break in oil race engine

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quick_16

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What kind of additive package and weight would one look for in a "engine break in oil". I think I went to a synthetic too soon and have very poor leak down in a 14.6:1 BBC race engine. The hone finish was a little more course than wanted at a 280 grit. I need an oil to promote ring seating without hurting the rest of it. It's about 900hp injected meth.

Most of the break in oils I have seen are loaded with Moly to help with the huge issues with flat tappet cams. I'd guess that would play against ring seal???
 
Paul, you are not getting hot enough oil temps for moly to interfere with ring seating. The build and dressing of the ring cylinder interface is the issue, as you mentioned.

I emailed a response to your question as I do not choose to publicly consult on this one.

Bottom line is that if the build is poor nothing will help. However if indeed, the rings seat eventually w/rotational force you mentioned it will be a great setup.

Terry
 
IMHO you need about 1200-1500ppm Zn for Aw or more correctly "Anti Scuff" protection. Also a lower vis oil will help to keep rings from "floating" on a havey film so i would run a straight HDEO in a 30wt or less vis range.
bruce
 
Are you trying to break in the engine with it in the car or on a dyno? I would pull the thing back out, I'm assuming it is in the car, and run it on the dyno with break in oil. I've used some commercially available 10wt brake in oil on the last engine I built. 640, blown, carb'd and dyno'd after breakin at 1821 HP. As buice381 says, anti-scuff additives are very important during break in of an engine like this.

I like high load and low RPM to help seat the rings. With the 640 I ran it about 6000-6200 RPM (low RPM for this engine) and pulled it down HARD several times. Let it run with little load and cool off and then did the same thing again. This seems to work pretty well but you will have to adjust load and RPM for your specific engine build.
 
I just put in Schaffer's X-200 Moly Bond SAE 40 I do not have a a VOA or used oil analysis but did test some Schaeffer;s 40W Micron Moly race oil and it had 141 Moly and 1100 zinc on a used oil analysis. Local VR-1 20W-50 oil I also tested in the past and it had almost no Moly and 1400 zinc on a used oil analysis.

When you say HDEO what brand and model are you talking about?

I know how Terry feels about the Moly but that is a ring friction modifier and if I was to promote ring seat seems to me I need and oil with no Moly????
 
I think bruce is referring to a diesel engine oil SAE 30wt. Shell, Delo and many others have HDEO SAE 30wt's, but they are not as common as they used to be and you may need to go to an oil supplier, HD pars house or truck shop to find that grade oil. It's also fairly inexpensive so giving it a try wouldn't hurt the wallet much and would probably solve you ring seat problem.
 
OK Thanks

Any comments on a Moly level of 150+ and how that will effect NEW ring sealing?
cheers2.gif
 
I'm not a chemical engineer so I can't say for sure. In my experience I have not had a problem during breakin with high moly oils. With new rings and a fresh hone on the cylinders I think there is plenty of material for ring to cylinder seating and that the moly will not interfere with this process. I think the moly is great during brakein for the cam and overhead.

Although not a high performance application, I've been able to reseat rings in diesel trucks at work with high moly oils.
 
Quote:

Are you using moly coated rings ?

Click to expand...

Yes these are file fit 1/16 Plasma Moly faced rings and a Napier design 2nd.
I'm trying to make the best of too course of a hone finish.

I could care less about ring face life. I expect maybe 100 runs before it all comes apart. I want to promote friction on the ring face to cylinder wall so the moly will knock down the peaks of the hone finish. It's that simple.
cheers.gif
 
Makes sense.

Back when I was mucking around with engines, I wished that they were two compartment (at least for run-in). Straight 30 for the rings, and something good for the cam.
 
moly disulfide binds to metal, so it will reduce the clearance between the rings and cylinder wall, reducing consumption. that is what you have on your rings. the moly in most motor oils is NOT the disulfide, but rather a boundry layer friction modifier and antioxidant.

after breakin if you add submicron moly disulfide to the oil it *should* bond to the cylinder walls where it comes in contact with the rings, decreasing the clearance, improving compression, reducing friction and oil consumption. moly disulfide is also oleophilic, so anywhere it bonds to will keep oil clinging to that spot for longer.

for direct contact wear during breakin the moly wont really do much to mess it up as wreckerman says, as long is there is enough ZDDP.
 
for beak in all you want is anti scuff the ZDDP, NO MOLY, NO BORON, NO other mileage additives run a stright wt HDEO bruce
 
I would check with Castrol they have a break-in oil that a lot of track racers use here. I would also use the high load off throttle technique mentioned above, it sends the rings to from one end of the spectrum to the other and should help promote the wear you are looking for.
 
There is going to be metal removed from the jug no matter what...and IMHO the secret is not to simply promote this initial metal removal, but rather to possibly control what happens when these asperities are being removed.

During the mating of the peaks, severe micro-heating occurs. And without proper lubrication, the result could be the metal surrounding the asperities going to weld, and also being gouged and ripped away, leaving a less than desirable surface.

A better lubricant can help to ease the severity of the tearing of asperities, and leave the surrounding metal more intact.
An even better sort of lubricant or rebuild fluid could actually change the way the molecules react when being torn, allowing for the best possible surface condition, yet still allowing the other mechanisms to take place.
That is why some mfg's provide a rebuild fluid specifically for such events. Many are chock full of moly...some have none and use different mechanisms.

I'm curious if this is the first run with this engine? Can you see a drop in performance that is in line with the leak-down readings? In other words...did you have more HP when you were holding more pressure?
I ask because I think many use the leak-down of a rebuild as a "tell-all", when I think it is only one small thing to look at. Especially when the rate can be manipulated somewhat by the ring end gap, or use of a fancy ring.
 
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