While trying to make the jigs to drill my heads for twin plugs I ran into a
major problem. Where is the plug going to be located on the bottom of the head.
I made up this jig to located where the plug will be located.

Angle jig
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Test jig installed
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Installed
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Bottom view
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There are pics here or on STF or Jakes site.

Jake has done this and he ended up in the same place, for the same reason.

Rich

Nice idea for a jig.

It's quick and dirty and shows what is going on.

The next problem you are going to have is how to get enough material in that location for the plug to seat.
You are about to see why this costs so much.

And you'll still have to choose the plug carefully, make a socket to remove and install it and find the perfect spark plug wire for the lower set of plugs.. Have fun

That sounds like experience talking.

It's a little daunting trying to drill two angled holes in each head when each hole is at a different angle to each of the x axis, the y axis and the z axis, and not parallel or perpendicular to anything on the head.

Thats why I'm making jigs up to locate the holes, and yes it hard to drill the
hole but my mill can handle it after I modify it. After I'm done I can modify
a good set of heads.

I hope you're able to figure it out, that's a pretty cool project. not anything i'd use (v6 car here) but it's sure cool to watch your progress.

This is the engine I'm going to try them on. My version of a type 547 engine
Click to view attachment

The fan does cool the engine.

What are you hoping to gain from all this?

So I can say "I did it."

.I think that , based on some old 4-cam carrera information., a twin plug engine -a type 4-engine, could see a 5-to 15 percent increase in H.P....the more radical the engine the higher H.P. potential.-to a 15% increase....MM

What are you doing for a dizzy?

I'm using Megasquirt rotary option ( design for Mazda 2 rotor engine) to fire
the fire the plugs in wasted mode. Circuit has been tested and works on my
simulator

The heads will require lots of welding to accomodate the second set of plugs. Having done this to several pairs I can tell you from experience that it is a lot of work. Like Jake said there is a reason that it is expensive.
Good luck Larry!

Good enough

Curious... why a bus head? Are you planning a lot of other machine work as well?

Just a set of heads I had laying around, if they work out thats OK for a test.
Better to trash bus heads than a good set of 2.0 ltr heads.

isn't that angle going to be REAL close to the Exhaust?

In the 911 engines, going dual-plug generally lets you run about one full point more of compression on the same grade of fuel without detonation. A fair bit of the extra power comes from the extra compression, from what I can tell.

The 914 chambers are very different from the 911 ones; not sure how much (if any?) more compression you can run in them.

--DD

The plugs will be mounted on the intake side of the valve.
I'm trying to keep them away from the exhaust valve (heat)

If you succeed at this, the only logical next step is boost. Really, it is.

Oh wow!

Just noticed that they are squareport exhausts too.

This is going to be a fun project for you. If it was me and I had several scrap heads, I'd probably take a take a dremel and a drill to one side of the head to learn something about the available material, where you will break through, and where more material is needed.

In the end, success will lie in decent machining fixturing.

If a lot of welding is required, you may have to heat treat the heads to restore the precipitation hardening. A lot of people don't realize that when you weld aluminum that is T4 or T6, welding removes the hardening back to soft condition. That process requires a bit more heat than a cooking oven can produce.

Good luck,

Ken

Vacuum furnace type heat treating?

I have been chasing reading material down on this stuff, I found a local place that has the facilities. I would like to start getting own stuff done proper.

You are like a vault of random valuable knowledge.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...4=263602_263622

You can get everything on ebay now. Wow.

Nah, vacuum or inert gas heating is for titanium and some precipitation hardened stainless steels. Might be more uses but I know those two uses well.

Aluminum is ok in air and I think precipitation hardening is a little over 1000 degrees F.

Thats what I plan to do if they work on my test engine.

Having done my first twin plug TIV engine in 1999 I have learned there are HUGE capabilities to be unlocked with the addition of a second plug in the chamber.

The second plug starts another flame front and the two meet in the center of the chamber, reducing overall timing necessary and increasing efficiency greatly.

BUT when this is done all standard engine combinations and compression ratios are thrown out the window, else the result will be an untunable engine that makes no more power than a single plug.

The key is cylinder pressure and a large bore. The large bore LOVES the second flame front. I do not twin plug a TIV engine with a bore smaller than 102mm because the gains have proven to be nil due to bore size.

To date the most power we have made on PUMP gas with a 2.9 liter engine is 274HP at 6,400 RPM with twin plugs. Combinations as small as 2393cc (with a 105.07mm bore) have made as much as 265 HP. The 2.9 liter engine in my Wife's beetle back in 2007 made 249 HP with twin plugs and put down 200 of that to the rear wheels on pump gas while attaining 35 MPG figures on the highway.

It took more than five solid years for Len and I to figure out the best way to outfit the heads and just recently have I complete the ignition system that allows twi plugs to be applied easily.

Its a never ending evolutionary process...

It wouldn't break my heart if we didn't do any more twin plug T4's. Big pain in the a$$ for the guy doing the heads!

if 250+ HP is achievable it may extend the long term attraction to aircooled motors.
I for one am looking at the subaru just because they figured out how to get over 300hp out of it...which is impressive considering the displacement and architecture.

What type of torque are you seeing in your large displacement twin plug motors?

Rich

Its more than achievable, Len and I have been doing it since 2006.. I had actually done it as early as 2002, of course normally aspirated.

The engine that made 274HP made 280 lb/ft of torque at 4K. The 235HP engine made 250 lb/ft @ 3500. The 250 HP engine made 265 lb/ft at 4,200 RPM.

Those are the 3 that are the most memorable.
of course today it is more accepted to bastardize cars, so less people are looking to the -4 to make these kinds of extreme numbers. All the engines I mentioned above were for VW conversion customers.

Are you still making/selling the twin plug heads?

Rich

Only for turnkey engines. These heads do zero good in the hands of those that don't know how to apply them.
I wasted thousands dollars learning what didn't work.

Len hates to do the work, he is working on the only twin plug heads he'll do all year right now....

Jake. I am bound by circumstance to butcher for my speed fix.

I have to admit it, the only real reason i am shying away from a big power Type IV or a 6 cylinder Porsche motor is simply due to cost.

Instead of wasting anyones time talking, thinking I just know I can not afford it. I am ok with that, but still love to see them.

I see the merits in staying air cooled for simplicity and can see serious power.

274hp at atmospheric pressure out of an air cooled type IV is insane. You are now almost at 100hp/l and that is a type IV. Not a honda cylinder head.

To give you an idea the 2.7l stroker/bored out K series honda guys are getting to 300whp just now with a very well though out port design, electronic cam phasing, and very well thought out internals. On a motor i dont know, 40+ years newer.

But, I look at it from my single income wife/kids perspective and it is just out of my reach, at least at this time. I know it takes a lot of quality materials, and R&D to achieve those results and thus why it costs so much.

I also know there is no compromising getting those results from something like a type IV.

Thus, no big power type IV for me. I think a lot of others are in the same boat. But to those of you doing big stuff with Type IV motors, I salute you.

It is 100% totally rad and respectable.

I hope to one day be in that spot to have something like giant displacement type IV with a 30R attached to it. But for now, I have commitments to my family and children that chew through money, energy cost spikes and inflation make it worse.


To the OP(904 SVO):

If you decide to go turbo, Precision's new billet wheel turbos are the bees knees. They get rid of the poor flowing Garrett wheels, and basically just use the CHRA with their own flavor of bearings, if you go the ball bearing route.

They will make equivalent or more power with better spool than a Garrett GT series, cost less, and I believe are made here. Garrett stuff is all chinese/mexinese now.

That or Borg Warner Bullseye makes some very nice stuff. They are more like a mitsu design, with the extended tip stuff. They are also very cheap to rebuild.

We've been at 100Hp/ liter for quite some time, but only up to 2300ccs or so... As the big engines get bigger the ability to achieve the efficiency to make the mark gets more difficult with a two valve head and pushrods, NA

The engine in this video is only 2.3 liters, based on a Type 1 and made this power with the fan belt and cooling system in place, here on my chassis dyno. It is a STREET CAR that competes in unlimited street, meaning it has to make 25-50 mile cruises, then take it to the track.

http://www.youtube.com/watch?v=EgwnJsCaHtw

Ten days later another engine that I designed put down 5 HP more than this one, also 2.3 liters.. Having two 500RWHP beasts on the dyno back to back is an accomplishment for me.

Twin plugs have great possibilities and we are still finding the perfect chambers, cams and dynamic compression ratios that boost their effectiveness... Its ground where few have gone before, so there are no rules, no questions that can be asked and no reference materials to follow. If their was I probably wouldn't be wanting to do it.
None of it is cheap and it never will be... Its also not super profitable for us and never will be.

There are cheaper ways to go that offer compromises. If I want something more modern, I just jump in my 996 and I reserve the vintage iron for what belongs in it and make that bastard haul ass.

I like the big engines too. I get pretty stoked when Jake sends me dyno graphs from the big boys with the twin plugs and all of the latest features.
Lately though I have been drawn to the idea of smaller more effencient engines, (the kind no one wants to buy because they cost as much as a larger engine) I would love to do a 1500-1600cc T4 and see how much over 100hp/liter we could get. We are making strides with our 1832cc race engines, where the rules force us to be super creative and take risks to get power, and we can easily see that specific output will go up as the displacement goes down.

Maybe I need to talk to you Jake.

Maybe I could find some sort of combination for my budget. I could be pretty satisfied with light amounts of forced induction and a water to air intercooler setup.

I am even ok with stock displacement.

I just worry about detonation, and internals. I also have no clue how to tune an air cooled motor. 100% newb, and tuning a car without a knock sensor until you hear detonation is not my thing.

I am kind of at a loss for words. That is soul ticklingly delightful.

Q for Jake - how much of the work you and Len are doing on combustion chamber design is based on experimentation, versus drawing from the engineering theory on this subject? There is a ton of research and practical texts out there that would probably be of use.

So when are the four valve heads coming out???

Have you made any progress on this?

This is why when I decided to twin plug 2 extra cylinders came into the equation.

Yes but I don't want the weight penalty of a 6.