Enough of the hype, how about some serious facts & dyno proof on this conversion. Correct me if I'm wrong, but if an engine it tuned to its optimal, there is no advantage unless a plug or lead fails. I'd rather spend the money on a dyno tune or head work....but then you couldn't tell your mates you had twin plug heads....Just the facts please, perhaps we can all learn something. Dont get me started on cryogenics! Damn those magic beans!
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Yep, some real info would be great. Would be nice to compare to some of the new style open spark point plugs as well.
I guess the difficulty will be eliminating the benefits of the different ignition systems for real "apples with apples" results.
I have a set of heads ready to go but haven't got them on the car yet, so I can't give you a dyno back to back as yet....But..
One thing to remember that this is nothing new, it's been around for decades and decades... and manufacturers such as Porsche,Mercedes,Nissan, Ford,
Chrysler,Alfa Romeo, Toyota, BMW, Harley-Davidson, Aprilia, Yamaha, Honda, Kawasaki and Ducati have used and are still using this technology today.
When researching this subject some years ago I found that all Porsches racing the SCCA series in the USA were banned from using Twin Plug ignitions.
One would ask why ban them solely on this fact if there is no benefit to it?
As a quick summary on twin plug ignition and what it can do,
1. More complete and efficient burning of mixture in the combustion chamber.
2. Reduces the likelyhood of detonation.
3. Allows you to run less timing advance (or add more compression!)
4. Increases mid range power substantially. (killing one set on hill test)
5. Especially useful in bores of 94mm or above...
So effectively, you will see big bore, short stroke, predominantly aircooled engines using twin plugs.
Another way of looking at it, is, just think about driving around with a 48 equipped big bore engine with an FK89 and having grunt at 2500rpm.....
Here are some more links for those interested.
http://www.sportster.org/tech/dual-plug/
http://www.motobins.co.uk/displayfinal.php?function=show&subs=009&tit...
http://www.centralpaporsche.org/more/cothard/
http://www.autofarm.co.uk/new.php3/classiccar.pdf
http://www.rennsportsystems.com/2f.html
http://www.germancarfans.com/news.cfm/newsid/2031121.001/mclaren/1.html
http://www.356registry.org/Articles/LaDow/
http://www.motorcycledaily.com/21october02ducatids.html
http://www.pioneercentres.com/bmw/sales.php
http://www.nashcarclub.org/nccaphot/twenty/29_460-6196b.html
[Edited on 26/4/2005 by GregWard]
Man, some hell interesting sites there. Great reading.
Where did you get the +94mm bore thingo, or are you just refering to 1916s?
BTW, What does stan charge to machine the heads for it?
in 1992 in germany you couild buy a twin plug aircooled vw head...i have a photo of such a beast and always thought it to be a good improvement....from what i was explained they worked better in a semi hemi chamber ..not to sure on that.luv to try a set. cheers dsk member
Hi Pete,
I'll try and find the original artical, I think it is in that rennsport link, but it definitely states something like, big bores of 94 and above,
definitely not a 1916 only thing, but it did catch my interest as that was my bore size and one of the main reasons I even considered it.
I haven't looked at all of them in depth but the Ducati in the link is 94mm bore x 71.5mm stroke, one of the Porsches is 98mm bore...
I'm not too sure about current prices, but to machine them wasn't expensive, just don't forget you need a special distributor and 2 coils, that is
the most expensive part!
what about efi? I am running no Distributer (crank angle sensor) and coil packs. Does this mean I have to run double the coil packs. Maybe an eight
set off a GEN3 Crummydore?
T54
They are of use in big bores where the stroke isn't sufficiently long enough. The piston speed is too slow relative to the bore that's why they
don't get a clean burn.
Longer stroke and/or a sensible bore/stroke ratio doesn't require two plugs to get a good burn.
T54, that'd work perfectly seeing you have no distributor...
Matt, I don't think that's the reason, I think it has more to do with the flamefront starting on one side of the big bore chamber, and not much you
can do about it with one plug because of the position it has to be in.
Start it from 2 sides and there you go...
I'm pretty sure all those BMW bikes which have made it mandatory from the factory since 2003 and that link that shows you a new Mercedes Mclaren
wouldn't be purposely building engines "where the stroke isn't sufficiently long enough" and then sticking twin plugs in as a band aid??
Where does the 2nd plug come out on a Type4 head?
That is, is there an issue with the exhaust piping and such?
I had seen this on a BMW bike down in Torquay earlier this year but didn't really click to a VW head. The articles explain a fair bit and think it
would suit my motor perfectly. I also went and spoke to a porsche mechanic friend this afternoon about this and he said that a twin setup is so much
better than the single esp. in turbo's like you said. Smooth power and you can run more compression without the dreaded ping. Can you either post or
U2U me the contacts were I can talk to someone / send my heads off to get this done.
Just one more question. what happens to head chamber temps? Do they go up because of double the spark? I am running street eliminators which already
run slightly hot so will they run too hot?
Cheers for the info. T54
Pete,
No they miss heater boxes and everything.
However, new AMC heads are mandatory, cause there is not enough material on the old heads where the new spark plug position is....
Cheers Greg,
T54
As turbo54 asked, Do the twin plugs make for hotter head temps?
They should be cooler.
You get a BETTER burn (cleaner, faster, more central flame front in VW's two valve head configuration) no matter what your piston speed is. It gives
you more grunt down low, and reduces emissions. I know, because I'm actually running it, and it IS something you can feel in a before/after
comparison.
I have a high revving engine, that also pulls hard from LOW rpms. I can FLOOR it (not ease the power on, i mean 'bang' to the floor) at 2500rpm and
it will pull thru to over 7000 with no hesitation. Ask me, I've been doing the double bunger for about a year now (it's also a bonus having no
points to wear out.. ahhhhh). Ask someone who flies a plane how much harder it is to take off on one ignition system, or speak with the myriad of
trike riders who have one fitted, or the kombi owners (is that a 'sensible' bore and stroke Matt?) who can take off in third gear with the twin iggy
fired up.
it's TORQUE at idle!
not idle talk.
have a squiz at greg's links, and check out some other facts on Ducati, Harley and BMW sites, the info is all out there, people. The net's actually
useful for more than flaming and ranting. not to detract from Bad Attitude or nuthin
The problem is that it's not something your average backyard hamfisted spanner throwing amateur can make happen, hence it's not as widespread as it
should be.
Look at it this way: to get the secondary spark plug angle and position EXACTLY right you have ONE go. there are two extra per head. four chances for
error in total. Stuff one up and you could be up for thousands of dollars for replacement heads for the customer... how many businesses are willing
to risk that? far easier to talk shit and say it's worthless than to lose a customer for another, less difficult off the shelf electronic ignition.
I'm not saying it happens, but I imagine the temptation is there for people who are, at the end of the day, out to make money from selling you their
stuff.
Once you have the heads and plugs sorted you have to be able to fire them.... also not a simple job. Unless you have EFI already, and a crank angle
sensor and several dedicated coils lying around your engine bay. And going EFI and the ignition computer path is not exactly cheap, or simple. When
was the last time you saw EFI looms, computers and hardware in a neatly labelled box at your local vw supplies? it's way too hard to build a system
that will work with everyone's budget and requirements reliably, especially when the demand is so intermittent. EFI would be great, but not practical
for most of us...
am i going off topic now?
yes..
the world is ROUND people, get with the times before some inventive bugger finds a way to ban free thought and interesting developments in the vw
scene.
this is going to be interesting....
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So what's the solution Matt?
And, to be fair, we're all talking about aircooled VW motors here. They all have inherent design flaws, but we know that. We're just trying to make
them run as well as possible given those flaws. If we wanted to re-invent the wheel we'd by a rotor or a Sarich 2 stroke...which, by the way, I
reckon would go heaps well as an aircooled boxer conversion. :thumbs
BTW, what do you do for a job? and where are these databases?
Be nice to look them up.
benefits that are side effects of mandatory applications (in the case of dual ignition piston engined aircraft, for safety and reliability) are still
benefits. If we completely redesign the flat four vw for the best possible engine concept.... I guarantee it's no longer anything like a vw. I would
argue that EVERYTHING we do to vw engines to increase power, reliability or longevity is a 'stopgap' by your definition. we aren't trying to
reinvent the wheel, just make it roll better. until engines (vw or otherwise) contain no moving parts and are powered by controlled fusion reactors
that produce healthy life-enhancing vapours and allow you to do 4 second 1/4's AND quietly run up to the shops for my lung-friendly cigs, lets
consider what's out there now.
the fact is it's feasible, available, and proven.
that's pretty damn good.
I will stand by what I've said a number of times now...
NO-ONE is reinventing the wheel, have you looked at that very last link I posted? 1929 is when I can find it is first done!!!
And I will restate, that all the companies I have mentioned are STILL doing it and it is MANDATORY on a lot of manufacturers bikes, and not in 1929,
but in 2003!!!
We always compare our cars to Porsche, and rightly so, they are from the same designer, the "stop-gap" and band aid measures that Matt is reporting
are not there!! WHY the .... would they do it, not because some engineer said, oh shit, we completely stuffed that up, we designed an engine, made
20,000 of them and now we realise we calculated the bore and stroke wrong so, we'll retool the machines and band aid it with a twin plug.
I purposely never mentioned Planes because the standard answer is "so they won't fall out of the sky". Forget planes, and look at all the
manufacturers and links I have posted above.
I know some have taken the time to look at these, and that is the only reason I responded to this question from Dave, so we can all learn
something.
No-one here can redesign our terrific engines, and no-one (especially myself, re my first post) is saying that this is what a twin plug system amounts
to.
Perhaps I shouldn't have gone to the trouble of finding so many manufacturers that think the same way...
Perhaps we should say that Motec or Autronic or bigger valves or bigger cams, or new designs of heads with different port shapes etc... etc....
shouldn't be tried because our engines were designed 50+ yrs ago...
Sorry, not me...
And the right combination of stroke to bore produces the same power without needing the extra plugs. Dynos prove the theory time and time again...
My profession Pete is Information Technology. Information technology before the term was hijaked. Specialist engineering databases are available
through many universities and others by specialist organisations. My training and profession is to be able to find what academics, researchers and
developers need and what they produce - most of which isn't available to joe public but through subscribed or on request access. I have personally
done the leg work for one developer working on retro fitting clean burn technologies.
Well, thanks to all for their responses. As I suspected there are plenty of people out there who are happy with their conversions, & were happy to
tell every one that they were "twin plugged". Having done a little research, & with still more to do, here are some of my observations:
1:nearly all the engines that actually had proven benefit were of the hemi, or deep open semi hemi design chamber that typically requires alot of
ignition advance...inefficient burn.
2: the VW chamber is generally good in burn quality, considering its age of design.
3:the VW before & after comparisons almost inevitably were lacking spark energy in the " before" tests by using old points systems & totally
different advance curves.
4: switching off one plug (in a 1929 Nash...come on!) results in an inefficient burn because of the reduced advance setting used with dual
plugs...even in the VW.
5: the engines that benefitted, that did not have poor chamber design,had poor atomisation of the air fuel mix, or high volumes of liquid like
methanol or nitro engines.
So, it seems that when it comes to designing a chamber that is both burn efficient, & shaped so as to allow maximum valve area some comprimises have
to be made...
& it seems that the VW air cooled head has good burn quality but small valve curtain area compared to hemi or pent valve multi-valve chambers...to be
continued,
& keep your views coming. Regards DB.
[ Edited on 1-7-2006 by dangerous ]
One funny thing I always think when this comes up is that one of the proponents of this was not too many years ago telling us that porting was a waste of time!
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Any smaller than 94 may have some shrouding effect with respect to airflow.....
Why doesnt some one find the specs...if you can on Jim Fueling 4 valve head that he kept secret till he died.
His normally aspirated 94x83(not 84) with hilbourne injection made 450 hp.... nearly 2x any thing else.
Dyno results would be nice.... I heard it is $1800 for the twin plugg change.
matt
Isn't the proof in the pudding......
For those that have twin ignition, theres proof that there is an improvement - yes or no
wheres graig/winerot havn't they got twin plugs
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The Twin Plug head mods and ignition I believe is approx $1500.
To my knowledge at this time nobody has had dyno time with their new systems!
I know there are plans for a couple of twin plug runners to get some dyno time shortly.
Having spoken with the guys that have the system on their Kombi and Bugs, all parties are more than happy with their decision to purchase the 2-plug
sys.
[Edited on 3/5/2005 by Craig Paton]
this is mine