Ak Miller's 200 six Turbo Kit

Thought you may get a kick out of seeing the original Ak Miller Turbo Kit for a 200 six.
Purchased the kit in 1990 for $1500 (less exhaust manifold and carburetor).
Blows 10# thru a Motorcraft 2bbl (1.08).
Been running her ever since; now it's time for a rebuild and I would like to pose a question to you guys.
I suffer from the same maladays most of you suffer with this log head; Cylinders 3 and 4 are always rich and the outers lean.
By the design, fuel distribution is poor but I also tend to think that poor atomization is to blame also.
so for the next rebuild; I'm going to go draw thru. My idea is that I can achieve a more homogeneous mixture with the air/fuel passing thru the turbo. Your thoughts?[attachment=1]Overall.JPG[/attachment][attachment=0]engine.jpg[/attachment]
 

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Draw through represents challenges that are not present with blow through. First of all, you can't intercool. Second, you need a turbo with positive carbon seals. Most turbos use a piston ring kind of deal to seal the shaft in both the compressor housing and the turbine housing, but engine vacuum can easily draw oil through that seal. I've seen carbon seal back plates and kits available for a few different turbos on ebay, so a little creativity and a couple parts might be all you need (I'm setting up my cj7 with a draw through turbo setup off a '85 pontiac turbo trans am, and I'm dealing with the same stuff).

Pipe dream setup: tripower with large square stock plenum to feed all three carbs turbo air from a single inlet?
 
Fix the fuel bAlance problem FIRST.

It exists because you need more points of dispersal, not a different kind of turbo kit.

Add three YFA Carters on an Offenhauser adaptor, and put the air mix bewteen the carbs at two spots above cylinder 3 and 4. Problem solved.


Ak Miller totally knew what he was doing. He did what he did because for a 10 pound boost, a 1.68 boost ratio makes another 68 horspower easily with a stock 1.08 Motocraft carb. For a time, the whole kit was CARB legal if you kept the gasoline emissions gear on pre 1980 engines, and most of his other kits were Blow Through Propane or Draw Through Gasoline with a Holley 4bbl.

Ak Miller basically looked at making sure the stock pistons wouldn't let go...his systems were all based on that one fact..with a stock engine, what can I add here?.

The answer? About the same as a good nitrous kit with perfect Excess fuel....about 90 to around 135 hp. He targeted about 68 hp increae on his 200's and 250's, and about the same on a stock 300.

If its a stock 3.3 automatic in a 2600 pound car with a 256 degree cam, you can add about 18 pounds of boost if you can get the fuel pump and power valve like Does10S[/b had on his older incarnation of Kellys Falcon turbo]....and you'll get a reliable 14.5 second quarter mile or better. For that boost ratio, thats 220 hp at the flywheel, up from about 85 to 94 hp net stock. If you wanna kill it, equal to about 300 hp net at the flywheel if its got over 20 pounds of boost. The little six can do crazy amounts of boost. Then it donates due to lean or rich fuel, which over loads the rings, overspeeds the engine, and it blows a head gasket or takes out a ring land. Or maybee a rod, although that's very hard to do with the 200 because its a lot stronger than a 250.


The way to stop making your 200 a pile under boost is to just add three Carter YFA's without a staged throttle. This is what you cal a postive way to create Excess Fuel Factor to avoid lean outs.


Add a Ak Miller style 270/290 cam withabout 470 thou lift, and if its a rebuld, have the machinist hone out the bores to a proper cylinder wall roughness measured by a proper lazer profilometer. If the shop doesnt have one, and they can't give you the included angle, the Rpk, Rk and Rvk readings, then you've got the wrong shop. Run away, and never return to it. All that old average Ra roughness count crap has ruined more engines with 5/64 compression and 3/16 oil rings under load because of what happens to the oil retaining part of the cylinder wall under boost. It destroys it if the wall texture is stock, and the oil evaporates. The crook air fuel ratios do the rest. Blow or draw through won't help or hurt, its about fuel wetting the whistle of those six cylinders properly.

The plug readings will tell you plenty, but the old timers like Ak Miller were very conservative, and he got sales to ensure he kept the engines on song under boost. If you llok at any article written about the late great Ak Miller by the late Jay Storer, you'll see that the engines were designed around the application, and that they were quite conservative, with ductile iron rings, or chromium if it was dual fuel and you could run them in. Things have changed. Metric ring packs are low tension, and require a much smoother finish with plaueau honing to a target Rpk, Rk and Rvk reading. An average Ra reading is useless for a modern rebuit Old 200 Turbo.

A good US made piston by Silvolite for the Australian 200 or 250 six will work great in a Turbo 200.
 
The taller 9.469" deck of the 250 vs the 7.83" of the 144/170/200 allowed Ak Miller some other options with the TC-1 and turbo position

Here are some pictures I found


AkMillarEnterprisesAME400250FordturboandTC-1contoller45.jpg



Verses your low deck 200


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some day...if I'm ever st my shop long enough I want to mock up a FISH carb with draw through.

question : the poor fuel distribution, does velocity of the fuel / air have anything to do with that distribution under boost?
furthermore, does positive pressure help hold fuel in suspension, even maybe bond fuel to air molecules?
 
Books have been written on gasflow in the propane performance book realeased in 1985 by the late Jay Storer and Ak Miller. Others like USA from UK transplant David Vizard have gone into air flow with sone detail. Nothing specific relates exactly to a log head Ford small six.

In my opinion, the specifics are what Ford found in the premium Ford V8s..
Supercharging, big carbs or many of them with large intake manifolds and big intake ports can work fine if the cam timing and compression ratio is right for fuel dropout to be avoided. Adding port area and size is not always good. Air speed increase is always bad: what is critical is the fluid flow geometrics; the number of flow paths verses the number of pressure drops. One carb is one flow path that has to be split into six rabbit holes on an inline six like ours. The pressure drops must be equal to the flow drops. If you add pressure, ie, turbo charge, you then must have more flow drops to avoid an air fuel ratio problem (rich or lean variance to each of the six cylinders).

Its in my opinion unlikely to create a better draw through or blow through single carb turbo fuel supply pattern by better carb design or "vaporisation/atomization"...there are six goals to hit with only one ball adminstered at one time. The molecular or particle theory of matter offers no silver bullet.

Ak Miller basically tried to get a 50 to 75% performance hike with nothing but an extra hit of fuel and he did try many other better ways to do that without turbos. He'd looked at minimum things to do on his performance journeys; taking a basic Small or Big Six, and just add boost on a low compression in line six. The whole package needs a whole lot more holes to work the volumetric efficiency and power curves. The measure of power is work done, with a speed factor. Injecting fuel right to the point of burning ensures fuel to air mixing isnt so much of an issue.

Others can discuss the postive attributes of creating high velocity, high airflow atomisation, and how smaller port area will help keep gasoline air fuel mix in suspension, but it is all at odds with one hole feeding six cylinders through the straw pipe that is a log head six.

Ak did the best job with what he had.

This should be a post not on my ideas, but on what is proven to work. Read stuff on what Ak did to make these things work, and copy stuff others have done. Mixing and matching is just fine.
 
that's a ton of stuff to diggest.
it will mean a read of the propane book for starters.
something I have every intentionof doing.
a propane blow thru turbo is simplest then I believe I like the ford efi on turbo next...
 
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