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Ben, to me there's something fishy about that calculation[:0]. To me it looks more like it applies to a single rather than a siamesed port. I have been trying to check on this in Phil Irving's "Tuning for Speed", but no luck.If what I have said is correct, wouldn't the pipe now be half that length?John EvansThink logically and do things well, think laterally and do things better.
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Ben : You wouldn't happen to know how to calculate a tuned pipe for a 2 stroke 2 into 1 exhost would you ? or for that mater just one of the cylinders...My 447 rotex could realy use a good tuned pipe on it ! thanks !Bob......" Momm'a alwayse told me , Son the impossable is only a little bit Harder... and ya know I do believe She was RIGHT ! "
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We in Bundy had in the past one of the best speedway exhaust guys in OZ note Bundy has many national champs in different classes.Speedway is akin to gyro motor tec as revs & requirments for torque aproximatly the same in liter car class the champs car had cones in exhaust at the head I helped make these & ratio goes like this small end = valve seat size big end = exhaust port size @ flange facelength of cone = distance between valve seat & flange face This led to 2 national titles as bottom end torque was increased greatly with no neg effects on top end this ment Ricky tapscot was first to corner from start & pulled out of corners quicker despite weight disadvantage he was 100kg against some 60kg driversthis is in a 8 port 4cyl I have yet to try this in EA81 but may work also
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Sorry about 2 posts had to go But we also worked out that joining exhaust @ about 18"-22" gave the afect ben speaks of also don't go to subaru brat page you will be dumber for the experience. Subabrat said to extend slots in distributor to get more advance this is **** 34deg total advance MAX EA81 non turbo no argument I have paid for the dyno time ps if you have vac adv hooked up you are running 30deg of mec adv + 15deg of vac adv + static timing aprox 8deg this = 53deg total advance welcome to ping/knock heaven & a dead engine.
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Also fit an ego meter & watch your mixture change to lean as you advance your timing beyond 38deg with motor set @ 4000 revs I have done this have any of you?
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Not an EGO Meter ...but a see through sparkplug where you can see the color of the explosion ... changeing the times has a big effect on the burn indeed !Bob..." Momm'a alwayse told me , Son the impossable is only a little bit Harder... and ya know I do believe She was RIGHT ! "
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Showing my ignorance, what is an EGO meter?Aussie Paul.[
]www.firebirdgyros.com
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Paul, I believe he is referring to an exhaust gas oxygen meter. They are actually very easy to set up and use.Get an oxygen sensor from a wrecker, or someone who installs imported engines, [they throw them out] buy a suitable nut-18mmX1.5 I think, modify it on a lathe, then weld it in your exhaust.You don't really need anything fancy to read it as a multimeter will do, stoichiometric is about 0.6 volts.Jaycar have a couple of kits you can assemble to either have a LED readout or a digital display.It has to be up to temp before it reads anything usefull, and will be "poisoned" if you use leaded fuel.I would query the allegation that mixture goes lean when the timing is over-advanced. That may well be an artefact caused by the mistiming.John EvansThink logically and do things well, think laterally and do things better.
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Paul I have a draw full of useable older type ego meters But I have since found that a newer 2" gauges respond extremly fast & have more led's which makes them more acurate they are also cost effective I am importing them & can sell a KIT for $245. kit contains NEW gauge NEW ego sensor 18mm half nut & 18mm block off bolt so onr gauge setup could be used on more than one gyro I have one with it's own wiring harnes & a large clipboard clip taped to the gauge this holds it securely. while testing have found fuel quality to be poor & of varying quality from fill up to fill up
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Gee Steve, that seems expensive, the one Paul and I are using costs $14.95 from Jaycar. It certainly responds quickly, when I had it on Llewella's Mazda it was tracking the computer's input very well- enriching the mixture for hard accellation and leaning it of for economy in cruise. Its catalogue number is KC 5195.If you really want to lash out KC 5300 costs $62.95 and gives you a direct readout of the air/fuel ratio These are kits, but fairly easy to assemble.I'm using it at the moment to monitor the mixture from a Camira throttle body fuel injection system I've used to replace the original carby on my EA 81.John EvansThink logically and do things well, think laterally and do things better.
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Ahhh good info John thanks ! Bob....." Momm'a alwayse told me , Son the impossable is only a little bit Harder... and ya know I do believe She was RIGHT ! "
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As I said they the Jcar ones work but the new autometer ones work better I know this because I'v tested both & the dyno I use has a $2000. gas analiser it use's a broard band sensor these cost $400. I know they are better again but I'v tested autometer against these & they are are comparable in performance but not in price
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I've read that the broad band sensors are the only ones to have to get a true and accurate picture of whats happening for the purpose of tuning.Brian
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Yes brian they are the car tuners choice but in a gyro the standard sensor & meter I speak of & import & sell dose not go off scale this was tested in flight after my mate with $2000. set up tuned Tim warners EFI gyro He also tuned a 3.5lt range rover which we have also fitted with ego meter & it will go off scale in over run [lean] & heavy acceleration full load [rich] but gyros dont have these loads
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