weird results: octane matters?

[MeteorGray]

Another reason that a wet air cleaner is a bad idea is that the added restriction has been know to cause the air cleaner element to fail and collapse. Such a result could cause the engine to "eat" the filter and its grit, and/or to cause a hole to develop in the filter, thus allowing unfiltered air to contaminate the engine.

So, don't try that Internet Idea.

[teoman]

Indeed, you are really missing the idea though.

It is a quick test, filter will not collapse unless you use significant rpm * throttle. And you will know if humidity has an effect on « perceived » octane rating of fuel.

Forget the air filter, install soaked and non restrictive rag in filter box.

The objective is to determine if water (humidity) has an effect on fuel economy. If it does, then more elaborate non-temporary solutions can be devised.

[MeteorGray]

I won't belabor the point any further except for one last observation:

The idea of a soaked, wet rag in the air filter box doesn't sound like too good of an idea either. The results might be less than desirable if the rag is sucked into the engine, and for what? To see if you notice the effects of the water ingested into the engine? I doubt this could be achieved by such suggestions.

Finis.

[redpoint5]

I've already got water in my fuel, thanks to E10. My cars have all gotten much worse fuel economy since the mandatory E10 law was put in place.

I say the person suggesting the experiment try it first, and report back to us. The only time I've had a wet air filter, the car choked and died due to the air restriction. I had to take it out to drive home, and then let it dry out.

If water was a good idea, then probably the best way to introduce it would be post-filter via an ultrasonic humidifier.

Better yet, why not just drive around in fog and report back the results? Fog is 100% humidity. Heck, just driving around anywhere in Florida should tell us if humidity helps anything.

[Isaac Zackary]

Originally Posted by teoman

Indeed, you are really missing the idea though.

It is a quick test, filter will not collapse unless you use significant rpm * throttle. And you will know if humidity has an effect on « perceived » octane rating of fuel.

Forget the air filter, install soaked and non restrictive rag in filter box.

The objective is to determine if water (humidity) has an effect on fuel economy. If it does, then more elaborate non-temporary solutions can be devised.

When I had my diesel it had crossed my mind once or twice to make a "swamp cooler" somewhere in the engine bay that would feed the intake with cool moist air. The idea was I wanted to see if I could take the car to an emissions testing facility and see if I could bring NOx down. Apparently NOx is heavily influenced by both temperature and humidity. By decreasing temperature and/or increasing humidity NOx should be able to be reduced to a mere fraction.

I also thought of it as a way to make high octane engines need less octane. But I decided that it was not worth the effort due to the greater space needed. (The car I have now has so little space under the hood that Toyota put the 12V battery in the trunk!) Also because it wouldn't work well in the winter. (It hit 0° F last night and snow has stuck to the ground without melting since Sunday.)

The thing is that it would likely have a greater effect at full throttle than at part throttle. At full throttle is when you really benefit from having enough octane or detonation resistance. So the rag would have to be made to allow full throttle air to pass through.

At part throttle the extra humidity and cool air could actually increase fuel consumption. A really cold and humid intake charge should have a harder time burning up all the fuel than a warm one. So you get more HC emissions that have to be burnt up in the catalytic converter.

These effects are basically what water injection research has also supported, which is basically the same thing only more controlled. When I was working on my Air Cooled Super Beetle one guy that raced them said he started getting great fuel mileage on his turbo setup during races when he added water injection to his turbo charged engine. He was able to lean out the air/fuel mixture and advance the timing and he got more power at the same time and his engine ran much cooler with the water injection. So much so that the stock VW cooling system was plenty to keep it cool.

So there is some truth behind adding humidity or water to the intake. But the only thing that engines will likely control in response is the timing. Modern cars won't lean back the rich air/fuel ratio at high load and also can't increase their CR, things that could be done on a dedicated engine. Also you would probably have to "turn it off" at low loads and startup's. And then there's the freezing weather problem.

[Piotrsko]

Traditionally water injection includes some form of alcohol additive. All the high hp and diesel kits use either proprietary fluids or window washer fluid.

Solves both the detonation and freezing problems.

Stock aircooled vw's are typically 10% rich for a cooler temp

[Isaac Zackary]

Originally Posted by Piotrsko

Traditionally water injection includes some form of alcohol additive. All the high hp and diesel kits use either proprietary fluids or window washer fluid.

Solves both the detonation and freezing problems.

Stock aircooled vw's are typically 10% rich for a cooler temp

From what I've researched and tested on my own air cooled VW, the jetting became stoichiometric, if not a bit leaner, like all the other cars by the early 70's. I was running between 15.5:1 to 14.5:1 at cruise and around 13:1 at full throttle with stock jetting on a 1974 carburetor. Of course the worn throttle bushings may have contributed a leaner cruise, but even after addressing them I didn't get much of a difference. And this was with a thermostatic air cleaner and running at 5,000ft altitude!

However, it was and still is a common practice to jet them richer for assumption that they needed it to run cooler. On the other hand, some of the guys that have had years of experience building these engines say they run cooler if you jet them to around 16:1 or leaner at cruise and leave full throttle at 13:1.

Personally I tried all sorts of jets and with my Oxygen sensor A/F ratio gauge and assortment of temp sensors I have to say that they were right about running lean at cruise is actually better for both a cooler engine and better fuel mileage.

[redpoint5]

My '69 Beetle had a valve burn up. Some say that was due to running lean. Either way, I treated the throttle as an on off switch. The car was gutless but fun, especially with the tiny aftermarket steering wheel which made it feel like a go cart.

[Isaac Zackary]

Originally Posted by redpoint5

My '69 Beetle had a valve burn up. Some say that was due to running lean. Either way, I treated the throttle as an on off switch. The car was gutless but fun, especially with the tiny aftermarket steering wheel which made it feel like a go cart.

Those Beetles where quite the cars!

Up through 1970 all Beetles had single port engines with the oil cooler in the cooling shroud. This made the #3 cylinder vulnerable for three reasons. 1. It and the #2 were offset farther from the center of the cooling shroud than the #1 and #4 cylinders which gave them less air to cool. 2. It and the #4 cylinder also were after the oil cooler, which gave them pre-heated air to cool them. And 3. the way the single port heads drew in air caused the #2 and #4 cylinders to get less air and fuel as they started the momentum of the air down the long skinny intake to the head, but the #1 and #3 cylinders got a whole lot more air and fuel as the intake charge was already moving in their direction making them do most of the work. The only cylinder to have all three disadvantages was the #3 cylinder. All the others only had one of these disadvantages. VW worked around this by making all their single port distributors run the timing retarded in the #3 cylinder compared to the others. But when the distributor was replaced most people dropped in the infamous 009 distributor which didn't have retarded timing on the #3 cylinder. At that point anything could make the #3 cylinder overheat, ping and burn up valves and such, including, but not limited to, running just a tad bit lean.

When VW went to the dual port engine they resolved all those problems. 1, they put air vanes on the cooling tin to direct the same amount of coolin air to all the cylinders. 2, the oil cooler was removed from the shroud that cooled the heads and cylinders so all received the same temperature of air. And 3, the new dual port design gave each port a longer individual runner to help make them all receive the same amount of fuel and air and do the same amount of work.

[redpoint5]

#3 sounds familiar, but that was a lifetime ago, when I was in high school. The rebuilt engine was very peppy and responsive, but didn't stay that way. Pretty quickly it went fairly sluggish again, and I wonder if that valve just burned up again? Flat out on the freeway it would only do something like 65 MPH. I didn't do any of the work, so I can only assume nothing was done about the timing on the #3, assuming that was the reason it burned up in the first place.