# Lets Talk Spark! | Stock or Aftermarket coils!



## temporalwar (Nov 26, 2003)

I havent seen alot of writeups on the Coil system on 8vs.
I have a DigiII and I would like to try burning a little more fuel
I an running stock coil and Bosch Silver plugs (all OEM spec)

looking @ adding/upgrading to somthing like this:









and this (work as kit I have seen)


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## Issam Abed (Feb 12, 2004)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (temporalwar)*

Pointless
Upgrading your stock coil with an aftermarket unit is such a myth.The stock coil does the job quite well.
If you have plans to upgrade anything to do with the ignition then it should be the system (i.e. your ecu) .Once you have upgraded your ignition system,then you can upgrade your coil as you can now tell your coil what to do.
No matter what coil you upgrade your stock unit with,the ecu is still going to be sending it the same signal.
I hope this clarifies your answer...thats as simple as I can break it down. http://****************.com/smile/emthup.gif


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## antichristonwheels (Jun 14, 2001)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (Wizard-of-OD)*

Right on, spend the money elsewhere.


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## quadmodrophenia (Dec 6, 2002)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (art.clemens)*

So none of you ever rev over the factory limits then?
A factory coil is not wound well enough to keep a continued full spark at higher rpms. Upgrading my coil to the MSD blaster SS made a huge difference above 4,000rpms. Throttle response is much crisper and the rpm's are a lot smoother because the upgraded coils can recharge and send spark out faster than the factory unit.
Granted I spin my car to about 6,000rpms every time I drive it so I needed the extra spark. If you're just looking for extra power your're not going to find it in a coil.
You will find better fuel economy (I gained 20 miles a tank) a cleaner burn 27ppm on my emissions test total and smoother revs at high rpms.


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## Peter Tong (Jun 17, 1999)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (temporalwar)*

I can't speak for Dig-2, but if you have a high revving motor running the TCi-h with knock sensing ignition that came in the A2s, then even the factory upgraded the coil for the 16v vs the 8v units. So I would follow the factory in this case and upgrade to the Scirocco 16v coil...
I haven't had trouble with the factory A2 knock box setup boosted (worked just fine for 10 psi). I can tell you that when I installed the Crane Hi-6 the car idled, and ran smoother. This was immediately noticeable when I switched back and forth between using the Crane Hi-6 and the stock 16v coil.
It is beneficial if you go with a Crane hi-6/MSD type setup that you have control of the timing curve otherwise you won't be able to take full advantage of it...the Crane/MSD stuff is also nice if you need ignition retard under boost, although the way it retards has two flaws in my view... on my car I've remedied one of these flaws, but not the other...
As far as the Digi-2 stuff, no opinion. The Mk3 ABA cars have coils less reliable than the old A2 coils...
hope this helps,
Peter Tong


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## TBerk (Oct 9, 2000)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (temporalwar)*

Another thing to consider is having a not good, but Great path for the electron flow on the return side of the circuit.
By this I mean Ground Straps.
The connections between the chassis and the block and the battery have to convey that Mega-Blue spark we all strive for, and lots of talk about fat silicon jacketed plug wires and coils goes on but that's all Hot Side. 
The block is the grounding point for the spark pugs and it doesn't really have any ability to 'soak up' the spark, it wants to pass that energy on. 
Get them there electrons back home to the Chassis/Battery where they belong.
btw- VW put a grounding strap from the coil's mounting point to the block. It doesn't really influence the Hi-Voltage spark directly as such, as I understand things the car will however begin to show effects of poor running if it's left disconnected or is degraded.
Fundamentals, basics; these make for a good platform to base your upgrades on. 

TBerk


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## antichristonwheels (Jun 14, 2001)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (quadmodrophenia)*

"A factory coil is not wound well enough to keep a continued full spark at higher rpms"
I ran my euro 1.6 GTI at 5300+ RPMs for up to 2 hours at a time on the autobahn. Stock coil with over 200,000kms, kein problem
"So none of you ever rev over the factory limits then?" Why bother? my 16v makes 150 whp at about 6500. why go past 7200?
Didn't Techtonics make 450 some HP on a blown 1.7 running 30 psi on alky with a (gasp) stock coil?
I blew zeros across the board with a 1.8 16V at a washington state emissions test. once again stock coil.


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## quadmodrophenia (Dec 6, 2002)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (art.clemens)*

I'm sorry mr god's balls...
I never said you couldn't run a factory coil and expect good things. I just said that there was something to gain off of an aftermarket unit, not even talking about price difference between MSD for instance and factory. I got my blaster for $32.
I was talking from an 8v standpoint, our little peon engines don't normally get up passed the 6,000rpm mark so any little help I can give me engine I'm happy with.


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## wclark (Mar 28, 2001)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (quadmodrophenia)*


_Quote, originally posted by *quadmodrophenia* »_So none of you ever rev over the factory limits then?
A factory coil is not wound well enough to keep a continued full spark at higher rpms. 

Let me ask. How do you know this? Did you bench test the OEM coil and have data?


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## K.I.M. (May 19, 2004)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (temporalwar)*

FWIW there is a guy in PA with a Corrado drag car, was an 8vT, putting out over 400whp using standalone and the stock coil.


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## temporalwar (Nov 26, 2003)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (K.I.M.)*

so if I bought both, and installed it and gained 5-10HP and got better MPG, you would call BS????


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## quadmodrophenia (Dec 6, 2002)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (wclark)*

I didn't but MSD and the other fine companies that spent cointless millions making upgraded products for some reason did, check the website, talk to anyone who knows how they work. The recharge rate is better on the aftermarket unit it's a freaking fact.
I'm done with the argument, it's freaking stupid.
Ever drive a rotary with more than one coil? Ever wonder why 99.99% of car companies have coil packs now instead of single coils? Efficiency man, more fire, even burn.... and so on.
Anyone can run big numbers with a factory coil, it's like when fuel injection first rolled onto the game, I HAVE 500HP CARBS!!! WHOOO!!! How on earth could the fuel injection possibly be better than 500 HP CARBS!!! BOOM! Efficiency.
Peace and I'm out


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## Digiracer (May 5, 2002)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (temporalwar)*

Just leave it stock man, I ran a stock MK2 style coil on my Nawz injected, turbo 1,700 WHP Supra Drag Car & it fired every time. LMFO








Is their some kind of resistance against the developement of these cars?
On one hand you have a far far superior ignition coil, the MSD. On the other hand you can pay up to 3 times more for an inferior POS "Bosch Coil" 
I don't know man, I'm thinkin Bosch. I wanna keep it stock.
Na i'm with Quadmodrophenia on this one. I've noticed the same improvements + easier starting. I also got some mileage back, & great pull to my 7 k cutoff in any gear.
I paid $32 at Summit Racing, I'd never go back to Bosch lol.
I "upgraded" my ignition coil to an MSD SS Coil after my OEM Bosch began to fail at 110,000 miles. 
It's a rare opportunity to upgrade a part on a car & actually spend less money on the part.
& for whoever that made 900 HP on the stock coil, I'd bet money the MSD would make more lol
I'm not trying to be an @ss, I just see this so much on the Vortex. Someone inquires about something, EX) Headers, UD Pulleys, Light Weight Flywheels, etc, & you have atleast 10 @ssholes that say they don't work. I'm done ranting


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## Issam Abed (Feb 12, 2004)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (quadmodrophenia)*


_Quote, originally posted by *quadmodrophenia* »_So none of you ever rev over the factory limits then?
A factory coil is not wound well enough to keep a continued full spark at higher rpms. Upgrading my coil to the MSD blaster SS made a huge difference above 4,000rpms. Throttle response is much crisper and the rpm's are a lot smoother because the upgraded coils can recharge and send spark out faster than the factory unit.
Granted I spin my car to about 6,000rpms every time I drive it so I needed the extra spark. If you're just looking for extra power your're not going to find it in a coil.
You will find better fuel economy (I gained 20 miles a tank) a cleaner burn 27ppm on my emissions test total and smoother revs at high rpms.

I would have to say from reading the above that the gains felt were all mental.Until someone actually goes to a dyno,changes the coil and shows me a dyno plot showing a Power Gain then all your feeling is a mental gain.
And as for factory coils are not wound well enough to keep a continued full spark at higher rpm...








Javad Shadzi uses 5 stock coils and turns his engine over to 7600 rpm's.Like I said before if you want to upgrade something....upgrade your Ignition system.Not your coils.








And this is mine....4 Stock Coils


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## wclark (Mar 28, 2001)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (quadmodrophenia)*


_Quote, originally posted by *quadmodrophenia* »_I didn't but MSD and the other fine companies that spent cointless millions making upgraded products for some reason did, check the website, talk to anyone who knows how they work. 

I checked the MSD website. No data is published and unlike places like K&N they dont make any unsubstantiated claims of power or efficiency gains. If they had data that made the case that their coil was better than the Bosch OEM, I would be surprised they chose not to publish it.
Sorry, I am still skeptical. I see no compelling reason to replace a good OEM coil in a VW. In my 35 years working in electronics and automobiles I have seen many cases where a replacement part performed better than the old one simply because the old part was defective or replacing the part resulted in cleaned up connections. I have seen many more improvements that were imagined. Without reproducable test data, claims are just opinion. Also, I spent many hours picking the brains of a couple of the most experienced VW race car prep shops in the country. Their experience with these ignitions is there is nothing to be gained over a good Bosch OEM system.


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## VWguyBruce (Dec 3, 1999)

I think everyone is arguing the same point in their own way. One side is saying you can't "measure" an improvement when changing out the stock coil. The other side is saying who cares because my "driveability" has improved. I can't agree with anyone who says improvements in driveability ie easier starts, better gas mileage, smoother revving, are all in your head. I think the first group is saying spend your $$ on a more proven upgrade first. I also hear people saying that a coil alone may not offer any gain which may be true if your ignition is running at it's peak potential and the MSD, Jacobs, Etc may only be masking an ignition system that has issues. Just my observations... I myself believe in moving to a "better" coil, I have a Bosch "blue" coil on my 6V Beetle and it must've shaved .0000000001 off my ET in the 1/4 mile







I also converted my distrubutor back to points because I understand that technology better and I'm more comfortable with it








Maybe we should do a double blind test under scientific conditions and gather some real data









_Modified by VWguyBruce at 9:40 AM 2-24-2005_


_Modified by VWguyBruce at 9:41 AM 2-24-2005_


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## quadmodrophenia (Dec 6, 2002)

*Re: (VWguyBruce)*

Alright, if I said go out and replace all you coils with MSD somewhere I apologize. Most every part of my electrical system is bosch and it's always worked great but when it came down to replacing a unit that was going bad of course I pushed for the upgrade that was less expensive than the factory part. Every time I replace anything on anything I own or work on it's hardly ever with a factory part unless there is nothing better.
Cars, computers, scooters, motorcycles... There's almost always something cheaper and better that's aftermarket so I like playing the field until I can find something that works.
Edit: I think the pepsi challenge of coils would be fun


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## madeingermany (Sep 30, 2004)

I'm using an aftermarket ignition system in my Jetta and the reason is, being a tech gets me some good deals on equipment and time to do testing. I found the 86 gti engine (8V)running the cis-e jetronic would actually work fine with revs up 7K even in hot weather without problems, but the wimpy 0.028" spark plug gap left me wondering if I could improve my idle/fuel mileage/BHP.....so I opened it up to 0.030" and ran the same test(using OE coil/wires)...... engine @191F/5800RPM travelling up a 4degree slope and 92octane at sea level with 26Celcius ambient outside temps, and the engine began to "miss", swapped coil out for aftermarket unit and no miss was felt until 6400RPM, changed the wires to aftermarket(50ohms/ft, 9mm spiral) and voila!...no miss right up to 7Krpm...........Opened my plug gap to 0.032", no missing or noticeable problems, opened gap to 0.034", slight miss beginning at 6700rpm........Swap out ignition coil for another different coil, and rewired battery to engine/body and replaced power wire to ignition coil with a relay and 8gauge power wire from battery......0.034"..revs to 7Krpm no problems and after rewiring, opening plug gap to 0.034", car now idles smoother, starts better and is slightly better on fuel......downside so far is distributer cap and rotor wear out faster than usual.............notice I did not mention any "brands", however, from my own testing, I believe that the O.E ignition wires are junk, and the wiring to the coil/battery/engine need to be upgraded, the coil is probably satisfactory but I personally hate canister oil type coils(E-core resin ones seem best)
Don't think I gained much anything for HP but maybe 1Hp with larger plug gap/cleaner & better HV to plugs.........again, this was all free for me to test and keep, but for probably $150 I would certainly upgrade the wires and coil and basic chassis wiring. But, if you don't like messing with your plug gap and don't plan on reving past 6K or are satisfied with fuel mileage, it's probably not worth doing.......I run an MSD 6AL in my Xr4Ti, but that's a different reason., and no I didn't notice any difference from the OE EEC-IV TFI, I wanted a fancy rev limiter that looked good under the hood.
P.S. One of the best working coils I used wasn't aftermarket!....I got my BEST results with an OE Audi 5KTurbo epoxy E core type coil!
EDIT+++ My conclusion is that VW/Audi OEM coils are actually very good units, HOWEVER, their ignition wires are JUNK and something has to be done about the wiring(chassis)........try a relay kit on your coil(similar to a relay kit on the headlights)This seems to improve everything.


_Modified by madeingermany at 3:52 PM 2-24-2005_


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## VWguyBruce (Dec 3, 1999)

*Re: (madeingermany)*

Have you got some photos? Or even better, is there a post regarding the rewiring of the coil? Standard 30A 12V Bosch relay? I'm trying to envision 8 Ga wire slipping onto that tiny lead. Did you buy the tool to terminate your own ground wires? Good post on your experience, thanks. Could you IM me with the brand you're using


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## madeingermany (Sep 30, 2004)

*Re: (VWguyBruce)*

I'll post some pics later(It's storming/snowing now)........but I used a Bosch 40Amp relay and the coil is currently the one from the Audi 5KTurbo, it is the plastic black one "E" core design and it has a nice connector block attached to it's mounting hardware so you can easily run large gauge wires to it. The wires I'm using are MSD 9mm(50ohms/per foot).(I also used an MSD BLASTER E core coil, but it "appeared" to perform exactly as the OEM Audi unit does)......Another extremely good coil you can source at a wrecking yard is from a Ford, look for any 85-89 fuel injected cars with 4 cyl - 8 cyl, that use Ford's "EEC-IV" with the TFI module,(Escort EXP/GT, Topaz, Merkur, Mustang, etc...) this coil looks identical to the one in the picture of the first post and these are very powerfull units from my research, however; their downside is they actually fry out occasionally so keep a spare........I used an ACCEL "electronic super coil" the gray plastic square type and it lasted maybe a year of use and began cross-firing internally causing engine miss and no starts in damp weather.
EDIT>>Coils I've tested as follows:MSD, Blaster ss/Accel electronic super coil/Accel canister OE replacement/Audi 5KTurbo OE "E" core epoxy coil/Ford OE EEC-IV(TFI) E core coil.
Results..OEM VW canister oil coil=unable to increase plug gap/difficult starting *sometimes, rough idle
MSD Blaster coil=seemingly quicker starts, smoother idle, able to increase plug gap, coil runs hot
Accel electronic(square super coil)=pure junk, worked as well as the MSD for starting, however upper revs missed with gap opened, and coil failed within 1 year
Accel canister coil(OE replacement)=no noticeable difference from VW OEM coil
Ford TFI/EEC-IV "E" core coil=plug gap opened larger than MSD, no missing, coil runs at normal temp, quick starts, smooth idle(best of tests of all coils)however;these are known to fry occasionally, must keep a spare.
Audi 5KTurbo OE "E"core coil=plug gap limited to 0.034" from 0.028", easily handles up to redline without missing, runs cooler than other coils, good starting all weather and smooth idle.
I currently use the Audi OEM 5K Turbo "E" core epoxy/plastic coil and combined with MSD 9mm(50ohms/per foot) custom made wires and the re-wiring of the coil(+)terminal with a Bosch 40Amp relay with 8gauge(Monster Cable) power wire with gold plated terminals........the reason for re-wiring was I noticed around a 1volt drop between the battery and the coil(+)terminal, after adding relay/power wire(10gauge would be fine as well)the voltage is exactly battery voltage...after re-wiring the coil I was unable to ever get any missing in the higher RPM's. And a slight increase in power*seemed* to be felt, but no dyno proof....gas mileage did increase about 4 miles/gallon!!(original mileage was probably poor from crummy OEM wiring)


_Modified by madeingermany at 7:36 AM 2-25-2005_


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## wclark (Mar 28, 2001)

*Re: (madeingermany)*


_Quote, originally posted by *madeingermany* »_My conclusion is that VW/Audi OEM coils are actually very good units, HOWEVER, their ignition wires are JUNK and something has to be done about the wiring(chassis)........try a relay kit on your coil(similar to a relay kit on the headlights)This seems to improve everything.


Interesting info in your note. I can see where higher peak voltages from a new or improved coil could help, particularly when you are increasing the gap.
By ignition wires do you mean the 12V wiring to the coil in particular or the HV wiring from the coil to the plugs? I assume you mean the 12V wires, but you also mention using 9mm wires which are probably HV. I would agree that much of the 12V wiring in the A2 is merely adequate and better performance (lighting, ignition, etc.) can be found by improved capacity. Your approach to control the coil power similar to the way it is often done with high current lighting is appealing. Did you also upgrade the low voltage minus side of the coil back to the Ignition Control module and the control module ground wire? I believe they are also 18ga. and represent the other half of the current loop for the coil primary. When I built up my rally car and moved the battery to the floor behind the front seats, I switched all the high current functions over to direct wired with high current relays controlled by the old wiring. I also replaced most of the high current wiring and ground wires with new and larger wire. Not only was a lot of the old wiring small but often frayed at the connectors making them even worse. For instance when the full lighting package was turned on the alternator was outputting 1V more than the main battery wire (000) was registering thanks to the 4' length of frayed 10ga between the alternator and starter motor. I went on a campaign to find and eliminate significant losses in the wiring and replaced a LOT of the primary wiring and using a lot of the relay control direct connect approach to implement the changes. 
The OEM quality HV wires really need to be replaced about as often as the distributor cap since they degrade with use (I understand some aftermarket replacements are better than OEM in this regard but they all eventually become marginal). About the only exeption to this is if one is using shielded non-resistive wires (copper core) which will last as long as the terminals on them are solid, but I heard these type wires can cause EMI issues elsewhere in the electrical system of these cars and should be avoided. I used to use this type wiring on my pre-computer controlled cars since the only interference I had to worry about was with the radio.



_Modified by wclark at 9:24 AM 2-25-2005_


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## temporalwar (Nov 26, 2003)

*Re: (wclark)*

When I wrote the question I had no idea I would get such great opinions and long explanations.
only the Vortex


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## madeingermany (Sep 30, 2004)

*Re: (wclark)*

Yes, the (-) side of the coil was upgraded as well to only a 12guage wire(again Monster Cable, fine/multi-strand) was used, I've also rewired the entire harness from the ECU to all sensors with similar wiring(but similar gauge to OEM, just better quality wire). Also anything powered through the ignition switch is now powered through a relay with a direct source to the battery(to take load from switch) and I also "relocated" the voltage regulator from the alternator to a custom heatsink mounted near the airbox to keep it's temperature lower, this also resulted in the alternator outputting a higher voltage regardless of heat(cold starts would be around 14volts and as heat builds up, it drops to low 13Volts, now it stays around 14volts)......
My next experiment is swapping over to Ford's "EDIS" system, which is the "EEC-IV" ECU controlled with DIS(distributor-less ignition system) or simply I might go the easier route with Ford's "EEC-IV" "TFI"(Thick Film Ignition) which uses a VAM/sequential multi-port FI and probably(in my opinion) one of the strongest ignition systems using a distributer type ignition for OEM applications.


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## s3ri3s1 (Jan 12, 2005)

*Re: (madeingermany)*

what ever you do, keep heat away from the TFI module. Ive had plenty crap out on my due to heat.


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## madeingermany (Sep 30, 2004)

*Re: (s3ri3s1)*


_Quote, originally posted by *s3ri3s1* »_what ever you do, keep heat away from the TFI module. Ive had plenty crap out on my due to heat.

Yeah, I own a Merkur XR4Ti, and Ford has been in legal crap over this poorly designed TFI module(this is why TFI II came around)....I have designed a "remote" TFI module re-locator and heatsink for the troublesome units that originally fastened to the distributer for heat transfer(whatever Ford Tech's were thinking???)but thanks for the heads up anyway.......also, I use a military synthetic spec heatsink compound that works amazing for better heat transfer.


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## VWguyBruce (Dec 3, 1999)

*Re: (madeingermany)*

Accidental repost somehow, apologies. Accidental bump










_Modified by VWguyBruce at 7:17 AM 2-26-2005_


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## Issam Abed (Feb 12, 2004)

*Re: (madeingermany)*


_Quote, originally posted by *madeingermany* »_
EDIT+++ My conclusion is that VW/Audi OEM coils are actually very good units, *HOWEVER, their ignition wires are JUNK and something has to be done about the wiring(chassis)*.........

http://****************.com/smile/emthup.gif 
The Stock Coils as stated before are very good units.Upgrading to an aftermarket unit would be

_Quote, originally posted by *Wizard-of-OD* »_Pointless


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## VWguyBruce (Dec 3, 1999)

*Re: (Wizard-of-OD)*

Re: (Wizard-of-OD)
A single stock coil with stock ingition and your own car as an example are apples and oranges. I'd be interested in hearing your personal experience with ignition/coils. Or do you just do things you've seen other people do and disagree with everyone who doesn't feel the same way you do? It appears you place a great deal of emphasis on a dyno as if it were the empirical end all. Dyno is as subjective as the seat of the pants. Dyno is merely a baseline of numbers on which to build. Dyno is not real world application. I see nothing substantial in your posts. So if you'd care to share something of substance that would be great or maybe you could just quote yourself again.


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## Issam Abed (Feb 12, 2004)

*Re: (VWguyBruce)*


_Quote, originally posted by *VWguyBruce* »_A single stock coil with stock ingition and your own car as an example are apples and oranges. I'd be interested in hearing your personal experience with ignition/coils. Or do you just do things you've seen other people do and disagree with everyone who doesn't feel the same way you do?

Huh?
_I disagree with ignorant people who refuse to use logic_.If you check any and all of my technical posts you will see that I dont post garbage or post for the "sake of posting"
This forum = 8V engine forum,everyone in here is either running a 115bhp 8V or 90 bhp 8V.Because MSD says that "x" coil will increase performance of your engine,are you going to believe it?The same coil that comes in the 1.8 8V Golf has been tried and EXHAUSED on numourous inline 5 Turbo Audi's...so the stock coil is more than up for load.
I am in no way comparing apples with oranges...I am comparing apples with apples and oranges with oranges.
If you have stock engine + stock ignition then use a STOCK COIL.
If you have a Performance Engine (ported/polished head etc etc ) + Aftermarket ignition (in my case 034EFi Standalone) then use either:
*1.* Stock Coil
*2.* 4 Stock Coils
*3.* MSD Coils
*4.* Toyota Coils
*5.* Whatever coils... 
IF I decide to upgrade my stock 1.8 8V Coil to an MSD unit wont you agree that It will still be controlled by a STOCK Ignition System.Please answer yes or no and maybe I can learn a thing or 2 today...
The Dyno comment was to simply _*Clarify*_ that changing your coil does increase your engine performance.Peter has plans to do a dyno test where he tests his engine performance with a stock coil and then with an aftermarket coil.I will host the Dyno chart for him and If it is Proven that an aftermarket coil does indeed increase performance on a stock 1.8 8V then I will gladly retract my statements....


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## VWguyBruce (Dec 3, 1999)

So, I didn't check your Vortex "credentials" before I posted a response and now you're calling me ignorant. I take exception to that. I posted in reponse to what you posted in this thread. However, your final post has some meat, thank you. Not just comments like "don't" or "pointless". Your post definitely had the appearance that you were comparing the 8V with you Audi setup which looks far different based on your photos. And your last statement lends itself to the dyno being the end all again, if there isn't higher HP/Torque numbers from a coil swap then you say it does nothing for "performance" regardless of driveability or gas mileage. I'm using your logic from this thread. I guess we should have defined the words "better", "improvement", "gain", and "performance" at the beginning.


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## Issam Abed (Feb 12, 2004)

*Re: (VWguyBruce)*

np
http://****************.com/smile/emthup.gif


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## madeingermany (Sep 30, 2004)

*Re: (VWguyBruce)*

Comparing canister oil filled coils with "E" core epoxy coils would be a good comparison to make first.....generally canister type coils deliver on average 25,000volts(IIRC) and MOST "E"core units are nearer to 38,000volts and more(please don't quote me on those voltages).But the iron core/E core units are more efficient generally(check the internet to save me from typing for two hours)
I can see how it makes sense that if your engine is bone stock and operating within stock parameters(OE plug gap/NOT revving into redline/running perfect A/F mixture, etc...)then the need for a newer style coil or wires or even a ignition module is really not necessary.
BUT.....we all try running higher rpm's, maybe hotter climates/cooler climates and unfortuneatly the A/F ratio may consequently run into a leaner than normal area if any added headwork/exhaust/intake, etc.....is done. In lean conditions, it is very difficult for an OEM 25Kvolt coil to properly and efficiently jump a plug gap as the revs go higher or compression is increased, so missing begins to happen and we either go smaller plug gap or increase the voltage to the plugs.
Compression increases cause "resistance" in the cylinder between the plug gap and this makes it difficult to jump a spark across the gap, so more voltage is needed.
OEM engine with a new coil and wires(all aftermarket) is true that it probably will not improve HP or Fuel mileage, BUT this is if you ONLY keep the engine completely stock and drive it moderately how a manufacturer would suggest........but as fuel systems became more complex and engines come with forced induction and higher CR's, manufacturers now have a reason to upgrade the OEM ignition system, so DIS systems came about, with one coil per pair of cylinders, the coil's saturation problems in higher revs was decreased so they can keep large plug gaps(good for economy) and still be able to rev to high limits without voltage loss and missing. I have researched a COP DIS ignition system that OEM can handle full voltage output of 40Kvolts to 60Kvolts and up to 12,000RPM before voltage drops!......these DIS systems would never need a coil or wire upgrade or aftermarket unit.
But for most all pre-1990 car owners, the ignition systems leave a lot to be desired especially if there are plans of engine building to any extent or addition of forced induction.......More HP and fuel mileage can be obtained by increasing a plug gap larger than OEM standards and supplying sufficient voltage to cross this new gap without causing damage to the ignition module, so when increasing plug gap it is also important to monitor the temperature of the ignition module and either adding more cooling for it or replacing it for a different unit.
OEM VW specs are 0.028"plug gap, with OEM HV wires that are near 20,000ohms resistance(IIRC) and a 25,000volt coil, increasing the gap without aftermarket wires/coil would possibly cause a loss of HP. 0.028" gap is very small, considering many other vehicles are 0.040" and more and the reason must be related to the ignition system, is it the coil or wires? maybe, but I also believe alot of this can be resolved with changing the ignition module itself.
So, it may be true that changing the oem ignition system is a waste of time, but maybe it's not.....are you planning to do anything to the engine to make it work harder or rev higher?....I certainly would not want to overlook something as simple as a coil and spark plug wire upgrade that could potentially increase my power/mileage/ dependability. I personally noticed much faster starting and better idling with aftermarket parts on my ignition and improved fuel mileage with my 0.034" plug gap, sorry I didn't notice or can't say I noticed a HP increase, but I'm an idiot who actually "indexes" his spark plugs for that possible 3% burn efficiency and 0.1bhp potential gain...........if I get the chance this early summer to dyno test the car, I will do it with a stock ignition system, and one built from MSD and other manufacturers.
My mods are: 1.8L, 8V 10:1 CR engine, big valve head with *extreme* ported intake/exhaust with AUDI 5K intake manifold(5th runner cut off), cis-e motronic air/fuel dizzy assembly/Mercedes injectors/oem 4-2-1 gti header and 2-1/4"exhaust, no cat one muffler, also custom CAI with aluminum polished 3" fuel dizzy to TB, ECU currently Jetronic CIS-E with "Fuel enrichment"device, 12 BTDC timing with Bosch Supert CU plugs, G-grind camshaft running hydro cylinder head with custom "solid lifters".and stroker crank.............OEM ignition system crapped out on me when I changed my camshaft and did the exhaust only.........


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## Digiracer (May 5, 2002)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (temporalwar)*

Here's some good technical info regarding OEM Bosch Coils & high performance Bosch & other aftermarket Coils.. 

http://www.vintagesaab.com/son...l.htm
Some more interesting reading regarding aftermarket coils. 
http://www.hotrod.com/techarticles/17399/



_Modified by Digiracer at 10:50 PM 3-1-2005_


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## R (Oct 28, 2000)

*Re: Lets Talk Spark! | Stock or Aftermarket coils! (Digiracer)*

Yes good reading indeed. As most of the posts in this thread have been.
I have to say honestly when I opened the this thread I would have been inclined toward the "don't waste your money" opinion.
The information shared here has made me realize how much for granted I have been taking the ignition system.
Thank You gentlemen!
Rick


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## wclark (Mar 28, 2001)

*My recent observations*

After digesting this note a bit I decided to make some changes. One area I ignored when building up the rally car was the ignition, other than replacing the HV wiring and dnistributor cap.
I felt the increased wire size in the igniton low voltage wiring as suggested by "madeingermany" might be a good thing since losses in the wiring is very unproductive. 
I did little signal and circuit analysis to see what the low voltage wire losses might mean. 
The coil primary resistance is around .5-.7 ohms. From a DC perspective this means 10' of good 18ga wire from/to the coil would drop 10% of the DC voltage present. As it happens I measured the length of wire from the - of the coil to the control module (about 4') on my car and it measured almost 1 ohm terminal to terminal. It appears to be slightly smaller than 18ga wire and showed some surface corrosion so the crimp connector at the coil end was probably marginal too.

The coil also has an inductance. Most of the oil canister types are around 8mh. At the pulse widths used for ignitions this means the coil impedance is going to be a couple orders of magnitude above the DC resistance of the coil, so if the the wire losses might not be as big an element as its seems when thinking about this as a DC circuit. However the method to produce a current in the coil primary is opposite what one might assume. The control module allows the - side of the coil to float at the battery + level, so no current flows, up until around 10ms before it wants to produce a spark, then it slowly lowers the voltage and clamps it to 0V (current is now flowing in the coil). At the start of the spark cycle the control module shuts off the current and the coil - terminal goes from 0V to about 250V to 350V for a few microseconds - this probably initiates the spark thru the secondary and the level is a function of the coils turns ratio. After that the control module either drives or allows the coil minus terminal to float at around 40V for 2milliseconds (at idle) or less as RPM increases. This is probably done using a "flyback" or inductive kickback from the coil secondary to the primary. This period is probably to sustain the spark (once an arc is created, a lower voltage will sustain it). After 2 milliseconds the control module clamps the coil - to + battery, shutting off the current and this is how it sits until just before the next desired pulse. So there is one period where a low resistance wire path from the battery, thru the coil and back to ground thru the control module will be useful. The 10ms period when the control module grounds the coil. Toward the end of that period, the more current passing thru the coil just before the module cuts it off, the more energy is transferred to the secondary of the coil. This time period is long enough so the coil impedance is down to a few ohms, meaning typical supply wire resistance becomes a meaningful loss factor and reducing it is useful. This is opposite to what one might conclude after seeing typical spark duration cycles of 2msec or less and coil inductances in the 8mh range. One other point worth noting. As the RPM increased, a point above 4000 RPM came where the peak at the start of ignition began to drop and by 5000 RPM the peak had dropped significantly (I didnt try to measure it). This would likely be the onset of coil core saturation. The original coil is a Bosch unit with the VW and Bosch part numbers called out for this RD engine. 
Given the apparant poor condition of my wiring and the above it seemed prudent to do something about the wiring.

Since my car is a rally car, subject to an amazing amount of shock and vibration I decided replacing the OEM oil filled coil with one that is more mechanically suited to the high vibration environment would be a good thing as well. It might not hurt to find one with greater output as well since the engine on on my bench ang going into the car this spring is a little more high strung than the one in the car today.

I pulled back the stock wires to the coil, used the original + wire from the igniton switch to power a 40A Bosch type relay and removed most of the original - wire. They were replaced with 12ga stranded wires, coil + to the relay then battery + and the coil - back to the control module pin 1. I also replaced the control module ground wire with a shorter than original wire of the 12ga stuff to improve the modules ability to clamp the coil - at ground. Before doing anything I looked at the signal at the coil - and noted a few key things. One of them was that the time before ignition when the coil - should be at ground it was closer to +4V. Another was the peak at the start of ignition was under 200V. With the new wiring in place the the signal just before ignition was as close to 0V as I could determine on the scope and the peak at ignition was a bit over 250V. 
I decided to go with the MSD Blaster High Vibration coil since it offers a higher than OEM output along with an epoxy package with the OEM form factor. This makes spares and replacement at an event with a Bosch backup should the need arise simpler. One note on the MSD bersus Bosch. The HV terminal on the MSD is looking for the typical American style coil wire terminal and the Bosch has the screw stud style. I adapted the Bosch coil wire to the to the MSD coil terminal with a SS machine screw that had a head the right size to be captured in the MSD coil receptical and threads that would screw into the Bosch coil wire terminal. The scope trace looked a little different. The peak measured at the coil -, at start of ignition, was up to about 350V. Otherwise it looked about the same. I also observed the peak as the engine speed increased. There was no noticable drop until a little under 6000 RPM and even at 6000 it was probably still over 90% of the level at idle. This coil avoids core saturation better than the original coil. 
My point in writing this was to acknowledge that some apparent improvements in igniton performance suggested in this thread are indeed possible. I dont yet know what effect they might have on engine performance and I cant say how much would have been achieved by simply replacing OEM old with OEM new (wires, connectors and coil). I also like to write these things for others since it helps me be sure I have the details straight. In the process of writing this I went back to the car at least 4 times to make and verify observations, which resulted in several significant statement and conclusion revisions.


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## VWguyBruce (Dec 3, 1999)

*Re: My recent observations (wclark)*

Killer write-up







http://****************.com/smile/emthup.gif 
I can't quite picture in my minds eye how you adapted the screw on connector to the MSD coil, could you clarify? What it also seemed you said that once you positively screwed down the wire to the MSD coil that max voltage increased by 100V and better maintained it at high RPM, is that right? 
Thanks again. Guess I'm gonna get some wire and a relay soon when I start fooling with my new car


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## wclark (Mar 28, 2001)

*Re: My recent observations (VWguyBruce)*


_Quote, originally posted by *VWguyBruce* »_Killer write-up







http://****************.com/smile/emthup.gif 
I can't quite picture in my minds eye how you adapted the screw on connector to the MSD coil, could you clarify? What it also seemed you said that once you positively screwed down the wire to the MSD coil that max voltage increased by 100V and better maintained it at high RPM, is that right? 
Thanks again. Guess I'm gonna get some wire and a relay soon when I start fooling with my new car









Sometimes my descriptions are clear to only me








I will assume you are familiar with the screw/stud setup onthe Bosch so the thing that is vague is on the MSD side and how the screw works there. The MSD has a female barrel inside the coil tower. This barrel is uniform except for a groove around the inside of barrel about 1/4" down from the top of the metal connector in the tower. The groove is created by stamping the barrel. With the "American system" (for want of a better term) the end of the coil HV wire will have a ridge around its split metal connector end that would lock into the barrel groove when the end is inserted. The screw head I used is the same diameter and about the same thickness as that groove. so when it is shoved into the barrel it snaps into place in the groove. Now one thing I didnt mention before is the barrel isnt split vertically because the "American" style plug would be, allowing it to compress when shoved in then expand when it hit the groove. I removed the barrel from the tower and split one side vertically to just past the groove with a Dremel cutoff wheel. This allows the barrel to expand as the screw is pushed in then return to its original diameter as the screw reaches the groove. 
An alternate solution would be to locate a screw that is the same as the one holding the barrel in place and long enough to reach up to where the Bosch wire connector would reach, cut the head off the screw and figure out how to screw it in tightly. I didnt have such a screw in my misc screw box, so I went the way I did instead.
The MSD seems to maintain the peak voltage to much higher RPM than the OEM coil did. It was not related to me screwing it down but to the coil being different. I didnt try to run or test it until I had a tight fit on the connection.
Did that help?


_Modified by wclark at 4:26 PM 3-3-2005_


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## quadmodrophenia (Dec 6, 2002)

*Re: My recent observations (wclark)*

So what your saying is that I win, right?


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