cylinder bore fuel wash question

[Belgian1979]

Subject is a SBC.
Is it possible for fuel to go down the bores on the inside of a V8? I would think that if there is fuel dripping into the intake manifold, heads, etc, it would run down the bores on the exhaust side of the block due to the inclination of the intake runner and valve.

How much fuel in the oil is acceptable? If you can smell it?

[BobbyB]

I don’t think we can be sure the fuel will only go to the exhaust side. I believe that raw fuel in the intake is very bad… and why fuel injected engines last longer, mostly. I have seen fuel wash kill an engine very quickly when a carburetor bleed was filled with trash and fuel siphoned into the intake.
Can you get the oil analyzed?

[Belgian1979]

It can be analysed but I do smell fuel in the oil. The engine is fuel injected. Having the injectors tested. One other aspect which might be a problem is the injector aimed at approximately 90° into the airstream due to space constraints on the manifold.

[RAS]

YES! kill a plug in an EFI engine and you will wash that cylinder or hydraulic lock it. Racers are changing oil 2 gallons and finding 3-4 gallons coming out! not that unusual in 2000 + hp engines. 1/2 oil 1/2 alcohol.

[Belgian1979]

Meanwhile the injectors were tested: in perfect order. So that's certainly not it.

[piston guy]

If the symptom is skirt scuffing , there are some "usual" causes. Scuff or "black death" as it is sometimes called is caused by metal to metal contact. Aluminum and iron must have lubrication to avoid scuff ans the friction induced heat causes the piston to begin melting. So if the piston to wall is too tight , when the piston heats up the clearance is lost and scuffing starts. Fuel wash , excess fuel "can" wash the oil off of the cylinder wall and this ''usually'' causes a "downside" scuff because of gravity making the fuel accumulate at the lowest point of the cylinder. High crankcase vacuum ( over 16"s) can also decrease the amount of oil "flying" around and landing on cylinder walls. Ring installation can also be a problem. Upside down rings can actually "pull" oil up into the combustion chamber instead of down onto the piston skirts. Excess piston to wall "can" allow the top ring land above ring to rub heavily and begin to scuff. Internet photos are tougher to diagnose than actually having the piston "in hand". IIRC yours was the second ring installation. That would scrape the oil upward off of the cylinder wall instead of down onto the skirt. You are NOT the only person to have done something like this. I have seen gapless rings installed upside down ( quick kaboom) , second rings in the top groove AND upside down , rings that "bottom out in the back of the groove and too little end gap which causes butting and eventual piston failure. I know at least one piston ring company that has stopped putting ring installation sheets it their ring sets. This may be what caused your issue if you had instructions I sure you would have followed them to a T.

[BillK]

Upside down rings can actually "pull" oil up into the combustion chamber instead of down onto the piston skirts.

That is exactly the problem he had. Its in one of his other posts.

viewtopic.php?f=1&t=64689

[Belgian1979]

If the symptom is skirt scuffing , there are some "usual" causes. Scuff or "black death" as it is sometimes called is caused by metal to metal contact. Aluminum and iron must have lubrication to avoid scuff ans the friction induced heat causes the piston to begin melting. So if the piston to wall is too tight , when the piston heats up the clearance is lost and scuffing starts. Fuel wash , excess fuel "can" wash the oil off of the cylinder wall and this ''usually'' causes a "downside" scuff because of gravity making the fuel accumulate at the lowest point of the cylinder. High crankcase vacuum ( over 16"s) can also decrease the amount of oil "flying" around and landing on cylinder walls. Ring installation can also be a problem. Upside down rings can actually "pull" oil up into the combustion chamber instead of down onto the piston skirts. Excess piston to wall "can" allow the top ring land above ring to rub heavily and begin to scuff. Internet photos are tougher to diagnose than actually having the piston "in hand". IIRC yours was the second ring installation. That would scrape the oil upward off of the cylinder wall instead of down onto the skirt. You are NOT the only person to have done something like this. I have seen gapless rings installed upside down ( quick kaboom) , second rings in the top groove AND upside down , rings that "bottom out in the back of the groove and too little end gap which causes butting and eventual piston failure. I know at least one piston ring company that has stopped putting ring installation sheets it their ring sets. This may be what caused your issue if you had instructions I sure you would have followed them to a T.

There were no instructions in the set and even no marks on the second rings (manufacturer did confirm this so maybe we're talking about the same people). Should have looked at the bevels, but I didn't know that at the time.
The reason why I initially asked this question is because the piston company said it was bore wash...Injectors are doing their work so they are not it. If bore wash was involved it could only have come from the difficult injector angle which can create some pooling, but it would indeed be on the down side of the piston as you stated. Not much I can do about that injector angle.

[piston guy]

Again , "internet photos" can be tough to figure out versus having a piston in your hand. The information about the ring upside down did change the probable cause in my mind and likely would have changed the piston manufacturers as well. While that company has "only" been around for 15 or so years , most of them have over thirty years in the business.