In the very competitive game of bracket drag racing, the engines are covered by many extremely restrictive rules. Any small horsepower gain that can be found within these rules is a huge advantage. Reduce the internal "drag", or rotational resistance, and you have a more efficient, more powerful engine. Some "old" drag racers have known this for a long time. They have been connecting vacuum pumps to their engines for an overall gain of nearly 10 horsepower. Small gain, yes; but an advantage of about 5%!!
In this application, we will put the engine's own Positive Crankcase Ventilation (PCV) system to work for us. We use the PCV system to reduce the pressure inside the engine's crankcase, thereby reducing the quantity of air that must be displaced by each piston as it travels downward. With the reduced air resistance within the engine, it naturally rotates easier.
So, how do we do this? What you need to understand is how the PCV system works. It pulls filtered air into the engine block. This purged air is then pulled into the intake manifold, where it is burned in the engine. Simple, all we have to do is cap, or plug this airflow INTO the engine's crankcase. This is usually done with a small (1/2") tube that leads from the airbox (or downstream of the air filter) to the engine. It is generally connected to the engine on one of the valve covers. By capping this tube, be certain that you are preventing air infiltration two ways: into the tube leading to your valve cover; and into the air intake, or airbox. Because we don't live in a perfect world, make sure that all the tubing connections are tight. Let me go beyond that, they need to be VACUUM TIGHT. This may not be an easy task on older vehicles, as I will explain later, but well worth it.
We are now causing the crankcase air pressure to be changed from near atmospheric to at least -4" mercury (HG). The manifold vacuum usually runs at about -24" HG at idle. This is transferred to the crankcase by blocking the air flow. (The nasty vapors are still drawn off and burned in the engine, so the emissions have not increased, and the EPA will be happy.)
Does this REALLY work? The first engine I modified is my 1976 Pinto with a 2.3 liter 4 cylinder. (Yes, they still DO exist!) This engine now has 291,000 miles, and runs as well as anything else on the road. I probably have driven about 1,200 miles since I capped the PCV, and I have seen no increased oil consumption, or other adverse effects. This is a true high-mileage engine with plenty of wear and blow-by. In my mind, if any engine is going to bite the dust through this, here is a classic case. (I wasn't especially worried because I have a rebuilt engine awaiting the day this old one dies). The around-town MPG increased from 21 - 23 up to 25 - 27, depending on the temperature. (Since this is a carbureted engine, the choke does play a role in economy). After the first tank of fuel, the MPG dropped back down to the normal (22 MPG) range. Slightly discouraged, I took a closer look at the whole PCV system. What I found was a bit of a shock. The oil filler cap on the old Ford was set up for a hose to the air filter. I had simply blocked this at the cap. After a while, the oil that had soaked into the seam of the two-piece metal cap had been pulled out by the vacuum, creating a new air leak. I eventually replaced the cap with a non-breathable one from another application. This, along with being extremely aware that vacuum leaks are nasty little annoyances and, careful attention to the gasket on the cap, cured the leak. The crankcase vacuum now runs at -4 to-5" HG at idle. The in-town fuel economy again changed for the better! Back up to, per the latest tank of fuel, 26.49 MPG. Not bad for November...
I did this on my dad's 2003 Ford Ranger. This is a two-wheel drive, 4 cylinder with a manual transmission. He was getting similar MPG's around town, averaging 22 to 23. In the latest report, he is still getting 26 to 27 MPG in town.
I want to point out that the on-board computer in newer vehicles doesn't care about this modification! (The computer does not control or monitor the PCV in any way.)
In both cases, this is an increase of 17%
I honestly do not have enough data on highway mileage to conclude anything, but I suspect the increases would be slightly lower. More in the range of 5 – 10%, due to the decreased manifold vacuum at highway speeds.
Now for the possible down-sides of doing this, and what I have observed.
o Will the oil retain more contaminants?> I believe it will. Since the PCV is not as effectively removing the volatile contaminants from the crankcase, the oil will become the reservoir for these contaminants. This means, simply, change your oil at the recommended intervals!
o The water vapor cannot as easily be purged from the engine.> When we look at how this water vapor enters the engine, it becomes very clear. It comes into the crankcase via the normal PCV system. Since we no longer have an open air inlet for this moisture to enter, I believe the water vapor that is now in your engine will be pulled out, albeit more slowly. However, the influx of water vapor is now nearly eliminated.
o What about a negative affect on the gaskets and oil seals?> Again, I have not seen any oil leaking from the Pinto engine. And I do mean that there is virtually ZERO leakage from the main seals (or anywhere, for that matter) on this engine. (I truly hate a leaky car.)
o Will I see increased oil consumption?> This old 291,000 mile Pinto engine has always used some oil, and I've driven the car daily since May, 1988. I can count on about 1,600 miles to the quart of oil consumed. This has not changed.
o Rough idle?> No, I think it actually idles a bit smoother.
o Why hasn't Detroit done this years ago?> The auto manufacturers are after one thing, your money. They simply don't care how much that new car costs to operate.
I am only trying to pass along information that I believe is important enough to share with everybody who will listen. Again, I am not making a dime on this, nor do I expect to, ever. Please give this some thought, as a lot of fuel is potentially at stake. Consider at least trying it for a while. My satisfaction will come in the knowledge that I may have had a small part in reducing emissions and our country's dependence on imported oil. Any oil, for that matter!
UPDATED INFORMATION:
In reference to the previously mentioned negative affect on the engine's oil seals... I have some new data to share.
Problem: Rear oil seal leakage: I modified the PCV system on my Chevrolet S-10 class-C motorhome. The engine is a 2.8 liter V-6. In late July, 2006 we were leaving town for a long weekend of camping. I started to smell oil burning; never a good thing to experience! After finding a suitable wide spot on the highway, I noticed that the rear main oil seal was leaking quite well. Actually, it was nearly a steady stream of oil at idle. Now, please understand that we had driven this vehicle on a 7,200 mile tip across the US in September and October of 2004, with not a bit of mechanical trouble. This just had to be caused by the mods I had made to the PCV system. The process of replacing the original PCV system was done very quickly (it took about 10 minutes, tops!) and I proved to myself that it had indeed been the cause.
What had happened is this: the engine's crankcase had a negative pressure that was actually opening the rear main oil seal. This seal is supposed to be held closed by the pressure of the oil pushing against it from the inside. But a deep enough vacuum pulled in air past the seal, allowing oil to be pushed out.
The oil leak immediately stopped, and hasn't dripped since.
In fact, my 1992 Ford Ranger pickup and my brother's Ford half-ton PU both have a distinctive "whistle" after we shut them off from an idle. This indicates a deep vacuum within the crankcase, with absolutely no adverse affects! In fact, my brother's Ford pickup idles at about -20" HG., and this engine has no problem with oil leaks. So, some engine's oil seals just seem to be more sensitive to a vacuum.
I never did check the vacuum in the crankcase on the Chevy's engine; maybe I should have. But I tend to believe it has more to do with the design of the oil seals than anything. I've chosen to run this engine without the PCV modifications due to the limited in-town or moderate loading of the engine. However, I have come up with a remedy, should this be a problem to others.
Cure: I have researched the availability of an adjustable vacuum relief valve. They are a simple device that will prevent the crankcase vacuum from reaching below the valve's setting. A ¼" NPT model is in stock locally for about $10 (Grainger's). This will need to be installed in line between the valve cover and (preferably) the air box or air cleaner. If this valve setting is adjusted correctly, probably 6" to 8" HG, then it will open as needed at idle and downhill, etc. With the tubing run into the clean air stream, the engine will not have a new influx of dirt.
How are my other cars doing? The old Pinto is still running flawlessly at 298,750 miles (as of 11/18/06). It's still averaging right at 26 MPG in town!! This is not running on the highways; it is 99.99% stop-and-go city driving. The Ranger pickups are still running fine. We are still seeing a similar MPG stated previously.
What about the highway mileage? I really haven't seen any increase in MPG over the 7,700 miles since I first modified the Pinto. But, there hasn't been any DECREASE in MPG either. Our Ranger pickup; pretty much the same highway mileage, also.
Please feel free to copy and forward this to as many people as you wish!!!
Mike Richardson
That is some seriously good info. I like simple mods that actually produce measurable results.
Thank you Mike.
Very interesting and glad you posted it!
I'm sure we will see more members with this modification in the future!
Just for reference, what exactly needs to be plugged up on a 2.3l Pinto engine?
http://www.fordpinto.com/smf/index.php/topic,9240.0.html
Quote from: dave1987 on March 30, 2008, 03:51:53 AM
Very interesting and glad you posted it!
I'm sure we will see more members with this modification in the future!
Just for reference, what exactly needs to be plugged up on a 2.3l Pinto engine?
What I had to do is change out the ventilated oil filler cap, with a sealed one. I found that a 1970's GM 350 CI cap works just fine, with a bit more of a neoprene rubber gasket on it.
Mike
How about the hose where the PCV valve connects to to the block?
Quote from: dave1987 on March 31, 2008, 08:17:07 PM
How about the hose where the PCV valve connects to to the block?
Definitely leave that in place! That is your vacuum source from the intake manifold to the block (crankcase).
Mike
how about a diagram to explain this better?
So are you saying that by just capping off the vented oil cap with a sealing one will improve horsepower and MPG??
I do not see any logic in this.
Quote from: dave1987 on April 01, 2008, 02:21:02 AM
So are you saying that by just capping off the vented oil cap with a sealing one will improve horsepower and MPG??
I do not see any logic in this.
Okay, so simply don't do it! Nothing ventured, nothing gained...
No loss for me.
Mike
I still plan to try it out, even if I do not understand it. I just need to get to a pick-n-pull to get a sealed cap. :)
I set it up on my car today,Noticed a marked improvement in overall drivability,and it seems to have a little more low end as well.We will see how it goes from here.
what do you mean by a little more low end?
My over all low end seems to have improved a little.I can now use 5th gear at 35 instead of 40 to 45,and at that speed it seems to pull harder at 35 when you mash it than it did at 40 before.Most would call my car cantankerous on the street as it acts like a 2 stroke,No pull than tire rubber.This seems to have smoothed that out.It is not nearly as sudden as before.
I went out to the pick-n-pull today and pulled some caps off some engines. I found one with a good seal and put it on. So far everything is okay.
Before with the stock cap I could pull the cap off without a problem, now I can't even get a good grip on it from so much vacuum. Good or bad?
I have noticed an increase in driveability though. I shift into third at 30mph instead of 25 and the engine definitely runs at a lower RPM when driving in town at 35.
I cannot tell if it has increase my MPG though, since I still need to readjust the idle mixture and the curb idle. I will update in a week to let you all know though.
This is on my 78 Sedan without the EGR valve and tube, running off a 4spd tranny and the 2.3l engine
Sounds like you are definitely on the right track, Dave!
At idle, you probably won't be able to remove the cap. That's a good thing, and why this actually helps you out!
Now, keep a close eye on the MPG's, I would love to see your results posted here.
Mike
It seems, so far, that my MPG has dropped a bit. I do not know why or if it has anything to do with the tuning of the car. Vacuum pressure has not decreased or increased on my gauge (still getting 17-19) and I have not yet adjusted idle mixture or curb idle.
Well at this point I have noticed an mpg increase..Yesterday I had to make a trip to Fall city was running late and did not have time to gas up.I knew I had enough to get to where I was going but would have to re fuel before going home.I was shocked to see that my fuel gauge had moved very little after getting to my destination.Well I figured I'd take a chance and just head home.I could not believe I still had fuel after getting back,and still was able to do some running around town after that.I figure I went 40 miles on 15 to 20 miles worth of fuel,I'm one happy camper.My speedo is off by 10 mph so I cant get exact,Anyone know a formula for calculating with speedo error.By the way,Thanks for the idea Mike,I'll keep you posted.
You also need to consider that the gas formulas change for the summer right about now; this alone might have an effect on your milage.
Bill
So far so good. Engine is still running smooth and I'm actually seeing the MPG increase now. I filled my tank to the brim two days ago. With my regular driving around town, errands and work, it usually drops slightly below the full line. So far it hasn't budged! I will post again when I hit 3/4 tank.
Now while on the topic of improving gas mileage, does this trick actually work?
http://www.mdwholesale.com/Improving_gas_mileage.html
I have been using denatured alcohol for years as a fuel system cleaner and octane booster,about 6 to 8 oz to the tank.As for fuel blends,If I'm seeing improvements with winter blends It should get better with the less volital burning summer blends.
Well it's been about a month now and heres what I have found out about this little trick and the results I've gotten so far. with all the tuning changes my fuel mileage has gone from about 16 to 17 in town to about 23,for a 6 to 7 mpg increase,very nice.And I think there is more to be had but tuning with this system can be a challenge.My next step will be a jet change,leaner and a power valve change,it seems to be running a little rich at this time.As for what I found out about this little trick,this is nothing new.Dirt trackers around here have been doing this for years free HP.But if you live in a dusty area unless you allow a small amount of air into the block it WILL draw air in past the seals,with the air comes DIRT.At idle my engine starts to make a sound like a belt slipping or a water pump bearing going out.As it turns out what I'm hearing is the air being drawn in through the aux shaft seal.Now for the fix,And Mike this should fix the prob with your Chevy.Pills are the answer.With my set up I have a bolt threaded into the hose on the cap to block it off,Tacky I know but it was an experiment.Next I got a couple more bolts and cut them into .75 in sections,then using wire drill bits drilled holes through the sections giving me the pills I needed.From there i just start with the smallest pill and work up till the problem stops.From there you just install a filter on the line you have the pill on to stop dirt from entering.The drawback to this is the air entering the block through the pill makes a little noise,very little but the filter seems to muffle it.More on this later as we are looking at installing an crankcase evac system for hi rpm as the other does nothing there.
Doc.
One way to reduce the dirt infiltration into the vacuum system would be to run the "bleed" hose end into the filtered air. In the case of an older Pinto, this could be done rather easily by running a longer tube into the air filter can, inside of the filter.
Just a thought...
Mike
My air filter wont allow this so I'm using a small breather filter that slips over the end of the hose.All this is temp till I get everything figured out anyways.
Anyone else besides Earthquake willing to try this?
Just curious since I haven't seen any more comments/complaints for a while!!!
Any more news from other Pinto drivers on this?
I am very interested in trying this, but still unclear as to how it is done. How about a step-by-step walkthrough (with pictures?) of how you do this. I have read the instructions several times, but I still don't get exactly what needs to be done. ???
Basicly it's just an oil cap conversion.
Instead of using the "vented" one that leads back to the air cleaning through a hose, you are using a sealed cap.
I pulled the cap I was using off an old Chevy 350 motor in the salvage yard (which had a good seal). It is the cap on the valve cover.
Uh,I just looked and my 71 200cc motor doesn't even have a PCV valve. No dice for me on this one....
should be under the intake manifold plugged into the vapor canistor (?) that is stuck into the block
I am still unfamiliar with my 200cc. I need to investigate further I guess.
Exactly as DAVE1987 said, on our Pintos, it is simply an oil filler cap conversion...
The long story is, however, that you should do all you can to seal up the engine in addition to changing the cap. For example, the oil mist eliminator, on the side of the block, may require removal and sealing. The rubber seals tend to be a bit sloppy after years of thermal cycles.
Anyone else do this mod and have stories to share?
I love having the sealed cap on my motor, it really does make a difference in low end power (most noticeable on take off), at least on the 2.3. If you don't believe me, try running your motor like this for about a month, then go back to using the stock cap and you will feel the change.
I noticed a DROP in gas mileage, so I don't regularly use it. However, I keep a sealed cap in my trunk with all of my emergency supplies so I can throw it on if I want to do some cookies in a parking lot this winter (and it does help :)).
FYI: I checked out a mini hydroplane racer this past August. Guess what!! It's powered by a 2.3 L Pinto engine. AND, the engine is completely air (and water) tight! They are running the PCV system to the exhaust header, which provides adequate vacuum in the application!!
Hey Mike
The boat is using an Evac system.This works the opposite of yours.The Evac only works at high RPM,above 3500.Not a streetable system.