jbz12

I haven't considered this yet and believe I have problems with my coil/s. The stock ones have been quoted to me at $285 and $585. I can use $24 JC Whitney parts? ANd from the above, more is better, right?

J

DAVID GRIMES

Yes, I know you can use aftermarket coils and it would seem the higher the better.

What about the fact that we ( most of us ) have four (4) gaps to spark ? Wouldn't that require or love more voltage ? Seems to me it would ...

NewRXr

There's a lot more to coil specs than maximum escape voltage. Check out this article from HotRod.com it's a good read I just read it a few days ago.

http://www.hotrod.com/techarticles/17399/

I've had a WOT misfire problem with my SE for a year now, I've made many improvments but it's still been there to a degree. I swapped a old Blaster Coil in the other day just screwing around and it got much worse but when I put the stock coil back on (Primary) it was worse than before I swapped in the first place. So I said screw it and ordered two brand new Summit Racing coils based on the published specs and price that was totally the best. I used the specs from the HotRod article to find the best coil for the job (rotory) and it turned out to be the best deal also at less than $35 for two. Check out the mH (mili Henrys) below 1.0, this and the ultra low primary resistance 0.700 ohm make for a coil that can carry itself into some high RPMs without fading as bad. The winding ratio makes for plenty of voltage at the plug.

http://store.summitracing.com/partde...1&autoview=sku

I put them in before I left the shop today (I'm a auto tech) and the dang car runs better than it ever has since I and the previous owner had it. No more cutting out after 6K and it's very smooth and so quite that I turned off the radio and rolled up the windows trying to hear the engine. That's something because I'm used to a "rotorary hum" and it's gone.

Just make sure the coil is designed for electronic ignitons and not points. Most no name chrome super duper volt coils are for points. They don't swap well.

Vernon

NewRXr

By the way I'll report on them again when I've had more time to judge them.

Vernon

Paradox

iTrader: (1)

are the MSD Blaster 2 coils you guys are using a direct fit for the 12a? i was just at NAPA trying to find some and the only coils they had in the MSD catalog werent a cylinder type..

better yet anyone have a part # for the MSD Blaster 2's they've used in their Rex?

jbz12

I am speaking into reference to a 2nd gen rx-7. The car has an upper and a lower coil. Can I put 4 seperate coils in the palce of the two stock coil sets? This is MUCH cheaper than the $900.00 I was quoted for the stock replacments. Does anyone know the logic behind the upper and lower coil sets? Why is one quoted at $300.00 and the other quoted at $600.00 when I can replace them with 4 $16.00 coils!

Thanks,

Jim

IanS

iTrader: (4)

1 of those is leading and the other is trailing. Most likely the 600 dollar one is for leading as it most likely needs a stronger spark, as it does most of the work on a rotary.

Tech_Greek

God oh mighty...that's a LOT of coils lol!

So, the question remains, will a higher volt coil increase hp/tq?

- Tech

numan2

The best way to think about it is:
The voltage forces the spark to jump the gap kinda like water pressure makes a garden hose spray further like a 1/4 hose @ 150psi and will make the coil run cooler.

Amprage is how hot the spark is like using a 1/2 hose @ 100psi and will make the coil run hotter.

So as you can see above the smaller hose will force the water further than the 1/2 hose BUT the 1/2 hose at the lower pressure will provide a larger stream and more soak. The higher amprage coil will provide a better spark as long as the inital spark jump has been made.
What I'd look for in a coil is the lowest primary resistance and the largest diameter secondary wire (more amprage) and the highest secondary voltage (most windings on the secondary). The hard part to this is the physical limitations (a coil configured like this would be pretty big) but would give the best performance.
Also about the spark jumping the gap the higher the compression, the higher boost, the hotter tempture, the leaner mixture or excessively rich mixture will require more voltage. The lower the compression, lower boost, lower temputure and the richer mixture (but not excessively rich) will require less voltage the jump.

nevarmore

Is there a law of diminishing returns here?

I assume that there is a point at which if you're running some sort of hyperspace altering superport with 4 or 5 bar of boost from eight turbochargers, then an extra volt of spark will help, but on a streetable car once you get above xx,xxx volts then you won't really notice the effects.

Jeff20B

iTrader: (13)

nevarmore, yep. It's basically what I said a couple pages ago.

hammmy

At some point, and especially at high RPMs, aren't you running out of fuel and oxygen molecules to combust in the area near the spark? So that no matter how much hotter you make the spark, it can produce no more useful combustion due to limitations in how quickly the combustion event spreads versus the decreasing time period between compression and exhaust cycles? Or is the speed of combustion so fast that it's irrelevant?

Higher-voltage coils = lower emissions scores?

nevarmore

anything that helps the fuel/air charge combust completely = lower emissions scores

hammmy

I was wondering if there might be some hard data on that from some of the folks here that have experimented with their ignitions. Probably not many have stayed stock or emissions-legal, though.

jbz12

Thanks for the explanation on the coils Ian. So the other question is, can I use 4 single coils to replace the two sets on the 2nd gen? Since you the coils are of different strengths, do I need to put varying strength coils on the car or can I use 4 coils equal to or stronger tha the stronger of the two sets?

I read from a post in another forum that increasing the fire in the engine would cause the heads and valves to scorch, decreasing the life of the valves in the heads. Will increasing the spark in the RX cause any problems in this area? I haven't seen or found any discussion on this.

Thanks

jbz12

So, I DO have a manual...however...I'm in TN and my manual is in MI. Can anyone give me the specs for the resistance on the 2nd Gen coils? I have them in the oven baking even as I type. The resistance was 6, 8, and 8 cold. I have them at 200 degress for about 50 mins (like a rotary pie, huh!) and at 200 degrees they are reading 8, 10, and 10.

With this I think the coils are fine. The igniters appear to be in good condition as well. The wires are in good shape and there are no burn or scoring marks. Does anyone have any specs on the igniters?

Thanks,

Jim

jbz12

So I have my coils baking in the oven, yes baking. The resistance was 6, 8 and 8 cold. At 200 degrees for 50 mins they are 8, 10 and 10. I don't think the coils are bad Can anyone give me the spec 2nd gen numbers? I do ahve a manual, but it is in another state.

Thanks,

Jim

jbz12

So I have my coils baking in the oven, yes baking. The resistance was 6, 8 and 8 cold. At 200 degrees for 50 mins they are 8, 10 and 10. I don't think the coils are bad Can anyone give me the spec 2nd gen numbers? I do have a manual, but it is in another state.

Thanks,

Jim

jbz12

Make that .8, 1.0, and 1.0