Cooler air in cylinders equals more, P O W E R Options

[gregrobbins]

At the DE today at Firebird Raceway, there was one very quick 2.0L 914.

I met and talked with the owner John Seymour for awhile. One of the innovations he came up with really looks interesting. Instead of the stock air filter box. he looked for a way to get cooler air into the motor. Study the photo (I have more if you want me to post). He ran a PVC pipe from the TPS to hoses that go down to the J tubes. From there they are connected to the air ducts in the longs and finally, he is pulling air from the opening in front of the windshield. He claims it works like a charm. I don't doubt him, as he is running D-jet and was as quick or quicker than the 2.0L cars that had been converted to carbs.

[Hammy]

So what's the conclusion...does it add power?

[Mueller]

QUOTE (Hammy @ Nov 14 2005, 03:14 PM)

So what's the conclusion...does it add power?

dunno, too variables to be an arm-chair engineer, only testing would prove/disprove it.....

I'm guessing if it didn't work, the owner would have removed it by now since it sounds like he's been running it for a while....

[jsteele22]

Most of the time an intercooler is used in a turbocharged car, b/c the compression of all that air genereates a lot of heat. Since the compressed air is so much hotter than ambient, its (relatively) easy for the intercooler to extract some of that heat. I would think that on a N/A car, there's not much use in an air/air intercooler, since the air doesn't (shouldn't) get that hot anyway; just make sure to grab the air from some place cool.

Going *below* ambient should also increase power, but it gets down to a question of practicality. ( Actually, part of the boost from nitrous is due to cooling : just like when you let air out of a tire or use a spray can, the nitrous gets cold when you squirt it.)

I haven't heard about dry ice being used. Although it's cheap, safe and easy to get a hold of, the big problem is that its a solid, so its hard to make a good thermal contact with, say, an inlet air pipe. If somebody wanted to mess with something really crazy (i.e. : I'm not saying that its a good idea), you might try mixing dry ice with acetone. This combination forms a slush (like rock salt and ice in the old ice maker) at a temperature of -108 F. So you'd need a container that doesn't leak, doesn't turn brittle at low temp, and allows the CO2 to boil off without exploding. Run your air pipes through there and I'm sure you'll feel some extra oomph, at least until the dry ice is gone.

[scotty b]

flow rate could easily be increased with two of the aftermarket blowers made for vw heating systems. Put one on each side, towards the rear so it would pull from the front and give a little boost just before the intake. I've thought about it befor but I was thinking of running it through the firewall and then through the center tunnel. Pvc in the tunnel, flex pipe at the walls.

[Andyrew]

Heres my response to your PM srbliss
I couldnt get my internet to let me send a pm... its on the fritz right now... sorry
Others might also know.

"Hello Andrew,
I think we met at the metalshaping class a few months ago.
I have an odd question that only an engine swap guy with a running car could answer. What direction does the air flow in your engine compartment? I was hoping to get you to do a quick test next time you drive your car - if you don't mind could you tape a sheet of paper or cardboard on your air intake (grill) and note if it was sucked down or blown upward by the air flowing (if it flows at all) thru the engine compartment."

I am asking because I am starting a Subaru engine and transmission swap and would like to setup the radiator in front of the engine and use whatever natural air flow that exists.
Thanks
Steve.


"I'll give you a quick answer and send you another answer a little later.

I currently have the factory sweeper things that used to go in front of the engine under the car, 72 plus cars had them, they throw air onto the bottom of the engine. That said, I do not think there is much pressure what soever at the engine grill. I think that all the air gets sucked to a medium by the headers and then gets thrown out the bottom of the car, and the air that is from the top of the car just goes right over the grill.

I'll get a piece of paper and test it out in a little.

Andrew"

[ein 6er]

hey ........ why not run hoses to your ac vents and crank the ac to high?!? (IMG:http://www.914world.com/bbs2/html/emoticons/lol2.gif)

here is a bimmer air box i saw at sebring.

[jsteele22]

QUOTE (scotty b @ Nov 14 2005, 05:28 PM)

flow rate could easily be increased with two of the aftermarket blowers made for vw heating systems. Put one on each side, towards the rear so it would pull from the front and give a little boost just before the intake. I've thought about it befor but I was thinking of running it through the firewall and then through the center tunnel. Pvc in the tunnel, flex pipe at the walls.

That's really just a supercharger, but powered indirectly (and inefficiently) via alternator/wires/motor instead of a belt. If the fan motor is wimpy (like a VW heater blower) you aren't really gaining anything noticeable in terms of power. If it's not, you are placing a huge load on the car's engine (and alternator). In general, a supercharger is less efficient than a turbo, b/c it takes "good" energy to drive it (from the crankshaft) as opposed to "bad" energy (from the exhaust stream). So says Corky Bell, anyways.


The problem with this kind of thing, is that to get any significant increase in power, you have to increase the number of O2 molecules significantly. Just wafting them along through a tube won't cram many more of them into the cylinder. To get a feel for it, imagine using a bicycle pump to pump a car tire from 0 psi (gauge) to 10 psi (gauge). It's no manliness contest, but it does take a little time and effort. Compare this to a decent turbo setup which runs at 10 psi of boost. Since atmospheric pressure (for you lowlanders) is about 15 psi, that means an increase of around (25/15 -1) or 65% in oxygen going into the engine. So, ignoring lots of details, you get around 65% more power. Now for a 2.0L engine at 3600 RPM you breathe (3600/2 /60 * 2.0L) or 60 liters of air per second. Thats about 16 gallons of air. I don't know the volume of a car tire, but it seems rather less than 16 gallons. And 3600 RPM is kind of timid. But just imagine having to pump that tire up to 10 psi once per second, and you get a feel for the kind of job a turbocharger (or supercharger) has to accomplish. If you try something that's wimpy compared to a turbo/super charger, you'll get a result that's wimpy as well.

Using cool air, though modest, does help. It's like letting nature take care of all the hard work ahead of time. Working in absolute (Kelvin) degrees, density is proportional to temperature, if pressure is held constant (like atmospheric, fer example). So going from 55 C down to 35 C (i.e., 131 F down to 95 F), which is a 20 degree diff at (273 + 35) K, gives an increase in O2 (hence HP) of 6% without expending any effort.

[Dave_Darling]

QUOTE (scotty b @ Nov 14 2005, 04:28 PM)

flow rate could easily be increased with two of the aftermarket blowers made for vw heating systems.

Hey, just keep adding more and more blowers and you'll have an electric supercharger!! (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)

I think you'll find the fans will impede flow at higher velocites, so your engine may get a little boost down at low RPMs but it'll be choked somewhat at higher revs.

--DD

[Eric_Shea]

I think you neighbor's alredy got a patent on it.