Not trying to argue, just on a road trip.
I don't understand what you mean since nothing solid or liquid combusts, only its vapors but I am reading that you say it doesn't vaporize?



I do agree EGTs are the grim reaper but would you have the EGTs without excessive DP?

To the OP sorry about hijackin your thread

 

Wood is solid and it combusts, coal is solid and it combusts, so solids can and do combust. Heavy petroleum products fall into the same category. They don't vaporize easily so they need to be atomized to smaller particles and mixed with oxygen to promote efficient combustion. The bonds on diesel molecules are pretty strong so it takes quite a bit of energy to break them. High pressure and relatively high temperatures to start the combustion process. The upside is once you break the bonds the energy released on the conversion is quite high.



Sure, I garantee a 21 cm housing is not having problems with DP but you push over 40 psi and enough timing a gen 1 would eat a gasket. Been there done that.

 

[QUOTE=no_6_oh_no;2420216]Wood is solid and it combusts, coal is solid and it combusts, so solids can and do combust. Heavy petroleum products fall into the same category. They don't vaporize easily so they need to be atomized to smaller particles and mixed with oxygen to promote efficient combustion. The bonds on diesel molecules are pretty strong so it takes quite a bit of energy to break them. High pressure and relatively high temperatures to start the combustion process. The upside is once you break the bonds the energy released on the conversion is quite high.[QUOTE/]


Come-on, you yankin my chain?
For the most part nothing combusts in its liquid or solid state! It must be first heated until its physical state converts to gas.
Atomised liquid fuel changes to a gaseous state known as ' vaporisation ' and its molecules attach to the air oxygen molecules, 'volatilisation '. Liquid fuels cannot burn until they are volatilised.
So if the volatilisation reaction is generated from heat (be it from temp,pressure,chemical reaction,etc) is it not logical to assume if the reaction took place with-in a higher temperature it would happen sooner (IE hotter cyl)? Are you saying it's a matter of its physical properties only allowing it to convert at X rate?





I can build a few set-ups guaranteed to fail also but in the majority of failures I have seen are stock turbo trucks. I have not run a DP gauge on all these rig but do know in my personal cases DP and EGTs go hand in hand.

 

In as much as you described the process it is correct. I cut a few corners rather use the correct language and descriptions which is REALLY off track for this thread. Consider what is actually happening though. Combustion is the naked apes poor attempt to describe the physical manifestation of unknown phenomena. In reality it is a chemical reaction driven by and producing energy in the form of heat.

Does it happen faster the higher the temperatures? Is it measurable? How much is the difference? A more likely description is the "combustion" is speeded up somewhat by the presence of more energy to drive the process, but, I don't think initiation is going to happen any faster at 400 degrees as opposed to 1400 degrees. Given the presence of adequate oxygen in the form of high boost you could very well see faster spikes in pressure that may emulate what advanced timing would do.

The common factor I do see in most failures is excessive heat and EGT's. Given we can run 70-80 psi of DP as long as the compressor is capable of delivering the same volume of "good" air and not have the same problems for the most part I surmise that the DP is a symptom not a cause. Really though, anybody running 650-700 hp is o-ringed, fire ringed, studded, and a really expensive head gasket. Not quite the same thing as relying on a stock head gasket and stock turbo.


Thats my s-s-s-story and I'm stickin' to it.

(or until I can understand the physics and chemistry better)

 

Really, ya think?

 

At least we can both agree we derailed this thread LOL

 

Here is a monkey wrench in the whole thing. Since combustion (oxidation or exothermic reaction) requires O2, if there is a lack of O2 there will be no fire no matter what the pressure or temperature is in the cylinder.

So if there is excessive residual exhaust in the cylinder that has depleted O2, then even if it is hot it will delay or inhibit the combustion.

 

Understood and accepted.

Unlike a naturally aspirated motor, a turbos charge is a pretty constant pack.
In the beginning stages of TIP being to high I doubt the residual is excessive but still present enough to limit the next charge somewhat. It does seem reasonable that it would compound with successive cycles, no?
This residual charge however contains unspent fuel that gets the next ride up with an now over abundance (new charge) of O2 and heat. To me, this is the Monkey wrench.

My head hurts need sleep

 

Forest for the trees, forest for the trees....

 

It won't delay it but it will inhibit total combustion. This is normal for a 600 series engine and is what allows them to run more DP and still function adequately. It is a problem though when you push beyond a very narrow operational limit. Not a lot of leeway to add fuel and not cause problems.


You are just not going to get a lot of compounding even with high DP. Most of the combusted charge is going to be evacuated by the piston coming up on the exhaust stroke. You will get some mix on the intake stroke with the valve overlap but the incoming charge is much heavier and denser than the hot combusted air and will displace a lighter hotter charge at even higher pressures. Since the exhaust flow has to stop and reverse to back fill the cylider that also will tend to minimize the mixing. The overlap is not that large you will get large amounts of mixing rathe rjust enough to provide control in a stock situation.

I doubt you will see any measurable amounts of uncombusted fuel back filling the cylinder though. This would mean the fire has essentially gone out on the previous event and you are already loosing exhaust temp and flow thru the turbo. When that happens DP drops, boost drops, power drops, and things just get really hot and smoky.

More likely you get some mostly combusted fuel with no oxygen left mixing with the fresh charge. Net effect is probably still going to be a negative effect on total combustion temp and pressures.

 

Boy what a can of worms the OP started with such a simple little question