crankcase vacuum pumps

[SeptemberSquall]

generally a good idea i have heard
what amount of vacuum should i be trying to create?

i've got a 3T-C air pump here ( ran the air injection or EGR or some such), would this be useful as a crankcase vacuum pump?

[Billzilla]

Up to about 7psid or about half atmospheric pressure is used on dry-sump engines.
But you'll have to have a good think about how the air flows through the engine when you do that.

[SeptemberSquall]

how so?
ten characters

[Billzilla]

The air will flow in the reverse direction to what it normally does, and that's a good thing. Also some of the seals may not work properly or even get sucked into the engine.

[SeptemberSquall]

cheers. did some research on google and etc and mostly found links to moroso etc selling pumps and not a great deal about what the process/benefits were

[MWP]

Benefits:
- Better piston ring sealing reducing blowby and slightly increasing engine power.
- Clean crankcase air = cleaner oil
- Stops oil leaks

[SeptemberSquall]

Benefits:
- Better piston ring sealing reducing blowby and slightly increasing engine power.
- Clean crankcase air = cleaner oil
- Stops oil leaks

yeah, that's what i figured
would the toyota air pump cope reliably with oil vapour?

[MWP]

Only one way to find out...

How are you going to set it up? What are you going to use to control the pressure?

[af300e]

Dyno pump belt on, pump belt off if you go ahead with this plan.

[SeptemberSquall]

yeah, will do
i think the difference will be marginal

[Turdinator]

I looked into this awhile ago. I believe the air pumps will work fine but the general concensus was not to take the pump its self over 4k rpm or they shit them selves. Never got around to trying it tho.

I can't find the exact thread i was looking for but there's some info HERE.
Bit more info HERE to.

[MWP]

Oil in the air being pumped might help the pump last longer.

[JZA70 R]

interested in this topic, was looking for an electric vacuum pump not long ago but only came up with the moro$$o unit.

on a twin cam engine ie the 1JZ, what do you think about disconnecting the balancer pipe between the cam covers, putting a filter on one cover and running the other to the vacuum pump?

[MWP]

Wont work.
Youll just draw air straight through and not create a vacuum.
This is what the standard PCV system does.

You need some kind of pressure valve (the opposite of a pressure release valve?) on the clean air inlet side to regulate the vacuum.

[Mike-e]

was looking into this myself earlier this year.

Stolen from the GZ motorsports site

Vacuum pumps can be rated by their ability to flow air, the more air a vacuum pump flows the more vacuum it will make on a given engine. A "small" vacuum pump would indicate a less airflow capacity than a "big" vacuum pump. Airflow is measured in CFM (cubic feet per minute), vacuum is measured in "inches of Mercury"

All engines create a certain amount of "blow by" (leakage of compressed fuel and air past the rings into the pan area). The "blow by" airflow created creates pressure in the crankcase, the vacuum pump "sucks" air out of the crankcase with its "negative" airflow. The net difference between the air low being "sucked" out and the airflow being "blown" in by blow by yields vacuum. If the airflow being "sucked" out is less than, or not much more than the air flow being blown in, the vacuum pump is not creating enough "sucked" airflow to eliminate pressure in the crankcase or to create adequate vacuum to not only stop leaks, but to create horsepower.

Typically smaller engines generate less "blow by" and don’t require as "big" of a vacuum pump as large displacement engines. However the addition of low tension ring packages, power adders such as Nitrous Oxide, Alcohol, Blowers or Turbochargers (and the ring and piston types, clearances and modifications that go with those power adders) will increase crankcase pressures requiring either a "larger" pump or to spin a "smaller" pump slightly faster. The following guide is based on our experience of testing vacuum pump airflow rates and typical crankcase pressures found in racing motors.

A "small" vacuum pump, that is making inadequate but almost adequate vacuum on an engine may be made to act like a "larger" vacuum pump by increasing the rotational speed, or RPM, of the pump. Of course maximum engine RPM needs to be considered as well, as vacuum pump RPM should be considered. Although we have vacuum pumps being successfully operated at a maximum RPM of 7000 or so, we highly recommend keeping the vacuum pump RPM below 5000 RPM. Alternatively, a "larger" vacuum pump could be used instead. However, our experience has shown that using a vacuum pump that is to "big" may eliminate horse power gains altogether because of the parasitic horsepower it takes to run the pump. Keep in mind that it takes horsepower to pump air, so one should choose a vacuum pump based on your specific application, bigger isn’t always better.

How much vacuum should you use? You should check with your engine builder as there may be some special issues or firm opinions that they may have. In general GZMS recommends no more than 15" of vacuum in a drag race wet sump application without pressure feeding oil to the wrist pins. In our own in house testing, anything over 12" seemed to offer relatively nominal increases in horsepower (maybe 15% between 10" and 15").

Why limit vacuum? Engine builders appear to believe that the lack of oil to wrist pins caused by removal of too much oil mist from the crankcase causes wrist pin damage. Some engine builders report fluctuations in oil pressure above 12", we have not noticed that on engines we have observed during testing. However in a recent article, it was suggested that the air velocity passing through the block to heads at the oil return locations causes resistance to oil flowing back to the pan, which could indeed reduce oil pressure. An air line from the fuel block off on a Chevrolet to the valve cover helps mitigate this problem as well as possibly helping to balance the vacuum in the crankcase to that in the valve cover.

Why use a Vacuum Control Valve? Naturally to limit the maximum vacuum. Also, it is more advantageous to achieve maximum vacuum early in the power band, so if you wish to do that it makes sense to use a vacuum pump with enough air flow to require the use of a vacuum control valve. If you do not want to install a vacuum control valve use a smaller pump than recommended, check your vacuum and determine if you really need one.