Has anyone built/installed a true, pressurized ram-air intake? By this, I mean an intake system that actually results in an overpressure in the airbox? I know that there are a few "cold air" systems out there (both commercial and home-made), but I've not yet seen anybody post results from a true, pressurized ram-air setup.

This should offer big performance, both from feeding the engine with the coldest air available, and also from the "pre-boosting" effect.

I'm designing such a system right now, and I have a fabicator lined up (almost, a little more bribery should seal the deal). This will incorporate the stock airbox, fed by a fabricated aluminum "ram air" assembly. Not the simplest system to engineer, due to the lack of available "real estate" under the hood and up front in the grilles.

I plan to install a vacuum gauge and a temperature gauge in the upper chamber of the airbox (above the filter element). I'll test the setup with the stock inlet in place, then blanked off (sealed). Note that you can't have a ram-air system with the stock inlet hole open - you will lose any overpressure back into the fender.

What I'll be looking for, of course, is for the temperature in the top chamber of the airbox at "ambient" and for the vacuum in that chamber to drop to zero at some speed (at WOT for the toughest test of the concept). With the vacuum at zero (or some positive pressure - no boost gauge available is sensitive enough), you will be enjoying a true ram-air effect and at that point exceeding the performance of ANY aftermarket conical filter arrangement. The best those systems can offer is a slight vacuum (low restriction) at the MAF and intake temperatures presumably above ambient (due to ingestion of warm air from the engine compartment).

Has anybody worked on such a system? My concerns right now center on:

1) Feeding the airbox with a large enough duct to handle the flow. The Eaton pumps almost 700 CFM at redline and 10 PSI boost. Through a 4-inch round duct, this requires a flow velocity of 91 mph to feed the engine. Thus, with NO flow losses all the way to the MAF (a really crude assumption), you would need to be rolling at a minimum of 91 mph to achieve a positive airbox pressure (a ram-air effect) at redline with a duct of that size. Unfortunately, this is the only size of flexible, but "rigid" aluminum duct I've been able to find. With a 5-inch duct, the theoretical speed for a positive airbox pressure at redline/WOT is 58 mph (much better). Does anyone know where I can get proper flexible round aluminum duct of this size?

The air must be SCREAMING through the little stock inlet hole at redline - 150 mph maybe? That's a huge restriction - I can't imagine how high the vacuum is in the upper airbox chamber of a stocker (enogh to reduce the boost pressure by a couple PSI, I guess).

2) Will such a system disrupt the MAF reading or screw up anything else? I've heard a couple whispers about experiences with Mustangs, but nothing regarding a Lightning. Any experience (38 TopGun)?

3) Ingestion of water through a low-mounted inlet (although I never willingly drive in the rain or off-road).

I'm looking forward to your thoughts/comments. I need to get the engineering on this correct from the get-go. I think that I'll only have one good shot at it. I suppose that the worst I could end up with is a good cold-air induction setup that bleeds off the airbox overpressure at high speeds through the stock inlet. Still not too bad. I just want to see what a system offering pre-boost will do for performance.

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Silver Y2K Lightning
Bone Stock w/ Duraliner, Ford Hitch Cover

Best 60-foot: 2.063
Best 1/8: 8.876
Best 1/4: 13.789
Best MPH: 99.67

Silver (matching) Y2K ML320 Benz
Burl (ML430) Shift ****

1992 Grand Prix SE
Commuter Mule (G-Tech 17.3 @ 81)

 

Whitelightnin':

Those morons at ROAR aren't worth the bother. Familiar with their products/site - ricer geeks that know nothing of fluid mechanics, not to mention syntax, spelling, or grammar. Their stuff isn't nearly beefy enough to feed a 'Bolt, anyway.

'Dog:

There's plenty of room to work - it just becomes a question of motivation. You can definitely get a 4-inch hose out of the engine bay through the driver's side fender liner - there's already a big enough hole there (not certain about tire clearance). A 5-incher will clear the hole with just a little trimming. From there, It's a pretty straight shot to wherever you want to put an intake. I also think that you might be able to get a hose out of the bay by running it straight toward the ground from the airbox. I admittedly need to put in a little work on the creeper this weekend, though.

For intake location, the obvious way to go is tear out one or both of the fogs - nice big, round holes in a high-pressure portion of the air dam. I'm not crazy about that location, though, as I like the look of the fogs. On the side portions of the lower grille is also an option, although you would need to open up the honeycomb and frame clearance looks tough there. My current though is to bolt the intake scoop to the frame some distance back from the front of the air dam, with a (single/couple/few) inches hanging lower than the lower lip of the air dam (ground clearance issue). There's an advantage of NOT having your ride lowered, I guess. Buys me 2 free inches of scoop protrusion. I think I'll be able to hang enough of the scoop into the airstream to catch some decent high-pressure air. Of course, my goal is still to find a good spot out in the nose of the beast somewhere. I'm not averse to stealing a little air from the front of either radiator, if necessary. There sure is a lot of componentry from the firewall forward in one of these things!

I'm still searching for some decent 5-inch flexible round aluminum duct. Any leads? The 4-inch stuff is available everywhere, but is just a little small for the application, I think. It will do in a pinch, of course. Anything is better than the stock setup.

 

just a question for you, what device are you going to use to "create" this pressure that you want?!? You will need a mechanical device to actually force more air into the filter housing, besides what you get driving along with the air that is normally going to be flowing in. There is no way of getting more air into the system (like I said besides what availble air you get by driving along) w/out using some device to "force" (or a pressurized ram-air set up as you put it). I think most people would call it a supercharger, hehe. Am I understanding that this is what you are trying to do?!?

[This message has been edited by Yoda (edited 01-03-2001).]

 

Yoda:

You need to study up on your fluid mechanics a little (actually a lot). I, unfortunately, need to brush up a little also to give you the exact numbers.

It go-a-little-sumpin-like-this. When moving fluid (air is moving, relative to the truck, at speed) stagnates (hits a wall or other unyielding object), the kinetic energy (or momentum, hazy recollection) of the fluid is converted to static pressure. That's why your arm tries to rip out of your shoulder when you stick it out the window at 150 mph - pressure acting over all of the square inches of your appendage as the 150 mph air gives up all of its kinetic energy.

As you blow ever-faster air into a closed duct, the pressure in that duct becomes ever higher. If your 'Bolt was capable of several hundred MPH, you could bypass the Eaton at speed and still get 10 or 12 or whatever psi of boost.

Indeed, a true ram air setup into a sealed airbox will feed the intake under positive pressure. It's not a lot of psi, but it is a positive pressure.

Unfortunately, at WOT/redline the air in a 5-inch round duct feeding the airbox will actually be ACCELERATED to feed the engine at speeds below 58 mph (resulting in a vacuum at the intake). Above 58 mph, the air rammed into the duct actually has to slow down, shed kinetic energy, and provide pressure.

If you need the equations and a more detailed explanation, I'll have to hit the books a little. Please, PLEASE don't make me do that. But trust me, you can and will force air under pressure into the intake of an engine with a sealed ram air system under the right conditions (based on duct size, vehicle speed, frictional flow losses in the duct, and airflow demand into the engine). That's a fact.

 

Its been a while for me too with fluid dynamics, but what if you had a larger scoop up front to catch a larger volume of air before traveling through the 4" tubing? it would still have to travel your ~91mph through the tubing itself, but with a scoop your truck would only have to be moving at some fraction of that speed (say ~60mph for instance). theoretically, the larger the scoop- the slower you would have to be moving. i've also been looking at cutting out two holes in the outer portions of the lower grille (as not to interfere with the air that already flows over the cooler- i don't really want to have to "give to gain" if you know what i mean), but don't have the resources or time right now to get any further than thinking about it. what if you had a long, thin rectangular scoop mounted where you said- just protruding below the lower front fascia. if the area of a circle (or the 4" dia. tubing we're talking about) is Pi*r^2, i'm guestimating the area to be just over 12 in^2 (since i don't have a calculator with me that has a Pi function). am i thinking this through correctly- that if you double that area for a scoop (24 in^2), you halve the mph you'd have to be traveling (91mph / 2= 45mph)? if that holds true, you could make a scoop that was triple the original size (36in^2, or 3" tall by 12" long) and would only have to be moving at 30mph, which last i checked was about 10mph below redline speed in a stock rearend equipped lightning. that seems more reasonable to me than greater than highway speeds. again, i don't know if my physics holds true, but it might be something to think about. hope it helps. let us know how its coming. later...

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Play the game- Don't let the game play you!!!
(((garrett)))
'00 Silver Lightning
'00 KX250
'00 NESC MX Amateur Champ

Quickest (accurate?) G-Tech/Pro Results (12/26/00):
(Bone stock, full street trim, F1's, 6200 miles, 19 degrees F outside):
0-60mph = 4.64s
1/4 mile = 13.01s
RWHP = 394
motoxer@wpi.edu

 

MXRacer:

Great idea - unfortunately it doesn't work that way. We're dealing with pressure here, unfortunately, which behaves in ways that sometimes defies basic intuition.

The easiest way to analyze what you're proposing is to look at different containers of water of the same height. Think of a cylindrical one (a bucket), a funnel-shaped one (wide part at top), and the same funnel-shaped one reversed (wide part at bottom). Fill them all to the same level. The pressure at the "bottom" of each is the same, period. This will seem illogical to some, but unfortunately that's how Mother Nature works.

Since we are dealing with pressurized FLOW here, not just static pressure, the size of the "scoop" does have some minimal significance - its projected area normal to the flow direction has to be at least as large as the duct in order to get the full ram-air pressurization effect in the duct. Other than that, you could have a scoop the size of Texas and not deliver any extra pressure to the intake. Also, the scoop should not provide any flow restriction even at the proper cross-sectional area (for instance, a duct a mile wide and 10 microns high would not cut the mustard due to frictional flow losses).

This is starting to make my head throb.

Now, if you're putting the scoop in an area that's partially obstructed (back on the frame somewhere), a larger area may pay dividends in trying to catch enough "square inches of fast-moving air".

 

Silver,

I always get a kick in reading your posts.....

I concur with your thoughts on "RoarInc", What Brave Sierra.

Though I am interested in your findings, I trust the words "Megaram", "Pulsewave", "nano weight coagulate", and "hyperactive cooling" will NOT be included......

Robert

 

Hmmmm...let me think about that one for a bit.

Interesting thoughts.

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2000 Red Lightning - #835 of 4966 Born 3-8-00 / Delivered 3-22-00
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Best time: 13.45 sec. @ 101.99 mph

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get a large 330cu ft compressed air cylinder in the bed, a hi-flow regulator to supply huge amounts of cfm to the air box/tube as the eaton is gulping it down, and you might have enough for a 30 second "test"

 

I have tried to figure out where a real ram-air setup would fit in the L, myself, and I just don't see the room for anything except a through-the-fender setup, or by running it through hood scoops like the Cervini/JDM Enginering prototype.

Through-the-fender will require a significantly larger hole, as you noted. and plumbing that puppy would require some significant fab work on the L fender.

JDM's approach looks like a cleaner install, but I imagine it would be awful expensive.

You should be able to find pics of the JDM setup around here somewhere. I haven't anything about its commercial availability.



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Regards,
Gordon

'99 Red Lightning
Johnny Lightning Superchip
Johnny Lighting Ram Air Kit
Century Tonneau
Best 1/4 mi. ET: 13.249 secs

 

http://www.roarinc.com/


Silver Y2K...please research..no time here...thanks for your support

 

Robert, The Sultan Of Speed:

Thanks for the shout-out. I'm dead serious about this project. My strong overall tendencies are to keep the whole thing stock, but my wife got me a VDO boost gauge for Christmas. So as long as I have to butcher it...

I'm really trying to do my homework on this one. My goal is to produce the best performing induction system possible, period. With the right design and fabrication, it should be a piece of cake to better the aftermarket units (no ram effect and ingestion of lukewarm-at-best air). The "blastgate" home-brewed ststem KGM (?) put in is a step in the right direction, but that can be bettered, for sure. I plan to design it right, have my fabricator build it right, install it right, instrument the snot out of it, then rigorously test it.

If it all works out, I'll post the 'prints. Note that it will be some time before I have any good results. The 'Bolt is garaged until at least the first of March, maybe longer (weather, salt, and travel commitments).

What can I say about those weenies at ROAR? You would be better off putting magnets in your fuel tank or one of those inserts in your air cleaner that make the air "spin" (a "Vornado" or something like that). Or maybe some "Motor Up" or "Slick 50" or "Marvel Mystery Oil"...

The precise science by which internal combustion engines operate is not well, if at all, understood by the "layman". Whenever things aren't well-understood, much gets attributed to what I like to refer to as "Mystical Forces". These "Mystical Forces" are scary. Cave men didn't understand the causes of various weather phenomena - feared it - "Mystical Forces". I work with chemistry and my wife with radioactivity and electricity. People fear the SNOT out of these things, on balance. Definite "Mystical Forces". And unfortunately, a lot of otherwise well-understood principles governing the function of a simple Otto-cycle internal combustion engine are beyong the comprehension of many, if not most folks. That's where the infomercials and ROAR and all the rest come in. Essentially, you make a financial sacrafice to the gods of internal combustion to "calm the demons", or so you hope. When all you REALLY need is to prevent boundary layer separation on the inside radius of the intake tract 3.6 cm upstream of the valve seat by strategic removal of 8.2 grams of aluminum alloy with a rotary cutter in the immediate vicinity...

Honestly, that ROAR stuff is such bullshizznit that it's funny. You could almost be led to believe that the site is one elaborate joke poking fun at us high-performance guys. Unfortunately, I know the mentality of "the group that they market to", and the "high-tech features" that their products offer are right up their alley, if you get my meaning.

 

Silver...Here is a link that maybe helpful to you for the hose.http://www.ramairbox.com/home_page.html I just ordered their 4x11 fiberglass snorkel to replace my 6" into 4" which should be a bit better. I have no test results on "blastgate" to help you, but seems you are on to something and look forward to your findings.

 

KGM:

You are my new hero and role model. I'm referring specifically to the 5-inch flexible aluminum tube available from the guys at RAMAIRBOX.COM. I'm pretty much free to "design at will" at this point.

It was your photos of the "Blastgate" system that got me thinking in this direction in the first place.

A good test would be for you to plant a vacuum gauge in the top chamber of your airbox and make some passes with the Blastgate open and closed. Then blank off the stock inlet, open the Blastgate, and make some more passes. The less vacuum, the better, of course. You could also instrument the top chamber for temperature, as well. This would also be useful information. I plan to do this, but results will be some time off. The goal is to implement an induction system that produces a positive pressure (as indicated by zero vacuum) in the top airbox chamber under some conditions (high speed, lower RPM at least), and minimizes vacuum at that point under ALL conditions.

All right. I'm headed to our library to dig out the necessary fluid mechnics texts and work out some more numbers. Stay tuned.

 

Silver...I would stay away from the aluminium, tried that first, to many bends to make just got all beat up look'in. May try your vac gauge soon. Wonder if someone makes a 5" "blastgate"?