PCV was a good thing.

[cleatus12r]

I finally got around to paying attention to more forums than just the ones that interest me. I simply read the forum subtitle and got frustrated enough to add my shilling.

I will say that smog pumps, lower compression, retarded cam timing, and catalytic converters marked the beginning of a depressing era for automobiles in this country. It's sad to think that we were doing very well as far as emissions, economy, and power were concerned until a select few people figured that there was money to be made on mandating WORSE economy, WORSE emissions, and LESS performance.

Think back to when this all happened (I wasn't born yet, but I know how it went down). We went from efficient, small quench combustion chambers and flat top pistons to ridiculously large swimming pool-esque combustion chambers that lent themselves to detonation. If you recall, detonation causes high combustion temperatures and increased levels of NOx emissions. So, they introduced EGR to cool the combustion temps and use the inert gasses to quell the flame propagation. It makes perfect sense to solve one problem with another problematic system, right? Yeah.

While we do that, we create a system to overcome the shortcomings of our newly found inefficient combustion process to burn off the excess hydrocarbons that are a result of incomplete combustion. A.I.R. pumps and oxidizing catalysts. Sounds exceptionally exquisite, huh? Not so fast. Add all of this up and see where we're at....

Low compression equals dismal performance and crappy combustion.
EGR adds inert gasses to combustion taking up valuable space.
The first catalytic converters were horribly restrictive.
A.I.R. pumps take power and make noise.

The first systems were archaic in their design and were operated mainly by vacuum signals from a "ported" source on the carburetor. If there was enough vacuum present, a diaphragm would be actuated and a valve opened. Not really too precise.

As we progressed, computer controls began taking control of some of these systems....but they still had their shortcomings. The engines still used carburetors which are only good at two things....idling and WOT. So we now have the advent of the computer controlled carburetor with an electronically controlled metering valve that is commanded by a computer after looking at an oxygen sensor voltage. Wow. Accuracy is getting there. However, performance was still dismal due to the low compression and EGR that worked way too well.

I'll skip a few generations and get to where we are now.

We have computers that are fast.....really fast. We have the ability to control fuel trims on at least a bank to bank basis and sometimes cylinder to cylinder basis. We can run higher compression due to fast knock sensors and infinitely variable timing on individual cylinder coils. Most vehicles don't need EGR or A.I.R. systems anymore and the combustion process takes place inside a very efficient combustion chamber. Our catalytic converters are efficient. They flow very well, even when there are commonly 2-3 in each exhaust pipe. Our backpressure numbers are in the .5 PSI range at full load and max RPM.

However, nothing has been more effective than the PCV system. Its original intent was to capture the crankcase vapors (high hydrocarbon content), reintroduce them to the combustion chamber, then burn them. This can cause detonation in some instances (lots of blowby) but it's pros far outweigh the cons. Engine oil lasts longer, crankcase moisture levels are far less, and leaks are reduced due to a vacuum being placed on the crankcase vs. relying on pressure to force the gasses out.

It seems to me that we are now being forced to go through a very similar situation with the present-day diesel engines in our light duty trucks. We have emissions systems that do not do any favors for the environment. They consume more fuel to run the emissions systems, they introduce ungodly amounts of inert gasses into the combustion chamber to lower NOx emissions, and they are forced down our throats to unknowing customers with the LIE that they are "CLEANER".

Maybe one day, diesels will be right where the gasoline engines are today (and yes, some gassers are now direct injected too) and we will once again have something to look forward to. Today's gassers run exceptionally well and make even the big block power kings of the late 60's look anemic....even with 2/3 of the displacement.

[Jackpine]

Great post, Cody! Since I used to drive cars with the old "standpipe" method of purging the crankcase, I agree 100% about PCV being a good thing. As I recall, there used to be a possibility that the standpipe could get blocked, which would really put you in a world of hurt. I guess it didn't happen often though.

But do I EVER remember the the crummy EGR system in my Mercury! I loved that car, but when I started hearing pinging, I knew it was time to clean out the EGR ports. That damned valve would just fill up with a hard, brown carbon "plaque", sort of like what happens in people's arteries when they are about to get heart attacks. It was always a pain to clean too, due to the tight curves in the narrow passages and the fact that the stuff was really "hard". Just a brilliant piece of engineering ***NOT***.

The smog pump was another wonderful invention, wasn't it? Took engine power to run, which made you burn more gas, producing more emissions.... I also seem to recall those things having a habit of breaking down, thankfully, mine didn't.

Don't you think though that some of the new "environmental" efforts against diesels are the result of the very visible particulate matter that some of the badly tuned ones can produce (although I am seeing far fewer of those today). I can't help but cringe when I see the "smoke show" tune for diesels. Is this a really good idea, or are we shooting ourselves in the foot?

Thanks for the trip down memory lane though. It brought back a lot of fond and not-so-fond recollections of time spent out in my carport or garage with the hood up and parts of the engine all over the place.

- Jack

[88Racing]

Great post Cody!
The best motors out there are still the non emission type with the electronic ignition on top.

Lars

[sam8]

I guess I am an automotive dinosaur.
At 50, I can still tune a Holley. Got a box or two full of jets, power valves, etc.
I know what a Dwell Meter is, and even have one that works.
I love my F-350 PSD, but have no interest whatsoever in messing with "fun" cars that need a computer to run, unless it is just an MSD.
Give me my '40 Ford with it's little 302.
My '56 will have a 460 in it if I ever manage to put the $ together to build it.
I know electronics are here to stay, and they do improve performance in many cases.
There is just something about looking under the hood of a hot rod and seeing a wiring harness that looks like an octopus laying across the top of the engine, (where the double-pumper should be) that strikes me as wrong.
So this dinosaur is thanful for folks like Bill who understand & like playing with the electro-whiz bang stuff that makes my PSD sing while hauling my camper and pulling the toy trailer.
If it were my responsibility to build the stuff, I'm afraid diesels would still only be in Class 8 trucks, and we'd all be getting 5-6 miles to the gallon on premium as our big blocks and double pumpers strained to haul all our junk around.
PCV remains a good thing.
It keeps the M/T valve covers clean.