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Thread: ESE's works engine tuner

  1. #37141
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    Thanks Wobbly. Done deal. I’ll get something consistent figured out. Admittedly, we pulled the under plug thermocouples off after the first pipe so although the pipe starting temps were consistently tested throughout the dyno runs, the cylinders/heads were a “go feel them” thing, which is obviously not super accurate.

  2. #37142
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    .
    If you are running lots of Methanol and some Nitro in a two stroke dragster. In my opinion EFI is the way to go.
    Simply because it is much easier to deliver the volume of fuel required and you have much more precise control over fuel delivery.

    The interview in this clip https://youtu.be/eRItqiCFuQE shows a very fast injected H2 Kawasaki dragster.

  3. #37143
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    Quote Originally Posted by Frits Overmars View Post
    No. The restrictor diameter depends on the power produced by the engine, not on the type of fuel. But why do you ask Husa? I am curious about your line of thought.
    In line wth my experiances.

    Some more info for the guy going over to meth from petrol:
    I have found that one can often make the restriction a little bit larger than calculated when running meth.
    This i guess keeps things under control when trying to max out a meth engine(temprature control)
    And i have learned that methengines delivers the best around 430-450c exhaust temp(three piston diams from piston)
    Thereby one need to calculate with that exhaust temp when designing the pipe.

  4. #37144
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    Quote Originally Posted by Condyn View Post
    The (considered to be unsafe) 75.5% exhaust port held the ring without incident
    Considered unsafe by whom? Not by me. 75,5% need not be unsafe, provided that the corner radii are large enough. But the minimum safe radii for a port width of more than 70% of the bore will reduce the blowdown area at the upper part of the port (the yellow areas in the picture), where it counts most because that is the area that is open for the longest time. A port width of 70% of the bore is not the maximum width; it is the optimum width.

    Quote Originally Posted by Condyn View Post
    Best of all, Engmod2t and my dyno results are all within .75 Hp
    I could not find the total power figure you quoted for that engine, which left me wondering how good or how bad this 0,75 HP difference is.
    Is it 0,1% , 1%, 10% or 50% of the engine power? Percentages often give a better impression than just raw values.
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  5. #37145
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    Quote Originally Posted by Frits Overmars View Post
    Considered unsafe by whom? Not by me. 75,5% need not be unsafe, provided that the corner radii are large enough. But the minimum safe radii for a port width of more than 70% of the bore will reduce the blowdown area at the upper part of the port (the yellow areas in the picture), where it counts most because that is the area that is open for the longest time. A port width of 70% of the bore is not the maximum width; it is the optimum width.



    I could not find the total power figure you quoted for that engine, which left me wondering how good or how bad this 0,75 HP difference is.
    Is it 0,1% , 1%, 10% or 50% of the engine power? Percentages often give a better impression than just raw values.
    Pardon my ignorance to the 70% rule Frits. The TIME part of the phrase specific time/area sometimes slips my grasp. I will have to do some experimenting with the OPTIMUM port shape and compare the results.

    My Engmod2t data is within 1% of the real life eddy current engine dyno data. Just the same as real world testing, the temperatures in engmod2t play a major roll in the measured outcome. I am slowly learning the level of influence that heat has in engines.

  6. #37146
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    You can make an ex port 78% I may have even run 82% non bridged.
    But roof edge must have a nice opening radius. And don't widen port much after transfer opening. Shape it like a bridged port.

  7. #37147
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    The traditionally accepted " rule" for the Exhaust port was 72% - this was used by Yamaha for decades in the RD based TZ range of customer race engines.
    But these had very generous corner rads that , as Frits drawing shows , restricts the Blowdown area available.

    I worked on a set of later model 4DP TZ cylinders ( 56 bore ) a while ago that had been " tuned " by a famous ex Roberts tech.
    The Exhausts had ben widened to 75% with no change to the radi.
    The owner wasnt overly thrilled when after the initial dyno runs , and two practice sessions , the new pistons timing edges were obviously belted to shit , and the rings were on the verge of trapping due to mental piston rock.

    Angle area as a port metric has been also used for years , but imho , this metric when combined with rpm , that describes a ports effective open area and how long that area is available at a specific
    engine speed ( STA ) , combines all of the data into a useful one for predicting power capability at a chosen rpm.

    EDIT - added info. In a water cooled 125 race engine the power drop from running at 65*C exit temp Vs 45*C is 1.5 Hp in near 50.
    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.

  8. #37148
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    I should mention the 78% ex port was on a snowmobile. 200deg ex 132trans (ex had height room above transfers) and only 8000rpm.

    We would do this on our drag sleds. I did it on my personal trail sled... rode it 3 months no issues.

    Rpm is a big factor in ring/piston life. 192ex 130trans not much room for good safe 78% shape

  9. #37149
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    Radius's

    This exhaust port edge radius and no camber on the transfer ports edges for good power and long mechanical life is fascinating to me. Before I spend a significant amount of time searching this thread on this subject has some one done a detailed post about this?
    Compare Pornography now to 50 years ago.
    Then extrapolate 50 years into the future.
    . . . That shit's Nasty.

  10. #37150
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    A short report of the Nitromethan/Methanol test:

    There where some thougts before the beginning, based von calculations Frits published some time ago. Fore some chemical/physical data you find different Numbers on different sources, but all of them are nearby, so I used the following:

    Air Fuel Ratio:

    Petrol: 14,7:1
    Ethanol: 8,4:1
    Methanol: 6,52:1
    Nitromethan: 1,8:1

    I`m not quite shure whats the right translation for "Heizwert", so I call it "energy potential":

    Petrol 43600 kJ/kg
    Etanol 26800 kJ/kg
    Methanol 20100 kJ/kg
    Nitromethan 12100 kJ/kg

    At first we wanted to know wich AFR we would have to use. So a 50%/50% Concentration of Nitromethan/Methanol would be:

    0,5*6,52+0,5*1,8= 4,16

    In relation to petrol you need 14,7:4,16= 3,533 times the mass of NM/M to burn a fix amount of Air then you need with petrol.

    The energy potential would be:

    0,5* 20100 kJ/kg + 0,5* 12100 kJ/kg = 16100 kJ/kg

    And becaus you need 3,533 times more of it its: 3,533*16100 = 56881 kJ/kg

    Compared to petrols 43600kJ/kg ist 30% more Energy paired to the same amount of air sucked in the engine. So roundabout 30% more power should be possible.


    But 1kg Fluid isn`t 1l:

    1kg petrol = 1,389l
    1kg Ethanol= 1,267l
    1kg Methanol = 1,266l
    1kg Nitromethan = 0,877l

    so 1kg 50/50 NM/M is:

    0,5*0,877l+0,5*1,266l= 1,0715l

    3,533*1,0715l= 3,785l

    Compared to petrol its 3,785/1,389= 2,725 times the volume.

    Based on Frits a Racing twostrokes needs 7ccm/PS/min petrol.

    So we would need (2,725*7ccm)/1,3PS/min = 14,67ccm NM/M /PS/min

    I`m aiming for 33/34 crank hp, cause at the Moment we got about 26 on petrol. That means: 14,67*34= 498ccm/min.

    We are using selfmade carburators, based on Lectron principle, but with seperate Fuel Chamber and smoothebore. Because of the seperate Fuelchamber there are no vibration issues and the rotary Inlet likes the shortness alot:

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    In Need of the great Number of Metering Rods you need for different engines/carb sizes/fuels we started to grind them ourselves.

    So I calculated the needed Area in Relation to Petrol/E85 and grinded some rods:

    Click image for larger version. 

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    Its the calculated rod and 2 wich are leander and richer in 1/10mm steps, big differences, but there is still a Powerjetsystem.

    today we could do some first testing:

    therefore I removed the Stinger reduction complety (now 17,8mm) an retarded Ignition from 14 to 10° flatline. The Powerjet System on our carburator I jetted from 60/100mm to 120.

    The engine starts great an idles realy good, in the beginning it was a little lean on idle, but taking the rod higher solved the problem. At the moment there is no choke system, so if you try to rev agressivly in the first seconds the enginge will die, but waiting some seconds maybee 20 seconds solves it, the enginge becomes richer an reves.
    When it was to lean he bulked quite a times out of the carb, now richer this is gone.
    Up to half throttle everything is ok, full throttle seems to be ok or even a little rich when reving in neutral. If i make a pull on the dyno I don`t reach the same revs as petrol (petrol ca 13000, NM/M ca 12000 U/min), and after closing the carb slide he won`t rev down fast enough, even keeps running with ignition cut down. Seems like clearly to lean, but its already the riches rod I´ve made (2/10mm to rich). Even the lower rpw would say to rich, or is 4 degrees retarded to petrol to less, an he ignites to early? From petrol to E85 I had to advance the Ignition roundabout 3-4°, so I thought 4° retarding could be a good starting point, cause I found no info about that. First result after 2 hours of testing 3,5hp less than on petrol, but without Stinger reduction, carb far away from perfect, ignition changes not tried until yet...
    Would be great if someone knows something about the running without ingnition, ignition timing etc. Maybe there are mistakes in my before calculation, let me know!

  11. #37151
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    I forgot:
    Out of the fuel tube from the seperate chamber come constantly over 700ml/min, directly to the little reservoir under the neddle tube, so I won`t believe its running out of fuel, but I will take al look at this tomorrow, would be happy for any advice.
    Ignition is an ignitech dc cdip2 2 Channles plugged to a crane coil PS92, Brisk LR08ZS, combustion ratio 13,8:1 like on petrol. I`m unshure about the last parameters in relation with NM/M.

  12. #37152
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    Hoebra - why are you only using 13.8:1 compression as was run on petrol.
    Plain Methanol can be run at 18:1 as it has an effective octane of 130 petrol - seems to me you are leaving a huge power loss on the table with just that small change.
    And when you have that high com number the ignition can remain as it was optimized on petrol.
    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. #37153
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    Diesel - here is what you want in a nutshell.
    The transfers dont need any chamfer at all as the ring does not bulge outward into the relatively small chordal widths.
    All they need is the edge at the bore broken with a cotton mop.
    A proper " chamfer " at a transfer timing edge creates severe flow eddies off the corner , causing the transfer stream to loose coherency and thus directional control.

    The big radius on the Aprilia Exhaust timing edge was instituted by Jan in response to his boss producing a new exhaust design that lost alot of top end.
    Increasing the Blowdown efficiency by dramatically increasing the just opening ports Cd value , proved to eventually give more power everywhere.
    Many years later I discovered that if you do an STA analysis on the ports , it would appear that the transfers were some 10% ahead of the Blowdown capability - just from the raw chordal data.
    But the clever implementing of an increase in Cd of the Exhaust port ( that the sim code cannot recognize unless its written in as an option ) would in reality , bring the two most important sets of port data back into alignment.
    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.

  14. #37154
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    I wanted ti start somewhere, so I left Combustion as it is. Methanol high compression ok, but there is also 50% Nitromethan, so I wasnt sure. You mean I should take more compression an ignition schould be increased? In my opinion ignition timing has to be retarded with higher compression an even without I already have self ignition?

  15. #37155
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    Quote Originally Posted by wobbly View Post
    The traditionally accepted " rule" for the Exhaust port was 72% - this was used by Yamaha for decades in the RD based TZ range of customer race engines.
    But these had very generous corner rads that , as Frits drawing shows , restricts the Blowdown area available.

    I worked on a set of later model 4DP TZ cylinders ( 56 bore ) a while ago that had been " tuned " by a famous ex Roberts tech.
    The Exhausts had ben widened to 75% with no change to the radi.
    The owner wasnt overly thrilled when after the initial dyno runs , and two practice sessions , the new pistons timing edges were obviously belted to shit , and the rings were on the verge of trapping due to mental piston rock.

    Angle area as a port metric has been also used for years , but imho , this metric when combined with rpm , that describes a ports effective open area and how long that area is available at a specific
    engine speed ( STA ) , combines all of the data into a useful one for predicting power capability at a chosen rpm.

    EDIT - added info. In a water cooled 125 race engine the power drop from running at 65*C exit temp Vs 45*C is 1.5 Hp in near 50.
    Confused i thought 1000km or so for the pistons half that for the rings with the cranks about 2000km that prior the big bangs. the price of power i would guess the 125 ad 250s were changing stuff at a much quicker rate.
    pistons every race cranks at 100
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




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