Cold air intake?

[Tristin]

Carb'd cars love moist climate. I once read somewhere that a small increase to moisture in the air (fog, mist, etc.) really does add performance to a carb'd vehicle to the fact that the molecular amount of water seriously heightens the violence of the flame front due the fact that water can be compressed several times more than air/fuel before it will ignite. Granted this is on a molecular level... We all know what hydro lock is :-D

 

Liquids cant be compressed (at basic levels)... thats the entire governing principle of hydraulics. 

 

 

 

And just to talk this out, youre saying the water actually makes fire better? Id like to see these articles youre reading. Granted, this is my first carb'd vehicle, but none of that sounds remotely close to accurate. 

[mhub91]

No, no, no, sorry maybe I wasn't clear. I meant that in a moist environment the compression stroke not only compresses the air/fuel mixture but the molecular amount of water introduced. Basically it's A/F compression + H2O molecular compression. The acceleration of the 'explosion' or flamefront of the A/F mixture is less than that of the 'explosion' of the moisture.

[mhub91]

Liquids cant be compressed (at basic levels)... thats the entire governing principle of hydraulics. 

 

 

Yes, exactly... basic levels. Basic level here with be literally liquid water entering the carb.

 

I'm talking on molecular level here.

[Tristin]

The only time Ive heard water being a good thing in engines is in water injection systems which are used for cooling cylinders, which retard detonation issues. 

 

 

Yes, exactly... basic levels. Basic level here with be literally liquid water entering the carb.

 

I'm talking on molecular level here.

 

No, I dont think youre understanding right. Even at a molecular level, you cant compress a liquid. You can pressurize it... Theres no way that an engine produces enough compressional force to reduce the volume of a liquid. Cylinder pressure is ~150psi... thats not even remotely close to the level at which you would need to compress a liquid.  

 

Can you provide any articles supporting your thoughts? Id love to read them. 

[Dawa]

It varies by the type of ECU programming. Normal MAF systems will work exactly the same in regards to cold air vs. hot air. MAFs are built to ignore temperature and pressure when calculating air volume so it gives the same fuel for both hot and cold air. By cramming in the same amount of fuel with colder air, the MAF engine will produce higher numbers. 

 

If running speed density, then the ECU will adjust fuel for changes in temperature so on a base tune, almost anything below heat soak temperatures will be the same with any change in temperature. 

 

 

 

Having anything but a smooth pipe will induce quite the air disturbance in intake path. Thats the exact reason that people ditch the stock airboxes for ram or CAI (not including the ricer fanboys doing it purely based off racecar status). There would have to be some tests to see if the disturbances would negate the positive effects of the colder air. I have no idea. I think adding a water trap is just way too much work for what its worth though personally. 

^oh i agree. maybe using the 'trap door' (water trap) wasnt the correct thing to say

here is an example of what i really meant, a COUNTOURED door. that would not introduce turbulence in the system. 

 

and after drawing it out, i realize it would just be easier to disconnect the duct at the plenum end AND redirect the duct downwards. that way i dont have to 

block the funnel hole, AND the plenum is just sucking from engine bay

[Tristin]

and after drawing it out, i realize it would just be easier to disconnect the duct at the plenum end AND redirect the duct downwards. that way i dont have to 

block the funnel hole, AND the plenum is just sucking from engine bay

 

What stops all your incoming air from going out your trap door? Ive tried to come up with simple solutions to this as well since I live in a very rainy area. Ive come to the conclusion that Im just going to add a fine screen to the funnel on the bay side to minimize droplets from entering. Something like a grease screen when youre cooking. 

 

PS I love the doodle. Ill keep it forever :wub:

[Dawa]

the door would have some kind of hinge and latch

to stay shut, as well as some kind of gasket/o ring to keep it air tight. 

or even ghetto rigged, cut out the pipe and wire it shut. 

[Tristin]

the door would have some kind of hinge and latch

to stay shut, as well as some kind of gasket/o ring to keep it air tight. 

or even ghetto rigged, cut out the pipe and wire it shut. 

 

So with a light spring-rate it would only open under the weight of the water built up? Hmmm

[Dawa]

no.

the door stays shut during non wet weather. 

but upon wet weather, you completely block off the funnel, allowing neither air or water

through the funnel. but that would not allow the plenum ANY air, so the door is opened

so that non wet air can be ingested. 

[datzenmike]

This is being over thought. Just run a 1/4" hose out. Trapped water gets out and the mount of air out is basically nil. Seen these ducted air pipes in the rain.. the air filter gets damp and acts clogged from sucking in all the road spray.

 

The basic stock air intake is more than enough. It has a flap door that mixes warmed air with air from in front of the rad to keep it around 90 F. The engine is 'tuned' to run best near this range. If you think it needs 'cold' air just jam it open and plug the warm air pipe. But don't throw away because come next winter you will want warmed air to prevent carb icing.

 

Ram air? Right... you would have to go over 150 to see any effect.

 

Cold air? Perhaps a good idea when the outside temp gets above 90F.

 

 

If you are looking for some hidden power don't waste your time.

[Gary]

all my cars have had some kind of opened up intake and a pod

 

not for mad respekt or hp gainz, just for noise

 

noise is all that matters. if it sounds like you're going faster then you definitely must be going faster. newton used to say that a lot, cos of like physics n shit

[datzenmike]

Now there's an honest response. It sounds more powerful so that's why I have it. Way better than 'I want more power'.

[Z-train]

Cold air? Perhaps a good idea when the outside temp gets above 90F.

 

 

If you are looking for some hidden power don't waste your time.

Mike that picture is from my friends 71 Lemans Wagon.455 D-ports,with the only aftermarket parts being cam,lifters & headers.Everything else is scienced out proven stuff.The car weighs 4100lbs and runs 11.3 @ 124 with a 3.55 gear.If that cold air set-up didn't produce an advantage-it wouldn't be there.

 

Now will you see this improvement on a "normal Datsun"......maybe not.

[Jose720]

and slap on one of those plenums

 

 

any part number for this?

[datzenmike]

The 720 already has a cold air intake, why spend $75 on that?

[mrbigtanker]

thats interesting because i just read someone make the point of the complete opposite. 

they said that it works even better for carbs because the computer CANT adjust for temp change, etc

Carbs-rejet with cooler outside air instead of engine compartment air

EFI- you should have a air temp sensor,i got one on my FJ that will read the air temp coming in and readjust itself.

 

 

 

Cold air intakes work but not one still pulling air from the engine compartment you get more air not denser air,just think of the old days when they put ice bags on the intake to cool the intake manifold and cool the air coming in to the carb.

 

ANd is it worth it for maybe 3-4 HP gain at the wheels if you drag race do it but  for a rusty street car you aint going to feel it.

[Jose720]

just wanted to know mike, my truck has nothing of the intake, so i had to put a little douche filter to not get shit in my carb

[datzenmike]

Ah, well, fly at 'er or probably cheaper to get another one from a 720. And you don't have to look hard for the $30 K&N filters for them either.

[Tinman]

Carb'd cars love moist climate. I once read somewhere that a small increase to moisture in the air (fog, mist, etc.) really does add performance to a carb'd vehicle to the fact that the molecular amount of water seriously heightens the violence of the flame front due the fact that water can be compressed several times more than air/fuel before it will ignite. Granted this is on a molecular level... We all know what hydro lock is :-D

My 720 runs like a beast when it's cold and foggy at night!  Wish it ran like that ALL the time.

 

I have thought about water mist injection for hot days.

[genkiracing]

I'm so glad someone brought this up. I have been thinking of doing this project on my own 510 (L16 single weber 32/26). My concept was to run a single duct from a headlight through some kind of inline fliter to a plenum.

 

My big concern is that too much ram air pressure or too restrictive piping could somehow affect the venturi flow and mess up fuel draw. Anyone know about this?

 

I tried to do some back-of-the-napkin math to figure out a good diameter for the tube and concluded that at ~120mph at WOT and 7500rpm then a 2" pipe would flow pretty close to the 100k cc / sec the engine needs. In other words any inlet bigger than 2" will produce positive pressure at that speed.  However at low speed and higher rpm, like the top of 3rd, there is a loss and the engine has to suck air through the restrictive tube.

Anyways I arrived at 3" being a good pipe size as I want to lean towards a little over-pressure with no restriction at low speed high rpm.

 

Looking around I found that Redline has an adapter and plenum with a 3" inlet (part 99010.357)

http://www.carburetion.com/products/productdetails.aspx?part=99010.357

And Spectre has an inline 3" fliter (part SPE-9833) 

http://www.summitracing.com/parts/spe-9833?seid=srese1&gclid=COW7kNDO2bsCFWMV7Aod4mkApw

 

Does anyone have any actual experience throwing together a ram system like this? Any comments on the parts/brands I came up with?

 

If so I'd really love to hear about it. If not.... maybe I'll just build it and try it out.

 

And ya, as someone pointed out earlier in this thread, I'm not looking to make mad gainz. I'm looking to shave fractions (or dare I hope seconds?) off my lap times, at least on the straight sections over 80mph where the little 1600 starts to struggle to get to redline. ^_^

[Kytoaster]

Just ran across this thread...thought I would drop this here.

[Stoffregen Motorsports]

We tested it on a GT3 240SX KA24 on the dyno once. We did some math and figured that at 100 mph, the air box (if located properly) would receive about 5 lbs of boost. So we re-created that scenario and ran it on the dyno. It made about 5 more hp consistently.