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  • #31
    Originally posted by Doozer View Post
    Stoichiometric is in the middle of rich and lean.

    -D
    Yes and it's needed to stay within that range on the old gassers, not the new direct injection gas, there is no "mixture" - your only compressing air - then adding whatever fuel needed to get the job done, and if that happens to be idling or low demand your not even coming close to the old school ratio's - your pulse controlling your injectors to control the flame front not using a stoichiometric mixture ratio to do the same,

    the rule book for the gas engine has been re-written --- where have you guys been for the past decade???

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    • #32
      Originally posted by brian Rupnow View Post
      I read yesterday about a small single cylinder i.c. engine model that had a "regulator" that kept a slight negative crankcase pressure in the engine while it was running. This was a 4 cycle vertical engine with a "wet" crankcase. The negative pressure kept any oil from migrating out around the crankshaft bushings. I hadn't heard about that before and I think it is a great idea. The engine in question was the Silver Angel by Bob Shores. A visual inspection of this engine running on YouTube shows no connection from the carburetor to the crankcase. The only "oddity" I see is that the engine seems to have double oil filler caps side by side. Does anyone have more info about this?---Brian
      The 193X Lister Diesel I have does this too. Not a new thing...

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      • #33
        Originally posted by brian Rupnow View Post
        It is a simple 3/32" diameter ball setting in a tapered seat with a very light spring holding it in place. Pressure inside the crankcase lifts the ball off it's seat and escapes. Suction in the engine pulls the ball deeper into it's tapered seat and doesn't let any air in. This gives a negative pressure in the crankcase.
        That's exactly what I was talking about with the check valve in the breather hose on my dirt bike. Mine is a factory KTM part you can buy for around $20, but there are other automotive versions too.

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        • #34
          Originally posted by A.K. Boomer View Post
          Yes and it's needed to stay within that range on the old gassers, not the new direct injection gas, there is no "mixture" - your only compressing air - then adding whatever fuel needed to get the job done, and if that happens to be idling or low demand your not even coming close to the old school ratio's - your pulse controlling your injectors to control the flame front not using a stoichiometric mixture ratio to do the same,

          the rule book for the gas engine has been re-written --- where have you guys been for the past decade???
          Combustion chemistry for gasoline engines is still different than for diesels; you seem to be missing that. Lean burn has been around for a long time, it's nothing new with direct injection. Never mind though, you're one of those guys who'll keep arguing the point all day for no real purpose. I'm out.

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          • #35
            Originally posted by Yondering View Post
            Combustion chemistry for gasoline engines is still different than for diesels; you seem to be missing that. Lean burn has been around for a long time, it's nothing new with direct injection. Never mind though, you're one of those guys who'll keep arguing the point all day for no real purpose. I'm out.
            Your just "off the mark" with everything , of course the chemistry is different - it's different fuel, but guess what? the operating principle is actually becoming the same esp. with the gassers that are being built with no spark plugs - it's called compression/ignition, sound familiar? yeah just like diesels...

            and please do not confuse what the old gassers called lean burn with what's going on today - again here's all you need to know - the direct injection gassers are compressing nothing but air so it's impossible for the "mix" to go off until the fuel is then injected... big difference between having an injector pre-intake valve VS having one INSIDE the combustion chamber (LIKE A DIESEL!)

            read a book.

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            • #36
              Originally posted by ed_h View Post
              My understanding of common PCV valves is that they are basically vacuum regulators, included to keep a small vacuum on the crankcase.
              [correct]

              I always assumed that most modern vehicles used negative crankcase pressure.

              Ed
              my brothers' 2005 honda civic does not have a pcv valve connected to the intake manifold after the throttle, but rather directly vents the valve cover to the intake after the air filter. so the maximum vacuum is the pressure difference across the intake resonator, tube, and air filter. we tried plugging up the valve cover and sucking the air out of the crankcase with a hose connected to the intake, but.. the air leaking in through the rubber seals that seal the tube used to access the spark plugs through the valve cover.. made a strange.. flock of birds type whistling resonance that.. was annoying.. not to mention the air leaking in would bring water vapor and contaminates with it.

              we did a similar modification with a 1995 vw jetta and i suspect the crankcase vacuum reduced the oil leakage through the crankshaft oil seal. it also significantly reduced the water content of the oil, which was a problem with that engine (maybe very slow head gasket leak?) removing the water from the oil increased the oil pressure once the engine got up to temperature.. which was an unexpected benefit..

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              • #37
                The only "oddity" I see is that the engine seems to have double oil filler caps side by side. Does anyone have more info about this?---Brian

                Brian Rupnow. Four or two cylinder? Love your work!!! JR
                My old yahoo group. Bridgeport Mill Group

                https://groups.yahoo.com/neo/groups/...port_mill/info

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                • #38
                  Originally posted by A.K. Boomer View Post
                  Yes and it's needed to stay within that range on the old gassers, not the new direct injection gas,

                  Opps? The computer still likes to see what the O2 sensor is seeing !!! Heck, I put two O2 units in my 62 Nova.

                  Keep it stock and you are good to go.. JR
                  Last edited by JRouche; 06-15-2019, 06:54 AM.
                  My old yahoo group. Bridgeport Mill Group

                  https://groups.yahoo.com/neo/groups/...port_mill/info

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                  • #39
                    That's a damn good observation JR, my take on that is the fact that we still have cat's that we need to keep "alive",

                    if it were not for emissions we would be able to see yet again even more incredible gains in both horsepower and efficiencies but we are bound to certain rules and regs and systems that are incorporated into the modern day engine that have to be maintained,,,

                    yes we still need the dreaded oxygen sensor both upstream and downstream to know just where the catalytic converters performance is,,, if they do not coincide the dreaded "cat performance is below normal threshold" code will get thrown along with the check engine light...

                    all this info is being processed by the ECU, but what's incredible with todays DIG's is that we are controlling the burn rate inside the combustion chamber,,, much of this technology actually did come from the modern diesel engine doing the same due to ever increasing emission standards being inflicted upon it,,, it was inevitable that this leap over to gas engines doing the same would soon follow,
                    micro controlling the fuel as it's actually being burnt is a game changer - but sadly not all of it is going to better performance and efficiency - some also has to be used for needed emissions...

                    Comment


                    • #40
                      Originally posted by A.K. Boomer View Post
                      If there's something you do not understand about that statement then just say so,

                      You think diesels are concerned with Stoichiometric ratio's ? all's they care about is if they have enough air to burn whatever their going to be injecting into the chamber -- and overkill on the air ratio is not an issue,,, actually and technically diesels are always "running lean" with way more air than fuel (unless your into "rolling coal") - they can do this due to not having to compress a pre-mix of air and fuel - yeah, kinda like what's going on with todays direct injection gas,,, you no longer have to have a perfect ratio of air and fuel... you can have and do have many times more air than what is needed like at idle - no throttle plate, full charge of air yet tiny little spritz of fuel just enough to keep it running...
                      I ,also am surprised at this info. I have a 2015 chevy equinox with direct gasoline injection.I assumed that it had a throttle plate.I do all my own repair work ,but have never had any reason to poke around in the engine. It has 70,000 miles and I only open the hood at oil change time.It is only 4 years old,but is the most perfect car that I have ever had.Edwin Dirnbeck

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                      • #41
                        Originally posted by Edwin Dirnbeck View Post
                        I ,also am surprised at this info. I have a 2015 chevy equinox with direct gasoline injection.I assumed that it had a throttle plate.I do all my own repair work ,but have never had any reason to poke around in the engine. It has 70,000 miles and I only open the hood at oil change time.It is only 4 years old,but is the most perfect car that I have ever had.Edwin Dirnbeck
                        I cannot speak for every system out there as there's allot of variations but know that most if not all have abandoned it,

                        keep a closer eye on your air filter as you are pumping allot more CFM through it if your engine is "plateless"

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                        • #42
                          Boomer, please post links to specific unthrottled gasoline fueled engines. I want to know:

                          How does a fuel intended to NOT preignite (gasoline octane rating) work in a compression ignition direct injection engine?

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                          • #43
                            Im working right now but will try to find something later,,, the thing is - is there's lots of variations going on right now and the most common is they are still using spark plugs to "compensate" and trigger the fuel going off at the same time it's being injected,,, also - keep in mind they are no longer held accountable for using higher compression and take advantage of this fact to the extreme --- compression ratio's on some of these engines are over 14:1 and climbing,,, that's with running turbos --- yesteryears gassers had to have dished pistons and run close to 7:1 or the mix would prematurely "go off" , you know if that was happening that back then-then yes indeed it is possible to get gas to "behave badly but in a good way" with todays technology - in fact if it was premixed the engines would only last minutes regardless of "mixture"...

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                            • #44
                              Originally posted by strokersix View Post
                              Boomer, please post links to specific unthrottled gasoline fueled engines. I want to know:

                              How does a fuel intended to NOT preignite (gasoline octane rating) work in a compression ignition direct injection engine?
                              Boomer is *almost* right on this one. One or maybe more of Japan's car companies are experimenting with GDI engines that work as a normal spark-ignition engine and slide into a compression-ignition regime under certain conditions. Preignition is avoided by the simple fact there is no fuel in the cylinder. I'd imagine the injection pressure is astronomical and without diesel's lubricity, injector wear is bound to be an issue.

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                              • #45
                                Originally posted by strokersix View Post
                                Boomer, please post links to specific unthrottled gasoline fueled engines. I want to know:

                                How does a fuel intended to NOT preignite (gasoline octane rating) work in a compression ignition direct injection engine?
                                Well, CarlB is *almost* right on that one; https://www.caranddriver.com/feature...plugs-feature/

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