ignition!
07-11-2007, 10:58 PM
#51
07-12-2007, 03:59 PM
#52
Del--thanks for your input. One thing good about this forum is the amount of stuff we learn and the discussions occuring during the process. I am not an expert on ignitions but I listen well. I trust Speed Source and what they do (when it has commonality) and the additional direct grounding of the individual coils makes sense to me. And it will not HURT anything. Other than relocation of the packs (which MM agrees on) and keeping the ignition system healthy --there is not much more we can do?
MM is a smart guy but no one knows everything. He is willing and has tried different ignition solving remedies on the 8. So far no definite fixes that I am aware off. He is still trying.
You seem well learned in the area and I am listening --what recommendations do you have on the issue of frequent coil failures off our cars?
olddragger
MM is a smart guy but no one knows everything. He is willing and has tried different ignition solving remedies on the 8. So far no definite fixes that I am aware off. He is still trying.
You seem well learned in the area and I am listening --what recommendations do you have on the issue of frequent coil failures off our cars?
olddragger
07-13-2007, 08:16 PM
#53
Registered User
It is interesting that our local dealer has only changed 1 set of coils so far(less than 1% failure rate).
I assume the rate of failure is related to ambient operating temperatures.In which case relocation to somewhere cool would be a very good thing.
I assume the rate of failure is related to ambient operating temperatures.In which case relocation to somewhere cool would be a very good thing.
07-17-2007, 07:32 AM
#54
Registered
Old- (Don't worry I'm a lot older than you) - Thanks for your confidence. And I agree that MM is intelligent. He is also energetic, articulate, amusing, and generous. But he can also **** you off sometime when he assumes you know dick about something that you think you know quite a bit about. He carries a wealth of information, and I'll keep trying to shake what I want out of him, despite the frustrations.
And he sure has made me thing deeper about the workings of the ignition process. Everything I've said so far still applies, but what bothers me now is that if you follow it through, you end up with the resulting implication that the whole process is very inefficient. Specifically, when the arc occurs, it's resistance is quite low. The power dissipated in that circuit is proportional to the resistance, and since the secondary coil resistance should be much greater than the arc resistance, most of the energy will be dissipated in the coil. If you or anyone else has any ideas on this I certainly would be appreciative in hearing about it. In the meantime I am researching high voltage discharges in order to get some additional insight into this.
With regard to your question regarding coil failures, I must admit I know nothing about that area. But will that stop me from commenting on it. You bet it won't, but I believe the comment two rotors just made has the essential elements of the answer within it.
But let me ask you this first. What do you mean by grounding the coils? In the schematic it shows the ground wire as being supplied through the plug. Are you proposing to beef up this wire, or are you suggesting a firmer contact of the coil body with the metal mass in the engine bay. In other words are you trying to correct an electrical or thermal conduction problem.
And he sure has made me thing deeper about the workings of the ignition process. Everything I've said so far still applies, but what bothers me now is that if you follow it through, you end up with the resulting implication that the whole process is very inefficient. Specifically, when the arc occurs, it's resistance is quite low. The power dissipated in that circuit is proportional to the resistance, and since the secondary coil resistance should be much greater than the arc resistance, most of the energy will be dissipated in the coil. If you or anyone else has any ideas on this I certainly would be appreciative in hearing about it. In the meantime I am researching high voltage discharges in order to get some additional insight into this.
With regard to your question regarding coil failures, I must admit I know nothing about that area. But will that stop me from commenting on it. You bet it won't, but I believe the comment two rotors just made has the essential elements of the answer within it.
But let me ask you this first. What do you mean by grounding the coils? In the schematic it shows the ground wire as being supplied through the plug. Are you proposing to beef up this wire, or are you suggesting a firmer contact of the coil body with the metal mass in the engine bay. In other words are you trying to correct an electrical or thermal conduction problem.
07-17-2007, 11:09 AM
#55
dont know if you are older than me and can still see!(i'm 58!) lol
But, appreciate your input. I have been known to get to some others myself at times and I can understand what you are saying! lol. Over the years I have come to realize that I dont know as much as i thought I knew.
What i meant by my grounding is electrical in nature --I suppose. Speed source racing had a lot of problems with burning up their coils and their fix was running the coil grounding wire (beefing it up a little also) directly back to the neg battery post instead off having the smaller wire going to what appears to be an engine mount ground. So bigger coil ground wire from each coil directly back to the negative battery terminal. A lot of us already have grounding kits on our cars, including me and this was an easy add on. Speed source has a great reputation and this is working better for them. Some times it just pays to follow the leader.
I believe speed source was believing their coils were overheating leading to failure not because of external heat(which cant help anything) but because of internal heat related failure. Of course they dont have to deal with low speed under the hood temps either.
This is interesting.
let us know what you find out.
olddragger
But, appreciate your input. I have been known to get to some others myself at times and I can understand what you are saying! lol. Over the years I have come to realize that I dont know as much as i thought I knew.
What i meant by my grounding is electrical in nature --I suppose. Speed source racing had a lot of problems with burning up their coils and their fix was running the coil grounding wire (beefing it up a little also) directly back to the neg battery post instead off having the smaller wire going to what appears to be an engine mount ground. So bigger coil ground wire from each coil directly back to the negative battery terminal. A lot of us already have grounding kits on our cars, including me and this was an easy add on. Speed source has a great reputation and this is working better for them. Some times it just pays to follow the leader.
I believe speed source was believing their coils were overheating leading to failure not because of external heat(which cant help anything) but because of internal heat related failure. Of course they dont have to deal with low speed under the hood temps either.
This is interesting.
let us know what you find out.
olddragger
07-17-2007, 12:24 PM
#56
Originally Posted by Delmeister
... what bothers me now is that if you follow it through, you end up with the resulting implication that the whole process is very inefficient. Specifically, when the arc occurs, it's resistance is quite low. The power dissipated in that circuit is proportional to the resistance, and since the secondary coil resistance should be much greater than the arc resistance, most of the energy will be dissipated in the coil.
Originally Posted by Delmeister
But let me ask you this first. What do you mean by grounding the coils? In the schematic it shows the ground wire as being supplied through the plug. Are you proposing to beef up this wire, or are you suggesting a firmer contact of the coil body with the metal mass in the engine bay. In other words are you trying to correct an electrical or thermal conduction problem.
The ground pin on the coil connector only grounds the input transistor.
The thermal issue is because of the electrical issue.
07-17-2007, 12:50 PM
#57
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The mad scientist always has something up his sleeve and in the works for something better and more reliable.....
07-18-2007, 07:21 AM
#62
Registered
You have a variable resistor in series with a light bulb. You plug this into a wall socket and the bulb glows dim but it lasts forever. Reducing the resistance makes the light glow brighter but its lifetime diminishes. Reducing the parasitic obstructions to the delivery of power to the coils (and don't forget that this includes potentially even greater resistances from the battery positive) will result in the coils functioning better at the expense of reduced lifetime.
Temperature kills. The power transistor in these coils gets whacked with a pretty high voltage when the ignition current is interrupted. It's ability to withstand this repeated beating without degrading significantly will largely depend on it's temperature history. That history is determined by the electrical power delivered to the coil, the inefficiency of the coil pack in converting electrical input energy to spark energy, and the heat transfer characteristics of the whole assembly. It really does seem that the only thing you can really do to increase longevity is to try and improve the heat transfer away from the coils.
And 'better' is a relative term. The existing wires to the coil have plenty of capacity to handle the current. You fool with wiring if you have some 'inside' knowledge or experience that is not apparent from a schematic. For example your experience may be that the factory connectors tend to bounce around and make/break under race conditions. You may also only have suspicions, and that's OK too, but again, don't forget the other delivery part of the circuit.
Did I forget to say that all the above is only my opinion or that some of it has already been said by others? And don't get me started on those grounding kits.
07-18-2007, 03:22 PM
#64
Consider this analogy.
You have a variable resistor in series with a light bulb. You plug this into a wall socket and the bulb glows dim but it lasts forever. Reducing the resistance makes the light glow brighter but its lifetime diminishes. Reducing the parasitic obstructions to the delivery of power to the coils (and don't forget that this includes potentially even greater resistances from the battery positive) will result in the coils functioning better at the expense of reduced lifetime.
You have a variable resistor in series with a light bulb. You plug this into a wall socket and the bulb glows dim but it lasts forever. Reducing the resistance makes the light glow brighter but its lifetime diminishes. Reducing the parasitic obstructions to the delivery of power to the coils (and don't forget that this includes potentially even greater resistances from the battery positive) will result in the coils functioning better at the expense of reduced lifetime.
Consider this analogy:
Take you bulb from above and realize that the circuit you are affecting is on one side of the physics - the ignitor side.
Now put a hood of aluminum foil over the bulb with a pin hole in it and adjust your bulb until the light output through the hole is the same as it was without the foil. Note the increase in power needed but, more importantly, notice the increase in heat inside the bulb.
Now, this isn't a proper analogy because in the case of the coil, the ignitor is actually your variable resistor, not the lamp filament.
Yeah, really. I can't wait to hear the collision of theory with reality on that one.
07-18-2007, 10:10 PM
#67
RotoRocks Powered
What everyone is realllly, and I mean really interested in is how the hell to you get the smoking hot babes pose naked with the rx8 club sign?
Not only you know ton's of stuff about cars, but you got it going on too....
P.S.
For anyone who might find that I am taking the tread off topic... It is not me. It is the alcohol in me talking. RotoRocks has departed to a better place about an hour ago and won't be back until tomorrow.
07-18-2007, 11:48 PM
#68
MM god damnit!! this sucks!!! No one here really gives a rat's *** about the intricacies of what effect the loss of energy in the variable resistor has on the longevity of the darn weak *** coil that mazda was just to cheap to make a bit beefier. Still I am real happy with my measly 280-300 HP or so.
What everyone is realllly, and I mean really interested in is how the hell to you get the smoking hot babes pose naked with the rx8 club sign?
Not only you know ton's of stuff about cars, but you got it going on too....
P.S.
For anyone who might find that I am taking the tread off topic... It is not me. It is the alcohol in me talking. RotoRocks has departed to a better place about an hour ago and won't be back until tomorrow.
What everyone is realllly, and I mean really interested in is how the hell to you get the smoking hot babes pose naked with the rx8 club sign?
Not only you know ton's of stuff about cars, but you got it going on too....
P.S.
For anyone who might find that I am taking the tread off topic... It is not me. It is the alcohol in me talking. RotoRocks has departed to a better place about an hour ago and won't be back until tomorrow.
i have been quiet for a while.. but what he said^^^^.
beers
07-19-2007, 07:24 AM
#70
Registered
rotorocks:
I don't think there is any magic bullet here. If you want to run these coils at really high pulse rates at high ambient temperatures, then you have to get the heat away from them to try and keep the temperature down. I think there have been some suggestions on how to do this but you could probably come up with as good a solution (to the extent that a 'good' solution can be found) as anyone else.
With regard to olddraggers query as to why these coils fail under heavy stress, I just believe Mazda did a cost/benefit analysis that went something like this. The vast majority of RX-8 owners will not stress their coils (I personally still have not redlined my engine), and their coil lifetime will probably be 'reasonable'. In this case incorporating more durable, and presumably more expensive, coils would be a waste of money. In a recent post, two rotors, who works at Mazda, said coil replacements were rare. Racers, and others who do stress ther vehicles are of such a breed that a lot will change those coils anyway, even if they were of somewhat better quality. It's just their nature to rip out stock stuff and put in top-notch expensive race stuff.
I don't have more time right now but I did want to say something pertaining to rotorocks concerns because he seemed quite upset. And I will want to have a closer look at MM's theory and respond to the grounding kit question. In the meantime can someone come up with a quantitative assessment of why these kits are beneficial? I assume they are installed to address problem x and correct it to degree y. 'I did it because it was cheap insurance' is not an answer. Some of the claims made for their benefit appear quite outlandish to me.
I don't think there is any magic bullet here. If you want to run these coils at really high pulse rates at high ambient temperatures, then you have to get the heat away from them to try and keep the temperature down. I think there have been some suggestions on how to do this but you could probably come up with as good a solution (to the extent that a 'good' solution can be found) as anyone else.
With regard to olddraggers query as to why these coils fail under heavy stress, I just believe Mazda did a cost/benefit analysis that went something like this. The vast majority of RX-8 owners will not stress their coils (I personally still have not redlined my engine), and their coil lifetime will probably be 'reasonable'. In this case incorporating more durable, and presumably more expensive, coils would be a waste of money. In a recent post, two rotors, who works at Mazda, said coil replacements were rare. Racers, and others who do stress ther vehicles are of such a breed that a lot will change those coils anyway, even if they were of somewhat better quality. It's just their nature to rip out stock stuff and put in top-notch expensive race stuff.
I don't have more time right now but I did want to say something pertaining to rotorocks concerns because he seemed quite upset. And I will want to have a closer look at MM's theory and respond to the grounding kit question. In the meantime can someone come up with a quantitative assessment of why these kits are beneficial? I assume they are installed to address problem x and correct it to degree y. 'I did it because it was cheap insurance' is not an answer. Some of the claims made for their benefit appear quite outlandish to me.
07-19-2007, 11:22 AM
#71
RotoRocks Powered
I just downed couple (well, maybe more) drinks, as it was my Mother in law birthday, and then was just having fun.
Didn't you read the little disclaimer P.S?
I was simply in a better place.
Back to the topic please Ladies and Gentlemen, Back to the topic....
Last edited by rotorocks; 07-19-2007 at 11:26 AM.
07-19-2007, 02:27 PM
#72
My local dealer replaces the coils almost as a matter of fact.
Coil replacements are VERY common.
Originally Posted by Delmeister
In the meantime can someone come up with a quantitative assessment of why these kits are beneficial?
Less current consumption and less sensor error.
Nearly everyone that has installed grounding kits reports a smother idle (myself included).
I also noted a change in the values at several sensors that wasn't uniform, so the relative reading of these sensors was inaccurate before making the ground plane uniform.
07-19-2007, 07:11 PM
#73
Registered
I was looking through an ignition book earlier and they pointed out that on a V8 that good grounds to both heads are needed with a performance ignition.
How does the Renesis get grounded in the RX-8? Are there grounds to both rotor housings?
If Mazda is being as economical as suggested, I would say probably not.
How does the Renesis get grounded in the RX-8? Are there grounds to both rotor housings?
If Mazda is being as economical as suggested, I would say probably not.
07-19-2007, 09:49 PM
#75
Registered User
Actually this is what I said: