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Thread: ESE's works engine tuner

  1. #32566
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    18th May 2007 - 20:23
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    .
    Posted for no other reason than to show the possibilities with bending the fueling curve.

    Click image for larger version. 

Name:	Red-Rich Blue Lean best MJ.jpg 
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    Red is a rich main jet, Blue a smaller one that made best power.

    The trick is to plump up the fueling curve with a solenoid power jet or trim off the top with the air correction jet to get the best curve.

    A whole lot easier with EFI of course.


  2. #32567
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    1st May 2016 - 13:54
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    Quote Originally Posted by TZ350 View Post
    .
    Red is a rich main jet, Blue a smaller one that made best power.

    I can understand significant power variations with mixture adjustments... but where/why/how does 1500rpm actually disappear with the richer mixture??
    Rich enough to put the fire out??...

    Cheers, Daryl

  3. #32568
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    Quote Originally Posted by Pursang View Post
    Rich enough to put the fire out??...
    Remember a carburetors air/fuel ratio at WOT becomes increasingly rich as the air flow through it increases with increasing rpm unless there is some sort of fuel correction.

    My guess is that the Red line is rich enough to change the wave action in the pipe.

    Basically the rich mixture and therefor cooler exhaust gas makes the pipe seem longer than it is. So it cuts the revs of earlier than it should. In much the same way that retarding the ignition and leaning off the mixture puts heat into the pipe. Making it seem ever shorter thereby extending the wave action over higher rpm. Play with the fuel (and ignition timing) and you could get three pipes for the price of one.

    Click image for larger version. 

Name:	Red-Rich Blue Lean best MJ.jpg 
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    Make it rich at the bottom for "drive" (Red line) then progressively correct the fuel at the upper rpm (top part of the Blue line) for "max power" and "over rev". Ignition plays it's part too.

    Anyway for what its worth, that is my take on it..........


  4. #32569
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    1st May 2016 - 13:54
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    Quote Originally Posted by TZ350 View Post
    Play with the fuel (and ignition timing) and you could get three pipes for the price of one....
    Anyway for what its worth, that is my take on it..........
    Very Cool TZ.. Certainly shows the value of back to back Dyno testing! And Wobbly's incremental improvements do too.

    One could drive him/her self crazy trying to sort that out using 'butt on the seat' tuning....

    I myself have obviously have spent way too long in "full power rich" tuning mode. (That's fuel Not money)

    Cheers, Daryl.

  5. #32570
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    17th September 2013 - 01:07
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    Quote Originally Posted by TZ350 View Post
    .
    Posted for no other reason than to show the possibilities with bending the fueling curve.

    Click image for larger version. 

Name:	Red-Rich Blue Lean best MJ.jpg 
Views:	190 
Size:	533.5 KB 
ID:	342996

    Red is a rich main jet, Blue a smaller one that made best power.

    The trick is to plump up the fueling curve with a solenoid power jet or trim off the top with the air correction jet to get the best curve.

    A whole lot easier with EFI of course.
    This was a real eye opener post for me! Great!

    Having read “turn off the PJ around peak power” so many times here, my reaction has more or less been “off course you do...it makes perfect sense”.

    Now I remember that I have read about the effect off the air correction jet before and all came together.

    Knowing and understanding is two different things I guess.

    Thanks TZ!

  6. #32571
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    1st May 2016 - 13:54
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    Here's Something that might be useful for Something.

    Click image for larger version. 

Name:	LAD 002.JPG 
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ID:	343003

    Perhaps someone, limited by something (say.. long parallel header pipes) could use something like this to rapidly diverge exhaust flow to a large diameter belly section, or something.

    Concepts of suitable wave duration profiles and timings would need reconsideration or something.

  7. #32572
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    7th October 2015 - 07:49
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    Quote Originally Posted by wobbly View Post
    Did some last minute dyno work last week before winning the final round and NZ ProKart KZ title.
    Not the latest cylinder design, but a prototype for the new R1 I needed to run in pistons for so outright power is down about 1.5 Hp.
    First test is a stock , thin 0.8mm ring piston , with a 4* conical dome.
    Next was a change to a new design with angled squish only then a flat top , with new insert to suit that brings the plug down
    4mm closer to the piston face.
    Last test was the " fluid diode " in the boost port - 3mm around 3 sides.
    Picking up 1/2 a Hp in an afternoon with no failed ideas was a bit of a surprise.
    Comparing this new settup with NT software , using live track data , and the latest cylinder showed closer to 0.8HP and resulted
    in a qualifying time 0.3 secs under the lap record.

    Wob, glad to hear that fluid diode did not disrupt power, thank you very much for this tests info.
    With 3mm crankcase step, it is possible to grind "riverbed" on case, for little more resistance.

  8. #32573
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    28th November 2013 - 21:58
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    Quote Originally Posted by Frits Overmars View Post
    I collected those pics over a number of decades, initially for my personal use, so I never worried about copyrights. All pics marked with F©S were made by me and I hereby declare them copyright-free, but not all other pictures were, so you may want to give this a little thought before using them for publications.
    Not sure that Tony Foale's book should be there from a legal or copyright point of view...

  9. #32574
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    Quote Originally Posted by guyhockley View Post
    Not sure that Tony Foale's book should be there from a legal or copyright point of view...
    You're quite right Guy, thanks. I only thought about removing Blair's book before making the collection public, but I missed Tony's book. I'll have it removed right away.

  10. #32575
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    22nd November 2013 - 16:32
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    Quote Originally Posted by Frits Overmars View Post
    You're quite right Guy, thanks. I only thought about removing Blair's book before making the collection public, but I missed Tony's book. I'll have it removed right away.
    Gone already, not the intention.
    "Perfection is the enemy of progress"

  11. #32576
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    7th May 2016 - 04:34
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    Hoping for a sanity check on inertial dyno roller/flywheel design (herein referred to as "roller"). If you feel like reading/thinking through all of this, please feel free to let me know if I have anything wrong here.
    Otherwise, feel free to use this for your own dyno, if you trust my math I can share a spreadsheet if anyone is interested.

    I am hoping to build a (hopefully portable) dyno at some point, mostly for 50cc engines -- but I am quickly realizing that engine size/power might not be the most important design input parameter for an "ideal" 2T dyno; rather the mass of the bike and rider may be the only important parameter. More specifically, for a chassis dyno with a thin-wall roller, the roller mass should be equal the mass of the bike+rider. Things can get a little more complicated for a engine dyno that operates from the transmission output shaft, with corrections needed for sprocket ratio and roller vs. tire diameter, but same basic concept.

    The core assumption comes from what I remember reading here: that for 2T development purposes, it seems there is some consensus that the "best" way to use a dyno is to replicate on-track usage; in other words, steady-state readings are not as useful as inertial readings while replicating on-track acceleration, in (large) part due to heat rates (e.g. exhaust temp). Please correct me if I am wrong, but if this is correct, then the dyno roller's inertia should replicate the mass of the bike and rider.

    The math:
    The equivalent mass (i.e. converting to linear kinematics) of a dyno roller is given by the following equation:
    mequivalent = Iroller * (1 / rroller)2
    Assuming the roller's circumferential speed matches the rear tire's circumferential speed, as on a chassis dyno, we just need to get the roller's equivalent mass to match the on-track mass.
    With the equivalent-mass equation above, and the equations for roller inertia:
    I ~= mthin roller * rthin roller2, or
    I = 1/2 * msolid roller * rsolid roller2,
    the roller radius cancels itself out - so assuming the roller's circumferential speed matches the tire's circumferential speed:
    mthin roller ~= mbike+rider, or
    msolid roller = 2 * mbike+rider

    Correction for engine dyno:
    If, however, the circumferential speeds differ (as can be the case with an output-shaft driven roller), the equivalent mass does change, by a factor of the speed ratio (roller circumferential speed / tire circumferential speed, or roller radius / tire radius) squared. So if the roller has the same mass as bike+rider but half the diameter of the tire and is driven at the same angular velocity as the tire, it acts roughly like 1/4 of the mass of bike+rider - of course only applicable for an output shaft-driven roller (not a chassis dyno).

    So two key takeaways here: thin-wall roller is most mass-efficient (of course); and to best simulate on-track usage (for a chassis dyno with said thin-wall roller), the roller mass should simply be roughly equal to the bike + rider mass.
    Therefore if I want portability, like being able to put the dyno in the back of a truck by myself, I need to overdrive the roller to be able to reduce its mass sufficiently (so a chassis dyno will not work due to the required roller mass).


    Personal Example:
    I am working on a 50cc moped with a single-speed centrifugal clutch transmission. Let's say that currently the specifications are:
    • Primary Ratio: 16:57 = 1:3.5625
    • Chain Drive: 10:60 = 1:6
    • Total Gear Ratio: 21.375
    • Tire Radius, rolling: 0.281m
    • Mass of bike and rider: 127kg
    • Maximum Engine Speed: 15,000rpm
    • This gives a top speed of 46.2mph (74.3km/h).

    Let's also assume my roller specifications, for an engine dyno driven by the transmission output shaft, are:
    • Mass: 20kg
    • Material: A36 steel, 7800kg/m3, 250MPa Yield Strength
    • Radius: 15cm
    • Thickness: 1.5cm
    • Length: 19.09cm
    • Inertia: 0.407kg/m2

    If I spin this roller at the same angular velocity as my tire, i.e. if I use 10:60 sprockets for the roller drive, then the equivalent mass of the roller is 5.16kg. Not nearly enough! This is derived from:
    mequivalent = Iroller * (omegaroller / vtire)2
    ...where the previous variables relate to engine speed by:
    omegaroller = omegaengine * gear ratioroller, total, and
    vtire = omegaengine * rtire / gear ratiotire, total
    Thus the equivalent roller mass equation is:
    mequivalent, roller = Iroller * (Zrear, tire * Zfront,roller / (Zfront, tire * Zrear, roller))2 * (1 / rtire)2
    ...where the "Z" values are the tooth counts for each sprocket.
    To get the equivalent mass to match up as closely as possible, I need to swap the roller shaft sprocket to a 12-tooth to overdrive it 5x as fast. Doing so gives an equivalent mass of 129kg, with a roller angular velocity of 3509rpm at 15000rpm on the crankshaft. A hoop stress calculation shows ~23.7MPa:
    stress = mroller * rroller2 * omegaroller2
    If I gear the moped for top speed rather than acceleration, say close to 80mph, I might use a sprocket ratio more like 12:42 for the bike, in which case my equivalent mass with a 12:9 sprocket ratio for the rollers is about 112kg (this is probably the practical limit to sprocket sizes). Hoop stress here is about 60MPa, so seems like it would still be safe.

  12. #32577
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    8th February 2007 - 20:42
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    My experience with engine type dyno is that you need to replicate somewhat a relevant acceleration rate as seen on track.
    This varies of course with each gear ratio , so the acceleration rate needs to refactored to give sufficient run time that the
    pipe temp reflects that as seen on track.
    In my case with the inertia I chose and using 6th gear I changed the sprocket drive ratio until a full throttle run from 7000 to 15000
    took around 9 secs.
    I do a couple of all gear runs , once the water temp has stabilised at around 40*C , to heat the pipe wall temp , then do 3 6th gear
    dyno recorded pulls.
    These are combined to give an averaged data set.
    The pipe temp in the header starts at around 450*C and I always rejet to see 630*C at the end of the pulls.
    This method was later checked as being spot on accurate , when I purchased NT software that uses our on track data logger info to show
    actual Hp delivered.
    The peak power was with 2/10 and the peak power rpm was within 200.
    But most important was that the results are always repeatable using the same test regime for every session.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  13. #32578
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    7th May 2016 - 04:34
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    Thanks Wobbly!
    I've got questions regarding jetting and EGT (for the same aforementioned project), but I think I should get a little more hands-on time before asking. I think I understand the basics, but things might be a little complicated by my almost 2000m elevation in Colorado.
    Hopefully this "try first, ask later" approach doesn't result in me asking how to un-hole my piston

  14. #32579
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    27th October 2013 - 08:53
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    heys guys i need to make some thrust washers for the small end of the rod and bearing. easily accesible materials i can use are aluminum, copper, brass, zinc, nickel silver ( mix of copper, nickel, zinc ?). is copper my best choice ?

    also has anyone made theyre own oiling slot or holes in the rod small end ?

  15. #32580
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    25th March 2004 - 17:22
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    Quote Originally Posted by wobbly View Post
    My experience with engine type dyno is that you need to replicate somewhat a relevant acceleration rate as seen on track.
    This varies of course with each gear ratio , so the acceleration rate needs to refactored to give sufficient run time that the
    pipe temp reflects that as seen on track.
    In my case with the inertia I chose and using 6th gear I changed the sprocket drive ratio until a full throttle run from 7000 to 15000
    took around 9 secs.
    I do a couple of all gear runs , once the water temp has stabilised at around 40*C , to heat the pipe wall temp , then do 3 6th gear
    dyno recorded pulls.
    These are combined to give an averaged data set.
    The pipe temp in the header starts at around 450*C and I always rejet to see 630*C at the end of the pulls.
    This method was later checked as being spot on accurate , when I purchased NT software that uses our on track data logger info to show
    actual Hp delivered.
    The peak power was with 2/10 and the peak power rpm was within 200.
    But most important was that the results are always repeatable using the same test regime for every session.
    That is interesting. I don't have. . .I'm going to say 'my' dyno, anymore, but had certain routines to get consistent results as possible. However I will venture that mine were clearly a compromise as despite the pretty serious 4ft industrial fan I didn't have enough cooling to do as you stated.
    I've been told. Dreaming`s free.
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    Everybody listen, do yours say, what mine says?

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