Difference between a pulling truck and a street truck?

spoolinram said:
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.
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Thanks for making it easy to understand.
 
spoolinram said:
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.
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If the given inducer size is the same or near the same, as well as the intake temperature, more pressure will make more power. There is a reason Hot/Super Farm, Limited/Light Prostock, and Prostocks run the pressure they do.
 
Depends on WHERE You are measuring the pressure. In the end, the more pressure of air in cylinder, the more fuel in cylinder, and the faster you get them both in and out makes the power.

Dynamic vs turbulent flow starts to come in when you are pushing large volumes of air. I do believe JSP was chasing this same problem last year on the dyno.
 
Agreed


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Laminar VS Turbulent flow. Was typing too quick at work earlier.
 
Not often i am working in the Shop as a field guy, they REALLY hate it when i am on my phone. Ninja i am not.
 
I'll bet they do when you're towing down a 10% incline and the grade braking kicks in and downshifts 'er to 5000rpm with no throttle....what's the A/F then???

It's all in your frame of reference.
 
Leiffi said:
Diesels dont run lean.
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Pretty much all factory diesel calibrations are limited to the lean side as to air fuel. 25:1-20:1. Well above a Stoich equivalence ratio. With this you could say a factory diesel is always lean.
To produce the most power for a given boost curve and therefore available oxygen modern diesels are matching that curve with fuel along side a set calibration air fuel equivalence ratio that produces no smoke.

Now pullers on the other hand are in a competition setting with a fixed inducer and therefore limited air. Peak torque occurs at a Stoich air fuel equivalence ratio and this is quite smokey as you are trying to use every molecule of oxygen possible and it's tough to do without even a surplus of fuel.

Thanks for that any ways.
 
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Joesixpack said:
Pretty much all factory diesel calibrations are limited to the lean side as to air fuel. 25:1-20:1. Well above a Stoich equivalence ratio. With this you could say a factory diesel is always lean.
To produce the most power for a given boost curve and therefore available oxygen modern diesels are matching that curve with fuel along side a set calibration air fuel equivalence ratio that produces no smoke.

Now pullers on the other hand are in a competition setting with a fixed inducer and therefore limited air. Peak torque occurs at a Stoich air fuel equivalence ratio and this is quite smokey as you are trying to use every molecule of oxygen possible and it's tough to do without even a surplus of fuel.

Thanks for that any ways.
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Stratified combustion engine doesnt have stoichiometric mixture, or maybe it's stoichiometric all the time because combustion always starts from the surface of fuel droplet injected into cylinder. AF gauge only tells how well you get fuel and air mixed, lower AFR without smoke = better mixture and more efficient combustion.

With smoke you sacrifice combustion efficiency for a little bit more power but there is limit when extra fuel starts to hurt power. You might get lower EGT with extra fuel but it also means less power because less fuel is actually burned so why not just reduce fuel to get same EGT and power with less smoke ?

Modern commonrail engines can get as low as 14:1 AFR without smoke and they start to lose power quite soon after smoke limit is crossed.
 
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