"swamp cooler" for induction? - PeachParts Mercedes-Benz Forum

Mike400E · #1 09-07-2004, 07:18 PM

This is something that has been bugging me for awhile. I have a 400E that is very sensitive to intake temperature. The cooler it is outside, the faster it goes. I have had a couple dozen cars over the years, and none have ever been so profoundly affected by intake temp.

I have an evaporative cooler in my house that cools the air temp at least 25 degrees. And it moves 7500 cubic feet of air a minute! Why wouldn't this same concept work for a car? Understanding that getting the right air to water vapor mixture would be tricky, it seems to me that compared to all the complexity of turbos, superchargers and NOS, a water vapor system could be done very simply and for low cost.

But - not being an engineer, I am sure there are some good reasons this kind of concept hasn't been pursued. One thing I can think of right away is that most parts of the country are already humid, and adding more humidity to the intake air stream wouldn't work very well. But for those of lucky enough to live in low humidity climates (Denver.) it seems like this OUGHT to work?

Any feedback or ideas from the smart folks on this forum?

Thanks -

sixto · #2 09-08-2004, 09:06 PM

I'm a long way from thermodynamics classes but the answer has to do with the power gain from the cooler charge being less than the power loss to cool the charge. I suppose you can duct your cabin AC to the air cleaner and see what happens.

Sixto
95 S420
87 300SDL

kerry · #3 09-08-2004, 09:46 PM

Your biggest problem may be the water tank for the device. Similar devices are marketed to motorhomers, although instead of cooling the air, they drizzle a stream of water in front of the radiator (coming from the motorhomes watertanks) in order to cool the radiator on steep grades.

I think those old canvas bags you see hanging in front of radiators on cars crossing the desert in the 1930's did the same thing. Perhaps you could hang a canvas bag full of water just in front of the air intake.

psfred · #4 09-08-2004, 10:17 PM

You're at 5000+ feet in a normal aspriated car. The colder it is, the denser the air, and the more power you get. At that altitude, you are WAY down on power, you will notice anything that increases it.

I'd bet you wouldn't notice this anywhere near as much at lower elevation.

Peter

afmcorp · #5 09-09-2004, 12:48 AM

Peter gets the gold star on this one. and to go one step farther when racing way back when we use to install cool cans. we ran our fuel lines thru them and would fill the can with dry ice. condenses the fuel molecules. combining cold air and cool fuel you can pack more into the cylinder.

and those canvas bags well they were for drinking water or could be used in the radiator. the air passing thru worked on evaporation to keep the water cool. [when i was a kid my dad always had 1 or 2 on when we crossed the desert to vegas or phoenix. man it sucks getting old]

your car if from the denver area should have been jetted out to run in the thinner air. [your car might be able to tune in the fuel / air ratio] just like when i took the 68 road runner up to reno and it bogged out something fierce. ran way too rich. just a big black cloud of gas belched out. back then carter carbs sucked had to take the top off to re jet unlike the holleys.

the symptom you might be experiencing is that fuel / air mixture is too rich and as the air condenses it's catching up with the fuel increasing the air mixture to fuel so the engine runs a little cleaner.

if you guys think back there use to be an after market product that injected water into the fuel system and had claims like 15 or 20hp. my father in law used something like this water injector on his 64 ranchero. didn't last long.

Mike400E · #6 09-09-2004, 09:40 AM

Thanks for the input so far!

First, I am not having jetting problems and the car doesn't run badly. I know all I need to do to get 20% more power is move to sea level! (I think that would be hard to explain to my wife, however..........)

My idea was not so much to cool the radiator or fuel, as to directly add water vapor into the air intake stream, cooling it and making it more dense as well, I think. I realize a water resevoir would have to be on board somewhere, and maybe that's the real buggaboo. You'd probably have to fill it up daily, unless you had a huge tank, which would be heavy. But conceptually, I don't think anyone has come up with a good reason it wouldn't work yet.

More ideas?!

Duke2.6 · #7 09-09-2004, 11:23 AM

The bottom line is partial pressure of oxygen. Though cooling the air will increase it, evaporative cooling increases humidity, and the two tend to offset each other.

I don't think evaporative cooling of inlet air would be very effective even if you could come up with a system that worked well. It would be bulky and require constant water addition.

The biggest problem with the 400E is the very tall final drive ratio - 2.29 or thereabouts. Even though it's a fairly large V-8 the tall final drive really saps the performance potential.

Duke

ke6dcj · #8 09-09-2004, 01:56 PM

Drop a 3.06 or 2.82 diff and your 400E will "come to life".

The 400E automatically adjusts for altitude. Yes, cooler air would be best.

If you can find room, perhaps an intercooler installation would be best.

Damp air from a "swamp" cooler is denser because of the water-molecules in suspension. What you want is denser AIR with no water.

:-) neil

afmcorp · #9 09-09-2004, 02:36 PM

mike

note my last line there is a system or there was a system that injected water into the carburator. it worked on a siphon principal. the air coming into the carb actually drew a small amount of water from a container which mixed with the air and ultimately with the fuel. you could see them at fairs and such.

the problem is i haven't seen that thing or anything like it in an very long time. however....all u need is a small 12v pump, a reservoir of h2o and a tube that has a metering ability. the metering is no problem just cap off a small fitting and drill what ever size hole you need. i would start small. maybe .030 to .060 or so. there are a dozen places to pickup a small 12vdc pump. as for your reservoir on the right hand side where the overflow tank is has more than enough room to put a big bottle. i keep one in my car a 1 gallon milk jug.

now your problem is how to control the pump when at idle. this is why it takes only a trace amount of water. at idle there is not as much air and for that matter fuel.

again i don't know where your car comes from but it should be adjusted for colorado's elevation. have you ever discussed that with a denver mechanic? it's just like calif cars suck due to all the extra smog stuff. they are down on power as well. over all i don't think there should be a noticable difference between 65 and say 85 degrees. i have rented many many cars from the denver airport and i can't recall ever feeling like they had a noticable difference. just my 2 cents

hope this helps

Mike400E · #10 09-10-2004, 06:05 PM

Once again - thanks for the input! Actually another issue struck me as I was driving around in our unsually hot September. (89 degrees!) It would be difficult to keep any atomized water from freezing as it was injected into the air stream. Little pieces of ice in the air intake would not be a good thing, I suspect.

I have already done the rear dif swap to a 2.82 - what an incredible difference! My question was more hypothetical.

afmcorp - I misunderstood what you said. I thought you meant that the fuel was cooled before entering the cylinders. I am not enough of a DIY-er to try something like this on my precious 'benz, but I might mess with something else - Like my old beater Explorer. Was just hoping for solid engineering insight and feedback, and I think I got it!

psfred · #11 09-10-2004, 08:41 PM

You have a modern fuel injected engine, the only thing you would get would be some greater air density from cooling it.

Air/fuel ratio is controlled, reguardless of atmospheric temperature, pressure, or fuel density, by the oxygen sensor and mass air flow sensor.

You don't have fuel mixture problems, but you have a HUGE decrease in performance. My old Audi Fox (K-Jetronic fuel injection) ran fine at high altitude, but I had to run in 3rd gear most of the way from Vale to the top of the Eisenhower tunnel -- no horsepower. Ran as fast as I wanted in 3rd, but when I shifted to fourth just faded away. No smoke.

The difference in air pressure between a cold day and a hot day will be noticable. Turbocharged cars only suffer from serious turbo lag, performance is normal once the turbo comes up.

There is no cure, short of moving to a lower altitude.

Peter