possible cure for the 3B 'spark hop' issue?

[rs200]

lot of people drive 350-400 hp on distributor and stock ignition sistem ...but if you are on high revs , 1.7 bar of boost, there are only one spark hop is enough to destroy rods..

my rods bend at stock engine on 0.5 bar of boost ... what are we talking about?

this distributor are only good because they have hall sensor , and you can use them in AAN/ABY aplication...

if you asking to me...

1. 3B sistem of ignition are more than 20 years old tehnology
2. the sistem like AAN are today in new cars.. each coil on each spark.

different between 3B and AAN , are like heven and hell...

I have AAN sistem in my audi 200 20v which was 3B before.. I done loon swap and everithing looks like OEM.. now I will do one more swap from 3b to aan , on friends 200 20v , and friend from Serbija drive his car to me , to do the same... why ? because it is better...

if will somebody want to do swap, they can contact , and I will help them, and if you want I can come to your home and do the swap.. I will help to everibody ... just kick this 3B sistem , and ECU in the garbage ...

some tuners don't wont to do remap if you have 3B sistem, there are allways some problem with them..

[rs200]

Hi rs200, how many hp has you got??and what boost??

I know that multicoil conversion is the best option... but I think with a good rotor it's enought for me, becouse many people with 450-500hp haven't got any problem with spark hop ...

This ref. is from bosch, and what model correspond??

and the Sport Quattro, what rotor has it got??

now I drive on stock turbo and MTM ECU stage 1 - 264 HP

before I have 303hp with Revo SmS ECU, but something happend to them, they dont work like it have to be...

[Simons]

The simple way to cure spark hop on the 3B is to upgrade the coil, I know this sounds strange but bare with me . Spark hop is caused by there not being sufficient charge built up to fire on the required cylinder due to increased resistance in the combustion chamber when on boost, the spark fails to fire and then fires early on the the next cylinder where there is less resistance.
If you upgrade the coil you make sure that the there is sufficient energy so that the spark always fires and thus avoiding spark hop.

One question, why the boost increase the resistance?? due the pressure, density of the mixture...

Thanks

are you sure about that. i get your thinking and can see your theory .but this is how i see it, electric allways takes the easyest route so if the resistance of the air between the spark plug is to great for the spark to jump the gap and there for the spark jumps the gap to the next terminal in the dizzy. so if you put a more powerfull coil which would make a more powerfull spark, it still would be easyer to jump to the next terminal in the dizzy . you have just made it more easyer to do so as a stronger spark will jump a bigger gap

I think that the resistance is "smaller" respect the new power, for example, for 100v and one resistance of 10 Ohm the intensity is I=V/R, 10A. and for 500v and the same resistance of 10 Ohm the final intensity is 50A. With more power more intensity

This is my opinion...I don't say that it's better or worse solution than multicoil

[EspenW]

One question, why the boost increase the resistance?? due the pressure, density of the mixture...

Yep, follows to Paschens law:
http://en.wikipedia.org/wiki/Paschen's_law

[driftin jo]

Yes it follows paschen's law as EsepnW says above, as well as this petrol is an electrical insulator so the more boost the more fuel you have thus more resistance , it is also worth noting that ethanol is a conductor so you will get a better spark , all things being equal, when running on E85 or other ethanol enriched petrol.

[EspenW]

Yes it follows paschen's law as EsepnW says above, as well as this petrol is an electrical insulator so the more boost the more fuel you have thus more resistance , it is also worth noting that ethanol is a conductor so you will get a better spark , all things being equal, when running on E85 or other ethanol enriched petrol.

Newer thought about that really. That explains why E85 will still fire nicely at AFRs that would misfire bad on petrol. Stoich is 9.6:1 on E85 and full boost mixtures are in the 7's.

[Simons]

@rs200

I Know that muti coil system is better than a distributor and coil, a friend of mine (Rocco) told me about swap the ignition with AAN/ABY components, and he told me that on this forum there are a guy (who spoke with him) who may help him to swap it and he could do it here, perhaps you are the guy

Thanks for the info!

[denniselbows]

wile your all on the resistance subject at the moment. in the rotor arm there is a resistor does any body know the purpose of this resistor and what is likely to happen to it if you up grade the coil to a high out put jobby

[Simons]

@driftin jo & EspenW

Thanks for your info, I didn't know paschen's law

wile your all on the resistance subject at the moment. in the rotor arm there is a resistor does any body know the purpose of this resistor and what is likely to happen to it if you up grade the coil to a high out put jobby

I don't understand very much the first sentence, sorry...The resistor that you say, is the carbon brush??

[driftin jo]

wile your all on the resistance subject at the moment. in the rotor arm there is a resistor does any body know the purpose of this resistor and what is likely to happen to it if you up grade the coil to a high out put jobby

The resistor is for suppressing radio interference, I don't think anything is going to happen to it if you upgrade the coil.

[JP]

When I used to play with v8's and nitrous we had loads of these issues resulting in various engines not coming out the way we would like. i.e. in the bin.

For example to run nitrous on a carb'd v8 we would use an MSD timing computer to pull ignition timing out to compensate for the risk of detonation. 250hp shot of nitrous would require 8-10 degrees timing pull depending on cams and a secondary shot would of 200hp would require another 6-8 degrees.
This is where the problems started as the MSD unit would physically not retard beyond 15 degrees so if you told it to do more the thing just decided to do what it felt like resulting in all sorts of complications. The reality of it was we didn't need to pull out that much timing as when initially setting up the dizzy to factory static timing one doesn't take into account which point of the rotor tip is actually making the spark. So although timing appears to be correct it may be sparking of the leading or trailing edge which results in any further timing adjustments through an ecu to be incorrect resulting in disastrous consequences.

So the simple solution in old school terms was as follows buy a second distributor cap. Drill a sizeable hole by number 1 so that you can see the contact between rotor and spark lead pin. Then set up the dizzy with a timing light such that the ignition spark from rotor to pin occurs exactly at the central point of the rotor tip. This way any further timing adjustments through the ECU will be correct and not cause to jump to the next cylinder.

The trimming of the leading edge and leaving the trailing edge of the tip as aforementioned in this post would work as a primitive fix. but nothing beats setting up the dizzy correctly as to how it should be. One of the reasons the factory cars came with a lock over the dizzy clamp to prevent people tampering with them

[stt]

RWD19T -

Thanks for the information. It's helps for those of us that are reluctant or don't have the time, $$$, or patience to upgrade to COP. For years, I've heard that a 400HP 3b is dangerous; yet, I've heard of 500 and 600HP beasts in europe still on distributors.

[newsh]

Surely the spark will use a different point on the rotor tip depending on the advance angle being given by the ecu for the particular boost/ rpm/ temp etc at any point in time. The rotor tip has to be wide enough to cover all eventualities. So there's a maximum adv - retard before you go off the edge of the rotor. This is why static timing has to be spot on, to account for backlash you must be sure to turn the engine forwards onto the flywheel mark then check the dizzy is spot on, I do this by putting in gear and rolling the car forward onto the marks, if you overshoot back up and start again. It's essential that the dizzy gear is in good condition.

[JP]

Surely the spark will use a different point on the rotor tip depending on the advance angle being given by the ecu for the particular boost/ rpm/ temp etc at any point in time.

Yes which is exactly why it is important to set up the static timing correctly with the water temp sensor disconnected at 2000rpm.

[newsh]

With a timing light? Which marks do you point the timing light at? I was told that the marks on the bottom pulley and timing belt cover are not accurate enough. I've never ever used a timing light on a quattro in 26 yrs of ownership. You make sure the hall sensor window is correctly aligned to the crank and the ecu does the timing.