Twin Plug Conversion

I read a very interesting artical on the 356 registry site regarding twin plug conversions for 356 engines which increase the torque and engine efficientcy. Has anybody had experience of doing this modification to a type 1 engine?
Thanks Nigel

you could install a msd type multi spark system, same thing, more complete burn.

martin

adding multiple spark is NOT THE SAME as adding a second plug!

The benefits of a second plug on the opposite side of the combustion chamber is primarily the addition of a second "flame front" in the chamber. This means that instead of a single flame front burning across the chamber you have two flame fronts that start on the outside and burn toward each other, meeting in the center of the chamber.

What does this equate to?? Well in my experience we can run HUGE compression rations, and much less ignition advance with cooler running and more powerful engines.

Twin plugs are how I squeezed 257HP from a 2.4L engine on PUMP GAS. Here are the pics of those specially prepared heads.

http://www.aircooledtechnology.com/galleries/msheads/

+1 on what Jake said.

Nigel, by itself, twin-plugging will not gain you huge power. Some, but not enough to offset the aggravation and cost. Its when you add the big compression and radical camshafts that you start throwing down some big numbers.

By twin-plugging a well built engine, you gain everything that Jake mentions above, plus a few other bonuses. You clean your emissions up hugely. Remember the old Naps-Z engines? Nissan put those in a few vehicles, including pickup trucks, the twin-plugs allowed them to pass low-rpm emissions that they were otherwise failing. Also, with radical camshafts, you can clean up the idle and low rpm. You can make a streetable engine out of something that otherwise would not idle in traffic.

Big plus on the temperature drop that Jake points out. The twin-plug engines run cooler even when they are making more power. This is an expensive challenging conversion. Its a waste of money unless you've built an engine that will benefit from it. IF your engine is built to that standard, then the twin-plug is worthy every penny for driveability, longevity and power.
angela

As you've mentioned above just to add a plug without reshaping
chambers, dual ignitions etc..Thats quite a bit of work for a bug motor(imho) but there are quite a few talented people out there.....
http://shoptalkforums.com/viewtopic.php?t=93249&postdays=0&postorder=asc&start=0

It's all a lot of work... The reason why these engines haven't been developed to their maximum potential was because too many people have that same mindset of "It's jut a bug motor"....

No, it's the most widely adapted engine in the world and it's possibilities have only just been tapped into.

The future for these engines is much brighter, just because they started as the most simple engine in the world doesn't mean they have a handicap.

I'm with you on the best design ever!! But what I was trying to say was for your average
hobbiest this would be a stretch to do as an individual without;

1. previous personal experience doing this kind of work/machining/experimenting
or
2. a large chunk of cash paid to an individual for his time/expertise

Personally, I'd plunk a turbo on it and take my savings and go on a worldwide vacation

it really is the best design!!!!!!!!! A total package in one neat bundle!!!

Hey Jake, speaking hypoothetically, would Butch benefit from a revamp of the heads and a twin-plug conversion? I agree with your theory about our engines. Its as if a pact was made in the old days that VW would remain somewhat plebian and Porsche would get the bells and whistles.

Today's VW motor is a whole different story.

Twin plug heads on Butch's engine would beincredible! we could bump the CR another whole digit and I'd expect a 15+HP gain

...that's JUST what you need, Paul, for Butch to go FASTER!!

More power is more better, whether you're starting with 60 hp or 260.

Paul - DO IT!!!!
angela

I was playing around with my modeling software last night and made a hybrid model of the "Butch engine" and the "Mighty Spyder" engine I built last year with twin plugs. I used a CR of 10.8:1 and and then swapped out a couple of cams.. It looked like my 15HP prediction was way off as we got net values of no less than 245HP!

The torque was the incredible part (and it always is) as the engine made almost 240 lb/ft which is a solid 15% gain.

Talk about advancing (appropriate pun here?)at cross purposes! I am totally schizoid these days. On the one hand I keep tweaking Butch but I'm in a funk because I need to sell him (IRS hovering in the ever-closing distance) and nobody likes him well enough to pay me half of what he's worth!

Ad to that I have an opportunity to become a net branch operator and take over a loan company, potentially increasing my earnings potential, with everything in place except, uh, a few qualified buyers...

I think I'm better off taking a few of these extra plugs and sticking them

Jake watch for a PM

The question is - do both plugs fire at the same time? Some times the second plug is set up to fire at 2 or 3 crank degrees after the first plug. Intake flow, exhaust flow, flame front, cylinder mixture, etc. As Jake has said a few times - "it's the system".

Depends on the system (as you stated). Some fire at the same time, some fire the trailing plugs a few degrees back (like 3) of the leading plugs.

Further, some (like our spyder) fire a waste spark on the exhaust stroke. Basically, everytime the piston goes up, badda bing - BANG there's a spark. This is especially nice for smooth idle on a hot-cam engine or for emissions purposes.

The system in our car fires each coil pack so that one side of the coil is feeding the compression side cylinder and the other side of the coil feeds the waste spark cylinder (the one on the opposite in the firing order).

I really really love this system. If you are looking for a "Driveable" walk on the wild side Paul, let Jake hook you up!
angela

We can fire the plugs simultaneously or we can trim them for a few degrees of advance. The determining factor is the chamber shape and bore size more than anything else.

Butch will need the carbs tossed in the trash for an engine manegement system that will control EFI and direct ignition- its the only way to fly with twin plugs!

Toss in one of my new roller cam/lifter set ups and Butch will be a true beast!

Mwuahahahaha (evil laugh)....

You GO Jake!
angela

Hi Jake
Really interesting responses to my post. The increase in torque is what interests me. Any idea (Ball park) of how much a pair of modified twin pug heads and 8 plug dizzy set up would cost?

Cheers Nigel

Pauly,
Twin Plugs and EFI?. You're truly insane and... that's why we luv you.
Let not your exuberance get a hold of you during mundane conversation with Lady Di like the TransPowered 2,2 (O: I got your back.

no, Lady Di input, uh-uh, no more wet blanketzzz.
I shoulda gone ahead and bought that standard. fuck.

Nigel, twin dizzies? Crank trigger!!!

I would only do crank fire, but I'm quite in love with the simplicity and reliability of crank fire versus the other system.

However... For you guys that can't live w/o distributors - let me tell you about this cool setup I saw on a 356 at Parts Obsolete. This guy is using two Volvo distributors with a single drive. He machines them up himself - clever fellow. One drive, two four cylinder distributors on top, one for the leading plugs, one for the trailing plugs. Very nice looking setup. When I get back home, I'll see if I can find a picture.

But really, if you're going to do this, crank fire is so idiot proof that even I can figure it out! (watch the high-torque starter trick)
angela

Direct fire all the way.. I have witnessed 15% power increases with adding a direct ignition system with even a single plugged engine.VW Trends magazine featured my twin plug efforts in the June 2000 issue in the article "Two sparks are better than one" and I have been honing and refining the twin plug arrangement every since making huge leaps forward with it in 2006.

I am building a twin plugged roller engine using a dizzy and carbs currently, it is being done because the client already had a brand new Australian made twin plug dizzy for his 356 engine that he tossed out of his 912 in favor of a massIVe engine. He also had a brand new set of 48 Dell carbs that will perfectly outfit his 2563cc beast made for daily driving.

Our twin plug heads are not cheap, they have 10 hours of welding per head into them, thats before all the profile and CNC port and chamber work. This equates to a 4,000.00 expenditure on the heads alone and at that we literally don't make a dime on the heads!

When creating an engine this serious skimping on the ignition system to save a few bucks and keep the system dizzy based is just not wise. I was able to get 257HP from the Mighty Spyder engine from 2.3 liters and did so on pump gas- that would not have been possible without the insane accuracy of the direct ignition system. Being able to alter the ignition advance by one degree every 250 RPM with accuracy to 1/10th of one degree to 9,000 RPM is a serious capability that one must experience first hand to appreciate.

The capability of ignition retard as piston speed and RPM increase is huge for top end power, I have seen 15HP and 70 degree head temp reductions from simply manipulating the ignition advance with a true direct ignition system.

carbs and dizzys are yesterdays news, getting away from them is the first step toward making a more reliable, better running, easier to predict aircooled engine. this year I have built ONE street engine that was carbureted, with a dizzy!

Jake ? I know on T-1 it may be a waist of money but have you twin plugged any T-1s? We know this was done on the twin cammers with great sucess.

Would a smaller engine gain much in fuel economy?

No, I have never done this on a TI engine, but you might see it done in the future with a few.

MPG gains can be expected with twin plugs due to the benefits of the higher CR that can safely be ran.

I'd never set the CR of a twin plugged engine at less than 11:1,(on pump gas) at less than that the benefits are not being fully utilized.

Twin plugs open doors for more power through manipulation, the actual second plug doesn't add all that much 'power" at all..

Not much info but.......



http://www.shoptalkforums.com/viewtopic.php?t=112647

Twin plugs? Nothing new here as aircraft engines have done this for many, many years. BMW oilheads have twin plugs too.

Yes, the torque and power is great compared to one plug, but another benefit---extremely inportant in an airplane is redundancy. One plug fouls out of quits for some other reason---you have a working backup.

Jack, Hot Springs

Looks like the twin plugged Type 1 may be occuring a bit sooner than I expected:-)

Looking for 240 HP on pump gas woith ungopdly torque. The engine design is already done!!!