Starwagon culture shock?

[konadog]

Funny how little throttle it takes to raise temps once you install a Pyro you wonder how you drove without it...

I think you guys are getting a little pyronoid (pretty proud if that one). Just drive easy and all will be well.

[Rattlenbang]

Great pun! You'd think so, wouldn't ya? Yet I drove mine I thought quite carefully, but turns out, not enough...Oh well, worse thing that can happen is a head crack, and that never killed nobody.

[thedjjack]

Funny how little throttle it takes to raise temps once you install a Pyro you wonder how you drove without it...

I think you guys are getting a little pyronoid (pretty proud if that one). Just drive easy and all will be well.

My van does not need the pyro at all...it is near impossible to push it into the danger zone...however I think some vans the fueling is not set to factory and you can melt them down...I would be interested to know how many heads fail from motors turned a little hot so to speak..

But it is really nice seeing how hard it is working...I find lifting off just a little makes no difference in "speed" but difference in heat...second best mod I made after raising the roof...

[konadog]

My van does not need the pyro at all...it is near impossible to push it into the danger zone...however I think some vans the fueling is not set to factory and you can melt them down...I would be interested to know how many heads fail from motors turned a little hot so to speak..

Good point.
Reminds me of a story I read about the Americans in Vietnam, the veracity of I can't vouch for, but I think it's a good example of the point here all the same...
As I understand it, Colt designed and produced the M-16 rifle around a military spec. cartridge. After the rifle was in service the military, in an effort to make the rifles more powerful, started making cartridges with more powder and a heavier bullet. The result was heaps of over-heated rifles and guys getting killed or captured because they were fussing with a jammed rifle rather than shooting it...
An L-300 with a clean, working cooling system and a properly set I.P. that is driven with patience and care should never overheat. Btw, my pyro-gauge is the gas pedal: If I push it down and there is no increase in speed or revs. I back off and slow down (I may get a readable one installed one day, but it's not a priority). And I never drive with the pedal all the way to the floor. It's worked for me so far. I hope I get lucky and my bus lasts for many more clicks, but I think I have a whole lot of control over the variables at play.

[Rattlenbang]

My van does not need the pyro at all...it is near impossible to push it into the danger zone...however I think some vans the fueling is not set to factory and you can melt them down...I would be interested to know how many heads fail from motors turned a little hot so to speak..

But it is really nice seeing how hard it is working...I find lifting off just a little makes no difference in "speed" but difference in heat...second best mod I made after raising the roof...

It is possible that yours is actually unusually detuned rather than the reverse. It would be interesting if those with EGT gauges were to chime in here; I find it quite easy to go over the top when pulling a decent hill at hwy speeds. What have others found?

It might be a damn good longevity step to actually detune one's rig if not running a gauge, to make sure you have a situation like thedjjack. Of course he could just have a worn out motor that blows half the ignition gases past the rings, and needs a Coffman starter to get it going on cold mornings.

[thedjjack]

I also have the 5 speed so I have a little advantage in "power" to the wheels...

Rings are good...It fires right up....Only ever driven a few auto L300 to compare and similar..

What are we setting as the danger zone? My gauge lights up at 900...and I back off by 10000...I am preturbo in the EGR spot...

Today it got some new oil filter and a fuel filter...break in the rain..

My old VW was the motor that need rings....had to plug it in in the summer to get it to fire....and that was still not quick...eventually it started to pump oil out the dipstick tube....I miss that little blue Jetta...

[Rattlenbang]

From what I've read online, the consensus seems to be around 1200 degrees. That's not an engineer's opinion of course. But we do know that it's not hard to crack heads with any kind of turbodiesel, so excessive temps are a problem, a design flaw really. You shouldn't be able to grenade an engine with the throttle, IMO.

[TieMyShoe]

according to Banks Diesel Performance 1400 is the danger zone. 12-1350 is safe.

[Rattlenbang]

That would be nice if that was the case. Link?

[yojimbo]

There is the question of 'as measured where?'

[Rattlenbang]

There is the question of 'as measured where?'

I know this has been debated before, but I personally doubt it makes a big difference turbo/after turbo. The rate that exhaust gas is flying through there, it's in contact with the turbo (which is already at many hundreds of degrees) at most few milliseconds. The idea that hundreds of degrees of heat are conducted away in that time doesn't make sense.

[FalcoColumbarius]

..... My EGT comes with a (lack of better worked) "Itching betty" beeper when my EGTs are above 900, so I assumed that's what he was talking about, I did forget that some JDM car came with a speed reminder

A minor detail, Phill.... where is your EGT sensor located?

There is the question of 'as measured where?'

I know this has been debated before, but I personally doubt it makes a big difference turbo/after turbo. The rate that exhaust gas is flying through there, it's in contact with the turbo (which is already at many hundreds of degrees) at most few milliseconds. The idea that hundreds of degrees of heat are conducted away in that time doesn't make sense.

It makes a tremendous amount of difference. Take a campfire for instance: If you place your hand in the middle of the campfire you soon discover that it is very hot. If you place your hand just above that fire it's still burns but not quite as hot. Another six inches above that and it's bearable. Remember that this is in real time and while it's bearable where your hand is now, it's still very hot a few inches below your hand.

In the case of a diesel engine, the fire is contained, in an air tight container called a cylinder. The diesel depends on compression, that is a little diesel and air get squirted into the air tight (hopefully) cylinder. Then the floor of said container suddenly moves up toward the top of the container, ergo compressing the diesel and air molecules which makes them extremely irritable and presses them to a really hot state of mind, where like anyone who is pressed to this degree ~ they have a major meltdown and throw a royal wobbler. Fortunately, this situation is contained within a sealed container, but the explosion does cause the floor to run away really fast.

At this point a whole bunch of Air outside the chamber have heard the commotion and wondering what's going on come running into the chamber only to find a completely empty room, unaware that all the guts and carnage of the prior meltdown have been craftily removed. When suddenly ~ the door slams shut, they're locked in and the floor starts closing in on them! So they start screaming ~ at this point Diesel hears the screams and comes to rescue Air but when he enters the chamber the door gets pushed shut by Compression (hiding behind the door). Now Diesel, with Air behind him, turns on Compression and his dastardly moving floor and screams "Flame On!" and blasts Compression and his floor back to the other end of the chamber. Realising that they have a free moment, Diesel and Air make their escape and exit through a side door (exhaust port).

Heat is power, to a degree ~ then it becomes corruption. The air in the cylinder reaches roughly 550°C even before the diesel is introduced. Yet a cold engine is inefficient because it doesn't reach it's ambient temperature; ergo (i.e.) the piston never expands to it's operating size, leaving the rings unprotected to the cylinder blast. This erodes the rings over time. It's all about balance, it has to be.

Now let's look at the engine: The average ambient temperature of an engine is 100°C. The atmospheric pressure of the air is one bar (15 PSI). My turbo is set to just under nine PSI under load, that's about .6 of a bar. So, 100°C X 1.6 = 160°C. Next we need to consider the compression, which on the 4D56 Mitsubishi Astron engine (which I might add is a benchmark in the auto industry with the silent shaft and has influenced companies like Porsche, Fiat, Saab ~ to use the same license in their technology) operates at a 21.1 compression ratio ~ 160°C X 21 = 3,360°C. Now, considering that we're approximating and that there are massive error possibilities in what little information we have right now (one little zero can make a big difference in the grand scheme of things) ~ let's halve our results, which brings us to 1,680°C. This is the temperature (more or less) of the gaseous explosion in the cylinder at TDC. Now, how can this happen without compromising the integrity of the block or melting the aluminium head and pistons? Coolant and oil, may they never meet. The gas maybe 1,680°C but the engine around it is not, it's much cooler. Heat has a natural tendency to expand into cold so in that short period of time at 2,600 RPM that the gas moves from the cylinder into the exhaust manifold it loses a lot of temperature (a primary reason why the exhaust manifold is so hot to touch) and the further you move that gas, the cooler it gets ~ otherwise it would bugger the compressor impeller.

That's what I heard, anyway.

Falco.

[yojimbo]

Regardless of any heat conduction that may occur, there is also the expansion of the gasses from cylinder to manifold, you will see a drop in temperature from that anyway. Its how AC works after all ;)

[FalcoColumbarius]

Regardless of any heat conduction that may occur, there is also the expansion of the gasses from cylinder to manifold, you will see a drop in temperature from that anyway. Its how AC works after all ;)

That, too.

[Rattlenbang]

Although your metaphors were a good read Falco, I don't think the campfire one worked. I think a tiger torch in a pipe is more apt. Of course the temp drops further away from the engine you go, although I'm not sure if it would be a linear or geometric rate. I also think the picture is way more complicated than we describe; I suspect the temp in the middle of the pipe would be different from the edge, and while there would be a relationship between the temp of the surrounding metal and the gas, they would be different, and we are measuring the gas, which has a poor rate of thermal conductivity. There is also turbulence in the pipe which effects how temp is distributed and conducted.

When I think about it, there's also an assumption that internal cylinder temperatures are directly reflected in the exhaust gases, which may not be the case. It's possible that those internal temperatures are far more constant, but at higher RPMs and greater load, more of the energy of combustion is lost through the exhaust system, accounting for higher temperatures we read. If it was actually possible to "overheat" the combustion chamber, you would think the engineers would have devised a simple pyro feedback loop that limits this, and I've never heard of this in any diesel. Isn't it possible that the whole EGT thing we are monitoring is just a red herring? Maybe the head quality just isn't that great (mistubishi has had metallurgy problems in the past) and so some simply just fail. Given the intended market, maybe they just don't build a beefy head because it's not needed. I notice that other makes that have a problem with cracked heads are those with a history of quality problems (Ford ). It would be interesting to see if makes known for superior quality (Honda for example) have the same issue.

Those of us who use EGT to adjust driving styles might just be limiting engine load and therefore prolonging the life of our engines. The EGT might just be more an indicator of how hard the engine is working rather than an indication of the actual combustion chamber temperature.