Twin Turbo Small Block Master Plan


Okay, I'll admit it Turbocharged applications have always fascinated me. So I came up with this idea for a great combination based on the parts I already have with the twin turbo twist added in. Although I have yet to build this combo and it will probably be a few years before I get done with it, this is the game plan.

My long term goal (not really all that far away) is to have a good carbureted street Mustang capable of 12 second blasts down the quarter mile, but also have a second Mustang as an all out race car that is still streetable enough to cruise in and take to work occasionally. I have gathered, or should I say accumulated, most of the parts for the drag car in the last 10 years. So the master plan calls for a naturally aspirated dual 4 barrel 306 (302 bored 0.030) that should run mid to low 11s when properly sorted out.

The Parts List is as Follows:

* '68 302 block bored 0.030
* Stock rod and crank with excellent fasteners
* TRW pop-up pistons (L22xx)
* '69 351W heads full port-polish and 1.94/1.60 valves
* Ford Motorsport A313 solid lifter cam (282°/292° duration, 238°/248° duration @ 0.050 lift, 0.512"/0.536" lift)

and as icing on the cake -->
* Edelbrock XF8 dual 4 bbl cross ram intake
* (2) Holley 450 cfm double pumper carbs
Twin Turbo Small Block Master Plan

Of course there is more to it than just motor, therefore the rest of the combination goes something like this:
* Early '80s Mustang coupe @ about 2,700 lbs.
* Stock type suspension set up for drag racing
* Lakewood scatter shield, 11" flywheel, street-strip clutch
* Ford Toploader 4-speed
* Ford 8.8" rearend w/ 4.11+ gears

Okay so your wondering how I came up with mid to low 11s. Well Drag Strip Plus tells me that this combo if properly sorted should be good for a gross horsepower rating of 480+, and a net rating of 380+ Hp. That’s a lot of oats for such a simple combo, but certainly possible considering the low to mid 10s that the cars are running in "Hot Street" competition at the Mustang shows.

But in the long run no matter how fast you go it never seems like enough - so I'll go ahead and plan on going faster when the naturally aspirated motor above becomes a bore. You guessed it - this is where the interesting twist of the twin turbos comes in. I figure that by getting some junkyard turbos from a turbo T-bird, Mustang, Merkur or some Chrysler product and using some ingenuity can build a 10 second Twin Turbo Stang. Now this sounds pretty easy on paper but it will actually take a lot of fabrication and time to get the combo correct.

So where do I start - well #1 I have to have a plan and as you can see I already have that. Second I need to educate myself further on turbo applications, so I plan to read and review all of the references below. Next, my combination for the drag car above is not the perfect turbo setup - the cam and compression ratio could use some work. I may decide that a Motorsport A4 block is the way to go also and build the entire system then drop it into the car. Last, build the combo together and test / tune until satisfied.

That is what the plans are in a nutshell. I’ll update this page when the work begins so it may be a while. But if my twin turbo plans fail then I can always use the parts I have and build a cool twin nitrous Stang.

Turbo Food For Thought:

Check out this cool info I found in the Ak Miller Turbo catalog.

Twin Turbo Small Block Master Plan

First, this is the single turbo kit for the small block Ford. Items of interest include the exhaust crossover from the passenger’s side to the driver’s side and the special exhaust manifold on the driver’s side. This is a "blow-thru" type system where the carburetor is after the turbo.

Twin Turbo Small Block Master Plan

This is a closer look at the drivers side exhaust manifold - all exhaust from both sides exits the front of this manifold (toward the front of the car) and goes through the turbo.

Twin Turbo Small Block Master Plan

I thought this was an interesting picture of a "draw-thru" type turbo system on a big block Ford. In this system the carburetor is before the turbo.

Twin Turbo Small Block Master Plan

I know this is a Chevy motor but it illustrates a "draw-thru" type system in the twin turbo configuration. Each carburetor is mounted to the inlet of each turbo and then the two turbo outlets are connected at the top of the intake manifold.

Twin Turbo Small Block Master Plan

Two last pictures show a twin turbo small block Chevy with a single carburetor. This is a "draw-thru" type system with a special carb adapter.

Twin Turbo Small Block Master Plan

This is a close up of the carb adapter. The adapter is divided into two chambers. The carburetor sits on top and the air / fuel mixture is directed out the sides towards the turbos. The turbos pressurize the mixture and send it back toward the adapter. The mixture goes in the front of the adapter and directs it down into the intake manifold. COOL!!!!

You may also be interested in . . .