BackStreet Posted April 23, 2008 Share Posted April 23, 2008 How often does a cylinder fire at 6000 rpm? 6000 RPM * 1 min / 60 seconds = 100 Rotations / Seconds * 1 Spark / 2 rotations = 50 Sparks / Second 50 Sparks / Sec just seems high. Is there something wrong with the math? Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted April 23, 2008 Share Posted April 23, 2008 Think that is right. and looks right. Quote Link to comment Share on other sites More sharing options...
Iceman_40 Posted April 23, 2008 Share Posted April 23, 2008 Think that is right. and looks right. +1 Quote Link to comment Share on other sites More sharing options...
MrBadExxample Posted April 23, 2008 Share Posted April 23, 2008 Might it be 100 sparks/sec? Isn't every other spark in a particular cylinder wasted since one coil powers two cylinders (spark plugs). With this arrangement isn't there 1 spark/rotation? Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted April 23, 2008 Share Posted April 23, 2008 Might it be 100 sparks/sec? Isn't every other spark in a particular cylinder wasted since one coil powers two cylinders (spark plugs). With this arrangement isn't there 1 spark/rotation? yes, butt it don't count,,smart ass, so don't count it :icon_snooty: :icon_hand: :icon_nono: :icon_think: lol Quote Link to comment Share on other sites More sharing options...
79cbxmike Posted April 23, 2008 Share Posted April 23, 2008 Not trying to be a smartass or nitpicker! The numbers are correct but the units should be expressed as below. I only bring this up because the units should cancel out just like numbers. Sometimes just working with the units first makes problems much easier to get a grip on. 6000 Rot/Min * 1 Min/60Sec = 100 Rot/Sec 1 Spark/2 Rot * 100 Rot/Sec = 50 Spark/Sec Quote Link to comment Share on other sites More sharing options...
Banshee Posted April 23, 2008 Share Posted April 23, 2008 6000 Rot/Min * 1 Min/60Sec = 100 Rot/Sec 1 Spark/2 Rot * 100 Rot/Sec = 50 Spark/Sec That is per cylinder, so 50 Spark/Sec * 4 cyl = 200 Spark/Sec total in the engine. Quote Link to comment Share on other sites More sharing options...
MrBadExxample Posted April 23, 2008 Share Posted April 23, 2008 Might it be 100 sparks/sec? Isn't every other spark in a particular cylinder wasted since one coil powers two cylinders (spark plugs). With this arrangement isn't there 1 spark/rotation? yes, butt it don't count,,smart ass, so don't count it Oh not really trying to be a smart ass. But I wasn't sure if Backstreet wanted to the the sparks/sec or the explosions/sec. And for another bit of trivia, how many revolutions does the engine on a top fuel dragster complete in an average 1/4 mile run? Quote Link to comment Share on other sites More sharing options...
John01XX Posted April 23, 2008 Share Posted April 23, 2008 Wild guess would be 600 sparks in the average 1/4 miles run Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted April 23, 2008 Share Posted April 23, 2008 And for another bit of trivia, how many revolutions does the engine on a top fuel dragster complete in an average 1/4 mile run? 540 Quote Link to comment Share on other sites More sharing options...
Northman Posted April 23, 2008 Share Posted April 23, 2008 Okay, so, I run in wasted spark mode and my motor turns red-line at 13,200 RPM. I also fire 5 sparks per ignition, meaning 5 sparks per turn of the crank. Do the math on that one. Then figure out how many fast it has to spark in 4 degrees of rotation to get 5 sparks in at the top of each power and exhaust stroke! Hold on while I smoke a dube first! Quote Link to comment Share on other sites More sharing options...
Hooplehead Posted April 23, 2008 Share Posted April 23, 2008 Okay, so, I run in wasted spark mode and my motor turns red-line at 13,200 RPM. I also fire 5 sparks per ignition, meaning 5 sparks per turn of the crank. Do the math on that one. Then figure out how many fast it has to spark in 4 degrees of rotation to get 5 sparks in at the top of each power and exhaust stroke! Hold on while I smoke a dube first! Hooplehead Quote Link to comment Share on other sites More sharing options...
speedygeezer Posted April 23, 2008 Share Posted April 23, 2008 If I keep reading this thread does that mean my tires are cupped? :icon_think: Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted April 23, 2008 Share Posted April 23, 2008 Okay, so, I run in wasted spark mode and my motor turns red-line at 13,200 RPM. I also fire 5 sparks per ignition, meaning 5 sparks per turn of the crank. Do the math on that one. Then figure out how many fast it has to spark in 4 degrees of rotation to get 5 sparks in at the top of each power and exhaust stroke! MSD? Quote Link to comment Share on other sites More sharing options...
tomek Posted April 23, 2008 Share Posted April 23, 2008 Okay, so, I run in wasted spark mode and my motor turns red-line at 13,200 RPM. I also fire 5 sparks per ignition, meaning 5 sparks per turn of the crank. Do the math on that one. Then figure out how many fast it has to spark in 4 degrees of rotation to get 5 sparks in at the top of each power and exhaust stroke! Well,it fires 5 spark sequence 220 times per second,it takes 1/220X4/360 of sec to do it or it takes 1/220X1/360 of sec for single fire in the sequence.Basically it fires once in 1 deg of crank rotation. Now,I gotta go and put my head in the ice `couse it is smoking. BTW,what is the whole idea behind this multi spark deal ? Quote Link to comment Share on other sites More sharing options...
R1000 Posted April 24, 2008 Share Posted April 24, 2008 Okay, so, I run in wasted spark mode and my motor turns red-line at 13,200 RPM. I also fire 5 sparks per ignition, meaning 5 sparks per turn of the crank. Do the math on that one. Then figure out how many fast it has to spark in 4 degrees of rotation to get 5 sparks in at the top of each power and exhaust stroke! 13200 rpm=220 rev per second. Each rev is 360 deg giving 79200 deg/second. This is 19800 4 deg intervals per second and gives 1/19800= 50 uS between each spark that are separated by 4 degrees. Math is not my strong side, I may be wrong Another way of seeing it, is that the ignition then must be capable to ignite the engine 90 times more often (360 deg/4 deg) than a single spark system. This would correspond to 13200*90 = 1 188 000 RPM, so there seems to be something wrong here. My guess is that the ignition just produces one spark, or possibly two, at 13200 rpm. Which systems are you using, providing 5 sparks per ignition at 13,200 RPM? If I remember right MSD units is using multiple sparks up to a few thousand RPM only. E.g. producing a number of sparks during 20 degrees at very low RPM's. The basic idea with multiple sparks is to re-ignite the engine in situations where it has problem to run properly (when cold and @ very low RPM’s on high-reving engines with hot camshafts, large runners etc.) At very high RPM's, MSD systems (a couple of years ago) produced just one fat spark per ignition, to permit the ignition coil to recover for the next spark. Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted April 24, 2008 Share Posted April 24, 2008 Spark travel at the speed of sound or light? Quote Link to comment Share on other sites More sharing options...
BackStreet Posted April 24, 2008 Author Share Posted April 24, 2008 Spark travel at the speed of sound or light? A spark is light. The 'snap' is sound. Kind of like lightning and thunder. Quote Link to comment Share on other sites More sharing options...
R1000 Posted April 24, 2008 Share Posted April 24, 2008 It is indeed an MSD. I didn't know the number of sparks changed as the RPM's increase, but now that you have done some of the math, it sounds likely. MSD is good stuff. Even though the ignition box may deliver a single spark at high RPM, it is a real strong one both in power and duration. The coils primary is feeded with several hundred volts by the MSD box, instead of 12 volt and this makes a lot of energy which is almost a must in turbo and nitrous applications. Especially when the tip of a plug is burnt away where a stock system could not ignite but the MSD, which may save the engine from a major damage caused by misfire. Quote Link to comment Share on other sites More sharing options...
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