You got it!!

Some fires do NOT need extra fuel!!

 

The 3 main reasons why OEMs make design changes are 1) emissions, 2) cost, and 3) competition. Ford wasn't much worried about 3) because the 1997 OBS truck was the most popular pickup around but it couldn't meet the new 1998 emissions so out came the new 1998 truck which was actually called a 1999 truck even though it was produced and sold in 1998 which is when I bought my new F350 to go fulltime RVing.

Then in early 1998 the EPA told Ford and the other diesel OEMs that they could no longer certify their emissions compliance by just using their previous "open road test" method and that they had to also pass a "city driving loop" test. A long time ago we had this "sound emissions" vs "NOx emissions" discussion an I cited this 1998 EPA document and if I ever get caught up I'll try and find that thread because the document actually said the OEMs had been cheating in the way they'd certified their preproduction units and that they had to make things right or suffer some heavy fines in the future!

Anyway when Ford discovered their brand new 1999 truck couldn't quite meet this new "city driving loop" NOx emissions test they added the following "band aid" fixes... 1) compressor wheel to give more CFM at lower wheel rpm to enhance airflow during slow speed operation, 2) thermal insulation on the driver's side CAC tube, 3) a slightly improved intercooler, 4) an improved spider with an AIH which helped meet the PM spec without a CAT converter, and 5) larger plenums to improve air flow ...and they called the previous 1999 truck the "early 99" truck and they called the improved 1999 truck the "99.5 truck" and they introduced the 99.5 truck it in mid Dec 1998.

Now I've read the reports on FTE and elsewhere that the "wheel" and the "foil" are to reduce turbo whine but I don't believe that's the real reason. It's quite common for the Government, Military, and large Corporations to do something and then cite more benign reasons than their actual ones to explain their actions. Besides no one has cited any Ford source other than a Ford tech told so and so who told my neighbor who then told me!

The early 99 truck was only in production for several months before the redesign started for the 99.5 version so how could there've been many customer complaints about turbo whine? I couldn't hear any turbo whine in my early 99 truck but being new to diesels I could hear all manner of other strange sounds that concerned me until I figured out that they were normal and that diesels are inherently much louder than gassers.

Isn't it a little hard to believe that Ford would bear the huge expense of limiting a production run on a new truck to several months just so they could do some significant design changes to accommodate a few "whiny people complaining about how loud a vehicle is"?

 

Very compelling argument Gene. I don't have all the facts, but have heard all the rumors. How does the 17 deg HPOP fit in to your scenario that explains the rest of the upgrades?

I'm not saying you're wrong, but for the sake of argument I'll make up a story. Let's say Ford enlarged the intake plenums to increase airflow, upgraded the HPOP for better performance, then changed the wheel and added the foil to compete with the up and coming Isuzu engine (dirtymax) that GM was fixing to roll out. Since the Duramx was such a quite diesel that almost sounded like a gas motor, Ford also added an AIH to reduce some of the old fashioned stigma associated with a smokey diesel.

I'll admit your version sounds more credible, but how much of a factor would foil really have on emissions? If the 04 7.3 in Australia has a 17 deg HPOP, non-wicked wheel, larger intake plenums, then can we assume Ford did not add the foil for emissions purposes, or just as a cost saving measure? Would the 7.3, with the other mods included, not pass the city driving loop without the addition of the foil & insulation?

I don't know what upgrades our Aussie brethren have, but since they are shopping for a wicked wheel, I would assume they have all the same upgrades as a late 99 with the exception of the insulation. I find it hard to believe that the insulation & foil would be the tipping point in an emissions test after the other upgrades had been performed as you indicated in post #141.

 

Chris, NOX is very easily controlled by keeping the combustion temperatures below 2500 degrees.
It's very easy to understand what Gene is saying about the "upgrades" that Ford did to the 99.5. An increase in airflow and a change in tuning might have been all they needed to bring the readings back into the boundry box of allowable pollutants.
Also EGR is a very good way of controlling NOX by lowering the oxygen content (percentage) in the intake air.
It's all in the compustion temperature. Above 2500 degrees = a lot of NOX.
Below 2500 degrees = no NOX.
Even something as simple as a lower temperature thermostat.

 

I'll give a "technical based" explanation when I reply to Dan's post but for now here's a summary of my thinking based on the "programmatic" issues associated with the long range planning and designing cycle that typically occurs prior to the introduction of a new product such as the 1999 PSD.

I've worked on satellite projects that involved a similar long range planning and designing cycle and sometimes towards the end of the project one or both of the following things has happened... 1) the controlling agency (in this case the EPA) makes a last minute change to the spec or a change as to how the spec must be verified prior to launch, or 2) the engineers (me included) screwed up and some system doesn't actually meet the spec after all.

Since the launch date is carved in stone just like the release date for a new truck is when either of the above things goes wrong there's at first a lot of "hang ringing" and "finger pointing" and then virtually every "band aid fix" that anyone can come up with that might possibly help solve the problem and can be implemented in the short time that's available is in fact applied as a potential fix. There's no time for analysis and testing so out come the "shotguns" and I think the "foil" and the "wheel" fall into this category!

After Ford started production of their new 1999 model truck in early 1998 and then literally only months later shut down the production line for weeks so they could switch to the "new and improved" 99.5 version of the same truck they must've had a very compelling reason! If that was done based on someone's well thought out long range plan then I hope that person got fired!

 

I guess I'm just having difficulty believing that minute amount of insulation is enough to make any significant difference. But with Gene's explanation of it being part of the shotgun package, I could understand that.

Probably got a promotion instead.

 

Now for the "big question". Do you think they make these engines knowing full-well that there is a huge market for high-performance add-ons (look at the new 6.4 -- tuning, intake, exhaust = 500 RWHP/900 RWTQ), so they detune the bejeebers out of them to pass? Then those of us in the know can turn them back into the fully-opened-up hi-po machines they are. Y'all think that's part of the "game"?

 

PMR's dont' fit that scenario Joe. Unless the long range planner in Gene's story was promoted to engine design and that was his next move.

 

I'll try to clarify some of the issues raised by "White Buffalo" and others regarding the effects that increased AFIAT=Air Filter Inlet Air Temperature F have on the value of MAT=Manifold Air Temperature F and on the operation of the turbo in general.

When Tenn did his CFM tests for his 6637 AF=Air Filter and when I did my CFM tests for my 7.3L AIS AF we both measured ECAT=Engine Compartment Air Temperature F in the vicinity of the master cylinder location. Tenn used AE to monitor his AFIAT sensor which he zip-tied to his master cylinder and I used a Radio Shack remote thermometer at the fuse box location.

For any "open element" AF the AFIAT is equal to the ECAT which is the temperature of the air surrounding the upstream region of the AF element and for any "cold air intake" the AFIAT is equal to the temperature of the air entering the air box which is the temperature of the air surrounding the upstream region of the AF element.

To maintain a given MAF=Mass Air Flow lb/min through any AF element requires a AFVAF=Air Filter Volume Air Flow ft^3/min given by AFVAF={(MAF)(ADI)} ft^3/min where ADI=Air Density Inverse ft^3/lb and is given by ADI={(AFIAT+459.67)}/{(2.70325)(AFIAP)} ft^3/lb where AFIAP=Air Filter Inlet Air Pressure psi.

Now assume it's a nice summer day where the AAT=Atmospheric Air Temperature F is 85 F and you're at a 315 ft altitude because this is the standard reference temperature and altitude used when measuring a turbo's "compressor map" on a bench test and these conditions are the ones that apply to the location of the "surge line" on the turbo's "compressor map".

Now assume you've got an "open element" AF under the hood and you start the truck up cold so that initially ECAT=85 F and this means AFIAT=85 F. A 315 ft altitude corresponds to a AAP=Atmospheric Air Pressure psi of AAP=14.53 psi which is also the same pressure under the hood so that AFIAP=14.53 psi.

Under the above conditions the ADI={(AFIAT+459.67)}/{(2.70325)(AFIAP)}={(85+459.67)}/{(2.70325)(14.53)}=13.87 ft^3/lb which means that your AF needs to suck in 13.87 ft^3 of 85 F air for each 1 lb of air that's delivered into the engine and this fact is true independent of the performance of the IC=Intercooler.

Under the same above conditions assume you're at RPM=2,300 and BP=18 psi and that your engine is consuming a MAF=33 lb/min airflow. Since your AF needs to suck in 13.87 ft^3 of 85 F air for each 1 lb of air that's delivered into the engine this means a AFVAF={(MAF)(ADI)}={(33)(13.87)}=457.7 ft^3/min is required to maintain this MAF=33 lb/min airflow. This means your turbo needs to suck hard enough for your AF to flow 457.7 CFM across whatever the Inches H2O restriction of the AF element is at a 457.7 CFM flow.

Now assume you've been towing a load for awhile and your ECAT has increased to ECAT=145 F so that the AFIAT=145 F which is the value shown below in the 4th from the bottom row of Tenn's data table where the "black" measured numbers are RPM=2,300, BP=18 psi, MAT=129 F, and AF restriction=8" H2O. The black numbers are Tenn's measured data, the blue numbers are from my computer model, and the red CFM numbers are from the CFM airflow versus Inches H20 restriction graph for the 6637 AF.



The first point I want to make is that for a AFIAT=145 F the new ADI is ADI={(AFIAT+459.67)}/{(2.70325)(AFIAP)}={(145+459.67)}/{(2.70325)(14.53)}=14.4 ft^3/lb which means that your AF needs to suck in 14.4 ft^3 of 145 F air for each 1 lb of air that's delivered into the engine and this fact is true independent of the performance of the IC for trying to "undo" the adverse effect of the increase in AFIAT from 85 F to 145 F.

Since your AF now needs to suck in 14.4 ft^3 of 145 F air for each 1 lb of air that's delivered into the engine this means a MAF=33 lb/min airflow now requires a AFVAF={(MAF)(ADI)}={(33)(14.4)}=475.2 ft^3/min. This means your turbo now needs to suck hard enough for your AF to flow 475.2 CFM across whatever the Inches H2O restriction of the AF element is at a 475.2 CFM flow.

If you had a "true cold air intake" the AFIAT would be 85 F as before and your turbo would only need to suck hard enough for your AF to flow 457.7 CFM to provide a MAF=33 lb/min airflow instead of the higher 475.2 CFM flow that's required for a AFIAT=145 F.

This means if the two AF versions have identical "Inches H2O restriction vs CFM" curves that the "open element" AF makes your turbo work harder to maintain the same MAF=33 lb/min airflow into the engine and this fact is true independent of the performance of the IC for trying to "undo" the adverse effect of the increase in AFIAT from 85 F to 145 F.

Since this first point is very important I'll say it again in a slightly different way... 1) your turbo needs to suck hard enough for your AF to flow 13.87 ft^3 of 85 F air for each 1 lb of air that's delivered into the engine and 2) your turbo needs to suck hard enough for your AF to flow 14.4 ft^3 of 145 F air for each 1 lb of air that's delivered into the engine and this fact is true independent of the performance of the IC for trying to "undo" the adverse effect of the increase in AFIAT from 85 F to 145 F. I'll point out here that the AF restriction is a little less for 145 F air than it is for 85 F air but the turbo compressor wheel still has to spin at a higher wheel rpm to pull the higher CFM flow and that means more wear on the turbo bearing.

The second point I want to make is that the "surge performance" of your turbo as defined by the location of the "surge line" on the turbo's "standardized compressor map" degrades as the AFIAT increases to values higher than 85 F and as your operating altitude increases to values higher than 315 ft and this effect is determined by the density of the air that your compressor wheel has to contend with and this fact is true independent of the performance of the IC. If you tow heavy at higher altitudes you want to do everything possible to minimize your AFIAT because increases in altitude combined with increases in AFIAT have a "double whammy" effect on turbo surge!

Several FTE members have posted their MAT measurements using AE and then gone on to claim that their MAT results "prove" there's no adverse impact to using an "open element" AF such as the 6637. Then to compound matters many more FTE members quote these results to new members as the "gospel" which "proves" that all new members should also install a 6637 AF on their trucks!

I hope it hasn't escaped anyone's attention that I've already discussed two "potential" adverse impacts to using an "open element" AF such as the 6637 and I'm just now getting ready to discuss IC performance and its effect on MAT. Also just in case someone is actually paying attention to details and they noticed the slight difference in the CFM in my towing example compared to the CFM in the 4th from the bottom row of Tenn's data table please note that in my example AAT=85 F and AFIAP=14.53 psi whereas in Tenn's data table the AAT=90 F and AFIAP=14.6 psi.

Now consider the following thought experiment involving a "leaky bucket" analogy to help explain the "heat capacity" and "thermal mass" of the IC. You have a tall cylindrical bucket and along its entire height there's 1/4" diameter drain holes spaced every 1/2" all the way to the top.

As you begin to fill this bucket using a garden hose the water level in it initially rises fairly quickly but as more drain holes come into play the water level rises more slowly and then rises very slowly indeed until the leakage rate from all the drain holes covered by the water exactly equals the supply rate from the hose. This final water level is called the "steady state" or "equilibrium" value.

The IC is the bucket and the input heat flow from the turbo into the IC is the input water flow from the garden hose, the temperature of the IC is the water level in the bucket, and the heat flow from the IC to the ambient air stream is the water flow from the drain holes.

If you plot a graph of "water level" vs "time" you'll get one like is shown below for the "voltage" vs "time" on a capacitor that's charging from a battery through a series resistor and this is the same graph you'd get for "IC temperature" vs "time".

When you step on the throttle to accelerate the turbo spools up and air at a given AFIAT is sucked into the turbo and as this air gets compressed the inherent "heat of compression" is added to the "intake air heat" along with some additional heat that's produced by the "heat inefficiencies" of an actual turbo and all three of these "heat sources" combine and the whole mess of hot compressed air flows into to the IC "bucket" to get cooled off some before going the rest of the way to the engine.

The "IC temperature" vs "time" curve below shows that if you only accelerate for a time equal to one time constant "T" then the "IC temperature" only rises to 63.2% of the value you'd see if you towed a load up a long hill for a time equal to 4 or 5 time constants which is the time required to approach the "steady state" or "equilibrium" value of "IC temperature".



The above explains why in the 4th from the bottom row of Tenn's data table his "short term" measured MAT was 129 F whereas my "steady state" model gives a MAT of 167.5 F which you get by interpolating between the columns for AFIAT=140 F and AFIAT=150 F so as to match Tenn's measured AFIAT=145 F!

Of course an actual IC is more complicated than the bucket because the air in the IC is flowing through the IC so the air in the IC is a little hotter than the IC itself and also the IC temperature is higher at its input end than at its output end but as a ballpark estimate you could say that Tenn's "short term" measured MAT at the end of about a 20 sec run corresponds to (129)/(167.5)=0.77 or about 77% of the final "steady state" MAT value which is a little more than the 63.2% shown on the graph for one "time constant" so the "IC time constant" is about 15 sec or so and this means you need to sustain a load on the engine for about 5 time constants or 75 sec or longer to approach a "steady state" MAT reading.

So the bottom line is that hotter air going into a turbo makes the turbo suck harder and spin its compressor wheel at a higher rpm to flow more CFM to get the same MAF into the turbo as could be gotten with less CFM if the intake air was cooler and hotter air going into a turbo makes the turbo more susceptible to surge and both of these adverse impacts are caused solely by the reduced density of the air that interacts with the turbo's compressor wheel.

Also hotter air going into a turbo means more heat for the IC to deal with and even though the purpose of the IC is to remove heat having hotter air coming into the IC means hotter air going out of the IC and to find out how much a given increase in AFIAT increases the MAT you need to place the engine under a sustained load for 75 sec or more which only happens if you're towing up a long enough grade or on a load dyno.

 

Thank you Gene for taking the time to post this info.

But the point I keep trying to make and ask you about in previous threads is:

I am not seeing 140+ degree engine compartment temperatures. I am seeing 7-12 degrees above outside air temps when the truck is moving 30 mph or higher and towing the 5th wheel, even after 500 miles of towing.

I am not seeing the same temps that Mike did on his test run. I tied my AIT sensor to the same location and I monitored the MAT with the Predator Programmer.

I don't know what to think? Why such a big difference?

 

Well I don't have "the answer" yet but I think we all need to try and understand "why" there's such a large range of different ECAT=Engine Compartment Air Temperature being reported and that's the reason I pulled together the quotes below to make it easier for you and others to review and comment on some of the points that have been raised on this ECAT issue.

At the lowest end of the ECAT scale "CSIPSD" reports an ECAT that's less than 2 F above ambient and "Pocket" agrees by reporting the ECAT is nearly the same as ambient. Next in line comes your report of an ECAT that's 7 F to 12 F above ambient.

Then comes the data reported on the Dale Isley Tymar Performance web site of an ECAT that's 45 F over ambient when stopped and an ECAT that's 10 F to 20 F over ambient when underway but that data was for running empty in fairly benign conditions and "averaged" between several trucks in different parts of the country.

Next comes Tenn's data and as you can see by subtracting the 90 F ambient from the AFIAT measurements in his table his ECAT ranged from an ECAT that's 35 F above ambient when "Cruising small grade" to an ECAT that's 55 F above ambient when "2nd Hill Accel".

Then comes my years of ECAT measurements and one thing I observed is that everything else being equal the ECAT is highly dependent on whether or not the A/C is running. I saw an ECAT of 20 F to 30 F over ambient when driving empty, an ECAT of typically 50 F to 60 F over ambient when towing a 22K GCW on the flat, an ECAT of 70 F to 100 F over ambient when towing a 22K GCW while westbound in KS during a 103 F heat wave where for the first time it only took moderate grades to cause my radiator fan to go into its full lockup mode which normally it only did towards the end of long steep grades.

Since the bimetal spring in the viscous clutch is calibrated to cause full lock up of the radiator fan at an ECAT of 205 F I think having the radiator fan go into full lockup is a fairly accurate way of documenting an initial 205 F ECAT and then after the fan locks up the increased air flow reduces the ECAT some and the fan drops out of full lockup at an ECAT of about 170 F. Alan Miller once gave me this I think 170 F? number but I can't find it just now perhaps someone can check to see if it's correct.

I'm not the only one whose reported his radiator fan going into its full lockup mode...

I'll do some more analysis and see if I can justify my ECAT measurements based on some Physics which includes the heat rejected by the engine, the flow of air through the A/C condenser, IC, and radiator which enters the engine compartment, the flow of air which leaves the engine compartment from underneath the engine, and the exhaust flow which removes heat out the tail pipe.

Since any engine "rejects" about 2 HP worth of waste heat for each 1 HP it produces at the flywheel and since each 2 HP worth of "rejected heat" from the engine has about the same heating capability as the standard 1,500 Watt electric heater I'm currently using to heat my 40' fiver as I'm ridding out yet another late winter storm in the "four corners area" of NM I've got a pretty good "feel" for just how much heat is rejected from an engine operating at say a 250 FWHP load because that's about 500 HP of waste heat and that's the same as putting 250 standard 1,500 Watt electric heaters in my 5er instead of just the one I've got running now!

 

So did you get the 2-3' of snow they forcasted for the Denver region? Weren't you just in sunny Florida?

Well, for some reason I just can't let this subject go until I see or understand for myself if there is a big difference in IAT's for my truck & setup. I have the AIS and 6637. I'm gonna run both when pulling the 5th wheeler to South Dakota and see what #'s I come up with.

Thanks Gene.

 

Rich, I've run both the 6637 and the AIS.
No difference in pulling power or max boost at stock tune for towing.
Just a little quieter with the AIS.
I didn't take any temperature readings.
.
Gene where are you in the 4 corners area?
I've been there and it's a rather long drive to get to the spot in the middle of the desert.

 

I'm just south of Denver and we've been getting hammered since yesterday afternoon, and it's still going strong right now. No one can get out of our neighborhood right now. There's probably 2 feet of wet heavy snow sitting on the street.

$20 says I get my Honda Rincon 680cc stuck while snow plowing the neighborhood.

 

Tenn used "AE" to read his AIT sensor perhaps the "Predator Programmer" reads it differently? I've not been able to find any data on the "calibration" of the AIT and MAT sensors as to their "absolute" accuracy. I was able to verify the "absolute" accuracy of my Radio Shack wireless thermometer by comparing it to several other thermometers.

An interesting experiment would be for you to Velcro a wireless thermometer to your fuse box and compare that reading with your AIT sensor while towing. If you have an IR gun shoot some under the hood temps immediately after pulling into a rest stop and include the air intake tube to the turbo and both the cold and hot sides of the turbo case and both the upper and lower radiator hoses.

I hope F350 or anyone chimes in here and posts the official Ford procedure for calibrating the viscous clutch as I seem to have misplaced my copy. As I recall it says to block the radiator with cardboard and fast idle the engine and measure the temp at some specified location under the hood with the hood closed and the clutch is supposed to lockup at 205 F? and unlock at 170 F?

I'm assuming your clutch has never locked up so you could do this Ford calibration test using a meat thermometer and also read the AIT sensor to compare it to the lock and unlock temp for your clutch.

We're headed eastbound on I-40 and 4 days ago we pulled off at Exit 102 to let the storm pass but the only problem with that plan was the storm didn't pass us by and now I'm nearing the end of my last bottle of propane and the end of my last 6 pack of beer and neither one of those items is available here!

We got some snow at our 6,500 ft altitude but Mt Taylor (11,301 ft) is just outside our window and it's loaded with snow. We haven't been in FL for years it's become too crowded, too expensive, too humid, too etc..., but it sure sounds like a good place to be just now!