i'm not an engineer but i dont see any advantage to hooking vacuum up to your crankcase. if anything i think it would srew up your crankcase ventilation which is a positive pressure. if you have a pcv valve in your system it would cause it not to vent properly (open when it should) Maybe if you were to remove it and block the pcv to carb you might be ok but would also depend on whether you have a closed or open vent system. I think youd likely be sucking oil vapors into your pump. Windage can be improved by using a windage tray which keeps the excess oil away from your rotating crank. Your normal engine vacuum is created from your intake system (top half of your engine) and is sometimes reduced when you install performnce cams and intakes. Thats where the vacuum pump comes in to run accessories like power brakes and such. I wouldnt suggest a smog pump , those things have huge blades in them and will put a drag on your engine. Probably more loss than gain with one of those.
Many hi-perf/race engines use some sort ot active ventilation system. It maught be a pump or Moroso sells a system that hooks into the header and uses the venturi effect to pull crankcase vacuum.
The only serious side effect is a significant reduction in splash oiling. If you follow through, you should study the other mods that are recommended in order to restore oiling to certain engine compnents that rely on splash oiling. For example, piston pin oiling would be done actively through an oil passage in the rod, fed from the rod bearing. What I do not know is at what vacuum level (mild vs moderate vs heavy) these mods have to be done. It may well be that mild vacuum will not pose a problem, but you will also have less benefit. Lastly, a mild/moderate perf street engine proobably won't see much improvement, anyway, from positive crankcase ventilation (vacuum).
tos: the pump's output is directed to a catch can because you are right that crank case vapors and oil mist are evacuated and need a place to go.
The only serious side effect is a significant reduction in splash oiling. If you follow through, you should study the other mods that are recommended in order to restore oiling to certain engine compnents that rely on splash oiling. For example, piston pin oiling would be done actively through an oil passage in the rod, fed from the rod bearing. What I do not know is at what vacuum level (mild vs moderate vs heavy) these mods have to be done. It may well be that mild vacuum will not pose a problem, but you will also have less benefit. Lastly, a mild/moderate perf street engine proobably won't see much improvement, anyway, from positive crankcase ventilation (vacuum).
tos: the pump's output is directed to a catch can because you are right that crank case vapors and oil mist are evacuated and need a place to go.
Well, using the belt-driven vacuum pump and making all the other needed mods would be a lot tougher than just adding an '86 Seville, or similar, electric vacuum pump. Or even just a vacuum cannister like I have. Anyway, that's the conclusion I came to when I was building my 331 and planning for power disc brakes.
Others can add to the list, but (at the least) piston pins and the cam rely on splash oiling, and the piston is also cooled by splash oiling. There's bound to be a good dissertation on this somewhere on the web.
Others can add to the list, but (at the least) piston pins and the cam rely on splash oiling, and the piston is also cooled by splash oiling. There's bound to be a good dissertation on this somewhere on the web.
Forget the Smog pump. I tried that with a Canfield headed 302 that was spun up to 7500 rpms regularly. The Smog pump sucked up excessive amounts of oil and then imploded from the (too many)rpms. Not to mention it was a noisy little ****, I had to fab a muffler for it. It seemed like the motor made a bit more power, but I never dynoed it or track tested it (ET's) The Nascar racers use em, or so I've read somewhere, probably the same source you did.
Does a PCV system not accomplish the same thing, after all it is a valve controlled hose connected to manifold vacuum.
you could experiment with different valves to control the amount of vacuum being created.
I can see the exhaust header method evacuating vapors and mist, however I don't know(being a Canadian) what the California emissions people would think of raw oil vapor being dumped out the exhaust.
Old. like really old, engines used to use a simple down pipe which used vehicle speed to create a siphon type draw to evacuate oil vapor fromthe crank case.
regarding a pcv system, perhaps the down side is the oil vapor entering the combustion process, harder to calibrate air fuel ratios with raw hydrocarbons entering from the crank case????
however would the horse power gain be enough to make up for the parasitic draw of a belt driven pump?
And for the record yes the older 7.3L and even the old 6.9L diesels used a mechanical vacuum pump to supply vacuum for the brakes.
the more current diesels (ford anyway) use an electric pump for a vacuum source, and use P/S based Hydra boost for brake assist
Just some thoughts...
gtss
just had another thougt, regarding the NASCAR set up, do they not run a dry sump system , which would then affect the entire discussion, and perhaps necessitate a different vacuum/ ventilation system
you could experiment with different valves to control the amount of vacuum being created.
I can see the exhaust header method evacuating vapors and mist, however I don't know(being a Canadian) what the California emissions people would think of raw oil vapor being dumped out the exhaust.
Old. like really old, engines used to use a simple down pipe which used vehicle speed to create a siphon type draw to evacuate oil vapor fromthe crank case.
regarding a pcv system, perhaps the down side is the oil vapor entering the combustion process, harder to calibrate air fuel ratios with raw hydrocarbons entering from the crank case????
however would the horse power gain be enough to make up for the parasitic draw of a belt driven pump?
And for the record yes the older 7.3L and even the old 6.9L diesels used a mechanical vacuum pump to supply vacuum for the brakes.
the more current diesels (ford anyway) use an electric pump for a vacuum source, and use P/S based Hydra boost for brake assist
Just some thoughts...
gtss
just had another thougt, regarding the NASCAR set up, do they not run a dry sump system , which would then affect the entire discussion, and perhaps necessitate a different vacuum/ ventilation system
i believe the system would not only pay for itself, it would add power even on a street engine. how much over and above the power required to turn the pump i dont know, but an educated guess would be something like 10-12 hp gain on the average street engine. as to whether the engine would last longer, i cant say, but again and educated guess would be not really. remember that the friction loads will remain the same, you just reduce the parasitic losses from positive crankcase pressure, and since street engine dont develope the same internal pressures that a race engine does, the gains are going to be smaller. overall i think the addition would still be a benefit.
it also helps seal the piston rings which is why it produces more power. The PVC system does the same thing, however under hard acceleration there is little vac. to accomplish the sealing. You have to also consider it will wear the piston rings and cylinder walls more because of the better fit. I would not recommend it on something driven everyday.