Hard to tell how the power reduction program works without knowing the Ford source code and internal docs.
I know there are many defuel triggers, from overheat to oil temp, but there is also a torque / power sensor back in the transmission, fuel flow, etc. that allow the ECM to calculate when to defuel.
It may be a soft defuel, rather than a hard one --- where the throttle just backs off a bit (no matter what throttle input is), but not completely cut off fuel.
The magic of software!
Very few people really know what the software is thinking or doing, as the software is encrypted, and source code is not public.
Many people have no clue that engines can be functionally identical mechanically, exactly the same down the the part numbers, but with a different software, can do very different things.
Once had someone insist that since the parts are identical (looking), it must be the same, no clue as to tricks like heat treatment, coatings, software and sensor tweaks, and how all that can make an engine do quite different things, from the same hardware.
The giveaways is that when one engine is speced to have XYZ amount of coolant and oil sump, and the same basic engine in a different application uses a lot more coolant and oil, there is probably some major differences that are not obvious --- if you care to look.
NewsW wrote: Hard to tell how the power reduction program works without knowing the Ford source code and internal docs.
I know there are many defuel triggers, from overheat to oil temp, but there is also a torque / power sensor back in the transmission, fuel flow, etc. that allow the ECM to calculate when to defuel.
It may be a soft defuel, rather than a hard one --- where the throttle just backs off a bit (no matter what throttle input is), but not completely cut off fuel.
The magic of software!
Very few people really know what the software is thinking or doing, as the software is encrypted, and source code is not public.
Many people have no clue that engines can be functionally identical mechanically, exactly the same down the the part numbers, but with a different software, can do very different things.
Once had someone insist that since the parts are identical (looking), it must be the same, no clue as to tricks like heat treatment, coatings, software and sensor tweaks, and how all that can make an engine do quite different things, from the same hardware.
The giveaways is that when one engine is speced to have XYZ amount of coolant and oil sump, and the same basic engine in a different application uses a lot more coolant and oil, there is probably some major differences that are not obvious --- if you care to look.
As is contained in the link I posted, it is the EGR temp that causes the defuel in the Ford 6.4L. Temperature sensor "A" to be specific.
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You can see that by comparing the sheer size of the cooling systems in a real HD truck that is made to put out 100% duty cycle vs. the toy like cooling systems on the Dodge, GM, and Ford diesels.
As a rough rule of thumb, the cooling system need to dissipate about 65 to 70% of the heat in the fuel used / generated --- though some of it goes out the tailpipe and a small amount via radiation / conduction.
@ 400 hp/hr output (max for many consumer grade diesels), that is an awful fraction of heat it has to get rid of.
Today while I was running the Peterbilt 379 I was looking over that huge hood and seeing the size of the rad up front and I got thinking about your point regarding the how much bigger the cooling system is on a HD truck. I ended measuring the surface area of the rad on the Pete and compared it to the Ford pickup - I could hardly believe it - the Ford has more square inches/HP of rad frontage than the Pete does. (34 x 36 for the 550 HP Pete and 38 x 28 for the 400 HP Ford). The Ford also has more cooling fins incorporated into the rad but the rad is not as thick. I would think that front surface area is very key to how much cooling can be done as this is what is going to determine how much air there is to do the cooling. the rad could be a foot thick but once the air is the same temp as the water its not going to cool any more.
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You can see that by comparing the sheer size of the cooling systems in a real HD truck that is made to put out 100% duty cycle vs. the toy like cooling systems on the Dodge, GM, and Ford diesels.
As a rough rule of thumb, the cooling system need to dissipate about 65 to 70% of the heat in the fuel used / generated --- though some of it goes out the tailpipe and a small amount via radiation / conduction.
@ 400 hp/hr output (max for many consumer grade diesels), that is an awful fraction of heat it has to get rid of.
Today while I was running the Peterbilt 379 I was looking over that huge hood and seeing the size of the rad up front and I got thinking about your point regarding the how much bigger the cooling system is on a HD truck. I ended measuring the surface area of the rad on the Pete and compared it to the Ford pickup - I could hardly believe it - the Ford has more square inches/HP of rad frontage than the Pete does. (34 x 36 for the 550 HP Pete and 38 x 28 for the 400 HP Ford). The Ford also has more cooling fins incorporated into the rad but the rad is not as thick. I would think that front surface area is very key to how much cooling can be done as this is what is going to determine how much air there is to do the cooling. the rad could be a foot thick but once the air is the same temp as the water its not going to cool any more.
That sounds good in theory but, I have had quite a few vehicles that could be optioned with a 2,3, or 4 row radiator.
Living in Phoenix I have upgraded radiators on most of mine to one with more rows....Theory goes out the window as they DO cool better.
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#40Fan wrote: Ford EB's aren't very good is the answer to the equation.
I was under that impression also, based almost entirely on that "truck tow out" test where they used I-70 in Colorado and tested Dodge, Ford and Chevy going downhill from the Eisenhower Tunnel.
However, further reading and reviews seem to indicate it is just as good as the other two, albeit with the limiting factor that the starting decent speed on the Ford must be no more than 50 MPH. In the "truck tow test" I believe they started their decent at a speed higher than 50 MPH with all vehicles.
Now back to our regular program. I certainly do not have the know how to contribute any more to this.
I think you and seabiscuit are right in that we need to understand what our respective trucks are designed to do and operate them in that range.
Had Ford or Dodge been conducting the Eisehower pass test they would have chosen a different speed limit. The GM wanted to go down at 60 mph and may have required multiple braking applicatiins to keep it below 50. The Dodge may have been able to maintain 55 mph if it would have been slowed to 45 to get it into 2nd gear and the Ford would likely have been very comfortable at 45 mph in second gear.
There are two differences between Fords and GMs EB that explain why the GM's was more effective in that test. (one also explains the acceleration results as well)
I forget the exact ratios, but the Ford is geared lower than the GM in the 1-2 gears and taller in gear 3. The Ford basically has a hole in it's gear pattern that the GM does not.
The result was that in this test the GM was able to hold gear 2 just fine at highway speed. the Ford could not use gear 2 and gear 3 was too tall to generate much braking.
The other difference was not shown in the test. The GM EB is paired with the Allisons grade braking that all Dmaxes have always had, AND it is integrated with the cruise control. It is all activated by a switch on the dash, and pushing the tow haul button.
It will down shift as needed automatically to maintain the CC speed setting. You can actually slow it down for a slow corner by tapping the CC setting down. One tap = 1 MPH.
This is a great feature that they could not do a comparative test on as the Ford's EB is activated by applying the service brakes which. disconnects the CC.
The lower 1-2 gears explain why the Ford is slightly quicker off the line. When it makes the big jump from 2-3 is when the GM takes over.
* This post was
edited 04/10/12 07:47pm by Huntindog *
4x4ord wrote: I know my 03 Duramax never defueled pulling in the cool of the night and it overheated both the transmission and the engine on that same pass going much slower up the grade. To be fair though the Duramax has not been properly serviced and the cooling system was likely not functioning at its optimum level.
There probably is a built in defueling function in it, whether it got activated or not is another matter.
Many things can cause a defuel condition, for example, Fords defuel when RPM exceed a preset level.
That function is also commonly triggered using with certain mandated (by law) speed governors.
In any case, the 03 Duramax likely have a smaller set of triggers, reflecting less CPU capacity and a generally less sophisticated computer system designed a decade back.
4x4ord wrote: I ended measuring the surface area of the rad on the Pete and compared it to the Ford pickup - I could hardly believe it - the Ford has more square inches/HP of rad frontage than the Pete does. (34 x 36 for the 550 HP Pete and 38 x 28 for the 400 HP Ford). The Ford also has more cooling fins incorporated into the rad but the rad is not as thick.
I would think that front surface area is very key to how much cooling can be done as this is what is going to determine how much air there is to do the cooling. the rad could be a foot thick but once the air is the same temp as the water its not going to cool any more.
Actually not quite.
Normally, the A/C cooler is up front.
That gets the coolest air or, alternatively,
If you have a Charge Air Cooler, that is right there next.
The warmed air goes to rad next.
Thickness matters.
Look at this rad core pic here:
http://www.radiatorworks.com/p_radiators.php
Ask yourself, all things equal, which one should cool best?
Thermal transfer is a function of many things.
The metals used have different thermal properties for the tubing and fins.
Brass, aluminum, etc. all have different properties.
Then it is the amount of fluid flowing through --- pump volume, rate, thermal properties of fluid, the delta in temperature between the fluid and the air flowing through, and the amount of air being pulled through.
Make a high performance fan pulling air through, and you changed the thermal characteristics vs. just ram air.
In short, you cannot say just by frontal surface area how much heat it is dissipating.
Have to know many things, from the thickness (surface area of fluid flow, the flow rate of the coolant pump, delta temp, air flow rate over the rad, etc. etc. etc.
There are not many simple compares in life... or the engineers would all be out of work.
Answer to above.. one on left cools best... reasons.. can be discerned from the discussion here:
I have had quite a few vehicles that could be optioned with a 2,3, or 4 row radiator.
Living in Phoenix I have upgraded radiators on most of mine to one with more rows....Theory goes out the window as they DO cool better.
Wondering if there is a custom shop near you that can make the rad shown in the pic in the other post?
Basically, make it with a single row of thin but very thick fins rather than multiple rows of smaller tubes.
The other trick is aux. electric fans to push air through
* This post was
edited 04/10/12 08:49pm by NewsW *
4x4ord wrote: I ended measuring the surface area of the rad on the Pete and compared it to the Ford pickup - I could hardly believe it - the Ford has more square inches/HP of rad frontage than the Pete does. (34 x 36 for the 550 HP Pete and 38 x 28 for the 400 HP Ford). The Ford also has more cooling fins incorporated into the rad but the rad is not as thick.
I would think that front surface area is very key to how much cooling can be done as this is what is going to determine how much air there is to do the cooling. the rad could be a foot thick but once the air is the same temp as the water its not going to cool any more.
Actually not quite.
Normally, the A/C cooler is up front.
That gets the coolest air or, alternatively,
If you have a Charge Air Cooler, that is right there next.
The warmed air goes to rad next.
Thickness matters.
Look at this rad core pic here:
http://www.radiatorworks.com/p_radiators.php
Ask yourself, all things equal, which one should cool best?
Thermal transfer is a function of many things.
The metals used have different thermal properties for the tubing and fins.
Brass, aluminum, etc. all have different properties.
Then it is the amount of fluid flowing through --- pump volume, rate, thermal properties of fluid, the delta in temperature between the fluid and the air flowing through, and the amount of air being pulled through.
Make a high performance fan pulling air through, and you changed the thermal characteristics vs. just ram air.
In short, you cannot say just by frontal surface area how much heat it is dissipating.
Have to know many things, from the thickness (surface area of fluid flow, the flow rate of the coolant pump, delta temp, air flow rate over the rad, etc. etc. etc.
There are not many simple compares in life... or the engineers would all be out of work.
Answer to above.. one on left cools best... reasons.. can be discerned from the discussion here:
I realize that there is allot more to it than just front size but I sure wouldn't have guessed by just a casual look at the two trucks that the Ford had more square inches of rad/HP than the Pete. I have worked that Ford fairly hard - it quite regularly pulls 40,000 lb (gross combined truck and trailer) loads down the road and even out in cultivated ground and it has never come off normal on the temperature gauge. I can't say the same for the Peterbilt but it pulls 100,000 lb loads.The Duramax would rapidly overheat the transmission pulling even 30,000 lbs through soft ground. Now I'm not saying that the Ford could possibly compare to a Class 8 but in a couple of ways it does a better job of handling the 40,000 lbs that it is responsible for than the Peterbilt does of handling its 100,000 lbs. (staying cool is one thing - the other is delivering torque to the rear axle to start a load moving in soft ground - The Peterbilt's 18 speed transmission is great on the highway but too high for off road use) Just saying that these little trucks can hardly be called toys anymore.
I wouldn't have guessed the one one the left but I think it is the kind of rad that I would like for farm use due to it looks like it would be less likely to plug?
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