Well I'm in the process of getting my ram air duct working on my jdm front end. The question is what are the exact gains and drawbacks from the two setups below???

1. Ram air duct in bumper w/ dryer hose pointing at the Comptech Ice Box inlet horn. Maybe two to three inches away from it.

2. Ram air duct w/ dryer hose connected to Ice Box inlet horn

Things I would like to discuss are throttle response, intake air velocity, and whatever else you think might be related.

For those of you that don't know what I'm talking about, this piece goes in the plastic vent on the passenger side of the jdm bumper. The duct points directly towards my Ice Box.

 

Ram air on our cars has very little to do with stuffing air in the intake opening, due to our closed single plenum intake manifolds.

It has everything to do with sound wave resonance, and resonate waves bouncing off closed intake valves and amplifying in energy within the intake manifold.

 

As of now, the bumper is blocking any sort of ram air effect. Instead of having to suck air from inside the bumper, it's going to get pushed or forced into the horn. But at speed, the duct will be forcing air into the icebox and filter.

 

have it connected it the air horn on the icebox

please dont make this into a ram air debate thread

since you have already bought the scoop, u might as well finish it off. it should be a good mod regardless

 

I know that Bob has a duct with dryer hose as well, but the situation isn't exactly the same. Because my filter is enclosed within the Ice Box, and Bob's intake is a J's with the dryer hose pointing at it. It is not enclosed.

Essentially if I connect the hose to the horn I have an elongated intake tube sucking cooler air. So I might make more power, but throttle response might be sacrificed.

Bob has a short ram with cold air from the duct shooting at it. This allows him throttle response and cold air, but not as cold, because the short ram still leaves the filter exposed to the engine temps.

Not trying to start a debate, just want to weigh out the benefits and costs. Just attempting to learn a little more before I decide.

 

if i were you

I would first just put the duct in and drive around and see how it feels

after another week or so when u have more time connect the duct to the ram

drive some more and see how it feels

 

did something similar with my USDM front end

(click here for details:
https://honda-tech.com/zerothread?id=438312 )

Long story short, I felt a huge drop in throttle response with the dryer hose connected... Once I disconnected it (and left just the intake vent) the throttle response was much better. I dyno'd my ghetto intake vs. and open intake pipe, and there was only a ~1 hp difference - so this setup is definately efficient...

Here's another good thread on the "ram air" idea (where I got my inspiration):
https://honda-tech.com/zerothread?id=398042

 

I don't think that that setup will be enough to produce positive manifold pressure (hence the "ram" effect)...at best, its suppose to be a cool air vent...you car will run loads better in cooler weather with the duct installed.

but for giggles, you might want to install a vacuum gauge (sort of like a boost gauge for NA cars) to see if you are getting positive pressure. If you are, then use something like an AFC to feed it more fuel...that will give you more power.

 

This is on topic but not directly related to our ITRs:

On our Dyno today we had a 1.8T Jetta with a 2" tube direct from the stock air box straight through the headlamp to the front of the car. Home depot style for ram air.
We did back to back runs with it open and then with it plugged off.

I kid you not with the "Home Depot" ram air 15WHP and 20Lbft at the wheels on our Mustang chassis dyno.

Granted this was on a Turbo car, but cold air

Mattj

 

wow! that is a TON of power - especially on a Mustang dyno...
Did they dyno with the hood open or closed?
(I assume they used one of those giant fans too, right?)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
We did back to back runs with it open and then with it plugged off.
</TD></TR></TABLE>

out of curiosity, where was the airbox sucking air from when the hose was closed? (ie: open airbox, underneath, etc)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dropspeed &raquo;</TD></TR><TR><TD CLASS="quote">

I kid you not with the "Home Depot" ram air 15WHP and 20Lbft at the wheels on our Mustang chassis dyno.

Granted this was on a Turbo car, but cold air

Mattj</TD></TR></TABLE>


How was the cold air replicated on a dyno, I take a Fan was in front and how does this very in effect of wind at a gradual increasing speed?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jdmspoonitr &raquo;</TD></TR><TR><TD CLASS="quote">Well I'm in the process of getting my ram air duct working on my jdm front end. The question is what are the exact gains and drawbacks from the two setups below???

1. Ram air duct in bumper w/ dryer hose pointing at the Comptech Ice Box inlet horn. Maybe two to three inches away from it.

2. Ram air duct w/ dryer hose connected to Ice Box inlet horn

Things I would like to discuss are throttle response, intake air velocity, and whatever else you think might be related.

For those of you that don't know what I'm talking about, this piece goes in the plastic vent on the passenger side of the jdm bumper. The duct points directly towards my Ice Box.</TD></TR></TABLE>

If you're going to use crappy dryer hose, then definitely point it AT the horn rather than connecting it to the horn. That way your engine can suck in more air from around the horn if the hose can't deliver enough. It'll also preserve throttle response by keeping the sealed part of the intake track as short as possible.

You can't hope to get any useful ram effect (i.e., intake air pressure increase) out of it. The best you can hope to gain is the coldest possible air coming in. And since the Icebox already draws from a relatively cool area, there's really no point to connecting them at all.

On a related note, I finally got off my *** long enough to find a pressure calculator to determine exactly how much ram effect is possible. The answer: less than 0.2 psi at 100 mph. And that's only if your intake is perfect, which dryer hose definitely is not.

The calculator I used is at http://www.coolmath.com/calculators/atmosphere.htm if you'd like to play with it yourself. You'll have to convert from mph to ft/sec (ft/sec = mph * 5280 / 3600) and from psf to psi (psi = psf / 144). The number you're interested in is the Dynamic Pressure. That's the maximum amount of pressure that's available due to the motion of the air.