Let the cold air in

[sturgeon-phish]

Craig was asking about my mod to let cold air into the air intake and here are some pictures. It really made an improvment was cheap and easy to do.
http://i126.photobucket.com/albums/p81/sturgeon-phish/Truck/001_0010-6.jpg
http://i126.photobucket.com/albums/p81/sturgeon-phish/Truck/000_0011.jpg
http://i126.photobucket.com/albums/p81/sturgeon-phish/Truck/000_0012-5.jpg
http://i126.photobucket.com/albums/p81/sturgeon-phish/Truck/001_0013-7.jpg
Here is how I did it
1. Remove existing turn signal housing
2. make a bracket and attach to the framework behind the turn signal
3. mount an aftermarket turn signal to the housing attach with scotch locks
4. Keep both lights to keep turn signal working properly, (not giving indication of burnt out light)
5. Cut aluminum case material to fit opening
6. Drill holes for mounting screws
7. Cut 3/8

[a5150nut]

Nice! So air in passengers side goes to intake, where does the drivers side go to?

[sturgeon-phish]

As best as I can tell, it passes through the fender and out

[jon6.5]

mind posting a pic of it in the dark, i am intrested in seeing how the light looks through the mesh, why its nessary to have a light behind the mesh the corner lights will still work so what is the point. what kind of improvments did you notice.

Thanks Jon

[Craig M]

I like this idea. In looking inside my Yukon I am thinking of the following. Move the battery tray from stock location back about 24", right next to the overflow tank. Move the intake for the air filter "forward" from stock location to old battery area. Basically switch the airbox with the battery. Box in the intake area. Provide cool air from the lens area into this relocated intake area as per Jim's design.

[sturgeon-phish]

mind posting a pic of it in the dark, i am intrested in seeing how the light looks through the mesh, why its nessary to have a light behind the mesh the corner lights will still work so what is the point. what kind of improvments did you notice.

Thanks Jon
I'll go out tonight and take a picture at night. The corner lights alone may not be enough to be legal. When I made the change I did not have gauges. My average MPG went up almost 2 mpg, and it ssemed to run cooler. It may be a day or so before I get the pictures posted
Jim

[jon6.5]

tonight i went out in search of parts to do this and could not turn up the alloy plate to cover the holes. were did you find it?

[Shikaroka]

The driver's side might be a good place to mount the heat sink for your remote mount FSD.
I had thought about modifying the corner lenses, since one of them is pretty much a dummy anyways. But, I like this idea.

[sturgeon-phish]

Here is the shot at night
http://i126.photobucket.com/albums/p81/sturgeon-phish/Truck/000_0002.jpg
http://i126.photobucket.com/albums/p81/sturgeon-phish/Truck/000_0003.jpg
I agree the drivers side would be good for the FSD. I thought about using the cornering lamp location and leave the turn signal stock, but I did not care for the way it looked. I had about $25 in the mod 2 years ago. As far as the sheetmetal goes, I got it from a scrap pile of old PC cases. Diffusers for HVAC drop ceilings may work also. Just something with hloes but not so much as to llet water in.

[JTodd]

I went to a big sheet metal shop and they gave me a couple of scrap pieces for free. I outfitted mine the same way as here, except I painted mine body color - black. I think it works and looks great.

[sturgeon-phish]

Can you post a pic?

[JTodd]

Here is a picture of the painted screen. As mentioned, I literally was given a couple of small scrap pieces from a local sheet metal fab shop. What you cannot see is that I attached the bulbs in their approximate original position. They do not have any reflectors, so they are quite a bit dimmer, but they are still fully functional. With working corner lamps, visibility should not be a problem.
http://i36.photobucket.com/albums/e19/jtodd57/P1000690.jpg

[sturgeon-phish]

Looks good!

[sailun]

This might not have quite the ram air effect, but I think it should let just as much air in, as the screen. I also closed my airbox back up, so I only get cold air from the fender. Thinking about heat reflective insulation for the airbox, to try to reject turbo heat. Any thoughts ?

[sturgeon-phish]

This might not have quite the ram air effect, but I think it should let just as much air in, as the screen. I also closed my airbox back up, so I only get cold air from the fender. Thinking about heat reflective insulation for the airbox, to try to reject turbo heat. Any thoughts ?
It is bound to help and definatly cost effective, even more than my setup. Insulating the air box, it would not hurt anything, especially if materials were inexpensive.
Jim

[Shikaroka]

This might not have quite the ram air effect, but I think it should let just as much air in, as the screen.

I don't get it. What's different or been modified here?

[sailun]

Actually, that's just the response I was looking for ! :-)

Sorry, bad picture. I ground off the plastic trim above and below the lense, but left the the trim around the 4 mounting screws.

[Craig M]

Question "whats been modified here"?

The original GM design has a small gap around the lights, around 1/8 to 1/4 inch or so. The air that goes to the snorkel that goes to the air box has to go in the gap. By making a larger gap Sailun hopes to get better air flow and more of a ram air effect that stock. The other designs shown in this topic have used screens over total lower light area to do the same thing.

[Shikaroka]

Actually, that's just the response I was looking for ! :-)

Sorry, bad picture.

...or bad monitor on my end. It looked stock to me, but I understand what you did. Cool idea.

[sailun]

It's a bad picture. I was too lazy to turn the truck around into the sun, but it was too bright for the flash to go off. So no contrast.

Stock has at most 1/8 gap on top and nuthin on the bottom, now it's just about a 1/2 on each side.

I've been running without the lid on the airbox all winter, thinking less restriction. But, after periods of slow driving, like commuting, and driving kids around town (read warm air under the hood), it would feel doggy.

So after the first commute today, it seemed to not get the doggy feeling. But that's just one day. We'll see.

"Cool idea" Pun intended ?

I gotta say those screen jobs look right ! You gotta feel good when your mods look good.

I'm thinkin there must be a way to combine your screens with some LED's, and get the best of both worlds: Great airflow and great turn signal visibility.

If someone starts manufacturing them, just pay me the royalties ! $10 a set !

[sturgeon-phish]

And we can use the profit to buy an intercooler!!!
Or a Duramax!!!!!!!!!

[jon6.5]

269OK well i went ahead and did it. just go an extra little bit and put the new air supply to use i moved my battery and placed the air filter right in front of the hole. sorry for the poor pic i had a hell of a time getting the site to let me post it, so i had to make the quality very poor. my results were as follows with the current outside temp of 55.

before removing light
45mph=79 degrees
60mph=76 degrees

After removing light
45mph=64
60mph=57

I did not expect much of an improvement but the numbers proved it. I got this by placing a wireless thermometer right beside the air cleaner to get the temp of the air going into the air cleaner.

[Shikaroka]

"Cool idea" Pun intended ?


I'm thinkin there must be a way to combine your screens with some LED's, and get the best of both worlds: Great airflow and great turn signal visibility.


Yeh, I guess so.

I have actually been working with that idea for a little while now. I have several LED lights that should work well there, I just need to find a source for the sheet metal.

I am in the process of totally remaking the front end of my truck (will probably post pics soon) and I may incorperate some of these "cool ideas".

[Shikaroka]

before removing light
45mph=79 degrees
60mph=76 degrees

After removing light
45mph=64
60mph=57


That's pretty impressive!

[DennisG01]

Are you also taking off the black "scoop" that's attached to the back side of the headlight (where the air normally comes in and is directed into the fender)?

[sturgeon-phish]

I left the scoop in. It would interesting to see if it would make a difference.
Jim

[sailun]

What did you make your new intake out of ?

Have you been tracking the battery temperatures, before and after ? You could probly compare the driver side and the passenger side.

After a good long highway drive, or a nice slow commute in the summer.

What's the under-hood temps you're seeing ? Air temp in the fender ?

Curious minds, you know ?

I've been thinking about another light/airscoop design, but I'm gonna hang on to this one, before letting it loose on the 6.5 public.

BTW, I still haven't determined which is better: cold air/closed filter box/more restriction or warm air/open filter box/less restriction.

First indications are that overall performance and MPG went down.

But too soon to tell.

[jon6.5]

[QUOTE=sailun]What did you make your new intake out of ?

Have you been tracking the battery temperatures, before and after ?

After a good long highway drive, or a nice slow commute in the summer.

What's the under-hood temps you're seeing ? Air temp in the fender ?


well i did remove the black fender scoop but i did not track the battery temp. The only tests i have done were shown in my other post, with the current temperature then speed to temperature comparison. My intake is just a 3" tube i bent to a 45 degree angle and used a 3" coupler to connect the pipe to the turbo, very simple set up. i hope that helps a little but if not i will do as much as i can to help.

[DennisG01]

BTW, I still haven't determined which is better: cold air/closed filter box/more restriction or warm air/open filter box/less restriction.


I agree. Once I get my new engine in, I'll get a thermometer and take some readings. I'm curious to see how much heat the turbo actually transfers to my filter the way it is. With the air rushing out of the fender, I'm thinking that some mof that rushing air is going over and around the filter, thereby pushing the turbo heat away. Just a theory, though.

What I can tell you, though, is I saw no noticable difference when towing in the summer when I compared the stock setup to what I have done below. I used a measured-mile hill from a stand-still and recorded ET, EGT, Max Boost and Speed. Final numbers where close enough to say no appreciable difference.

http://www.thedieselpageforums.com/photopost/data/519/Air_Intake_a.JPG

[sailun]

That's a nice setup. It's gotta flow way better than the stock wrinkle-tube.

I've been thinking the only real way for us to gain any measurable improvement here, is a sealed, insulated airbox, with a high-flow filter, your nice intake, and some kind of large-diameter ram-air inlet. There needs to be more room around the filter, than the stock airbox allows. And a larger opening from the fender intop the airbox.

I'm not even sure we can get enough air through the fender. I don't know anything about air flows, but the plastic snorkel from behind the signal light up to the fender, has some pretty small openings in it.

The screens and LCD option just might force the most air into the system.

What are Kennedy, RJ, and all the other motor-builders , doing for air filtration ? If anyone would have optimized their air, it would be these guys. How about posting some pictures for us ?

[DennisG01]

That's a nice setup. It's gotta flow way better than the stock wrinkle-tube.

I've been thinking the only real way for us to gain any measurable improvement here, is a sealed, insulated airbox, with a high-flow filter, your nice intake, and some kind of large-diameter ram-air inlet. There needs to be more room around the filter, than the stock airbox allows. And a larger opening from the fender intop the airbox.

I'm not even sure we can get enough air through the fender. I don't know anything about air flows, but the plastic snorkel from behind the signal light up to the fender, has some pretty small openings in it.

The screens and LCD option just might force the most air into the system.

What are Kennedy, RJ, and all the other motor-builders , doing for air filtration ? If anyone would have optimized their air, it would be these guys. How about posting some pictures for us ?

Thanks - getting rid of that wrinkle tube was actually the main factor in making that new intake. I 100% agree - we need to come up with a sealed airbox. A straight shot from around the light area would be great, but I'd be somewhat concerned about water intrusion when using a sealed box (the nice thing about the using the fender is it would negate any water intrusion). However, I don't think *some* water is a bad thing. I think the only effect a moderate amount of rain coming in would have is to create a generic water injection system as it is pulled through the filter. I'm just not sure how much rain would come in. But, using a filter like mine with the closed end facing forward would atleast eliminate the direct spray of rain on the filter.

Banks makes an intake for the Duramax (saw it on Two Guys Garage a while ago) that starts with a scoop that is mounted under the bumper and then brings the air up and directly into the airbox. There are a few slits on the backside of the vertical part of the tube that I assume are there to allow some of the water and dirt to escape. Hmmmmmm. I've been thinking about this for about a year (obviously I haven't been thinking real hard as I haven't had any real progress! :) )

[JTodd]

I would think that with the configuration of the screened opening below the filter, there should not be any problem with water, unless you are submerged. Any engine can injest a fair amount of water without much problem and the higher filter would allow any residual water to drain back down.

Next time I find a big puddle to go through I will stop and check how wet things get behind the screen.

[DennisG01]

I would think that with the configuration of the screened opening below the filter, there should not be any problem with water, unless you are submerged.

You're probably right and I'm probably just thinking too much into this. My concern would ONLY be with the use of a cold air box where everything is directed straight towards the filter via ducting. It still may be fine the way it is, but possibly a few small slits running left to right on the bottom of the filter housing would be enough to totally eliminate this problem.

How about taking the scoop that's behind the headlights and re-working it so instead of turning the air 90*, it goes straight towards the air box. Or fabbing a larger scoop to take advantage of both the headlight inlet and the turn signal inlet some of you guys have made at the same time?

[JDave]

I did the right light modification that sturgeon did and the truck seems to run faster with boost coming up faster. Of course this is all seat of the pants, no temps or comparisons. I put a small hole in the left side to blow on the FSD cooler, should help that too.
I've thought about this over the years of owning this truck and I'm glad someone else was thinking the same way and wrote it up.

[jon6.5]

I think it helped!!! i just did the first highway drive, it was about 4 hours and some decent grades on the way.I never had trouble keeping speed. with this intake and the other things i have done, the drive was a breeze for it. my temps were a constant 190-195, compared to when it was stock on the same drive my temps sat at about 205 , back then It was sure choking to get the air in and fighting to get it out before i free'd things up.

[TurboDiverArt]

Did you ever think about opening up the fender to air box hole? It just seems like that hole looks small. I

[sailun]

Hi, Art.

Yes, I did notice a difference. How much, I can't say. Seems to run a little freer at normal speeds. I did go back and open up the flashing on the passenger side of the lense, as that seems to blow straight into air scoop behind the light. Also opened up the flashing in the grill, youll see when you open it up.

I'm pretty sure the screen and replacement lights force more air into the scoop, but this does work to some extent, and it's free.

mentally, I'm still trying to compare my open airbox under the hood pulling warm air, versus this attempt at cold ram air, and a closed filter box. At full throttle, lot's of warm air MIGHT spool up easier than closed box. But don't bet the kid's lunch money on it.

I believe the motor likes the cold air better, but we're dealing with lot's of little openings: scoop is small, gets smaller going into the fender, fender leaks in and out, small opening to filter box, yada, yada, yada,

I'm gonna stay with the closed box, and cold air, especially thru the summer.

I posted in the members forum, asking RJ and JK what their views were, RJ sez he's staying with the stock filter box.

[ronniejoe]

I posted in the members forum, asking RJ and JK what their views were, RJ sez he's staying with the stock filter box.

I think you mis-read my post. What I said was that right now, I am using the stock air box. I am seeing some indication that with the bigger turbo, it may not be adequate. I am looking at options with one possibility being designing a new one.

My experience shows that the stock air box is fine for anything you do as long as you keep the factory turbo. I'm running into trouble because this turbo can flow over 60 lb/min at 3600 rpm. The GM-X turbos can only flow about 40 lb/min at that engine speed, so they don't come close. The first indication that I was having a problem was that the rubber inlet elbow was colapsing at high boost and high engine speed...

I will reiterate my opinion that breathing underhood air is not the way to go for maximum performance potential.

[sailun]

Thanks for the good insight, Ron. I didn't mis-read it, but I did mis-communicate it. I'll use the 'Quote' function, next time.

Kevin

[94 at Large]

Ram Air is COOL. :D

Currently using stock air-box w/flat filter.

[jon6.5]

Ram Air is COOL. :D

Currently using stock air-box w/flat filter.


hey could you post another pic of your ram air system from the front.

[DmaxMaverick]

Ram Air is COOL. :D

Currently using stock air-box w/flat filter.

I'm interested in seeing some test data with this arrangement. I did some testing in regards to airflow around the front of 3 body models I currently have on hand (85, 95, and 01). The test involved nothing more than taping ribbon in various places. I found that a positive airflow (air flowing rearward) was present at that location below about 30 MPH, neutral up to near 40 MPH, and a negative flow above that. I had considered adding a scoop to the outer fender on my '01 because of my filter arrangement, which is an AFE with a long cone filter, so long I had to cut out the inner fender (both panels) to fit it. My early, unscientific conclusion was it would be counterproductive at speeds above 40 MPH, where I hoped to find the most gain. The same findings can be seen with the design of induction hoods, with the most effective designs having the "scoop" at the rear of the hood, facing rearward.

[sailun]

RJ, how did you determine that the intake elbow was collapsing ? Did you observe it in the shop , while stationary ?

IYO, where is the restriction(s) ? I'm guessing the plastic snorkel from behind turn signal up to the fender, and it's openings on each end.

GM sure didn't give us a direct route to work with.

[ronniejoe]

At first, I thought there was something wrong with the turbocharger that was stopping the rotor. The engine would be pulling hard with about 20 psi then there would be strange "whoosh" sound, loss of power and lots of black smoke. When I let off of it and got back on it things were fine.

While contemplating what could be happening back at the shop, I reached down and squeezed the hose. I then decided to make a stiffener and insert in the hose so that it would retain its shape. This eliminated the problem.

There is no snorkle on my truck. But the opening from the fender into the airbox is probably where the problem lies. I've been playing with that a little and made some improvement, but I think more needs to be done.

[94 at Large]

Not exactly a front-on shot but this is the closest. Scoop is from Banks that came with the exhaust and used stainless steel mesh to keep the bugs at bay. I suppose it was intended to replace the snorkel in the fender. I removed the snorkel but noticed no difference as far as audible whistle from turbo. Not one to be afraid of drilling holes in body work I opened it up and now I can hear the turbo spool up, at all speeds. I am assuming I am getting much more air. I do know that at idle it definitely draws thru the scoop so my guess would be that this is the path of least resistance.

Can't supply any real data as far as air flow but would think that with the scoop hanging out as far as it does it would be in the airstream. Remember also that even though the snorkel has been removed I have not blocked off the fender in any way that would effect air not getting to the turbo if there is an issue with air not getting thru the scoop at higher speeds.

[JohnC]

RJ:

My suggestion is that you add another compressor stage in front of the hose...

;)

[DmaxMaverick]

RJ:

My suggestion is that you add another compressor stage in front of the hose...

;)

Why stop there? How about a fan and compound compressor. It would be like adding an "almost free" additional turbo. High speed RAT's are very effective, if you can keep the airflow up. If you're into "the sound", the turbine whine would be substantial, like a leaf blower. Speaking of leaf blowers.........:D

[sailun]

The mind, it boggles.............. a leaf blower pumping air in to feed the turbo. Sort of a two-stroke supercharger, without the parasitic load on the engine. Then we could get rid of the crossover pipe, turbo, funny manifolds, and use real headers and dual exhaust !!

Are there any diesel leaf-blowers out there, so I don't need a seperate tank of pre-mix ?

On a slightly more serious side, what's everyone using for air filter elements, and a SOTP opinion.

Personally, I've kinda lost faith in my ability to get my old Amsoil oiled foam filter clean enough, and I always seem to put too much oil into it. It's got about 100k on it now.

Anyone using the new Amsoil filter, without the oil ? Or anything else ?

[JohnC]

Actually I was thinking more along the lines of using the bleed air from a PT6. No need for a separate fuel supply, and no equal for turbo whine...

[ronniejoe]

I would prefer an Allison Model 250...since I know them inside out.

[SoTxPollock]

You guys have a pretty good discussion going here on air flow. Based on your picture 94 at large, it will work at low speeds, but what will happen at high speed is your bug deflector will pop the air straight up over the hood, the air hitting the headlight and parking light area will push its way around the parking light , but be deflected outward at higher speeds before it can make the turn back in. IMHO the air scoop will be in a dead space at high speed and possibly a low pressure area instead of a higher pressure area.
However that all being said, I have to agree with RJ that the cold air outside will be definately be better than the hot air under the hood. Cold air is denser and the turbo blades will be more efficient at pulling in dense air vs hot thin air found under the hood.
Always leave a way for the water to escape, when its pouring rain, you really don't want that in you engine or turbo in large quantities.

[JohnC]

Yeah, the Allison will probably do the trick. I'm sort of partial to the PT6 because of the free turbine, but in this application that's irrelevant...

[ronniejoe]

Yeah, the Allison will probably do the trick. I'm sort of partial to the PT6 because of the free turbine, but in this application that's irrelevant...

Since we've completely hi-jacked this thread...:D

The Allison 250 has a free turbine as well. The 250 is not as big as the PT6, but has been around since 1958 (military T63). The PT6 is used largely in fixed wing aircraft with some exposure in rotary wing aircraft. On the other hand, the 250 is primarily used in rotary wing aircraft with only limited exposure in fixed wing aircraft.

[Craig M]

In stock form the air to the inlet filter is coming from the small gap between the lights and the front grill trim unit. This gap is 1/8" to max of 1/4". The larger opening (discussed in the beginning of this thread) will provide potential for increased flow. The discussion about positive or negative flow in the area in-front of the lights is interesting. If GM put the stock inlet area there, one would hope there is positive flow, If there really is negative flow then any increase in inlet size would have little effect on flow. A large amount of air flow will surely go over the hood area, but one would hope that some pressure would be available in the light area.

[sailun]

There should be lot's of air that comes straight into the grill area, doesn't go thru the radiator's, and is deflected into the area behind the headlights. We're just trying to get some straight-shot air to go directly into the scoop area, at very low cost.

[JohnC]

Since we've completely hi-jacked this thread...:D

The Allison 250 has a free turbine as well.


Yeah, Last time I saw one was at school...

I was thinking of the Garret TPE331s used on the MU-2...

[a5150nut]

There should be lot's of air that comes straight into the grill area, doesn't go thru the radiator's, and is deflected into the area behind the headlights. We're just trying to get some straight-shot air to go directly into the scoop area, at very low cost.

Banks used to put out a snorkel or scoop that crossed from the factory opening behind the light to the grill opening to get some of that direct air flow.

[94 at Large]

You guys have a pretty good discussion going here on air flow. Based on your picture 94 at large, it will work at low speeds, but what will happen at high speed is your bug deflector will pop the air straight up over the hood, the air hitting the headlight and parking light area will push its way around the parking light , but be deflected outward at higher speeds before it can make the turn back in. IMHO the air scoop will be in a dead space at high speed and possibly a low pressure area instead of a higher pressure area.

STP
Bug deflector has been removed as I considered that an issue with air flow and am contemplating an IC setup. Will delve in to the flow around the front to the side. What is considered high speed? Do you think 60mph will have that much effect on how the air flows around the front end? I realize that there may be some sort of wave formed but still the speed doesn't seem to be great enough to not allow the air to get around. Also, this scoop sits off the fender a couple of inches and may be far enough out that it will catch air, as was mentioned in a previos post. On a side note, I was running down the interstate @60 and passed under an overpass w/windows down and could clearly hear the turbo so I know that I am getting air from somewhere to keep it spinning.

[DmaxMaverick]

The "testing" I did was with and w/o bug deflectors. I didn't notice any difference at the fender area before/after. The hood area was very different.

On my '01, I have the AFE Stage II with an Amsoil cone filter (latest AE oilless element). The filter is considerably longer than the AFE, and I cut out the inner fender panels to accomodate the length, and the filter element has the inverted cone in the end (additional element surface area). The filter end is about 2" from the single sheet metal layer (fender), and my turbo whine is very significant. The before/after comparing the AFE element and Amsoil showed the Amsoil filter with cut out fender, the whine was about double than the AFE installed as per instructions before the cut out. Turbo whine now is about the same on the open road as in a tunnel/overpass. Not "loud", but very pronounced. OEM filter box, with and w/o the snorkel, with any filter element type is no where near the sound now.

I would consider "high speed" anything above about 40 MPH. Airflow changes were very significant above that, and didn't change much with faster, except for the hood area.

[94 at Large]

Did a little research and came across this on air flow:

Drag
A simple definition of aerodynamics is the study of the flow of air around and through a vehicle, primarily if it is in motion. To understand this flow, you can visualize a car moving through the air. As we all know, it takes some energy to move the car through the air, and this energy is used to overcome a force called Drag.

Drag, in vehicle aerodynamics, is comprised primarily of two forces. Frontal pressure is caused by the air attempting to flow around the front of the car. As millions of air molecules approach the front grill of the car, they begin to compress, and in doing so raise the air pressure in front of the car. At the same time, the air molecules travelling along the sides of the car are at atmospheric pressure, a lower pressure compared to the molecules at the front of the car.
Just like an air tank, if the valve to the lower pressure atmosphere outside the tank is opened, the air molecules will naturally flow to the lower pressure area, eventually equalizing the pressure inside and outside the tank. The same rules apply to cars. The compressed molecules of air naturally seek a way out of the high pressure zone in front of the car, and they find it around the sides, top and bottom of the car.

Highlighted area is pertaining to discussion on flows. With this in mind it appears that a scoop on the side can't help but have air flow into it. What do you think?

[JohnC]

Unfortunately, it's not that simple. Without going into details, the air can't make the sharp corner between the grill and the fender, so the flow separates and goes off at an angle towards the rear, leaving stagnent air or even low pressure along and near the surface of the fender for some distance behind the grill. The faster you go the farther this separation extends. In addition, air moving at high velocity is at lower pressure. It is conceivable that under some circumstances a scoop placed there could be a detrement.

[bbbear]

You guys have a pretty good discussion going here on air flow. Based on your picture 94 at large, it will work at low speeds, but what will happen at high speed is your bug deflector will pop the air straight up over the hood, the air hitting the headlight and parking light area will push its way around the parking light , but be deflected outward at higher speeds before it can make the turn back in. IMHO the air scoop will be in a dead space at high speed and possibly a low pressure area instead of a higher pressure area.
However that all being said, I have to agree with RJ that the cold air outside will be definately be better than the hot air under the hood. Cold air is denser and the turbo blades will be more efficient at pulling in dense air vs hot thin air found under the hood.
Always leave a way for the water to escape, when its pouring rain, you really don't want that in you engine or turbo in large quantities.

There's a good article on the subject by Jim Bigley and Lee Swanger called "More Power!!!" It's old, so it must be in the archieves. They not only route a 4" hose between the grill and a modified attachment to the air cleaner, which squeezes the air, ( they refer to as "the snorkel") but Lee Swanger also modified his air cleaner body by raising the top by two inches. That mod not only gives a 7"X3" olpening into the air cleaner body, but it also allows the air cleaner to take two 3" filters rather than the stock one 4" filter.

He also said one should drill a hole in the back of the aircleaner base, outside of the filter area, to allow any water to drain out onto the block, and it will continue to drain onto the pavement.

Well worth a read. BTW, there's a simular set up on the GMC 6.2, LL4 I just bought. As of today, it has got 429,000 oddKm on it and still running strong, is not an oil burner, and doesn't smoke. So at the very least, it must not do any harm, and probably works well!

[ronniejoe]

If it's in the right place...

In compressible flow, there is a phenomenon called turbulence that occurs when the air separates from the surface that it is trying to flow around. These trucks are fairly aerodynamic compared to older vehicles, but there is still some separation at higher speeds. If there were perfectly laminar flow around the front of the truck, your scoop would work great. At low speeds, that is exactly what you have. At higher speeds (it all depends on a parameter called Reynolds number), the turbulence problem arises. Dmaxmaverick has stated that he's seen evidence of reverse flow in that general area at high speeds. That's indicitave of separation and turbulence.

Drag is greatly reduced if you can minimize the separation and maintain laminar flow.

[TurboDiverArt]

There is no snorkle on my truck. But the opening from the fender into the airbox is probably where the problem lies. I've been playing with that a little and made some improvement, but I think more needs to be done.
Hey RJ,

Have you thought of opening up the hole from air box to fender? Taking it from a circle to more like a rectangle into the fender area?

Art.

[94 at Large]

Unfortunately, it's not that simple. Without going into details, the air can't make the sharp corner between the grill and the fender, so the flow separates and goes off at an angle towards the rear, leaving stagnent air or even low pressure along and near the surface of the fender for some distance behind the grill. The faster you go the farther this separation extends. In addition, air moving at high velocity is at lower pressure. It is conceivable that under some circumstances a scoop placed there could be a detrement.

If what you say is correct then it would also apply to flows over the hood. However, I have tested this with strings taped to the front of the hood and back a few inches. At low speed they flop around as if in turbulence but as speeds increased they would straighten out and lie flat. BTW, the fender is rounded at the front as is the hood and whether over the top or along the side my guess would be that air is air and the high pressure, created by the frontal area, would find a way to equalize, up down or around the sides. I realize that air can be considered a solid at extremely high speeds but I am not following the idea that it separates and goes off at an angle and if it is low pressure along the surface wouldn't it make sense that in an attempt to make all things equal (pressure wise), the air would rush from high to low to do just that? Scoops on hoods seem to work, I just don't see the difference between hood or fender when it comes to air flow. Again, I have not had the opportunity to test this but will this weekend and let you know what happens.

Appreciate all the input and patience with the un-enlightened, me.

[sailun]

Here's an easy way to visualize what the air is doing:

Air and water behave in almost the same manner when you try to push something thru it, the difference being that water doesn't compress.

Look at the bow wave and wake for any kind of boat under way. Pretty substantial, and you can see that quite a bit of water/energy is forced away from the boat at an angle.

When a semi passes you on the highway, ever notice how your vehicle gets both pushed away from the truck, then sucked back into into the truck ?

That's your bow wave, and low-pressure area.

And boats are a lot more slippery (aerodynamic) than the front of our trucks. Of course, water is a zillion times more dense than air, so the effects are greatly magnified. At least this allows us to see the example.

If you really want to see what's happening, stick ALOT of ribbons or yarns to your hood and fenders and scoop, and down the sides of the truck. Then drive down an empty highway, and have your buddy shoot video. Have the video truck stay at least one empty lane away, and stay about 200/300 yards away from any other cars in front of you. drive in both directions on the highway, to average out cross-winds. Hope you can find an empty highway, and let us know what you find. I'm kinda curious about the results.


Another great example: When your riding your motorcycle, in just a loose tee-shirt, the tee-shirt is sucked off your back, in a big low-pressure burble.

Or, while sky-diving, if you don't get your pilot chute out into the clean air, it will just stay stuck in your burble, for the rest of your life.......


I would love to see that Banks grill-mounted scoop, I've been thinking along the very same lines............ Anybody have one ?


I'm gonna look at the snorkel to fender opening behind the headlights, today. These are some pretty small openings.

[94 at Large]

Here's an easy way to visualize what the air is doing:

Air and water behave in almost the same manner when you try to push something thru it, the difference being that water doesn't compress.

Look at the bow wave and wake for any kind of boat under way. Pretty substantial, and you can see that quite a bit of water/energy is forced away from the boat at an angle.

When a semi passes you on the highway, ever notice how your vehicle gets both pushed away from the truck, then sucked back into into the truck ?

That's your bow wave, and low-pressure area.



As I am no fluid dynamics expert and haven't stayed at a Holiday Inn Express lately here is my take on this. I like the analogy of water and air because with water you can see what's going on but as you pointed out water cannot be compressed and I think this is the crux of the matter. I don't think there is a "wave" per say formed at the frontal area rather the compression of air and its attempt of getting back to normal atmospheric pressure. The pushing and pulling as a semi passes is the cause and effect of high/low pressure and its attempt to equalize, IMHO. The reason I say no wave is because I did the string thing down the side of the fender and about six inches from the front. I found that the strings went from limp to straight and level. I took my speed up to 60 or so, as that is my typical cruising speed, and there was no turbulence, no dead air. The placement of the strings close to the front was to determine if the air is actually deflected away. I even applied strings to the outside of the scoop and same thing, perfectly parallel with no flutter. So, I can only conclude that the scoop location, on my truck, is in clean air and should be quite functional at the speeds that I travel.

[ronniejoe]

There most certainly is a bow wave. That is not something that is up for debate.

As I said in my earlier posts, these trucks were designed in a wind tunnel, so they are probably pretty good. The results of your string test say that there is very little separation at the front of the truck, so your scoop should work.

[94 at Large]

There most certainly is a bow wave. That is not something that is up for debate.


Debate, no. Clarification, yes.

1. the wave generated on either side of a vessel's bow by its forward movement through the water.
2. a type of shock wave formed in front of a body moving at supersonic speed.

[sailun]

Well, 94, it sounds like your scoop is in the right place, and working. SOTP, does it feel like you got a boost from it ?

Any increase in MPG ? Spool up quicker ? More whistle ?

More bird strikes ? More shopping carts and pedestrians hit ? :-)

[94 at Large]

Bird strikes...........good one.

As I have had this in place for some time now the only noticeable difference has been turbo whistle, I guess it opened up available intake air. Oh, and a few strange looks by those wondering wtf that is for.

[sturgeon-phish]

On Myth Busters on TV I saw a show where they were testing MGP tailgate up or down difference, (whole different issue) and to "see" the flow over the truck they took a scale model, submerged it in a tank of water and forced a waterflow over the model. The fluid acted like air and showed the path of flow. Can't remember how they made the flow path show up but it was easy to see and very evident. I'm thinking this would be a neat experiment to video tape. I've got the model, any construction ideas?
Jim

[94 at Large]

A fish tank would allow you to see all around the model. Using some kind of circulating pump and that stuff snow globes are filled with might work. How about a table fan with colored thread strategically affixed all over, provided the model is big enough?

[JohnC]

OK, I over simplified it and didn't get the point across. Separation isn't the issue I was referrring to. Making the corner the air has to accelerate relative to air farther out from the side of the truck. Higher velocity means lower pressure, so the pressure along the side of the fender near the grill is lower at high speeds. The ribbons just show the flow is still laminar. In fact, once the flow separates the velocity goes down and the pressure goes up.

[94 at Large]

........flow next to any surface forms a "boundary layer", as the flow has zero velocity right at the surface and some distance out from the surface it flows at the same velocity as the local "outside" flow. If this boundary layer flows in parallel layers, with no energy transfer between layers, it is laminar.

........consider the finish on your car in non-rainy conditions. Dust and leaves have settled on the hood's paint. We go for a drive. At once the leaves blow off. But the dust remains. We speed up. Even if we go very fast, the dust remains because of the thin layer of air that moves with the car. If you drive with dew on your car, the dew will not so quickly be blown dry where the air flow has this thin laminar layer.

JohnC
I follow what you are saying and agree. As speed increases the boundary layer will thicken, pressure decreases. Also, you are right that all the strings are showing is that I have laminar flow along the fender........ I need to come up with a way to actually get the strings out away from but parallel to the fender to see the flows as they enter the scoop. That should be definitive.

For the most part, I think, the scoop will be functional but probably will never be able to figure its efficiency.

Thanks all for your time and input on this as this has been a bit of an eye opener.

[sailun]

Anybody notice how much faster the filter gets dirty, with these "ram air" mods ?

I'm rotating the filter to a new clean spot about once a week, and I've just about run out of clean spots.

The inside of the box is really building up dirt, too.

[cshade]

Made a homemade ram air like jon 6.5's setup. Was so impressed by the pic I went to work right away!

Used a 45 degree bend 18" aluminum tube to point the filter at the opening at the grill. Then took some 3" expandable tubing and ran the opening just under the passenger's tow hook and plumbed it under the fender by the shock inbetween the motor then pointed directly onto the filter element.

Relocated the passenger battery, which was tough due to hood clearance. I need top posts for my stereo system which needs lots of juice so I couldn't saw those off. Optimas are not quite as tall as stock batteries, so two redtops went in. A 5 dollar battery tray from pep boys rounded out the install. Took video of the whole thing...I'll post some pictures when I get a chance.

Anyone thought of wrapping the intake tube with exhaust wrap? I'm getting a lot of heat soak right now...

As a side note, thank you guys on this thread for a great idea! This page is an incredible resource for diesel 6.5 fanatics.

[spiff]

Tufting (which is what gluing yarn to an object to measure airflow direction is called) isn't really all that helpful here. It does show the direction of the airflow but says nothing in particular about the air pressure, which after all, is what we're really interested in. Since we really need the pressure at a specific point, what is needed is a manometer or pressure gauge. The pickup would need to be flush with the surface of the point where a pressure reading is desired, else the pickup itself will disturb the reading.

Using water and models to determine airflow is a mistake, as the Reynolds numbers are so far as to be useless for determining specific locations for aerodynamic features (such as scoops) as a dimensional analysis will quickly show. If water was a suitable media for designing shapes for objects immersed in air, Boeing, Lockheed and a host of other companies have wasted huge sums of money on wind tunnels. In point of fact, using water or other incompressible fluid will lead you quickly down the wrong path.

We may take advantage of prior work in the field, as shown by stock car racers in the 60's & early 70's as they were having to use shapes much like those we are talking about here. Look at, say, a 65 Ford Galaxy, as raced by Holman & Moody, or a Mopar product of that era. You'll notice that the hood scoop opening is just backwards of what one might expect. The opening is at the base of the windshield, which is nearly the highest pressure point on the automobile.

Which leads one to the good 'ole LMC truck parts catalog. It seems they have a hood for my GMC (an 84) which just happens to have a scoop in the right place and opening the right way. Doing some preliminary measurements on my vehicle leads me to believe that a box could be glassed to the underside of this hood which could have provision for enough flat filter elements to provide the airflow capacity we'd need for our application. This box could be set up like the old shaker hood air scoops of that era, or, using something like the turbocharged engine intake manifold and its entrance could be plumbed to the air box. There are a couple of details left to work out, but nothing of any difficulty.

This hood could also provide an interesting point of departure for installation of an intercooler, as at least in the body series I'm interested in, there's quite a bit of underhood space in that area. If your worried about not enough airflow at low speeds (say towing uphill) just stick one of those neat electric accessory fans to the bottom of the intercooler.

Now, how much was that hood and where did my piggy bank go???

Lloyd

[Shikaroka]

I believe you are talking about a "Cowl Induction" hood, which are pretty popular for trucks and muscle cars.
The base of the windshield is a very LOW pressure area, almost a vacuum. The purpose of those backwards scoops is to pull hot air out of the engine compartment. They wouldn't do much good at getting air into the intake, actually it would do the oppisite.

[94 at Large]

I believe you are talking about a "Cowl Induction" hood, which are pretty popular for trucks and muscle cars.
The base of the windshield is a very LOW pressure area, almost a vacuum. The purpose of those backwards scoops is to pull hot air out of the engine compartment. They wouldn't do much good at getting air into the intake, actually it would do the oppisite.

Faster moving air is at LOWER pressure than slower. The air flows over the hood, hits the windshield and continues on its merry way, quickly. At the base of the windshield the pressure there is higher and turbulent, at least from the aerodynamic flows I have looked at. That is why cowl induction works and if properly sealed to the intake will draw outside air and not from under the hood. I guess that's why it's called induction. :D

[94 at Large]

.
This hood could also provide an interesting point of departure for installation of an intercooler, as at least in the body series I'm interested in, there's quite a bit of underhood space in that area. If your worried about not enough airflow at low speeds (say towing uphill) just stick one of those neat electric accessory fans to the bottom of the intercooler.
Lloyd

Now you're talkin! I was thinking along the same lines only maybe build a box to house intercooler/fan and have ram air feed it and exhaust at the base of windshield to avoid any heat soak from engine. Also, at the other diesel site do a search for same as member Scrufdog did a top mounted IC setup with a scoop.

[spiff]

Actually, the base of the windshield, or cowl area, is a very high pressure area. If you have doubts about this I can likely find references in the literature. That's why the air intake for the vehicle's air circulation is there. Because this is a high pressure area, when using this as a source of cooling air for, say an intercooler, the air will enter, not exit, the scoop at the base of the windshield and will exhaust through the engine compartment. One could further refine this by using something like SCAT tubing with suitable baffling to exhaust the air that's passed through the intercooler to a low pressure area under the vehicle, thus even further increasing the efficiency of the airflow through the intercooler.

Perceptions being what they are though, folks seem to require that the opening face the direction of motion, which to make that work requires that a forward facing hood airscoop must resort to being quite high above the hood to put it back in the airstream. The Subaru WRX scoop is a prime example. I'd love to see manometer readings of that installation. The old 65 GTO scoop which was mounted in the center of the hood and was quite low was essentially aerodynamically useless but was visually appealing.

Since I'm now looking at adding a Banks or similar installation to my 84, the trade off becomes how to divvy up the airflow provided by a scoop between an intercooler, if I go that way, and induction cold air. Properly executed, this could provide a nice ram effect for the intake.

Lloyd, who will now go back to drilling out and helicoiling a couple of starter bolts, which has become a tale of its own.

[94 at Large]

spiff
Which, in your opinion, would be better, cowl induction or ram air via scoop? Either way, as you stated above, air could be ducted down and out thru the engine compartment using either method.

[a5150nut]

spiff
Which, in your opinion, would be better, cowl induction or ram air via scoop? Either way, as you stated above, air could be ducted down and out thru the engine compartment using either method.

This was gone over in the past and is something I have concidered. The problem that was brought up was cowl induction changing the air flow over the engin and reducing the cooling effect thru the radiator.Wish there was some technical info to back it up.

[spiff]

Both can work, in the case of a scoop, its going to be dependent on placement and how high it will need to be to be effective. (By scoop, I'm assuming that you mean the typical front opening kind of thing as is found on the Subaru WRX) With the intake coming out of the side of the vehicle, the same questions need be ask, how much airflow is needed, as well as what standoff distance is needed to get the scoop out into suitable airflow. Really, the scoop on the side is pretty much the same as a hood mounted scoop.

With a cowl induction, its similarly how wide and high the opening will need to be to flow sufficient air. Then, construction of the necessary plenum boxes for each, as well as filtering which will be necessary as these are road (and off road) vehicles. On question I do have about cowl induction is the pressure/speed curve. I'll try to find some empirical data regarding that.

I dislike some of the approaches mentioned earlier in these threads where the intake is below or at best even with the grill. Generally the higher you go with the intake, the cleaner the air. I recall seeing Cats used in very dusty conditions having quite long extensions added to the air cleaner precleaners.I also have no desire to have to provide for inhaling large amounts of water. I've seen the effects of an engine trying to compress water. That problem exists to some extent with cowl induction i suspect.

I doubt if a cowl induction intake would have any more effect on airflow under the hood than most of the current installations. I'm unable to see how a cowl induction could alter airflow through the radiator, unless the cowl plenum somehow obstructs airflow itself, and my suspicion is that the great majority of the airflow through the radiator exits around the side and down below the engine. Most hoods provide little exhaust for the radiator air. It would be interesting though, (and a bit hazardous) to inject some smoke at various places in front of the vehicle and see where it went.

I think to really answer your question about which approach is best probably requires more specific knowledge of the application, and of course, one's budget. My sentimental favorite is the cowl, but that's simply because I liked the looks of a 65 Galaxy 500 with a 427 side oiler which had a cowl induction type scoop.

Lloyd, who hears a bass calling his name...

[cshade]

Added a K&N with ram air under bumper scoop and while I was at it, upgraded the batt connections to O gauge wire in preparation for the several thousand amps that will eventually go to my new amplifier! I posted a video on utube of parts of the install--->enjoy

http://www.youtube.com/watch?v=hZxPyIJ7G_o

[Craig M]

What brand are those battery post connections. Look nice!

[cshade]

Thanks!

"Hooker" is the brand of most of the terminal connections. I bought the 0 gauge ring connectors are available at any audio store. I bought the terminal connections through about 3 referrals on a sunday afternoon store-to-store odyssey to find good terminal connections that would work with the dual battery/ground setup. Turns out the dub/getto blaster store only had 3, but they were nice enough to let me pull the fourth out of their show car. They also gave me a huge discount--10 bucks a pop versus 30. I think they felt sorry for my diesel affliction. The fourth connector has some ninja writing on it that I can't understand but is the same design. I think that competition sound stuff changes suppliers too quick to actually nail down the real manufacturer.

The dash amp meter read about .5 to 1 volt more than usual after the upgrade...If i get 14 volts mainlined to my amp it would nearly double the rms output:D

[cshade]

has anyone stumbled across this?

http://www.lmctruck.com/icatalog/csd/0035.asp

[Craig M]

I might be convinced to go $10 for a nice connector, but $30 would get my Scotish ancestors out of their graves and stomp me.

[j_k_auto]

269OK well i went ahead and did it. just go an extra little bit and put the new air supply to use i moved my battery and placed the air filter right in front of the hole. sorry for the poor pic i had a hell of a time getting the site to let me post it, so i had to make the quality very poor. my results were as follows with the current outside temp of 55.

before removing light
45mph=79 degrees
60mph=76 degrees

After removing light
45mph=64
60mph=57

I did not expect much of an improvement but the numbers proved it. I got this by placing a wireless thermometer right beside the air cleaner to get the temp of the air going into the air cleaner.

You have to be careful about the battery getting to hot like mine did. It was going to shorten my battery life or could possibly melt the batt. That is why I moved my batt to the drivers side.:) I need to finish my setup but you can make anysize box you want this way. Good luck with anyone moving the batt.

here is what I did
http://img2.putfile.com/thumb/5/12413272049.jpg (http://www.putfile.com/pic.php?img=5387441)

[cshade]

I spoke at length with the optima engineer. He said that no optima battery should EVER reach further than 170 degrees...period. He said that many people wrap their batteries with heat reflective sheathing, but in his experience, under no uncertain terms, stay away from the turbo! Bad news for my super plan of relocation. Could you explain how you performed your relocation? maybe with more pics :D


*desperately looking for a wireless thermo*

[j_k_auto]

It took me a good day to complete my relocation. I had to modify the bracket behind the drivers battery. It is a tight fit but my battery will be so much happier in its tight little new home. :D Here is a better picture

http://img2.putfile.com/thumb/5/12514161851.jpg (http://www.putfile.com/pic.php?img=5395078)

http://img2.putfile.com/thumb/5/12514161846.jpg (http://www.putfile.com/pic.php?img=5395076)

[More Power]

Here's member Brian Pederson's cold-air intake he designed for his 1994 Suburban.

http://www.thedieselpageforums.com/photopost/data/500/P1010011.jpg

Though he needed to relocate the battery tray, it's still on the passenger side.

Jim