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Oil Cooler delete SV650

  1. #51
    Super Moderator OreoGaborio's Avatar
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    Re: Oil Cooler delete SV650

    I just wanna say....... Called it!

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    Last edited by OreoGaborio; 08-15-18 at 05:26 PM.
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  2. #52

    Re: Oil Cooler delete SV650

    Looks like tuning an internal combustion engine is becoming a lost art. May be it's a good thing and we will all drive electric cars and ride electric bikes in 10-15 years, I dunno.

    Here is a non-scientific explanation as to why fuel injected engines make more horsepower:

    With fuel injection, especially full-on engine management that controls both fueling and spark you can get away with a much more aggressive calibration.

    A proper engine management system has all kinds of sensors attached to the engine. Oxygen sensors, knock sensors, mass air flow sensors, intake air temperature and barometric pressure sensors, coolant temperature sensors, crank and cam position sensors just to name a few. Engine management can detect detonation and react to it quickly by retarding the timing and enriching the mixture. That means that you can run more ignition advance and leaner mixture than you ever safely could with carb. And that means that you make more horsepower, because that's where horsepower is often found when tuning a spark-ignition internal combustion engine. Somewhere leaner of the stoichiometric point, but not too far on the lean side (melting pistons and producing tons on NOx is a bad thing). You just can't do a tune this aggressive with carbs, you will blow the motor sooner or later.

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  3. #53
    Lifer Kurlon's Avatar
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    Re: Oil Cooler delete SV650

    Primary difference between a Leccy style carb and what most people are used to is how the fuel is atomized and metered. In a traditional carb low pressure via venturi effect draws fuel up the emulsion tube where it gets air added before spitting out into the throat. On a Leccy the atomization occurs as the fuel goes by the needle as a result of the turbulence caused by the needle's shape, having a flat face on the backside. Metering is purely by the needle taper. The Smart Carb's improvement on the design is the fuel bowl that references directly against the intake flow, which is how it also achieves temp/air pressure/air density adaption. Given advancements in the understanding, modeling and prediction of fluid dynamics we're now at a point where you can dial in SC needles to match a given target AFR curve based on the desired fuel you're running, without knowing the motor you're putting it on.

    And yeah, I keep referencing the SC as I've got direct hands on experience with it, and the guy behind it is easy to talk to if one is curious about these things. If one guy's working on it, and the guys behind Lectron are still developing... it's not much of a stretch to imagine there are others exploring improvements in carb tech, I just haven't gone digging for them yet.

    On the lean burn front, modern engines aren't going lean burn chasing power, they're doing so chasing fuel economy. Absolute power is not found down in the danger lean zone, often it's on the fat side of stoich, which is why you get enrichment strategies even on modern EFI for when your foot's into it calling for more go. (My v10 takes it's sweet time waiting to enable that enrichment...) That said, the SC has hit EPA Tier II certification twice, without a catalytic converter, I'm curious to see if they can hit Tier III.

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  4. #54

    Re: Oil Cooler delete SV650

    Quote Originally Posted by Kurlon View Post
    Primary difference between a Leccy style carb and what most people are used to is how the fuel is atomized and metered. In a traditional carb low pressure via venturi effect draws fuel up the emulsion tube where it gets air added before spitting out into the throat. On a Leccy the atomization occurs as the fuel goes by the needle as a result of the turbulence caused by the needle's shape, having a flat face on the backside. Metering is purely by the needle taper.
    How is this different from Stromberg and SU carburetors, as seen on many an early 80s mercedes with M102 engine, Volvo 240, Jaguars, Land Rovers and a long ton of 70s and 80s vintage British machinery?

    Quote Originally Posted by Kurlon View Post
    The Smart Carb's improvement on the design is the fuel bowl that references directly against the intake flow, which is how it also achieves temp/air pressure/air density adaption. Given advancements in the understanding, modeling and prediction of fluid dynamics we're now at a point where you can dial in SC needles to match a given target AFR curve based on the desired fuel you're running, without knowing the motor you're putting it on.
    What Physics makes this work? Is the shape of the needle going to somehow magically change to provide adaptations that a typical engine management system does? How and why does "pressurizing" float chamber provide the necessary adaptations that the old SU/Stromberg design failed to provide?


    Quote Originally Posted by Kurlon View Post
    And yeah, I keep referencing the SC as I've got direct hands on experience with it, and the guy behind it is easy to talk to if one is curious about these things. If one guy's working on it, and the guys behind Lectron are still developing... it's not much of a stretch to imagine there are others exploring improvements in carb tech, I just haven't gone digging for them yet.
    So, they have designed a better needle for a variable venturi carb, using computational fuel dynamics. With modern manufacturing I can see how that would improve things over a 70s vintage Stromberg and SU carbs. I see no reason why this would be able to match the performance of the ancient (80s vintage) KE-Jetronic systems. It's just missing a whole bunch of feedback and regulators.

    Quote Originally Posted by Kurlon View Post
    On the lean burn front, modern engines aren't going lean burn chasing power, they're doing so chasing fuel economy. Absolute power is not found down in the danger lean zone, often it's on the fat side of stoich, which is why you get enrichment strategies even on modern EFI for when your foot's into it calling for more go. (My v10 takes it's sweet time waiting to enable that enrichment...) That said, the SC has hit EPA Tier II certification twice, without a catalytic converter, I'm curious to see if they can hit Tier III.
    Tuning goals depend on the application. For mass produced machinery the goals are emissions compliance, fuel economy and power. In that order. Some consumers may have different goals. That's why tuners exist.

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  5. #55
    Lifer isaac_'s Avatar
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    Re: Oil Cooler delete SV650

    Quote Originally Posted by OreoGaborio View Post
    I just wanna say....... Called it!
    I don’t know if there’s a clear winner here

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  6. #56
    Lifer ZX-12R's Avatar
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    Re: Oil Cooler delete SV650

    Quote Originally Posted by isaac_ View Post
    I don’t know if there’s a clear winner here
    When nerds fight, we all win!

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    "...i would seriously bite somebody right in the balls..." -bump909

  7. #57

    Re: Oil Cooler delete SV650

    Oil Cooler delete SV650-powgraf2-gif

    Relationship between mixture, power and economy. Similar pictures can be found in engine management and tuning books.

    The exact figures vary depending on specifics of engine and particularly combustion chamber design.

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  8. #58
    Lifer Kurlon's Avatar
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    Re: Oil Cooler delete SV650

    So, we agree on something, as I said power is found on the rich side of stoich, lean burn EFI is chasing economy not power.

    Back to the original discussion, you started this off with the blanket statement:
    Quote Originally Posted by juha_teuvonnen View Post
    (carbs are dumb devices compared to EFI)
    I've not claimed at any time carbs are inherently better across the board, or EFI sucks, just pointed out that your blanket statement is inaccurate. If we add in the fact that you acknowledge there are different solutions depending on the design goals, as stated:
    Quote Originally Posted by juha_teuvonnen View Post
    Tuning goals depend on the application. For mass produced machinery the goals are emissions compliance, fuel economy and power. In that order. Some consumers may have different goals.
    Carbs have their place, and are still in use in many applications because they fit the design goals better than EFI. But, that doesn't directly answer the 'carbs are dumb' statement. Fortunately, you've already noted there have been traditional carbs fitted with electronic controls before, making them only as dumb as the ECU operating them... But anyways, back to the SC 'cause I like exploring alternate ways to solve problems. (Have you seen my choice of bikes?)

    Traditional carbs, including the Strombergs you introduced me to (really blur the line between carb and mechanical fuel injection, going to need to read up on them some more) work on pressure differentials between the intake and atmosphere. Jets / needles are used to map the pressure response curve to the demands of the given motor. When dialed in, this setup can work very well especially when the desired goal is maximum power and throttle response. Where it has trouble is when the pressure differential to engine demand mapping changes, engine temp, exhaust temp, changes in weather all shift that mapping around, and short of additional hardware added to the carb it will not adapt to that. Because they work on pressure differentials you also run into the fun where a dialed in carb removed from one motor won't work well on a different configuration even if they're similar HP / CFM. The issue is a pressure differential only infers the amount of actual air moving through the intake tract. You can have a 5psi pressure differential between the outside and inside while barely moving any air, or running the output of an entire hurricane through the carb, and it'll spit out roughly the same amount of fuel because it sees the same 'signal'.

    The SC works by directly metering fuel based on the mass of air moving by the needle. The bowl is referenced to the intake pressure, so there isn't a pressure differential from vacuum alone in an SC to bubble air up to the venturi. Both carbs do also generate a vacuum signal from the venturi effect, in the SC that's not the primary metering system though as it is with a traditional carb. On the SC the turbulence of the air going around the needle creates eddies on the backside thanks to the flat face. The strength of those eddies is directly based on the volume/mass of the air moving around the needle, not the pressure differential. The engineered eddy is what is used to pull up a controlled amount of fuel and disperse it into the air stream. Because it's responding to the mass of the air, changes in engine demand from engine or exhaust temp, condition of the rings, etc are accounted for in the resulting change in air the motor moves. Cold, loose, not flowing yet, less fuel is mixed due to less air moving through. The resulting AFR stays the same. Hot, tight and flowing well, more fuel is mixed as more air moves through, AFR stays the same. This does the same as all the trim tables driven off oil temp, water temp, etc on an EFI setup. All of that responsiveness without requiring an ECU. If you do the same vacuum test on the SC vs the traditional carb, nothing happens. The bowl is seeing the same pressure as the intake, so no pressure differential to push fuel up and out without any air flow by the needle. Because the turbulence is dictated by volume, the impact of atmospheric trim tables, intake air temp, air pressure on EFI are accounted for. The needle grind and taper determines the base mixture rate, like a traditional carb this can be further dialed in by manipulating needle height.

    To put it in terms you'll be able to map to EFI, it's like going from a MAP sensor to a MAF.

    The weak point of the SC right now is idle/starting. It takes a certain amount of air flow to generate enough turbulence to get the fuel flowing, which makes getting the throttle stop position critical to hit the sweet spot of not choking the engine so it can't run vs too open to generate a usable signal. On the flip side, the simplicity of the design makes adding ECU control easy, a single stepper motor manipulating needle height in realtime can allow for direct AFR control over a decent range. I believe there are drones using this already, allowing for a rich AFR for power to take off, then lean burns for maximum flight time, all while not worrying about air pressure / temp changes as the drone goes from sea level to cruising altitude as the basic mode of operation of the SC accounts for that.

    It's not new physics as you keep hoping for, it's a simple matter of tackling an existing problem a new way. Same kind of thinking that got us first mechanical fuel injection, and then electric based. Same thinking that has Koenigsegg ditching throttles and cams by going to electric valve actuation, or all the variations on otto cycle combustion car mfgs are using to boost efficiency.

    (Sidebar - Later car carb setups have gotten the mapping from pressure differential to engine demand pretty stable, so that a 600 CFM Holley jetted well on a V6 could be moved over to a V8 built to make similar power and the jetting would be pretty close if not right on. Lots of passages and brass involved to get there.)

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  9. #59
    Lifer Kurlon's Avatar
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    Re: Oil Cooler delete SV650

    While we're on the topic of barely managed fuel leaks being dumb, have you looked at how Yamaha used to do it in the early 2000s? Because they couldn't figure out software to manage all the variables and trim tables well enough they resorted to vacuum slides in the throttle bodies and referencing the fuel rail pressure against the atmosphere as a bodge to improve drivability 'cause their system wasn't responsive enough on it's own despite having a decent suite of inputs. And it still can't handle full, closed, full throttle transitions.

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  10. #60

    Re: Oil Cooler delete SV650

    Quote Originally Posted by Kurlon View Post
    So, we agree on something, as I said power is found on the rich side of stoich, lean burn EFI is chasing economy not power.
    Well, if we were living back in 1966, before emission controls and catalytic converters running AFR in the 12ths would be the way to go. This is also the way to go for all kinds of off-road machinery that's not subject to emission controls. The problem with going to the rich side of stoich is growth in CO and HC. Catalytic converters glowing cherry red and setting things on fire are a very bad thing. Which is why, for road-legal machinery you start with a conservative rich calibration and lean it out carefully. You lower CO to acceptable levels, sacrificing a small amount of horsepower in process. That's not some abstract concept of "maximum power in an uncontrolled environment", but a much more practically usable "maximal power achievable without breaking the law and setting things on fire". How far to the lean side you have to go varies from engine to engine, and has a lot to do with combustion chamber design. As you go to the lean side NOx will climb if you go far enough you'll see detonation and misfire.

    Quote Originally Posted by Kurlon View Post

    Traditional carbs, including the Strombergs you introduced me to (really blur the line between carb and mechanical fuel injection, going to need to read up on them some more) work on pressure differentials between the intake and atmosphere. Jets / needles are used to map the pressure response curve to the demands of the given motor.
    All carbs that I know of work on the pressure difference in the venturi Venturi effect - Wikipedia and in accordance with Bernoulli law Bernoulli's principle - Wikipedia

    Some carbs (Strombergs, SUs, etc.) have variable venturi. In Stromberg carbs the venturi size is insreased by the manifold vacuum pulling piston up. The needle is attached to the piston and gets pulled up at the same time, allowing more fuel to flow. These carbs atomize fuel by means of needle and seat arrangement.

    Other carbs have fixed venturi size, emulsion tubes and jets. This is a rather inflexible arrangement that in vain quest to gain flexibility land driveability leads to designs with multiple barrels with different sized venturis and various contraptions that control them. The worst examples of this technology I have encountered in the field were Solex 4A1 found in many an old German car. With any amount of wear, none of them work well. Multiple fixed sized venturis was a very common design when cars had carbs. Basically, on a 4 cylinder engine with up to about 2 liters of displacement you could get away with one stromberg carb. For 6 cylinders and more than 2 liters it was either multiple strombergs or one multiple barrel carb with fixed-size venturis. Performance cars (12 Cylinder Jaguars, Ferraris, etc.) had multiple Strombergs because the owners could afford expensive maintenance associated with them. The rest of the crowd got by with 2 and 4 barrel fixed venturi carbs that most car guys are familiar with.

    In most carbs, your fuel is at atmospheric pressure or close to it. So you need a venturi with its pressure differential for the fuel to atomize. You are, therefore creating an artificial choke point in your intake. This choke point is an artifact of how a carb (ANY Carb) works. Introducing choke points into the intake does not do wonders for your volumetric efficiency and resultant horsepower and torque.

    With fuel injection you pressurize the fuel in the rail. There is no need to introduce choke points into the intake, because the injector will atomize the fuel. You can think of the fuel injectors as your "needle and seat" arrangement, except much more compact and closer to the intake valve. Since you can easily crank up the fuel rail pressure, I see no reason why a needle-and-seat variable venturi carb would be any better than a properly designed fuel injection system. I can see plenty of reasons as to why it should be worse, but not better.

    Now, there were some poorly designed motorcycle EFI systems roughly two decades ago, the computers used weren't powerful enough and manufacturers were still learning back then. Those teething problems are a full decade behind us.

    I see no reason why a carb would be better than a fuel injector. The argument about vortex (eddies) generated by air flowing by needle is entirely unconvincing unless backed by data.

    A carb has its place for some applications. Engines that are run at the same RPM most of the time, where emissions are not much of a concern. basically where flexible control is not needed. Chainsaws, small aircraft, etc. You can dial a carb just right for a given narrow RPM range easily and it's brain dead simple.

    Strombergs can cope better with RPM changes than fixed venturi carbs, but none of them come close to the versatility of a real engine management system.

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  11. #61
    Mophead going grey dontpanic's Avatar
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    Re: Oil Cooler delete SV650

    I'll bet the oil weighs more than the cooler.

    Just run it without oil.

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    Go fast. Have fun. Repeat.

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