Yeah, and we're looking at different ends of this I've realized...
If you look JUST at the cylinder, it's a FIXED volume (0.6 liters)...so to increase mass, you have to increase density...it's the only way.
...but the flip side of this is that to increase the density in the cylinder, the turbo has to ingest a larger volume of air that will be compressed, and will become more dense...thereby having more mass.
Anyway, sorry for the long replies...I was more thinking out loud trying to wrap my mind around this whole thing...rather than argue or prove you wrong.
...
Oh, and "WD"...that headache is from all that beer you had at the NICO/NOPI thing...hangovers are a *****!!! :p
- Brian
Any ideas for tuning a ka-t with an safc????
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:: orion ::
- Posts: 1483
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Re: (:: orion ::)
It's cool, I like having conversations about this stuff BTW if you're real interested in tuning and this stuff, check out EFI University (www.efi101.com), I took the 101 and advanced classes, they're awesome. The classes are expensive, but worth it.
Re: (D1 guy)
...so....aaaanyways...
How's the install coming? Get the engine in/running?
How's the install coming? Get the engine in/running?
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DRIFTEADOR
- Posts: 706
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Re: (slipnfall)
i went to the very first seminar at jotech and wasn't very impressed. maybe they just werent as organized back then being the first one and all.
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this is another link from turbo manufacturer, but its a much better explanation than, "turbos make your n/a motor x% more fuel efficient"
http://www.bankspower.com/Tech...o.cfm
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this is another link from turbo manufacturer, but its a much better explanation than, "turbos make your n/a motor x% more fuel efficient"
http://www.bankspower.com/Tech...o.cfm
Re: (DRIFTEADOR)
That might of been it, I don't really know how it used to be back then, from what he said they seem to have come a long way with the classes and improved them alot compared to back then. I was very impressed with the classes I took, Ben (the intructor) seemed organized and taught the classes very well. He was really good at explaining concepts and using analogies, and was extremely knowledgable. I was really impressed and thought they were great classes IMHO.DRIFTEADOR wrote:i went to the very first seminar at jotech and wasn't very impressed. maybe they just werent as organized back then being the first one and all.
Re: (:: orion ::)
Yep, I was gonna say that.:: orion :: wrote:If you look JUST at the cylinder, it's a FIXED volume (0.6 liters)...so to increase mass, you have to increase density...it's the only way.
- Brian
Anyway, for those still following this thread....
1. When I installed my turbo, STOCK fuel system, STOCK electric system I saw little to no reduction in my MPG. Of course I did not see ANY improvement, just a little reduction probably because my driving habits changed a bit. I believe since a turbo is a restriction at cruise conditions and anything below spool up and a source of power (more air mass and more fuel being injected) after spool up that it will hinder MPG results and not make a car more efficient. Now there could be other variable we are not taking into account.
2. In cruise conditions, and depending on the incline of the road I see around negative 12 to negative 5 mmHG... vacuum. If you're car spools up during cruise conditions on a level surface... you're turbo is too small, period.
3. Now, most of us are now getting way worse MPG than we did N/A. Of course. Why? Because most of us have bigger injectors and for one thing the ECU has a minimum ms cycle time programmed so at idle it does not matter if you pull the SAFC all the way down, once this miminum has been achieved the ECU will not reduce fuel anymore. Most of us have pulled the timing back to protect the engine, but this worsen MPG as it reduces the HP that the engine can achieve at a given AFR... meaning you need to push the throttle more (off boost) than before to get the same results... getting up my driveway for example.
In conclusion (my own at least) a turbo will not make a car more efficient, at least not if we are taking MPG here (maybe the links I did not read mean't something else), but will actually hinder it a bit. In my own experience to little to actually be noticed, as long as you don't change driving habits which play a major part in MPG... in the same car I get at least 30% more fuel economy than my mother.
Re: (huguetpj)
I also wanted to clarify a definition:
Quote »Volumetric Efficiency
The volumetric efficiency of a 4-stroke engine is the relationship between the quantity of intake air and the piston displacement. In other words, volumetric efficiency is the ratio between the charge that actually enters the cylinder and the amount that could enter under ideal conditions. Piston displacement is used since it is difficult to measure the amount of charge that would enter the cylinder under ideal conditions. An engine would have 100% volumetric efficiency if, at atmospheric pressure and normal temperature, an amount of air exactly equal to piston displacement could be drawn into the cylinder. This is not possible, except by supercharging, because the passages through which the air must flow offer a resistance, the force pushing the air into the cylinder is only atmospheric, and the air absorbs heat during the process. Therefore, volumetric efficiency is deter-mined by measuring (with an orifice or venturi type meter) the amount of air taken in by the engine, converting the amount to volume, and comparing this volume to the piston displacement. [/quote]So NO, a turbo will not increase the VE of an engine. Well depending on how you measure it. If you measure the ideal volume @ atmospheric pressure then yes, since the volume of air inside the piston will be "bigger" but at a higher pressure. But that defeats the definition since it's talking about volume and the volume cannot really be changed, so you should calculate both ideal volume and real volume at the operating pressure. So the VE still needs to be lower then 100%, and as you increase the amount of air trying to get in... the resistance increases which lowers the VE. That is why the engine sim shows a decrease of the VE as you increase pressure.
Quote »Volumetric Efficiency
The volumetric efficiency of a 4-stroke engine is the relationship between the quantity of intake air and the piston displacement. In other words, volumetric efficiency is the ratio between the charge that actually enters the cylinder and the amount that could enter under ideal conditions. Piston displacement is used since it is difficult to measure the amount of charge that would enter the cylinder under ideal conditions. An engine would have 100% volumetric efficiency if, at atmospheric pressure and normal temperature, an amount of air exactly equal to piston displacement could be drawn into the cylinder. This is not possible, except by supercharging, because the passages through which the air must flow offer a resistance, the force pushing the air into the cylinder is only atmospheric, and the air absorbs heat during the process. Therefore, volumetric efficiency is deter-mined by measuring (with an orifice or venturi type meter) the amount of air taken in by the engine, converting the amount to volume, and comparing this volume to the piston displacement. [/quote]So NO, a turbo will not increase the VE of an engine. Well depending on how you measure it. If you measure the ideal volume @ atmospheric pressure then yes, since the volume of air inside the piston will be "bigger" but at a higher pressure. But that defeats the definition since it's talking about volume and the volume cannot really be changed, so you should calculate both ideal volume and real volume at the operating pressure. So the VE still needs to be lower then 100%, and as you increase the amount of air trying to get in... the resistance increases which lowers the VE. That is why the engine sim shows a decrease of the VE as you increase pressure.
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DRIFTEADOR
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Re: (huguetpj)
i'll save you the trouble of clicking a link
"Some people think that once airflow is increased, additional fuel must be added at all times, and that would hurt fuel mileage. This is not the case during normal driving. Increasing airflow means an engine doesn't have to work as hard to overcome pumping losses. In other words, power that was previously consumed by pumping losses will be available to do work after airflow enhancements have been made. Or, looking at this from the economy standpoint, the same amount of work can now be done while consuming less power (fuel). So in effect, what really happens is that during normal driving, fuel consumption required to achieve equal acceleration or cruising speeds will be less than before the flow enhancements were made.
Let's look at this for both gasoline and diesel engines.
Gasoline engines differ from diesels in that fuel is mixed proportionately to total airflow (or air mass) through the engine. Because gasoline engines are "air throttled", power output is then directly related to the total airflow through the engine at any given time. This means that after airflow enhancements have been made and pumping losses have been decreased, a gasoline engine will be able to make the same power at a lesser air throttle opening. This subject of pumping losses for gasoline and diesel engines is described in detail in "Understanding Today's Diesel". When the throttle doesn't have to be opened as far, less air mass is ingested, and that means a proportionately smaller amount of fuel is used too.
The air throttle in a gasoline engine will create a pumping restriction for the intake cycle of the engine whenever the throttle is partially closed. Consequently, under partial throttle conditions, the majority of pumping efficiency gains for gasoline engines come from exhaust flow improvements. Things in the intake system, such as air cleaner capacity and cool air induction, help most at wide open throttle, or nearly wide open throttle. An unimpeded exhaust path helps at all throttle openings."
about volumetric efficiency, you may be mis-interpreting the definition (btw, whats the source if you dont mind?). instead of repeating myself, i'll post wikipedia's definition:
"In internal combustion engine design, volumetric efficiency refers to the efficiency with which the engine can move the charge into and out of the cylinders. More correctly, volumetric efficiency is a ratio (or percentage) of what volume of fuel and air actually enters the cylinder during induction to the actual capacity of the cylinder under static conditions. Therefore, those engines that can create higher induction manifold pressures - above ambient - will have efficiencies greater than 100%. Volumetric efficiencies can be improved in a number of ways, but most notably the size of the valve openings compared to the volume of the cylinder. Engines with higher volumetric efficiency will generally be able to run at higher RPM, and thus power, settings as they will lose less power to moving air in and out of the engine.
There are several "standard" ways to improve volumetric efficiency. The most common is to use a larger number of valves, see multi-valve, which cover a greater area of the cylinder head. Automobile engines typically have 4 valves per cylinder today for this reason. Many "high performance" cars in the 1970s used carefully arranged air intakes and "tuned" exhaust systems to "push" air into and out of the cylinders due to airflow over the engine. A more modern technique, variable valve timing, attempts to address changes in volumetric efficiency with changes in RPM of the engine -- at higher RPM the engine needs more time of a single cycle to move the charge out of the engine.
More "radical" solutions include the sleeve valve design, in which the valves are replaced outright with a rotating sleeve around the piston, or alternately a rotating sleeve under the cylinder head. In this system the ports can be as large as you need, up to that of the entire cyclinder wall. However there is a practical upper limit due to the strength of the sleeve, at larger sizes the pressure inside the cylinder can "pop" the sleeve if the port is too large."
"Some people think that once airflow is increased, additional fuel must be added at all times, and that would hurt fuel mileage. This is not the case during normal driving. Increasing airflow means an engine doesn't have to work as hard to overcome pumping losses. In other words, power that was previously consumed by pumping losses will be available to do work after airflow enhancements have been made. Or, looking at this from the economy standpoint, the same amount of work can now be done while consuming less power (fuel). So in effect, what really happens is that during normal driving, fuel consumption required to achieve equal acceleration or cruising speeds will be less than before the flow enhancements were made.
Let's look at this for both gasoline and diesel engines.
Gasoline engines differ from diesels in that fuel is mixed proportionately to total airflow (or air mass) through the engine. Because gasoline engines are "air throttled", power output is then directly related to the total airflow through the engine at any given time. This means that after airflow enhancements have been made and pumping losses have been decreased, a gasoline engine will be able to make the same power at a lesser air throttle opening. This subject of pumping losses for gasoline and diesel engines is described in detail in "Understanding Today's Diesel". When the throttle doesn't have to be opened as far, less air mass is ingested, and that means a proportionately smaller amount of fuel is used too.
The air throttle in a gasoline engine will create a pumping restriction for the intake cycle of the engine whenever the throttle is partially closed. Consequently, under partial throttle conditions, the majority of pumping efficiency gains for gasoline engines come from exhaust flow improvements. Things in the intake system, such as air cleaner capacity and cool air induction, help most at wide open throttle, or nearly wide open throttle. An unimpeded exhaust path helps at all throttle openings."
about volumetric efficiency, you may be mis-interpreting the definition (btw, whats the source if you dont mind?). instead of repeating myself, i'll post wikipedia's definition:
"In internal combustion engine design, volumetric efficiency refers to the efficiency with which the engine can move the charge into and out of the cylinders. More correctly, volumetric efficiency is a ratio (or percentage) of what volume of fuel and air actually enters the cylinder during induction to the actual capacity of the cylinder under static conditions. Therefore, those engines that can create higher induction manifold pressures - above ambient - will have efficiencies greater than 100%. Volumetric efficiencies can be improved in a number of ways, but most notably the size of the valve openings compared to the volume of the cylinder. Engines with higher volumetric efficiency will generally be able to run at higher RPM, and thus power, settings as they will lose less power to moving air in and out of the engine.
There are several "standard" ways to improve volumetric efficiency. The most common is to use a larger number of valves, see multi-valve, which cover a greater area of the cylinder head. Automobile engines typically have 4 valves per cylinder today for this reason. Many "high performance" cars in the 1970s used carefully arranged air intakes and "tuned" exhaust systems to "push" air into and out of the cylinders due to airflow over the engine. A more modern technique, variable valve timing, attempts to address changes in volumetric efficiency with changes in RPM of the engine -- at higher RPM the engine needs more time of a single cycle to move the charge out of the engine.
More "radical" solutions include the sleeve valve design, in which the valves are replaced outright with a rotating sleeve around the piston, or alternately a rotating sleeve under the cylinder head. In this system the ports can be as large as you need, up to that of the entire cyclinder wall. However there is a practical upper limit due to the strength of the sleeve, at larger sizes the pressure inside the cylinder can "pop" the sleeve if the port is too large."
Re: (DRIFTEADOR)
Thanks... sometimes I'm just lazy.DRIFTEADOR wrote:i'll save you the trouble of clicking a link
I still think that at no boost the turbo is more of a restriction than it is helping the air get into the engine. And since we mostly drive off boost (I know I do) then we are making the car less efficient. After the boost threshold is achieved then yes, the turbo is making more power than it is taking away.. but then we are burning more fuel... aren't we?
I think the subject has been beating to death enough already and that is why I posted my opinion. Not really trying to convince anyone, but my personal experience tells me elsewise.
Quote »"In internal combustion engine design, volumetric efficiency refers to the efficiency with which the engine can move the charge into and out of the cylinders. More correctly, volumetric efficiency is a ratio (or percentage) of what volume of fuel and air actually enters the cylinder during induction to the actual capacity of the cylinder under static conditions. [/quote]Ok. If it's under static conditions we are comparing to then I stand corrected. Sorry, don't remember which webpage I took my definition.
Re: (huguetpj)
pretty much as pressure is increased resistance is increased and the volume will be lower but density will be higher, so VE will actually be less, but the density overcomes that in terms of making power. Density increases, volume doesnt
Modified by deezlins at 2:54 AM 4/15/2005
Modified by deezlins at 2:54 AM 4/15/2005
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Craving4Boost
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Re: (deezlins)
ummm...is this the record high for a threat? lol
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PapaSmurf2k3
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Re: (deezlins)
why dont we all just agree that turbos are way more efficient than superchargers, and that in most cases, efficiency changes are so small they can be negligable (sp?) and are often due to a change in drivng habbits due to the fun factor
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sil80drifter
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Re: (PapaSmurf2k3)
PapaSmurf2k3 wrote:why dont we all just agree that turbos are way more efficient than superchargers, and that in most cases, efficiency changes are so small they can be negligable (sp?) and are often due to a change in drivng habbits due to the fun factor
PD: how I LOVE the fun factor