seagull ·
Aussieveedubbers · Tech Talk
8 spark pugs & two dizzys
https://forums.aussieveedubbers.com/threads/28407/8-spark-pugs-two-dizzys
HotRodMatt ·
Get an MSD and get 3 fatter sparks for performance.
56astro ·
And Matt, no they are not only good for aeroplanes. What makes you think that? Twin plugs provide a far more efficient fuel burn than one plug, especially when placed in the head correctly!! And other advantages that flow on from that.
56astro ·
Craig Torrens ·
Its not only a fatter spark that you want (MSD etc), but also an even burn across the combustion chamber.
Its worth about 10-15% more power in the bottom and mid rev range.
Craig Torrens ·
Several cars and trikes at Nambucca had them fitted, all owners have loved the extra power and better fuel economy.😉
HotRodMatt ·
Aeroplanes use them not for low rpm stability but for safety - if one plug fails there's still spark in that pot.
MSD and the like give mutiple sparks at variable times to create an even better flame front throughout the rev range and unlike dual sparks continue to work throughout the entire rev range.
Craig Torrens ·
Already proven Matt.....................oh and we are not talking about massive overlap cam engines either...................its already a known fact in the aircraft industry about the power/torque gained by the twin plugs.
HotRodMatt ·
Alfa who do a lot of twin spark themselves admit that variable cam technologies would be a better option than twin spark.
56astro ·
So if the engine runs better at low RPM, and as a result makes more torque, then doesn't that mean that power is increased at low/mid RPM??HotRodMatt wrote:Twin spark plugs DO NOT create more power. They have only the effect of curing rough running at low rpm.
And that was one of the flow-on benefits I touched on.
Matt, you've been following the wrong sheep if ya think that is the only reason. Time for a change of flock, or even a new shepherd!HotRodMatt wrote:Aeroplanes use them not for low rpm stability but for safety - if one plug fails there's still spark in that pot.
56astro ·
HotRodMatt ·
Better combination of cam will produce the same thing.
Difference between a sheep and me is I look at a whole solution rather than a compensation for bad combinations.
Working with old solutions is not revolutionary or advancement - if the same energy was devoted to looking at a better head design and truly revolutionary valvetrain design we would end up with much better engines. Instead we get a band aid for combinations that aren't effective at low rpm.
56astro ·
What, the same max power as seen in Troy's dyno chart but with a fatter and flatter torque curve. Lets see it then ..........HotRodMatt wrote:Better combination of cam will produce the same thing.
This is probably the best single cheapest performance gain apart from dual carbs. Sure, some combos might give better max output but at what cost and loss of drivability?HotRodMatt wrote:Working with old solutions is not revolutionary or advancement - if the same energy was devoted to looking at a better head design and truly revolutionary valvetrain design we would end up with much better engines. Instead we get a band aid for combinations that aren't effective at low rpm.
Craig Torrens ·
Look at the facts Matt.
The twin spark plugs will have a benefit on any engine combo that has a bore size of 90mm or more.
Anyone in the Aircraft industry appreciates the extra power the twin plugs creates and they are around the 2500 3000rpm range ! Not exactly high RPM cams.
Go fly a light aircraft and switch off 1 ignition and feel the power difference.
This is not about cams ,but about more even combustion
The benefits are there for any cam/engine combo.
The benefits a performance motor will gain is the fact that you can use a "Hot" cam that has High RPM HP as well as having the benefits of a "mild" cam for low and Mid range.
I would love to see your cam combo Matt that will give you this without the plugs...........because its not possible.
Craig Torrens ·
So where can I buy variable valve gear for my VW engine?HotRodMatt wrote:It doesn't increase the power merely compensates for the poor engine combination design at the low end.
Alfa who do a lot of twin spark themselves admit that variable cam technologies would be a better option than twin spark.
Maybe a better "big picture" option.........................but not available!
Lets just enjoy the benefits of what's available today, and all work on something better for tomorrow.
[Edited on 8-9-2004 by Craig Torrens]
HotRodMatt ·
This is just another 94 thread now...
By the way I have seen two great streetable and very racable motors that pull better HP from 2000 to 6000+ and better torque to boot. But they are both from strokers so it mustn't be true... Both have only one plug and only one had MSD!
BiX ·
SO keep it non personal and lets talk facts about both ideas that seem to be able to give our little vw engines more power!!!
[Edited on 8-9-2004 by BiX]
HotRodMatt ·
Quite simply - a properly conceived combination does not require either MSD nor twin plugs to operate effeciently under 3000rpm while still producing hp at high revs.
Craig Torrens ·
Craig Pattons stroker is currently being built by Stan and Peter Richards...........also with twin plugs.
Secondly,Matt this is about promoting a new option for anyone's engine that has not yet been utilised by any other VW builder, don't worry about the fact that Stan developed it.
Thirdly,nothing wrong with the MSD, its just one plug does not cover the same area as the two plugs can.
Matt, if you think its not needed then that's fine............your loss.
BiX ·
Peter Leonard ·
if you can imagine, the major difference is the LOCATION, and speed of the flame front propagation.
A more efficient head design would have a central spark plug (which makes the expanding flame front hit the crown of the piston dead centre, and travels with radial symmetry as it ignites. hard to do with two valves and an offset sparkplug like, say, a VW. MSD cannot change the direction, or speed of the flame front. The first spark sets it all off, and later sparks are just fudging a kind of increased duration, because the spark thrown by a cdi is bloody hot, but incredibly short lived.
How do you get around it? have two sparks ignite simultaneously from opposite sides of the combustion chamber, effectively fixing the offset, but more importantly starting the flame front from TWO places.... quicker and more complete burn... are we getting it yet? The dissy that powers the setup is a solid state unit, with great duration, hence no need for for MSD.
anyone with half a brain should understand what THAT'S worth. People like Ducati (ever heard of the 1000DS... but that's an old 2002 model) know the advantages, and they're not building engines in sandpits wearing funny hats.
In 2003 upon release of the 'Multistrada' reviewers said "The engine has been bored to 94mm for 992cc and updated with new cylinder heads with twin spark plugs and Marelli fuel-injection with twin 45mm throttle bodies.."
look it up. yes, they're 94's. so shoot me. But why does Ducati keep banging its head aginst the wall with these crazy twin ignition ideas... possibly for the same reason Porsche did it.. or BMW... or Harley, or Moto Guzzi... or Nissan... Or Toyota
Why is it not MORE prevalent? four valves per cylinder makes it kinda hard. Lucky for us we got 2.
why do more VW's not have them? It's a bloody dangerous job that's incredibly easy to screw up. To cover the cost of a a macining slip up you can pay up to 3000 bucks to have your single zapper heads converted to double bangers. Have a surf on the net. I did for four months before i decided it was a serious bet.
now get with it..
56astro ·
😀
Craig Torrens ·
Kai.A. ·
kai😎
Alex Holzl ·
seagull ·
very good reading , I think I told craig one of my customers has this donk in a plane over here .I left the dig at home that day bummer !
very interesting to see ( I just wanted to pull it apart there and then one the back of the ute .I call and see when it gets stripped next and take some shots .
Now my 1.8 turbo toyota has two per pot , and that is very fast .( for Me )
Peter Leonard ·
Guess you'll never know, Alex 😀Alex Holzl wrote:hahahha i have 8 plugs!! 4 in the glove box and 4 in the motor!!! 4 wheels, 4 cylinders, 4 gears, 4 spark plugs, 4 goodness sake stop it!!! Whats the whole kit worth?
Stick to four, it's way easier. 😉
and craig, sure.. ducati has never been able to design a cam. some 60 years of R&D and they still can't get it right.. somehow i don't think so. unless they're waiting for a rounder number to have a go at the cam. and to think how many world superbike titles these shitty cams have won.
but you wouldn't know anything about winning, craig. bags the first ride in the next killer btw. as long as you lose the shitty cam. :kiss
seagull, bet that turbo toyota has a shitty cam in it 😀 why can't HUGE manufacturers just get it RIGHT?
[Edited on 8-9-2004 by Peter Leonard]
lugnuts ·
barls ·
HotRodMatt ·
A little lesson in economics. Manufacturers look for the cheapest solution to their problems. Quite simply auto components are as standardised and interchangeable as possible. Majors are forced to go twin plug for a limited number of engines because it is much simpler and cheaper to tool for head work than it is to change entire combinations. They too are forced to use a less than optimal solution to the problems of incomplete burn. Have you noticed that it is only in engine combinations designed for high power at high revs?
Same situation here. A band aid is being applied to cure the rough running at low to mid rpm in a combination designed for high end power. Quite simple. None of the responses have addressed this – the engine where the majority of these systems will be fitted simply are not close to optimally performing at the lower end.
Why does the problem exist? There are a few reasons. Firstly the cams used for high end high rpm power have too much overlap for the fuel to burn efficiently at low revs – that is a fact Craig! It is not just spark shape, direction, duration or timing that will cure this problem but also the shape of the combustion chamber (a good head shape is not just about flow but also controlling the spark and flame front from ANY given direction), the velocity of the piston during combustion and the ratio between bore and stroke. Piston velocity is naturally greater with a longer stroke but a smaller piston on a shorter stroke will give a higher relationship.
The velocity of the piston is determined by the rpm of the crank but the important factor at low to medium revs is the relationship between the piston velocity and the bore/stroke ratio. The optimum static ratio for a clean burn combination is believed to be around 1.18. The efficiency is less crucial at higher rpm.
So what is a whole solution? Something that takes more than changing only one of the elements. A twin spark or a multiple discharge system will help but it is not the cure – it is a stop gap. Getting an efficient velocity relative to bore/stroke, using a suitable cam or even better variable valve timing, a better shaped combustion chamber and even direct fuel injection will get you much closer.
As you will see below the strokers often have an inherent advantage in their natural ability to have an efficient burn.
Some bore/stroke ratios (best static ratio 1.18):
85.5/69 = 1.24 (stock 1600 is pretty good!)
94/69 = 1.36
94/78 = 1.21
94/82 = 1.15
Now I’m not blowing anyone’s horn here – I don’t believe there are any engine builders in Oz (regarding VWs anyway) that are addressing the whole issue. Most are too busy building the engines their customers want – and that is always a compromise. The only people who appear to be looking at the whole picture are people who are prepared to fabricate and investigate. I’m not talking about looking at what other people are saying for a whole 4 months I’m talking about some of the people for whom I gather data for (my training is in information and research) – one of which has been researching clean and lean burn technology for several years full-time who has pulled down and modified and improved hundreds of engines including aircooled flat fours (even some by “renowned” engine builders) and has thousands of hours of empirical evidence that quite simply they are not getting it all the way right.
In the end I will say this with complete conviction – forget twin spark plugs do some critical thinking and find better combinations and whole system solutions.
Craig Paton ·
"Wat ever static ratio is!! :jesus
Cheers Craig P.
HotRodMatt ·
It's not an engine ratio but the ratio between bore and stroke - which indicates how far the piston will travel as the crank begins to turn. A longer stroke makes the piston travel further during the same amount of rotation than a shorter stroke. Too fast is not as bad as too slow in relation to the bore. That is why the ratio is static as the piston velocity has less influence as the revs increase.
Craig Paton ·
I'll have to meditate on that!!!!
Cheers Craig.
Alex Holzl ·
Craig Torrens ·
It will,using your words,"Band aid" the bottom end and therefore help with the so called inherent problems you believe the cam may have ?
So if we then change the cam combo to better suit low range performance, what then happens to the High range?...........well you loose it ! That's why variable valve timing has been developed...........unfortunately not available to us.
So Twin plugs has now given a high RPM HP engine the ability to also have increased bottom and mid range power.......... or what you call a "band aid " solution.
I'm happy to live with that bandaid, instead of being limited with high piston speeds.
Craig Torrens ·
for my hillclimb car or my new street car?Alex Holzl wrote:craigie when you getting your extra plugs?
Alex Holzl ·
Craig Torrens ·
warb ·
i also have a 16meg vid of the engine running, (the race one) let me know and i can email it...
wonder who that is on the left, not a bad engine... :p
56astro ·
He needs some rubber on the back that are as sticky as ...... um ..... band aids!!
:P
[Edited on 9-9-2004 by 56astro]
Craig Paton ·
Looks like a pretty good setup to me!
56astro ·
:cry
Craig Paton ·
You have a u2u
Cheers Craig.
Alex Holzl ·
the_addoniss ·
Also i was curious how much this cost?
Gracey ·
If you want a high revving VW engine with street manners to boot, then twin plugs are the go.
Andrew Grace
Alex Holzl ·
Alex Holzl ·
Craig Torrens ·
What category is your car?
What do you compete for..points/trophy/money/records.............surely REAL racing would have one of these to aim for.
Alex Holzl ·
Alex Holzl ·
Peter Leonard ·
Alex Holzl ·
VWCOOL ·
So, you've developed some magic way of altering the shape and speed of prop of the flame front, have you? Do tell!HotRodMatt wrote:MSD isn't just a better spark it's multiple sparks from one plug - usually at around 20 degrees of rotation...
Quite simply - a properly conceived combination does not require either MSD nor twin plugs to operate effeciently under 3000rpm while still producing hp at high revs.