big-phil Posted May 20, 2007 Share Posted May 20, 2007 Ever since I raced my buddies twin turbo 300z, I have been trying to run 20 pounds of boost. I blew a coil, then blew the vb921 in my megasquirt by trying to up the dwell by WAY too much (read the MS manual kids). Well after 3 months!!!--this morning when I went to get donuts I brought the laptop with me and hit the highway. With my Mallory coil, and a running dwell of 3.6 I can now run 20 psi boost in the top of 4th, and 5th. I upped the dwell slowly from 3.0, then 3.2, 3.4, and finally 3.6 and she runs at 20 psi. Feels VERY SWEET!!!! I need to race my buddies TT300Z again! I have not been putting up video because I could not get 20 psi, now that I have it.....there are videos to come! Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted May 20, 2007 Share Posted May 20, 2007 saweet!!! how much power do you think you are making? 300hp? 350hp? Quote Link to comment Share on other sites More sharing options...
big-phil Posted May 20, 2007 Author Share Posted May 20, 2007 man I don't know? Chris (tunner of my car) his last motor made 372 whp. He rode in it at 17ish psi and said it felt like 300 whp. It now feels better than that. Chris and myself are trying to make a Dyno date to know for sure. It sure feels HOT.....ver HOT! Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted May 20, 2007 Share Posted May 20, 2007 Very nice - can't wait to se 20PSI! Quote Link to comment Share on other sites More sharing options...
TravRMK Posted May 20, 2007 Share Posted May 20, 2007 Can't wait to see the video! I will be doing a similar setup in my 260Z. HY35, megasquirt, etc. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted May 21, 2007 Share Posted May 21, 2007 say bye bye to that tranny soon lol Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 21, 2007 Share Posted May 21, 2007 I'm going to forward this thread to JeffP so he can check it out---he's on the dwell thing with Nisstune right now, and his mallory coil is giving him fits... Quote Link to comment Share on other sites More sharing options...
ZDrifter Posted May 21, 2007 Share Posted May 21, 2007 Its been 6 hours wheres the video!!!! Lets see some more burnouts too haha. Good luck!! Quote Link to comment Share on other sites More sharing options...
steveosupremeo Posted May 21, 2007 Share Posted May 21, 2007 can't wait to see the video. whats your setup? Quote Link to comment Share on other sites More sharing options...
v8dats Posted May 21, 2007 Share Posted May 21, 2007 cool vid running that 300zx. car sounds great! keep us posted on the 20psi!! like i really have to ask ha! Quote Link to comment Share on other sites More sharing options...
jeffp Posted May 21, 2007 Share Posted May 21, 2007 I don't know what system you are running, but I have had some significant problems with my ignition with the Z31 ECU. The biggest problem is this. When the car is @ 7 K RPM's the Nissan box will not provide enough dwell time to properly charge the primary of the coil to get a 1.2-1.4 millisecond spark dwell time @ the plug. I have verified this with my storage scope. The next problem is that you have to increase the basic dwell time to about 2.2 milliseconds to get the required spark dwell to ignite the burn correctly. That is not a problem @ 7 K RPM's, but at idle there is to much dwell time and the power transistor gets hot and the coil gets hot as well, makes for a short coil and system life. I have also verified that the MSD 6A box, @ 7K RPM's is also having difficulties maintaining its spark duration. So that is what your problem is, I dont know enough about megasquirt, but you need to set your basic dwell time, based on what the coil secondary is doing. Also set the plugs to a suitable gap, say .030-.040 (the gap will be determined by the level of high voltage potential the coil can make on the output.) then adjust the dwell time. So after that is made and the idle is good, then you need to start adjusting the Dwell DUTY of the trigger. What this compensates for is the closer pulse spacing of the trigger pulse to the primart of the coil. You cant increase the dwell time as that will affect your idle negatively. So make the duty cycle increase that provides the positive voltage to the coil, that will compensate for the increase in compression of the engine and maintain the 1.2-1.4 millisecond spark line. You are not the only person having this problem with the ignition. I know just about anyone running a standard single coil trigger from any ECU is going to have problems. This is just the nature of the beast when you are using one coil! There have been a number of fixes for this problem, but overall I don't think the system is good enough for a performance engine. You may get by running N/A but add boost pressures to the engine and you start to have problems. The thing about the mallory coil is that it is so big and makes such high spart, that in the points ignition the coil works very well. You can make the adjustments to the point dwell to get the happy sweet spot. The electronic ignition systems seem to have difficulty maintaining the required dwell duty of the spark duration @ 7K RPM's That has been my problem, and I can tell you it is costing you power. If you want to run your engine to 6K then you should not have problems. The thing that I have seen is guys swapping out coils with various resistance on the primary of the coil, and as you know that will change the current and the output of the secondary of the coil. Anyway, I am trying to work on a 555 timer circuit that will give me the shorter dwell duty at idle, but still maintain the dwell duty at 7K RPM's. big problem for me, and I am just about at the end of my rope with this problem. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 21, 2007 Share Posted May 21, 2007 I guess my e-mail no longer goes to Jeffp's "Trash Bin"... LOL Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted May 21, 2007 Share Posted May 21, 2007 Way to go Phil. Nothing like getting in some tuning on a donut run . Looking forward to more entertaining videos. Interesting problem on the coil. I guess coil packs are the way top go for high boost. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 21, 2007 Share Posted May 21, 2007 I guess coil packs are the way top go for high boost. high boost and high compression and high rpm... the multiple coil setups allow charging time to a factor of six compared to one coil supplying the whole engine. if you have intelligent sensing of the charge of a coil, like the old TEC2, it remembered what voltage discharge it took to fire the cylinder on the last revolution, and will charge the coil to that specific output, and a bit more...then move to charging the next coil in the sequence. A TEC2 would run 10 amps for the whole ECU and Coilpack on a Turbo Engine, while an MSD box in the same setup would be running 20Amps +! Lower draw, less wasted spark energy. Allows smaller alternator, saves weight... Many benefits. Our dyno operator said the same thing about the Bonneville car: we could have gotten the same power from carbs, but the reliability you got from that crankfired ignition system is what kept it in one piece for four seasons! The distributor-based systems would not have that spark accuracy. Any engine will benefit from saturate coils discharging a good spark over a larger gap---lights off rich and lean mixtures more efficiently and consistently, meaning more power, and less cylinder to cylinder variation---which can snap a crank given the right circumstances! Quote Link to comment Share on other sites More sharing options...
big-phil Posted May 22, 2007 Author Share Posted May 22, 2007 say bye bye to that tranny soon lol I think about it every time I hit the gas:icon11: Quote Link to comment Share on other sites More sharing options...
big-phil Posted May 22, 2007 Author Share Posted May 22, 2007 can't wait to see the video. whats your setup? megasquirt holset n/a dished piston motor P90 head 12x24x3 intercooler 3" pipe 3" full exhaust Quote Link to comment Share on other sites More sharing options...
big-phil Posted May 22, 2007 Author Share Posted May 22, 2007 I don't know what system you are running, but I have had some significant problems with my ignition with the Z31 ECU. The biggest problem is this. When the car is @ 7 K RPM's the Nissan box will not provide enough dwell time to properly charge the primary of the coil to get a 1.2-1.4 millisecond spark dwell time @ the plug. I have verified this with my storage scope. The next problem is that you have to increase the basic dwell time to about 2.2 milliseconds to get the required spark dwell to ignite the burn correctly. That is not a problem @ 7 K RPM's, but at idle there is to much dwell time and the power transistor gets hot and the coil gets hot as well, makes for a short coil and system life. I have also verified that the MSD 6A box, @ 7K RPM's is also having difficulties maintaining its spark duration. So that is what your problem is, I dont know enough about megasquirt, but you need to set your basic dwell time, based on what the coil secondary is doing. Also set the plugs to a suitable gap, say .030-.040 (the gap will be determined by the level of high voltage potential the coil can make on the output.) then adjust the dwell time. So after that is made and the idle is good, then you need to start adjusting the Dwell DUTY of the trigger. What this compensates for is the closer pulse spacing of the trigger pulse to the primart of the coil. You cant increase the dwell time as that will affect your idle negatively. So make the duty cycle increase that provides the positive voltage to the coil, that will compensate for the increase in compression of the engine and maintain the 1.2-1.4 millisecond spark line. You are not the only person having this problem with the ignition. I know just about anyone running a standard single coil trigger from any ECU is going to have problems. This is just the nature of the beast when you are using one coil! There have been a number of fixes for this problem, but overall I don't think the system is good enough for a performance engine. You may get by running N/A but add boost pressures to the engine and you start to have problems. The thing about the mallory coil is that it is so big and makes such high spart, that in the points ignition the coil works very well. You can make the adjustments to the point dwell to get the happy sweet spot. The electronic ignition systems seem to have difficulty maintaining the required dwell duty of the spark duration @ 7K RPM's That has been my problem, and I can tell you it is costing you power. If you want to run your engine to 6K then you should not have problems. The thing that I have seen is guys swapping out coils with various resistance on the primary of the coil, and as you know that will change the current and the output of the secondary of the coil. Anyway, I am trying to work on a 555 timer circuit that will give me the shorter dwell duty at idle, but still maintain the dwell duty at 7K RPM's. big problem for me, and I am just about at the end of my rope with this problem. I have my megasquirt set to a running dwell of 3.6ms. I think thats at all rpm's but I'm not sure? I have the option of running the dwell at 50% of duty cycle, but was told not to do that...or I can't??? I really don't know much about the whole dwell setting thing? Thats why its taken months to finally play with it a little. Quote Link to comment Share on other sites More sharing options...
jeffp Posted May 22, 2007 Share Posted May 22, 2007 Hi Phil, I can ask TonyD about this to be sure how megasquirt works. But, here is the situation on the Nissan box. The car idles at X speed with a duty cycle of say 1.5 milliseconds. The car is running fine. So as I increase the rpm of the engine, what then happens is the the dwell time of the pulse decreases to about half the the idle pulse width (positive pulse portion of the complete cycle) so in effect the coil spark time, or width of the spark pluse, the length of the spark, is cut in half. Now we know that it is going to take at least 1.0 millisecond to properly saturate the primary of the coil, so that when power is removed from the primary, the secondary pulse is about 1.0 millisecond. That is a properly charged and discharged coil. My coil is being charged for .5 milliseconds, half of what it needs, the secondary fire or spark time is to short to properly ignite all of the fuel in the chamber, a misfire condition. You are on the other end of the sprectrum. You are charging the coil excessivly at idle. What this will do is heat up the coil, heat up the trigger transistor in the megasquirt, at idle. So if you are running excessive dwell time that is what you will find. The car needs only 1.2-1.4 milliseconds to properly ignite the fuel. The thing to keep in mind is this. If you took your coil and connected it directly to the battery. The coil resistance of the primary is going to determine the current draw off of the battery. 12 Volts say 1 Ohm resistance of the primary will draw 12 Amps. That creates alot of heat, and if the coil is not a beef moster, you will open, or partially open the primary windings. And if you don't have a driver that is rated for at least 4 times that much current, you will over heat the driver and risk damaging that part as well. When you think that it takes only 1.1 milliseconds to charge, or saturate the primary of the coil, you then become aware of the fact that charge time does affect how much current the coil will draw. Now it becomes an issue of how long does it take to build the magnetic flux lines in the primary of the coil. Once the flux lines are being built in the coil primary, you are drawing only a minimal amount of current to get to that point because the power of the circuit can do work building the flux lines. Once the flux lines are built, or saturated, then the only current flow there can be is determined again by the resistance of the primary of the coil, in this case 12 Amps. Not good at all, and a waste of time. So if the pulse becomes to long, what will happen, is that it is now providing a sufficient pulse width to properly fire the plug, but what happens is the the individual pulses for each cylinder become to close together. What the coil sees is basically a 12 volt battery across the coil primary. Quess what, if the primary power is not switched off, you get no spark on the secondary of the coil. You lengthened your duty cycle, in effect increasing the pulse width of the spark at 7k rpm's to make the car run well, but sacraficed efficiency on the low rpm range. And if to excessive will eat coils and damage the megasquirt driver. A single coil car, will be good only for about 8 thousand rpm's that is if everything in the system is in perfect adjustment and the electronics are good enough to have the spark accuracy. Quote Link to comment Share on other sites More sharing options...
nienberg.11 Posted May 22, 2007 Share Posted May 22, 2007 20 psi, eh? Just keep cranking it up, Phil. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted May 22, 2007 Share Posted May 22, 2007 there is only so much that stock pistons can take... Phil: I'd recommend that you lower the boost a little bit for regular driving and start finding parts to build a new bottom end. Then with the new bottom end built you can boost the poo out of your current block. There are a couple stroker cranks an other cool things near you if you want to go that route... I can find the exact locations if you want... I'm thinking...Big-"big power"-Phil will be your new name... I could see you up there with the other high HP guys in a year or less with a 2.9 or 3.0 bottom end. Quote Link to comment Share on other sites More sharing options...
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