Difference between a pulling truck and a street truck?

[jshalala]

Quick question: Why do pulling trucks smoke so much while on the track?

Many will say that excessive smoke from a diesel points to higher than desired EGTs and can lead to engine damage.
I've heard others say that pulling trucks dump extra fuel into the cylinders to cool them.

So what's the real reason? I want my trucks to run clean on the street and I don't think that smoke means power but I always get the argument regarding pulling trucks and how much they smoke and still put down big numbers.

Your thoughts?

[Nootch]

/sub

Never figured the whole differences out. I mean there are guys laying MASSIVE power down on dirt, and they can't make it skip, shuffle, and boogy down 1320?

[ComnRailPwr]

I'm no expert but Lean is mean but also burns up pistons. In truck pulling we don't really care about egt. At least I never have. We run much more timing than one would on the street because of the rpm we want the power at. Most pulling trucks lowest rpm is well over the maximum rpm you would run on the street. With all that said I can pull fuel, make more power and chance melting it down.

[Subman631]

It my understanding that some of the reason for all the unburned fuel in a pulling truck is it helps with EGT's, or was I misinformed?

[TheBigNasty]

You're also not likely compressor size limited on the street.

[97rada]

I was always under the impression it was to cool things down a bit

[budderbean]

On my truck, If i ran 2000 us tune she is clean but would bury my 2k pyro in the first 100 ft. switch to my 2600 us tune she is dirtier but I never rise above 1800 egt. For me, the extra fuel definitely cooled.

[spoolinram]

Too lean creates higher egts and will melt the piston down. It also can over drive the turbo blowing it up.
Add more fuel will cool it down . There is a point were you add too much fuel and can essentially put the fire out so to speak. Witch can cause low egts and an under driven turbo.
Also build sled truck motor to run a wot or at 75% too 100% of the throttle range. So the timing can be much higher. Sled trucks put together to run about 5000rpm+/- a few hundo.(varrys depending on set up)
Street trucks want a much more broader throttle range. So mostly street trucks are built different when it comes to injectors, pumps,and timing and even cam size. Smoke don't mean power,it means fuel. And boost don't mean power,it means restriction in flow.



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[biggy238]

I don't pull, not even going to try. I'm curious about the too lean destroying parts mentality.
There is a threshold between over fuel and quenching the combustion process.
"too lean" sounds to me like the stoich reaction is making more power in the cylinder, and the cylinder can't dissipate the heat. The counter to that is to quench and hope that you can yield the same power output and survive.

[Joesixpack]

A fuel air mix near Stoich will yield the most torque but is also the hottest burn possible. It is also pretty smokey even in a common rail.

Pullers are also using massive turbines which require a lot of late heat and therefore poor combustion but very favorable boost to drive ratio's.

[spoolinram]

Perty much. Its like a torch. Too much fuel don't get hot and don't do **** but soot. Too little fuel and all it does is pop and singe (hot as hell but as soon as you hit the oxy lever it just pops out). In our case it just melts us down before we know it .But get it just right and your good too go. The turbo itself is not adjustable so your air is set. You adjust your fuel pump output to make it just rite. The egt gage is your best friend when it comes to adjusting this reaction . Most street trucks don't have this problem .Most out of the box programmers will really only have the too much fuel problem endless the charger is changed.

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[biggy238]

Moving peak cylinder pressure closer to the exhaust event. I have it all in my head. I know jsp has the data somewhere to demonstrate.
I like to think of it in terms of energy rather than heat though.

[Leiffi]

You guys call yourself pullers and dont know ***t about diesel combustion ?

[Joesixpack]

Originally Posted by Leiffi

You guys call yourself pullers and dont know ***t about diesel combustion ?

I just can't help but wonder how many beatings you took in the playground when you were a kid.

Let's hear it from the master himself.

[SHughes]

This might get interesting...

[nwpadmax]

Yeah it's always a hoot when a total newb comes on and asks a simple question that makes some old timers look like dipshyts

You can go through the theory all you want. But for a fixed engine and turbo combo, you can set the fuel quantity to run clean....but adding fuel past that point will ALWAYS pick up HP and/or torque. Peak power is smoky. Always has been, always will be. Clean running diesels don't win.

[Smokem]

Originally Posted by spoolinram

And boost don't mean power,it means restriction in flow.

That isn't necessarily true.

[fox]

I tell people the smoke keeps the spark plugs and reed valves cleaner.

[spoolinram]

Simply turning up the boost you have does not mean you have more power in every case. The simple plain answer to a simple plain question is the answer I gave I believe. But if ya wanna make this more confusing for people that don't know all the technical terminology or the precise way of how a diesel works then so be it. Spitting out a slew of technical answers at a guy that may not know all the little working details of an engine will only inspire more questioning. In my opinion (witch don't matter anyway) if a guy is asking the question he asked then he proly is not as technology diesel smarts as "most" of y'all are. Hence the basic simple answer. What I said does equate to what can happen.
Too much fuel can great under drive and a poorly driven setup. Too little can create too much heat and over drive everything. Simply put if its too hot adding more can cool it down.
As far as boost goes. Do you realize how many people think that the more boost you have the more power you make? Alote. So instead of spewing out info in an elaborate detailed message I chose the simple easy beginners version. It wasn't meant to offend him or anyone else. But too each his own.

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[BRE]

Originally Posted by Joesixpack

I just can't help but wonder how many beatings you took in the playground when you were a kid.



Let's hear it from the master himself.

Originally Posted by SHughes

This might get interesting...

In it for the lulz