect the bottom of the intake gasket is not sealing correctly, and sucking oil onto the head ports(been there), especially if the block/heads have been decked.(head ports will be lower that intake ports)
There should be some blow-by even if only just a small amount if the engine is hot(especially with the pcv valve removed to be certain that its not sucking out the blow-by). If theres no blow-by that would re-enforce the suspicion that the intake gasket is sucking in some of the blow-by as well as oil. Just
my opinion.
If the block was decked, some would say to mill the intake the appropriate amount,(can find specs on internet) others say to mill the head intake mating surface so that the intake can be used on another stock deck engine.
For those interested:
"The MAHLE Motorsports Power Pak kit is our high volume shelf stock program developed for high performance enthusiasts and sportsman class racers. The Power Pak pistons are predominately made from 4032 aluminum alloy to allow for tighter cylinder to wall clearances, and improved
temperature stability. Some applications require 2618 alloy including the Power Pak Plus category. Each kit is complete with a set of high performance rings, containing a low drag 1.5mm, 1.5mm, 3.0mm set or 1/16’, 1/16”, 3/16” high performance Ring Pak standard with big block kits."
I bought a set for a 383 sbc w/6" rods(pn SBC125040F05) and they don't need an oil ring support rail as the pin hole doesn't intersect the ring groove. They came with a set of "File to Fit", "Standard Tension"(not to be confused with low drag), 1.5mm rings, and spec'ed for 0.0025"min.-0.0033max. piston to bore clearance.


ssmonty
ssmonty, thanks for the advice, yeah it does seem that there is virtually NO blow-by coming from the breather or PCV, there aftermarket VCs with baffles, I've been chasing this damn intake mating problem, looks to me the intake gasket doesn't line up properly in some areas, its a fel-pro with the im-bossed intake rings, Now, on this engine, it was just bored, the block wasn't decked, the heads weren't milled, the intake lines up nicely, its never been messed with, Thats why i'm blaming it on the gaskets, If i could find a good sealent to run around the intake runners of the gasket, this may cure the problem, maybe!
 
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