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Thu Aug 27, 2009 8:34 am

I have heard that you can get dual ignition heads for the VW air-cooled engine (2 spark plugs per cylinder). Do these exist and where can you get these? Are the benefits worth the added cost?

Thu Aug 27, 2009 10:08 am

You can for the 356 http://www.precisionmatters.biz/twin-plug-ignition.php

dont know of anything for a type 1 that isnt an aircraft application.

Thu Aug 27, 2009 10:40 am

i've seen scat split port heads with dual plugs per cylinder but it was on a vw powered aircraft.

i would like to see them on a street vw though... Ford had dual plug flat heads back in the day... two plugs per cylinder. would unique i think for a vw to run it.

Thu Aug 27, 2009 11:58 am

do a search for bugpatch

they have some for about $750 or so....

bj

Thu Aug 27, 2009 11:58 am

the only dual plug heads i know of are out of australia, the guy (stan p?) builds the motors for hill climb races, and uses them on the street. theyre pretty insane.

Thu Aug 27, 2009 12:40 pm

Jake does twin plug type 4 heads...

Thu Aug 27, 2009 1:00 pm

actually, len does the heads for jake. but i think the OP is asking for type 1 heads.

bj

Thu Aug 27, 2009 2:16 pm

I also build twin plug T1 engines and have head and ignition combos for them....
Find a copy of the July 2000 VW Trends for an article called "Two sparks are better than one" which featured my twin plug arrangement...

I have built a few dozen twin plug T1 and TIV engines dating back to 1999.. When the engine combination is optimized the results are amazing.. I made 250HP on pump gas last year with a 2.9 Twin Plug engine in my Wife's GL Vert and it still averaged 30 MPG.
Here is av ideo of the build of the car, the dyno sessions are in the video, the throttle response of the engine is incredible for such a large engine.

Thu Aug 27, 2009 2:21 pm

Jake Raby wrote: I made 250HP on pump gas last year with a 2.9 Twin Plug engine in my Wife's GL Vert and it still averaged 30 MPG.

Good God Jake!!! :shock:

Thu Aug 27, 2009 2:23 pm

Mr. Electric Wizard wrote: Jake Raby wrote: I made 250HP on pump gas last year with a 2.9 Twin Plug engine in my Wife's GL Vert and it still averaged 30 MPG.

Good God Jake!!! :shock:

Then I drove it 6,000 miles in two months :-)

Didn't touch it.. Now its in California and replaced with a roller cammed 2270 :-)

Thu Aug 27, 2009 2:35 pm

Was this a T4 engine?
Had to be right?

Thu Aug 27, 2009 7:21 pm

I have seen them on some Harleys but hadn't thought about vw aplication before.

Thu Aug 27, 2009 7:43 pm

Mr. Electric Wizard wrote: Was this a T4 engine?
Had to be right?
Yes it was..
BUT I built a twin plug 1915 T1 last year for Herbie Blash, Chief Tech Inspector for the FIA (F1) that made 165HP with 155 TQ on pump gas (89 octane) at 11.5:1

He loves the car, it went into a Beck Spyder.

Mon Aug 31, 2009 11:47 am

These folks do the dual plug work for aircraft conversions.

http://www.greatplainsas.com/sccylheads.html

Scroll down to the bottom of the page for labor prices sending in your heads.

Mon Aug 31, 2009 12:30 pm

it is done in aircraft for redundacy. Twin magnetos twin plugs. They can't just pull over when it comes to problems and fix a wire.

Tue Sep 01, 2009 1:11 am

Does anyone have long-term experience with 10mm plugs? Heard that they get fouled easily. Would a 12mm size plug be a good compromise for second-plug application?

Tue Sep 01, 2009 4:43 am

I've been using them since 1999 with no issues.. My experience is they resist fouling better than a larger plug.

Twin plug heads run so clean that you'll be hard pressed to ever foul them.

Tue Sep 01, 2009 7:10 am

SGKent wrote: it is done in aircraft for redundacy. Twin magnetos twin plugs. They can't just pull over when it comes to problems and fix a wire.

And to reduce the risk of detonation. Two flame fronts from opposite sides of the combustion chamber help a lot.

Tue Sep 01, 2009 7:40 am

nikita wrote: SGKent wrote: it is done in aircraft for redundacy. Twin magnetos twin plugs. They can't just pull over when it comes to problems and fix a wire.

And to reduce the risk of detonation. Two flame fronts from opposite sides of the combustion chamber help a lot.
Absolutely!
I have proven that with 2.9 liters, 11.75:1 and a 105.7mm bore.. On pump gas it made 250HP. optimized at 24 degrees of timing and ran head temps less than 300F at 80 MPH.

Tue Sep 01, 2009 7:44 am

How does the wiring run for twin plugs?
Only 4 posts on a dizzy.