I know some of you are thinking this may be a bit extreme but here we go anyway...

I was seriously considering the benifits of an evac pump on a daily driven high compression street car. As you might well know that pumping out crankcase pressure leads to better ring seal, and this intern would be my point, to prevent consumption of oil and to retain combustion chamber pressure.

Also i dont have problems with any off the symptoms mentioned above although i would just like to take some kind of precaution with evacuating crankcase gas. One other thing to keep in mind is that my lsvtec has no stock pcv system like the vtec motors because its a 00 b18b bottom end with out the air water seprator on the back. I had made a pcv system similar to the Endyn set up with the breather that has the lines coming off the valve cover...

What are your guys ideas on this?

Cliffs Notes: What do you guys think about crankcase evac pumps on high compression street motors. with out a stock pcv system.

-sander

 

I was wondering this myself. My only concern is, if the pump doesnt have a limit to the amount of vacum it can pull, it will eventually pull in your oil seals, right?

 

i would imagine that it would take a whole lot of vacum to start pulling on the seals, but im not too knoledgeable about this so who knows...

-sander

 

10 inches it will suck the seals in
There is a easy fix for it

 

so why not run a hose from the valve cover to the header? won't the exhaust create a vac. for the pressure to flow with? Also I would imagine that this would be a tad more enviromentally friendly, not that I care!

 

Most of the track guys just run a tube from the Crankcase and/or Valvecover vent to the end of the header inserted at an certain angle. The theory behind this is the scavangening effect of the exhaust gas as it passes through the header will pull/evacuate the pressure in the crankcase and the valvecover.

However, I think running a electric vacuum pump for a street motor is an overkill.

 

my thought- to add to the above post- is why add the extra weight and stress of the electic pump?

 

do you think that most of the scavenging effects would be at the collector? or right off the head, the ones that i have seen put the valve right on the collector (on the header in this case)

MAX_CFM - and your solution is?

-sander

 

A header Scavenge tube will never pull negative crank case pressure
you would need a vane style pump for this

 

CFM - do you think this is a reasonable idea though for a street motor in my circumstance? and doesnt Z10 sell a vane style pump?

thanks for your input
-sander


Modified by sander at 8:52 PM 10/27/2003

 

Why would you want to pull crankcase vacuum if the motor isn't built to take advantage? Reducing Positive Pressure would be beneficial, so would Pulling Vacuum, especially if you have a dry sump system to keep windage at a bare minimum. Also you would be able to run lower tension rings...There's better ways of spending money in this case.

Suprdave

 

Suprdave - I am quite possibly missing the point your trying to make, I was under the assumption that CC pressure would be more of a resistance force for your rings on the downward stroke of any motor. Like, when your piston is traveling down it encounters Crankcase pressure on the piston underside and the bottom of the rings, and when that pressure travels past the rings it becomes blowby gas. Mabye im just flat out wrong but what would be the problem of trying to remove that pressure all together? Mabye not so much as to create a vacum but enough to equalize the crankcase with no pressure as opposed to positive pressure or negative pressure.

Im not saying these things are written in stone although, this is just my interpretation of what i think would be the ideal situation.

-sander


Modified by sander at 9:19 PM 10/27/2003

 

thats what i thought also sander..i also have a question pertaining to this topic...will a vac pump have a negative effect on the up stroke (comp. stroke)? would it be benificial if the pump worked with a pulse or setup with some kind of crank trigger or other timing device??..do these pumps have different volume ratings?.....not trying to jack your thread..these questions just seemed appropriate for this topic..thanks any info greatley appreciated!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bruceleeroy &raquo;</TD></TR><TR><TD CLASS="quote">would it be benificial if the pump worked with a pulse or setup with some kind of crank trigger or other timing device??..do these pumps have different volume ratings?.....</TD></TR></TABLE>

Wow, that seems like a good idea to me, never thought about a variable rate pump, nice thought, bump for info.

-sander

 

Any drop in pressure in an crankcase is beneficial for the simple fact that it makes the air less dense and air that is less dense is easier to push out of the way of the pistons as for pulsing the vaccum, at the speeds seen in a motor i cant see how that would be possable Its not important anyway because when two pistons go up two more come down and they cancel each other out. The trick is to thin the air under the pistons so they can push it out of the way easier

 

i got a real trick idea about this topic

when a piston is on a compression or exhaust stroke. isent there less pressure under that piston ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by openloop &raquo;</TD></TR><TR><TD CLASS="quote">Any drop in pressure in an crankcase is beneficial for the simple fact that it makes the air less dense and air that is less dense is easier to push out of the way of the pistons as for pulsing the vaccum, at the speeds seen in a motor i cant see how that would be possable Its not important anyway because when two pistons go up two more come down and they cancel each other out. The trick is to thin the air under the pistons so they can push it out of the way easier</TD></TR></TABLE>

good point..........thanks.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by openloop &raquo;</TD></TR><TR><TD CLASS="quote">Any drop in pressure in an crankcase is beneficial for the simple fact that it makes the air less dense and air that is less dense is easier to push out of the way of the pistons as for pulsing the vaccum, at the speeds seen in a motor i cant see how that would be possable Its not important anyway because when two pistons go up two more come down and they cancel each other out. The trick is to thin the air under the pistons so they can push it out of the way easier</TD></TR></TABLE>

Very interesting, these are the responses i was looking for

Now my proceeding question is going to be, would a pump (at very light vacum) lead to thinning of air as you put it. It may seem like im trying to push this whole pump idea, im really not, i just think its very interesting and seemingly could help long term ring sealing under high rpm operations...keep em coming!

-sander

 

i know there are more people that would like to donate their two cents to this matter .

-sander