Since I switched to alcohol for fuel. I think I'm going to install a vacuum pump on my 421 SBM. I'm not really having any milky oil problems , every one else tells me that I should put one on it. I've been told that it'll probably also make a little more power. Anyone installed a vacuum pump and picked up any power?
Vacuum pump
- Thread starter tvt59
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For those of us not versed in 100% alcohol fuel , what's the purpose of a vacuum pump and how does alcohol create milky oil?
B3422w5
Well-Known Member
increases ring seal, can allow a thinner ring pack, more power
milky oil is condensation
I'm not well versed on the subject. Which is part of the reason for the post. But as I understand some run their alcohol tune up too rich and at too low of an engine temperature. This leads to excessive alcohol and moisture in the oil causing the milky oil situation. A lot of people run low tension oil rings. A vacuum pump is said to help with the ring seal of the engine so it helps make more power. Having the crankcase in a vacuum also reduces windage increasing available power. The vacuum also helps remove moisture inside the engine, lowers the boiling point of the water and the alcohol therefore helping with those issues as well.
These are my understandings. If someone more experienced and knowledgeable on this subject could chime it. That would be great.
These are my understandings. If someone more experienced and knowledgeable on this subject could chime it. That would be great.
Help me understand why you're doing it. From your post it's because other people are telling you to do it but you don't have problems. Is that right?
I am not having any problems at this time. But in the long term People that have much more experience with alcohol as a fuel than I have are highly recommending that I install one. They say that less maintenance on the engine and less frequent oil changes will be needed. Also if it frees up some hp that would be a plus. This is why I'm asking for information from people familiar with this subject.
B3422w5
Well-Known Member
Vic..I think you have a more standard type ring pack on your pistons, correct.
don’t you have flat top Icons?
My guess on your motor if you used a quality vacuum pump( STAR seems to make the best) is maybe 4 or 5 numbers in the 1/8th.
I think maybe a bit more with low tension rings.
Have thought about such an upgrade myself at different times over the years, but for the money and possible grief( wristpins, etc) have never tried it.
don’t you have flat top Icons?
My guess on your motor if you used a quality vacuum pump( STAR seems to make the best) is maybe 4 or 5 numbers in the 1/8th.
I think maybe a bit more with low tension rings.
Have thought about such an upgrade myself at different times over the years, but for the money and possible grief( wristpins, etc) have never tried it.
I do know this.....alcohol "washes" more than gas does, if that makes sense. There may be some truth in what they're saying, but heck, until I saw an issue, I'm unsure I'd make a move.
When we put it back together. We went with total seal stainless top rings since we were planning on switching to alcohol and the lowest tension oil rings they had available.
furrystump
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Alcohol attracts or absorbs water. If the water isn’t boiled off by running the engine long enough. It collects inside. Milky oil, also it rusts things. Like valve springs, then pop goes the weasel. Not insurmountable issues. I have heard of high end cars running shop vacs on the motors as they cool to limit the collection of water.
OldmanRick
Well-Known Member
Sound like the engine is fresh. Do you see any blow by in your breather system. If not, i'd probably run it and save the coin for a later date. Just monitor the oil and if you feel it needs changing a little sooner so be it. As for the HP gain, if your not running a class that needs max et, just dial that baby in and win some rounds.
I picked up when I put a vac pump on my car.
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