Kingtal0n

I was at my friend's shop the other day getting some parts welded up and the discussion fell upon PCV (positive crankcase ventillation)

He shows me his engine he is putting together and all these fancy lines running out of the valvecover, and just when I was about to scold him for not running those lines back into the engine vacuum and sealing up his crankcase, he tells me something that dropped my jaw.

" I plan to run the S2000 vacuum pump "

And right away I am thinking, what? How can this be? "Its electric?" I ask him. And he says yes, electric pcv pump.

I am still in disbelief of course. I ran to the forum and checked all your stickies. I checked google. I don't see any reference to any kind of PCV pump anywhere...

So... is it real?

Slowcrash_101

PCV valve is a mechanical check valve, nothing more, nothing less, it's design changed slightly after MY03.

Kingtal0n

I think you are missing my question.

How is PCV attained on the S2000 engines?
most engines use the engine vacuum to scavenge crankcase pressure.
Many High performance engines (1000+ horsepower) will use an external pump as this is worth 3-4% extra power

IS THIS WHAT HE IS TALKING ABOUT?
https://www.s2ki.com/s2000/topic/826...ions-air-pump/


That thing can provide crankcase pressure relief? any stats on it? how many CFM per unit pressure?
Seriously interested, I would love to have an electric pump for boost situations on my engine... and these things are cheap.
I am just doubting it's effectiveness... need stats!

Kingtal0n

So there is NO DEVICE on the S2000 that draws crankcase vapors out?

Its just a standard PCV -> intake manifold right?

Thats what I thought. too good to be true.


In other news, a PUMP by definition "creates a vacuum" aka a pressure differential to cause the flow of molecules. So I would re-word your post to be accurate, I think you mean to say this, "the device you see is a pollution control device, and would not provide adequate pressure drop when connected to a typical engine's crankcase"

Or something like that. Still I wonder, are you just saying that, or did somebody actually measure (get me the stats?) the pressure differential...

Slowcrash_101

It's an air pump, it helps with ignition when you cold start the car. The S2000 does not have scavenge pumps, it has a conventional sump.

Kingtal0n

This is what I expected. However I am still curious how much "air" it actually "pumps". I suppose I would need to buy one and measure it.
In other news, yes if you cannot tell yet, I am looking for such a pump. Something to draw a vacuum on my crankcase while my engine wanders into boost. And it must be electric, I am not interested in any belt driven device. Which of course means current draw is a big issue, which is why they are generally not seen on engines, since a pump to move that much air would probably not be worth the electrical utility.

but that is where I might make some changes. if you consider that I will only be in boost for about 12 seconds or so (enough time to get from 0 to 120+ mph) then there is much less consideration for time-spent drawing current. A large capacitor or larger alternator might do the simple trick (keep the battery from taking a beating). most importantly, it needs to be cheap, which is why I am simply looking for discarded OEM units from various vehicles.

VAD

Why not just vent the valve cover to atmosphere? In the old, pre-emission-controlled days, I believe they called it a "road tube". Just run a 3/8 inch fuel hose from your pcv valve down the side to the bottom of the engine. Positive crankcase pressure will force oil vapors into the hose whether you're in boost or not. If you want to get real fancy, you could even gut the pcv valve. I don't think that would be necessary though. People always over think pcv issues. Keep it simple.

Kingtal0n

Pulling a vacuum on the crankcase is a valuable, essential part of keeping an engine healthy by removing combustion by-product gasses (that would have diffused into the oil), and will also increase power output from 2-5% on many engines if done properly.


Would you like me elaborate? I will clarify any and all issues regarding why the space between gas molecules inside the crankcase is important. (remember that the lower the pressure with respect to the atmosphere, the more space will exist between gas molecules at any instantaneous interval when you take the area under the curve, or integral, which is necessary because there are still collisions between gas molecules)

Slowcrash_101

I understand that creating crank case vacuum would help produce power by limiting windage losses but our PVC system is very good at keeping crank case pressure in check. Take off the oil cap you will barely feel any air come out, do it on a BMW or Audi, even the performance models ie S RS M, these cars have dry sumps with scavenge pumps and they still emit more crankcase pressure than our cars.

Kingtal0n

Your cars maybe, sure. But mine does not. During boost, there is no significant source of vacuum for me. Your car doesn't have to worry about that

There is a guy local to me, who claims he is using your "air pump" as a crankcase evacuation system for big block chevy. I don't believe it, but he is promising me pictures, so lets see what will be produced.