twin plug discussions....

[bj]

folks:

after reading current and old threads (on multiple forums), i was wondering a few things:

1. when is twin plugging a benefit? small bore? large bore? forced induction? racing only? daily driver?

2. is the cost worth the 'upgrade'? ignition, work to the heads, engine configuration...etc...

3. what is the cost of something like this for type 4 heads? i know porches (some of them) already have twin plugs.

4. who does work like this?

5. how hard is it to change the s-plugs?

not that i'm looking to do this anytime soon but just looking to answer a few of these questions i had from reading posts about them. the porsche folks seem to talk about them a lot.

thanks.

bj

[Piledriver]

1: A faster, more even/efficient burn is probably a significant benefit at any bore size.

2: Depends...

3: The downside on T4 heads is that it requires welding on the head and precision machine work, and combination of the former and latter indicates a full head rebuild (by someone with genuine clue) and thus major $$$ overall.

If it was easy/cheap, we'd all be doing it for better fuel economy if nothing else.

4: Len Hoffman.

[bj]

i was reading on porsche forums...(pelican?) that since the burn is more efficient...you can increase combustion and pull timing as well.

i guess that's where some of the benefits come from.

what would an estimate cost be to do this? from talking with the machine shop here in hawaii, he said that it is an involved process and has never done type 4s...in fact i'm the first in over 40 years of his machining career that asked him about it. he's done type 1 heads and said that he's never seen any benefit from it on his dyno....but he didn't mention whether or not he changed timing/combustion or anything. just put them on and ran the engine and pulled wires to see if he saw anything...i didn't want to ask him about engine configs and such since he's one man shop and had my rods for over 4 months ....

he's even made distributors for it. he has one left that he's keeping for sentimental value i guess .

he used an 009, milled cam gear to hold the NapZ cap/rotor, and modified the inside to work as a distributor should. pretty cool.

i think the cool factor is definitely there....but was wondering what the cost for the work would be...i'm sure more than most will ever want to spend....

bj

[Can Drive Soon]

Len is the wizard of TIV heads, he does twin plugging but I am not sure if he will twin plug used heads and whether the high cost would justify using old heads for the project.

http://aircooledtechnology.com/cylinderheads.htm

Make sure you read Jake's head page. I do not believe it mentions twin plugging (I did a text search for twin and got nothing) but there are a few pictures of some twin pluggers. I would believe to buy BRAND NEW twin plugged heads, you would spend over 3k easily....

[bj]

i hear ya. just wanted to hear what benefits are worth the expense for a modification.

i guess the average daily driver won't need or be able to justify such modifications.

bj

[volkaholic1]

My twin plug distributors are similar to what has been talked about already, I 1st started with the 009 & modified for the Datsun twin plug cap & rotor, but switched to Pertronix since "new 009"'s are crude. I also made the 2nd ingnitor adjustable so you can set the timing the same as or up to 10' behind the primary ignition. The engine will be on the dyno soon (I HOPE!). The Pertronix is a real nice unit. I've sold a unit to a guy in Sweden building a type IV twin plug, I don't know where he got his heads done. I get my type I heads from The Bug Patch, real reasonable prices. Not sure about type IV.

You can see it here.
http://www.awesomepowdercoat.com/twin_p ... ition.html

[bj]

ah, i've been to your site before. very cool engineering.

what did the heads set you back?

from "talking" with some folks, twin pluggin a type 4 head is pretty labor intensive...and not a lot of people ask for this service so not many will go through the trouble 'jigging' up the fixtures and such for this.

Len is the only one i've found so far that does this....but i've only contacted 3-4 VW cylinder head folks. not sure if there are some porsche shops out there that do this.

i'm VERY curious to see your results. please keep us (or atleast me :- ) posted.

btw...what do you sell the distro for?

bj

[MRRAGPICKER]

Here's a link to some twin plug heads. What's nice about these is that
they have the exhaust setup like a type 1 head. (more header options)

http://www.engineplus.de/pages/en/zylin ... ilder.html

[bj]

yeah, i saw those....but for that price...i could just turbo the engine and make up for the twin plugs

those are real nice, but way out of my budget.

bj

[volkaholic1]

My Pertonix twin plug distributor sells for $550, more if you want a spare cap & rotor, plug wires, coils, etc.

The heads set me back like $750, not bad at all for brand new heads, big valvess, open for bigger cylinders & 2nd plug!

[bj]

wow. the type 1 system is cheaper than just the work/labor for doing a type 4 head....

have you thought about EDIS for the iginition system?

i was thinking a dual EDIS4 modules with 2 Megajolt lite jr's may work.

you can adjust timing for each spark plug and potentially use one trigger wheel and just split the signal from the VR sensor to the modules.

of coures not sure if splitting the signals like that would work or not.

thanks for the info.

bj

[volkaholic1]

I thought about the EDMS system, but this approach has the minimum amount of complexity & I think that is a definate advantage.

[Unkl Ian]

Some of the late model 4 cyl use dual plugs,to help with emissions.

What bore sizes do they run ?



If it will clean up emissions,by adding a second plug,
then it should be possible to get more power,even below 100 mm bore.

[bj]

from reading the porsche forums about twin plugs, since the burn is so much more efficient, compression can be increased and timing can be pulled as well.

jake was also commenting on the MPG increase as well.

still, when comparing $ per HP, not sure if its worth it for a type 4 being used as a cruiser/dd...unless the cool factor is worth it.

bj

[Piledriver]

$750 for new castings+big valves+dual plug mod... (sigh...)

I'm pretty sure you can't even get get bare castings for a T4 for that.