split-reduction Posted May 30, 2009 Share Posted May 30, 2009 My mechanic says that my plug wires need replacing and the coil on my 280ZXT (in '77 280Z) is only putting out 9KV and should be 15KV. He is suggesting this explains why my car is not preforming well on hard acceleration. I plan to get upgraded plugwires, and have looked for aftermarket coil replacements, but the only high-performance coils I've seen are specified for non-turbo cars. Does anyone know of a high-po coil that could replace the one on my turbo or am I stuck with replacing with a new stock coil? Thanks. Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted May 30, 2009 Share Posted May 30, 2009 It makes no difference if the car is a n/a or turbo. Any coil will work. Quote Link to comment Share on other sites More sharing options...
split-reduction Posted May 30, 2009 Author Share Posted May 30, 2009 Thanks for the reply. I did forget to mention, I am still using the Nissan ECCS computer and Nissan ZXT wiring harness, and I'm surprised that any coil would work since everywhere I've checked out for aftermarket coils specifies turbo only. I've got a stock coil or two from non-turbo Zs- guess I could try them and see what happens. Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted May 31, 2009 Share Posted May 31, 2009 like sweetleaf said a coil is a coil. And what kind of meter did the guy measure the spark with. Hi volt meters are expensive little rascals. I don't think a lot of guys got one. Quote Link to comment Share on other sites More sharing options...
Challenger Posted May 31, 2009 Share Posted May 31, 2009 If you think about it there are only 2 wires on the coil. The ignitor is seperate so in theory any coil that has the same wire style ( + and - ) should work. Correct? Quote Link to comment Share on other sites More sharing options...
Kash Posted May 31, 2009 Share Posted May 31, 2009 A coil is not a coil:)...the turbo coil is wounded differently than NA coil...don't know all the technical difference but they are different...both coils will function and run the car without any discernable differences but the coils are different. Quote Link to comment Share on other sites More sharing options...
jeffp Posted July 5, 2009 Share Posted July 5, 2009 Question: If all coils are the same, then why are there so many different coils on the market? First off to be able to read high voltage you need a good probe, and meter that will read into the KV range, or you can build a resistor network so that your oscope can read the HV or use a sun machine for ignitions. Running a N/A car and a turbo car are much different. It all has to do with cylinder pressure. So if you are N/A the cylinder pressure will be fixed, regardless of what cam you run, but determined by the compression. When the cylinder pressure is increased you will need a strong coil to spark the plug. Example: I was running a turbo car, my car, and for some reason I could not get the car to run correctly over 17psi of boost. In this case the coil was up to the task, but the plug wires were not. The coil would jump a 1" spark to ground before it would jump a spark across at the time .025 thousands gap at the plug. WHY? Pressure in the cylinder that is why. As you increase the pressure in a chamber/cell the amount of voltage will have to increase, and the power to make the plug spark. I for instance built a pressure chamber to test not only plugs, but the wires as well. I can take the pressure in the cell to about 30 BAR to simulate what the engine cylinder is being pressurized to under boost. You will see or find that some coils have 1-2 ohms across the primary of the coil and others muck lower like .75 OHMS the lower ohm unit will produce a much higher voltage out put then the 2 OHM unit. Basic electronuics guys. Then you have to take into consideration the time it takes to fully saturate the primary of the coil, and what the spark duration is on the secondary of the coil. For a good coil you are looking at 1 milli second discharge time to give you a 1 millisecond spark duration time. That should work for just about every turbo application out there. You look at top fuel drag cars. They have big mags that fire the plugs, now they run two mags and two plugs. I can tell you each mag will produce about 45 Amps, each to two plugs just to get the engine to run. Mallory made some of the best coils out there, and I have found that there was a period of time that you really could not get a performance coil because they were built so cheap, they would burn out. Take a look at this link and it may be helpful : http://www.impulsengine.com/kits/coil_direct_hits.shtml hope that helps Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted July 5, 2009 Share Posted July 5, 2009 thanks jeffp one of the most cogent explanations of why coils work I have seen on this site. Most people seem to think it is some sort of black magic. As you pointed out anyone tells you the voltage out of your coil better have a meter you can look at that specifically shows a high voltage range. they ain't too common. Also pressure in cylinder affecting spark ability is often overlooked (if known at all) by many. Quote Link to comment Share on other sites More sharing options...
jeffp Posted July 6, 2009 Share Posted July 6, 2009 I did a whole gob of research on the topic because I was having that problem with my car. I ran the MSD 6A with the HVC coil and the coil kept going bad in short order. I experimented with the Mallory Volt Master II coil, nice part to this day one of the best coils I have ever worked with. (well Pre 1983 coild) I bought a Heathkit analyxer, and I built a resistor network to plug into my oscope. I used the oscope as the heathkit display was to small for me and was lacking in resolution at least for me. I ran the car with the scope going, and that is when I found the first problem to deal with, the injecton, Z31 boxes are very hard to control @ 600 hp due to the electronics and how it calculates injector duty cycle. Not to get to deep into it LOL. So I got the injection fixed at least well enough to work, not ideal, but very workable. Then came the problems with the misfires. That was the hardest thing to troubleshoot. That is when I decided the Z31 box was just to much pain in the butt to make work. The duty cycle was a minimum of 2 milli seconds charge time on the primary of the coil @ idle. The coil was fully saturated by .8 milli seconds, so the coil was getting hot, the power transistor was getting hot all at idle! The other problem was that when the ECU was spinning @ 8000 RPM's (I did this testing on the bench) the duty cycle to the primary of the coil was about 500 micro seconds. That was to short to charge the coil. So the spark was getting blown out. Yes I did try all of the standard stuff with plug gap not help. The last thing I found were the plug wire boots. I was running the blue NGK wires at the time. I tested the setup, or wires, on a test fixture the simulated cylinder pressure and the boots were shorting to ground in stead of jumping the spark at the plug. I had a number of problems going at the same time, and it wastough to troubleshoot, in fact it cost me a set of pistons. So you could say I did an indebth study on the topic. I have an additional page for everyone to take a look at if it is still there, well I just tried the link and cant get to the Article. Here is the basic link maybe you will have better luck, the article is Anatomy of a Waveform by Bill Bill Fulton good read. anyway like you said, this is not magic and proper attention is really required. Quote Link to comment Share on other sites More sharing options...
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