[Diy_efi] Venturi effect crankcase breather

[Adam Wade]

--- Matt Porritt <porrittm at anet.co.nz> wrote:

>>> Not quite magic, but a vacuum gauge easily shows
>>> there is vacuum.

>> I suggest you test this teory at some point.

> Like me to start one of the many vehicles here and
> photograph the vacuum shown on gauge?

Between the atmosphere and the throttle?  Yes, I'd be
delighted, although I am sure you will be saddened by
the performance of such a vehicle.

>> Since a PCV line has to connect to the intake
>> BEFORE the throttle, no, it will eseentially be
>> indistinguishable from atmospheric.

> Hang on a second.. 1 minute you're taking about no
> vacuum at the plenum, now PCV before the throttle?

There is no PCV at the throttle.  IT always happens
before the throttle.

> Does it not matter which side the throttle is on the
> plenum?

Matters to the plenum, and to throttle response. 
Doesn't matter with a PCV connection, since they are
always upstream of the throttle.

> Hmm.. I'm looking at a PCV line that connects AFTER
> the throttle here at the moment.

That would essentially create a vacuum leak.  What
vehicles have such a setup?  I've never seen one
before.  Without a way to measure the content and rate
of flow into the engine from such a port, there's no
way you could accurately fuel the engine.

> On highly boosted cars, this is removed as the
> valves fail and 25psi+ into the crankcase is not a
> desired result.

That's sensible.

> I'm also looking at a crankcase breather, BEFORE the
> throttle body, with no PCV valve on it. 

It's quite common for vehicles to have an "input" into
the crankcase that is taken after the air filter, thus
keeping dust and dirt from entering the engine.

> I never agreed you points were valid.

S'funny, you sure didn't have a problem with them in
the previous posts.

> You brought 'Sports bikes' into the
> equation (Sportsbikes like a Zephyr?? HA!)

Who says a Zephyr is a sport bike?  Try to stay on
topic, please.

> Read what you wrote that I replied to.

I have.  It's not terribly coherent.

> I spend 10hours + a day under the hood of
> performance vehicles.

Maybe you should learn how to work on the, so you
don't have to spend so much time on them.

> You seem to have talked to someone at Harley
> Davidson.

Among many, many other things.

> Perhaps it is you that needs time under the hood.

No, I think 15 years is sufficient.

=====
| Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |

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