Engine/Transmission (1998.5 - 2002) Value of "special" aircleaner ducting...

[BTighe]

almost done.



here are some pics



http://www.nwbombers.com/membersites/diesel_freak/

you didnt happen to make 2 of those did you. :-laf nice looking setup there

 

[Gary - K7GLD]

Gary, I've always considered you relatively knowledgable on here, but surely you realize that the purpose of "hacking holes in the firewall" is to get more air into the engine to create more power, and not to solely reduce the temperature of the intake air by 10 degrees. In fact, I've never even heard that mentioned as a feature.



You act like you've stumbled upon some startling revelation here, when in fact you're missing the main point.

UMMmm - and exactly HOW does hacking holes in firewalls get MORE air into the engine than a completely OPEN filter under the hood?



Like THIS one, for instance:



#ad




The ball's in your court...



AND, before some wiseguy pops up here claiming "ram air effect", has ANYONE installed a pressure guage at the firewall location usually hacked to see what, if ANY pressure is developed there at say, 60 MPH?

 

[Diesel Freak]

I have a ram air effect now!!!!

 

[I-6DZL]

DF That is simply bad *****



If everything works out as it should, please post back.



I put dual yellow tops on my DS battery tray, and was thinking of a way to do what you've already done.



Measurements? Blue Prints ?



Thanks

Curtis

 

[nps]

DF,



To heck with the boost gains. The turbo whine at the front bumper should be a darn good deer whistle. :-laf



Where do you put the beer?

 

[Gary - K7GLD]

I have a ram air effect now!!!!

You indeed have a VERY nice setup - have you been able to determine if you get any measureable PSI increase with that setup? And what were you running before that mod?



Looks great!

 

[Lsfarm]

Ram rise or pressure points

Gary, there is valid reason for cutting into the HVAC trough at the base of the windshield. That is an actual measurable high pressure spot in the airflow around a vehicle. That is why we have our air intake for the HVAC system there.



HOWEVER with most vehicles it is not needed, wanted or even desirable from the standpoint of creature comfort in the cab.



With a direct passageway from the air filter to the HVAC intake the turbo howl and whistle makes for so much noise that only the semi-deaf enjoy it and those who aren't semi-deaf will soon be.



Most of the air coming into the engine compartment comes in through the radiator, and is pre-heated by the A/C condenser, intercooler and radiator. That which comes in through the factory hole in the inner-fender and around the headlights is not preheated. Where did you measure the filter temperature?? Did you install a temperature guage to read intake temperature when you are pulling your trailer up a good grade with the fan clutch engaged on a 95* day??? If you set up this scenario then I'm sure you would see the benefits of some extra cool air directed right at the air filter.



But I'm with you, I don't have any holes cut in my firewall, in fact you can't see my firewall for all the noise insulation installed over it. I'd rather roll down the window and stick my head outside to hear turbo whistle than cut a hole in the firewall. BUT there is a factual basis for cutting a hole.



I believe your test drive and conditions just don't match the tough conditions for which a hole in the firewall is valid. A five mile drive at 55 mph will hardly even use the cooling available from the radiator, and there would be little if any boost, so the intercooler would be at ambient and was the A/C running?? So try inducing as much heat into the engine compartment as possible and install a readable-from-the-cab temp gauge and then lets hear your results. I'm sure you will have a different opinion.



Greg L

 

[darkhorse]

... there is valid reason for cutting into the HVAC trough at the base of the windshield. That is an actual measurable high pressure spot in the airflow around a vehicle.





I'm right with you on this one, Greg. I've thought about cutting the fire wall hole but I don't want to turn the volume up on my turbo's song. I'm older & the music is loud enough. :-laf DF's slick unit solves that problem.

 

[Gary - K7GLD]

Fact is, I've made SEVERAL runs from 10 to 20 miles with the setup pictured in the lead post of this thread - both with the A/C on, and off - but this being summer, mostly ON!



And yes, the engine was fully up to operating temperature...



And temperature differential has REMAINED a nominal 10 degrees - and this is the scenario where the VAST majority of owners actually drive their trucks - relatively empty, and a mix of freeway and around town driving.



I'll have a better idea of "worse case" conditions when we go on a 1000+ mile RV trip in a couple of weeks... And yeah, I'll post results!



As to the physical or scientific validity of using cowl air to somehow "force" more air into the engine than is already availabe there for greater performance, at least as compared to an intake setup like mine, I'll reserve judgement until someone steps in to provide actual documentation, rather then assumption or theory...

 

[Lsfarm]

How are you

Gary, how are you reading the temperature?? If you are opening the hood and using a hand held laser thermometer, then you are not getting actual under hood running temperatures.



I do agree that most people use their trucks as you describe, as well as myself. And therefore do not need cowl induction or an additional cool air source. I tow only a few times a year. Mostly I make a 55 mile run from home to the airport parking lot. This 55 mile run is about 20 miles on freeway and the rest on two lane 45 mph roads, and I usually do the run in 65 minutes... do the math for freeway speeds.



I personally see no need for cutting into the firewall for more fresh air, but it is NOT assumption or theory, it is a fact that this is an aerodynamic high pressure point. Look at all the cowl induction hoods etc out there, it is a fact.



I think if you want to get really scientific about it install an air temp sensor in the air intake tube or the exit neck of your BHAF and read the temp during a bunch of different conditions. My biggest concern is the heavy towing, long hill, fan clutch engaged, turbo near max, and the engine needing as much cool air to keep egt's under control. Get backwith us with your results.



But I don't think that pulling into a rest area and poping the hood will give real time information, the temp needs to be read while all the above is going on. Just for an example, look at your egt gauge on the freeway during a good pull, then pull over, pop the hood, and laser the exhaust housing, you will see a significant difference in temp. I'm sure you can see what this difference would make a significant amount of heat near your turbo/airfilter heat shield.



I'm VERY interested in seeing the results from your tests if done with an in cab guage.



I'm also very interested in seeing either plans or a marketed version of DF's setup. VERY nice work!!!



Greg L

 

[Dl5treez]

Every NCTS, NBGNS, NNCS, and SCCA Trans-Am series car picks up their intake air from the cowl area, and have done so since way back before the 99. 9% sealed up aero noses became required to stay competitive.



Smokey Yunick was one of the first to pioneer using a system quite similar to the cowl pickup units available on the market today and back in 1967 implemented the device in competition on his SCCA Trans Am Camaro. He picked up the air from just above the heater case on the passenger side. I've got a couple grainy old photos of the actual unit from '67. It had been used before on other GM performance offerings, I've heard back to '62 or '63 but I don't have any data to prove it.



The base of the windscreen is a very high pressure area, one of the highest available on an automobile.



Do the cowl pickup/ram-air systems increase power directly? Not sure, never researched it.



The Air Bulldog ram-air hood & air dam systems do reduce operating exhaust gas temps, and there is a small increase in boost pressure, also--that's the only production unit I've played with.



Just my no-mind opinion.....

 

[Gary - K7GLD]

Gary, how are you reading the temperature?? If you are opening the hood and using a hand held laser thermometer, then you are not getting actual under hood running temperatures.



I do agree that most people use their trucks as you describe, as well as myself. And therefore do not need cowl induction or an additional cool air source. I tow only a few times a year. Mostly I make a 55 mile run from home to the airport parking lot. This 55 mile run is about 20 miles on freeway and the rest on two lane 45 mph roads, and I usually do the run in 65 minutes... do the math for freeway speeds.



I personally see no need for cutting into the firewall for more fresh air, but it is NOT assumption or theory, it is a fact that this is an aerodynamic high pressure point. Look at all the cowl induction hoods etc out there, it is a fact.



I think if you want to get really scientific about it install an air temp sensor in the air intake tube or the exit neck of your BHAF and read the temp during a bunch of different conditions. My biggest concern is the heavy towing, long hill, fan clutch engaged, turbo near max, and the engine needing as much cool air to keep egt's under control. Get backwith us with your results.



But I don't think that pulling into a rest area and poping the hood will give real time information, the temp needs to be read while all the above is going on. Just for an example, look at your egt gauge on the freeway during a good pull, then pull over, pop the hood, and laser the exhaust housing, you will see a significant difference in temp. I'm sure you can see what this difference would make a significant amount of heat near your turbo/airfilter heat shield.



I'm VERY interested in seeing the results from your tests if done with an in cab guage.



I'm also very interested in seeing either plans or a marketed version of DF's setup. VERY nice work!!!



Greg L

Here's where and how I take my temp readings:



#ad




THERE, see that little thermometer thingy secured to the BHAF? I leave it there as I drive, and when I stop, I very scientifically get out, lift the hood, and READ the temperature there, and compare it with the outside temp reading as registered on my overhead console - which checks VERY closely to several external sources I have available...



And if all we currently have is theory, mine is that typical underhood temps in normal driving scenarios will actually vary very little down the road, and rather slowly when they do - the vast volume of air moved by the fan and vehicle movement pretty much assures reasonably stable underhood temperatures - but sure, they undoubtedly WILL climb somewhat under heavy load conditions - but I doubt all that radically.



As to actual air pressure provided or generated at the cowl area, it would seem reasonable to expect that value to be about the same as seen at the vents inside the vehicle at various road speeds - in general at about 60 MPH, perhaps about the same volume and force you might get from a 10 inch electric house fan - and how much boost in engine performance could we expect if we somehow fed the air output from a 10 inch house fan into the Cummins intake?



Precious LITTLE!



And, being the fair minded guy that I am, I'm totally willing to accept similar "scientific" readings from other members here, as THEY provide real PSI readings THEY take up at the cowl area to display actual readings from that area.



If THAT isn't fair enough a method to reasonably eliminate theory and guesswork as to ACTUAL pressure at that area, let's hear some alternate suggestions...



Bottom line in case it's been clouded, is:



HOW MUCH real power generating improvement is available or documented by cutting holes in the firewall to feed a typical aftermarket underhood air filter, AS COMPARED to a typical underhood BHAF with NO cowl feed, such as mine?



I'm figuring little, to none, and waiting to be proved wrong!

 

[jwilliams3]

Gary,

You ought to take your own temperature.

 

[nps]

HOW MUCH real power generating improvement is available or documented by cutting holes in the firewall to feed a typical aftermarket underhood air filter, AS COMPARED to a typical underhood BHAF with NO cowl feed, such as mine?



I'm figuring little, to none, and waiting to be proved wrong!

Gary,



He said he agreed with you and wouldn't cut the hole himself so what's to prove, and to whom?



This is starting to sound like a politics thread.

 

[Gary - K7GLD]

Gary,



He said he agreed with you and wouldn't cut the hole himself so what's to prove, and to whom?



This is starting to sound like a politics thread.

Has it occured to you that OTHERS reading these threads MIGHT have done some checking? This isn't just about the 2 of us you know!





"Gary,

You ought to take your own temperature. "



Fella, this isn't the first time you have popped in with some demeaning bit of nonsensical crap aimed at me - so welcome to my "ignore" bin - I'm sure you and Csnyder will be very happy together!

 

[Diesel Freak]

I do not have the box completely sealed yet. I do have a relief port/valve in the bos just incase something pluggs the main intake on the bumper. One thing I have noticed is the effect on EGT at speds under 35-40 MPH.



Gary - K7GLD already stated the obvious... as the vehicle speed rises, the underhood temp drops. The first thing I saw was a noticeable drop in egt when cruising through town or stuck in traffic with the A/C cranked. The initial belch of smoke when taking off from a stoplight with the A/C on is slightly less.



So far the best thing is the reduction of noise from my HX40 (non silencer ring equipped) From inside the cab, it almost sounds stock!!!! But open a window and drive past a Soccer Mom in a MiniVan, and heh heh ya can hear her scream!!



Blue Prints? HMMMM never thought about it. There is a lot of custom fabrication and cutting/gutting of pieces/parts that were in the way. Definately not a bolt on modification. Overall, parts cost me just about$250-$300. Fab time could have sent the labor cost over $1000 at $40/hour if I were to have farmed the job out.



Let me think about it... . a Drawing of the box unfolded on a drawing would not be an issue..... the end user would have to perform all the other needed tweaks on their own. Since each truck is different, I may only just supply the print for the box which will need to be modified by the end-user uppon installation.

 

[darkhorse]

I've got an AFE Magnum Force unit which is not much different than Gary's home made shield. All & all, it works pretty good but even if it's a little like splitting hairs DF's unit can't help but supply cooler air, as pointed out that is greatest at lower speeds. At higher speeds there should be be a slight increase in air flow unless, of course the under hood pressure rises the same. Lots of room for Mr. Science projects here. :-laf

 

[Lsfarm]

You will never see

Gary, you will never see real time accurate underhood temps with your thermometer clipped to the BHAF cover. By the time you pull over, open the hood and take a look, the extreme conditions will be gone and the temp gauge will read close to ambient.



So your gauge will always support your theory since it will never read any extreme conditions since they will be gone by the time you open the hood. So your theory will always be a self-fullfilling one.



You ask for scientific data on the pressure at the cowl but don't want to take real temp readings at the air intake??



Gary, even with the engine up to full temperature, unless it is WORKING, it is not generating hardly any heat in the cooling system. ONLY with the truck under load will the cooling system be shedding a lot of heat. And unless the turbo is creating a lot of boost then intercooler will be cool, not hot. So untill you put a load behind your truck and get it working then you won't see very high under hood temps.



Just food for thought. Greg L



By the way: you started this thread, with some erroneous ideas, and an apparent lack of understanding of what is happening under the hood under light loads and are trying to use what you see under very light easy driving to support your theory.



Just think about it. Why do we have a fan clutch?? and a huge intercooler and radiator?? Not for an easy cruise at 55 mph. They are there to support the engine when is is working hard at full power. Then the under hood temps will skyrocket. The engine will be shedding tons of heat. Wait till you really work your rig, maybe, just maybe your thermometer will be able to retain high enough of a reading for you to see what was happening under hard working conditions. But only an in cab reading thermometer will show you the real temps under working conditions.

 

[Gary - K7GLD]

"Gary, you will never see real time accurate underhood temps with your thermometer clipped to the BHAF cover. By the time you pull over, open the hood and take a look, the extreme conditions will be gone and the temp gauge will read close to ambient. "



I think you are aware - as am I, that underhood temps get HIGHER, not lower when vehicle speed lowers or stops - meaning that if anything, my temperature differentials would be GREATER, not less - this isn't guesswork, I have verified this several times in various underhood components with an inrfared temperature gun.



The fact is that my thermometer type used on the BHAF is actually rather slow moving, and the only time it really has to change is what it takes for me to quickly raise the hood and take a reading - all of about a full second, hardly enough for radical swings in observed underhood temperature...



I think you are correct as to possible pre-conceived notions - the one seemingly most prevelant, is that there MUST be radical down-the-road increases in underhood temperatures above ambient, and that there must also be SUBSTANTIAL air pressure at the cowl area that could be tapped into to feed vast amounts of high pressure, cold air to the intake tract - and significant additional power for those who take advantage of that air.



To my satisfaction, I have NOT seen radical increases in underhood temperatures in normal driving situations, and have significant reason to doubt the availability of that "high pressure, cooler air" at the cowl area - at least in quantities to be of *measurable* benefit.



I have done my tests in typical operation to the best of my ability with decent equipment and methods - and made my point, which matches other far more detailed tests done by others in past threads - given my own readings - asked for opposing documentation - received NONE, just theory, guesswork and speculation - so readers are free to make their own judgements and act accordingly.



My own final deduction, until actual opposing test documentation is produced, remains the same - a decent low restriction air filter simply mounted underhood will very likely produce as good a benefit as those attempting to draw in additional outside air from the cowl area...



Cheers... .

 

[Fishin Guide]

There is no question that there is a high pressure area at the cowl. And how the temp at that location would compare to underhood temps, I do not know.



I would be curious to see what the mass airflow and temperature would be at a cowl hole. I am not sure that there is really any measurable PSI at the cowl hole, but it would be an interesting test.



The cowl hole could concievably act as a path for underhood pressure to release as well. Similar to a NACA duct.



I have no idea, just guesses.



Dave