Hotter the better?
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Lead Driver
Joined: Apr 2008
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Hotter the better?
So i think ive finally figured this out. I notice from time to time my truck just seems to run better. I have been keeping a better eye on it and trying to figure out when and why it does it, this is what ive found so far.
After a good drive, enough to get it warmed up and coolant circulated, say you go to a store. Shut it off go in buy some dew come out, fire it up. Gauge reads in the middle instead of the low side of norm. where i shut it off, normal heat soak.. but.. Its here when its hotter than it usually runs, that it runs better. By better i mean better throttle response, more power, less smoke, the whole 9. I was sitting in traffic earlier and my temp will creep up, under this circumstance i dont notice any difference than normal, seems like its tied to being good and warmed up, and after being shut off for a minute.
This sound like im going crazy or something diagnosable? I have a hunch its something to do with the pump, perhaps timing, not sure.
After a good drive, enough to get it warmed up and coolant circulated, say you go to a store. Shut it off go in buy some dew come out, fire it up. Gauge reads in the middle instead of the low side of norm. where i shut it off, normal heat soak.. but.. Its here when its hotter than it usually runs, that it runs better. By better i mean better throttle response, more power, less smoke, the whole 9. I was sitting in traffic earlier and my temp will creep up, under this circumstance i dont notice any difference than normal, seems like its tied to being good and warmed up, and after being shut off for a minute.
This sound like im going crazy or something diagnosable? I have a hunch its something to do with the pump, perhaps timing, not sure.
Elder User
Joined: Feb 2012
Posts: 888
Likes: 2
So i think ive finally figured this out. I notice from time to time my truck just seems to run better. I have been keeping a better eye on it and trying to figure out when and why it does it, this is what ive found so far.
After a good drive, enough to get it warmed up and coolant circulated, say you go to a store. Shut it off go in buy some dew come out, fire it up. Gauge reads in the middle instead of the low side of norm. where i shut it off, normal heat soak.. but.. Its here when its hotter than it usually runs, that it runs better. By better i mean better throttle response, more power, less smoke, the whole 9. I was sitting in traffic earlier and my temp will creep up, under this circumstance i dont notice any difference than normal, seems like its tied to being good and warmed up, and after being shut off for a minute.
This sound like im going crazy or something diagnosable? I have a hunch its something to do with the pump, perhaps timing, not sure.
After a good drive, enough to get it warmed up and coolant circulated, say you go to a store. Shut it off go in buy some dew come out, fire it up. Gauge reads in the middle instead of the low side of norm. where i shut it off, normal heat soak.. but.. Its here when its hotter than it usually runs, that it runs better. By better i mean better throttle response, more power, less smoke, the whole 9. I was sitting in traffic earlier and my temp will creep up, under this circumstance i dont notice any difference than normal, seems like its tied to being good and warmed up, and after being shut off for a minute.
This sound like im going crazy or something diagnosable? I have a hunch its something to do with the pump, perhaps timing, not sure.
Laughing Gas
Joined: Feb 2010
Posts: 859
Likes: 2
From: Port Orchard, WA
Well, I don't think it has to do with the pumps. Maybe, but I doubt it.
When combustion occurs, some of the energy is passed to the coolant as heat. The formula for this is:
Energy To Coolant (Q) = Cp * (Tcylinder - Tcoolant)
Where Cp is a constant.
As Tcoolant gets higher, it's closer to Tcylinder, and thus "Energy To Coolant" is less. That means more energy is present for the propulsion of the cylinder.
A 10-15 degree rise in the coolant temperature should make a (barely) noticeable feel.
Keep in mind I'm talking coolant temperature here, not ambient. If I'm not mistaken, these trucks will run better in the winter because the air is denser, which increases the AF ratio. In a diesel, there really isn't an ideal AF ratio, the more air the better (usually).
-Matt
When combustion occurs, some of the energy is passed to the coolant as heat. The formula for this is:
Energy To Coolant (Q) = Cp * (Tcylinder - Tcoolant)
Where Cp is a constant.
As Tcoolant gets higher, it's closer to Tcylinder, and thus "Energy To Coolant" is less. That means more energy is present for the propulsion of the cylinder.
A 10-15 degree rise in the coolant temperature should make a (barely) noticeable feel.
Keep in mind I'm talking coolant temperature here, not ambient. If I'm not mistaken, these trucks will run better in the winter because the air is denser, which increases the AF ratio. In a diesel, there really isn't an ideal AF ratio, the more air the better (usually).
-Matt
Elder User
Joined: Aug 2007
Posts: 589
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From: Nutter Fort,West Virginia
how about hotter fuel and a rise in coolant temperature?
i still think a fuel heater would help these trucks a little.
hot fuel cold air and a strong breeze to the south
i still think a fuel heater would help these trucks a little.
hot fuel cold air and a strong breeze to the south
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i ain't rite
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From: Marlboro Mental Hospital.
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Elder User
Joined: Feb 2012
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Nothing wrong with it, just kind of funny that you asked it.
Its a diesel, all diesels are gutless when cold, even electronic diesels.
there are several reasons....
Physically the engine itself needs to be warm, because the hotter the diesel is, the easier it burns... both cylinder temps and water temps contribute to this. Diesel oil will cause significant parasitic drag when cold.
The pump - HPCA increases housing pressure by restricting return line. Generally +6*... this is enough advance to help engine run when engine and diesel is cold, but also enough advance to make the engine gutless.
Its a diesel, all diesels are gutless when cold, even electronic diesels.
there are several reasons....
Physically the engine itself needs to be warm, because the hotter the diesel is, the easier it burns... both cylinder temps and water temps contribute to this. Diesel oil will cause significant parasitic drag when cold.
The pump - HPCA increases housing pressure by restricting return line. Generally +6*... this is enough advance to help engine run when engine and diesel is cold, but also enough advance to make the engine gutless.
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Lead Driver
Joined: Apr 2008
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I know that they have less power cold, and it does run better warmed up, but the reason i asked is because its not just a little difference.. its very noticable. I was wondering if its something to do with the pump when it gets hot after sitting a minute, or maybe just the thinner/ hotter diesel atomizes better or something. Basically id love to get it to run like that all the time.
As far as the "all diesels run better warmed up" how come there is no difference when it gets hot sitting in traffic? When i start it after sitting 5 minutes, there is a much smaller puff of black when it fires, idles smoother, revs faster and much more power / less smoke for well about a mile till it cools off again.
on a side note, i seem to have better low end when the HPCA is on, when it kicks off and im cuising i have to give it just a tad more fuel to keep the speed. Is my timing too retarded? Im about a quarters width advanced of the line, anymore and she dont sound very happy when its cold.
As far as the "all diesels run better warmed up" how come there is no difference when it gets hot sitting in traffic? When i start it after sitting 5 minutes, there is a much smaller puff of black when it fires, idles smoother, revs faster and much more power / less smoke for well about a mile till it cools off again.
on a side note, i seem to have better low end when the HPCA is on, when it kicks off and im cuising i have to give it just a tad more fuel to keep the speed. Is my timing too retarded? Im about a quarters width advanced of the line, anymore and she dont sound very happy when its cold.
Logistics Pro
Joined: Sep 2010
Posts: 4,411
Likes: 4
From: Victor, MT
idk bout that....seems like i get better response when my diesel has been sitting all day and its dead cold....if i floor it and its just been started(a minute after startup for oil purposes) I can twist the truck frame with it...
Elder User
Joined: Aug 2007
Posts: 589
Likes: 2
From: Nutter Fort,West Virginia
i know that my dad's truck is just about deafening when he starts it up in winter.
i hate helping him hook the plow up because of it...
has anyone tried insulating the intake manifold from the engine heat?
ideally your truck should have about the same amount of power with the advance on as with it off. i mean it is supposed to adjust for the time required to burn the fuel and give the highest power output possible no?
i hate helping him hook the plow up because of it...
has anyone tried insulating the intake manifold from the engine heat?
ideally your truck should have about the same amount of power with the advance on as with it off. i mean it is supposed to adjust for the time required to burn the fuel and give the highest power output possible no?
Elder User
Joined: Feb 2012
Posts: 888
Likes: 2
The HPCA advances timing to give the fuel more time to burn in the cold cylinder, to reduce white smoke. More of the energy is burnt in the cylinder before the exhaust valve opens. This will also make your turbo charger lag more.
Post Fiend
Joined: Feb 2009
Posts: 8,005
Likes: 7
From: Ottawa, Ontario
Having driven across the country, in many different elevations and climates, I find a cool, very humid night is the best for these IDI's.
In the dry summer heat of the desert of Nevada and Arizona, camper had normal power.
But in Florida, on a "cool" humid might, it had tons more power, and no black smoke at full throttle. In the dry desert, a lil over 3/4 throttle to see thick black smoke.
Reason is, dry air is less dense, humid air is very dense, and contains water, and water contains oxygen, so on top of dense air, it's got the extra oxygen from the water, giving the engine maximum air, it's like having a turbo at night
Same thing on the coast lines, I've been coast to coast in the camper, and on both coast lines, the ocean breeze gives it alot more power, and way better mpg also. It's on the coast that I hit my record mpg numbers!