Rebarreling and Home-Shop Machining

So far everything is a go.  This is an install of the Suzuki GSXR 750 motorcycle throttle bodies (see the topic below) that will be installed onto the Ford Focus 2.3 liter Duratec motor.  Note that this installation will not pass a visual state inspection in some states but hopefully will pass all the emissions tests and may add 20-25 horsepower.  Before and after tests on a G-tech unit which can calculate horsepower will be included. 

Picture 8 and 9 show some machine work which will be required on the throttle body. The large hole is where the stock Suzuki Fuel injectors go.  Fortunately, the Focus has a fuel injection rail and injectors that go straight into the head.  Instead, I plan to use these large size holes to inject EGR.  This will improve NOX emissions and prevent the engine computer from throwing a trouble code.  There is a small unused boss to the left of the fuel injector hole.  This will be drilled 1/8 inch and a hose barb of some kind installed.  This 1/8 inch hole will enter the throttle body bore just aft of the closed throttle plate.   The EGR enters just in front of the closed throttle plate but is normally off at idle.  I plan to build a 1/4 inch vacuum hose manifold to inject idle air from the idle control motor on the small boss.  This will let the computer control idle and boost idle on AC and high Temperature as is normal.

I completed the drilling and threading of the fuel injector holes.  (This was a ticklish job dueto very thin castings.  It might be better to make dummy injectors and press these in with a permanent clamp using the stock injector seal  There is a threaded clamping hole near the top of the brass fitting.)  I drilled the injector hole 9/16 diameter and 1/16 inch deeper to add another thread.  There was some tearout that can be seen in photo 12.  This area will be sealed by High temperature copper containing RTV.  The 1/4 copper pipe that goes through this fitting extends all the way to the bottom of the fuel injection port.  This was allowed by drilling the compression fitting out 3/8 inch on the lathe.  Any additional space in the hole was filled with 1/2 inch copper pipe so that all RTV layers are thin.

The 1/8 pipetap that I had a long but gentle taper.  After making three to four threads in the throttle body, the compression fittings still would not start.  I cut 1/2 inch off the buisness end of the tap with a 4.5 inch grinder equiped with a cuttoff wheel while it was turning in the lathe.  This allowed it to cut bigger threads.  This worked OK.  I finished by lapping in the threads of the fittings with some 320 grit compound. This created a little more engagement and allowed me to tighten them fully.

I needed two vacuum taps, one for Absolute Manifold Vacuum and one for Idle Air Injection.  There were a couple of unused bosses in approximately the right places.  Photo 6 shows drilling  the rear boss. I used a transfer punch to center punch the hole.  Then I used a center drill followed by a 3/16 inch drill.  I found a plastic 90 degree fitting that could be tapped gently into the hole with sealant

The quad throttle bodies required dissasembly.  Remove rear butterflies.  The rear butterfly shaft is one piece.  Remove two throttle bodies, then remove this shaft.  There are six springs and four rubber tubes and a felt gasket (on the threaded end of the shaft)  that must be reinstalled.  See picture 6.

I needed a port to inject idle air from an idle air motor.  I used the unused boss beside the fuel injection port.  I set this up to drill on the drill press by angling the table.  This was a pain due to the need for shims and tall clamps.  Instead I drilled the last two by hand and had better luck.  When the big hole was 1/4 inch deep I center punched the bottom of the hole near the back and drilled 1/8 inch to the throttle bore, keeping the hole back as far as I dared.  This nicely positioned the 1/8 inch hole inside the throttle bore to completely clear the throttle plates at all positions near idle.  I finished up by drilling the large hole about 3/8 inch long. See picture 4 and 5

Photo 1, 2 and 3 show the almost complete Throttle bodies.  I have made manifolds for several items which I will discuss a little. 

Idle Air Control  (IAC)

The stock ford manifold has an idle air control motor that bleeds air from before the throttle plate into the plenum after the throttle body.  Since there is no after throttle body plenum, any more, I thought I would inject air just aft of the throttle plates through an unused boss which I drilled.  I made sure the path to each throttle body was identical to insure a balanced idle.  The idle can be balanced further with the inter throttle body adjustment screws.  I am thinking this won't be neccesary as they are balanced at the factory andreassemble in a very precis manner.

Exhaust Gas Recirculation (EGR)

The Ford Focus EGR injects semi water cooled exhaust gas directly through the head into the front of the intake plenum.  I was wondering if there was efficient mixing to keep this balanced between the cylinders.  To insure this, I made a copper manifold where again the path lenght number of 90's etc would be the same to each cylinder.  This manifold may run a little hot but is sure to be cooled off to decent teperature before it reaches the throttle bodies.  I have used high temperature sealant at the Suzuki Air injection ports and plan to use 2% silver bearing solder in the manifold. Both of these products are rated to about 700 F.  The Throttle body itself will actually be self cooling from expanding gas. None of the rubber hoses nor the Susuki air intake plenum will touch these copper pipes.  I have mades some minor changes to insure this from previous photos.  The first 90 out of the injection port is now a little lower in photo 1.

(Absolute Manifold Pressure)

The Ford system measures Absolute Manifold Pressure inside the plenum after the throttle bodies but before the runners.  This is used to calculate engine load and thus fuel delivery.  I have no vacuum there so I will rum a vacuum line and make maybe a small chamber for the sensor from Vacuum taken after the first throttle plates.  I have summed the fourcylinders to avoid vacuum spikes and to average the vacuum.  This line will also purge the evaporative canister and run vacuum operated engine controls.

I took a used Suzuki airbox that was advertized to be for the GXRS 750/1000.  The throttle body clamps are a bit too large for my 42 mm throttle bodies and will require a rubber shim.  This clamp can be seen on the left in photo 14.  I removed one of the stock inlets with a zip bit in the Dremmel and the Dremmel large course Drum Sander.  I removed the internal filter and removed the plastic support near the Trumpets to smooth the air flow.  This required sealing the outside as a narrow crack developed.  I removed part of the flange just past the stock holes on the part of the Spectre inlet near the bottom in the photo.  The flange here is fit into a slot cut with the zip bit into the airbox.  The box can still be opened but the part near the inlet will require resealing with RTV silicone.  Now I just hope I have enough space for this generously sized box.  On the top most part of the box save some material from the stock inlet and fold it inward with a heat gun.  Clamp two short metal blocks to it to grab with the vise grips.  Heat near the edge and bend in.  Then sand the flange area mostly flat on a belt sander.

Picture #18

My intention was to use the Suzuki throttle position sensor to sense the main throttle blade position.  This will require some experiments of which I completed the first.  According to my tech the ford sensors normally work on 5 volts.  Full throttle will detect as somewhat less than 5 volts.  Closed throttle above zero a small amount.

I have a variable power supply that I can supply 5 volts.  I connected plus and minus to the Suzuki yellow and blue lead which are low in the pictured plug.  I sensed the voltage at the black wire which is high in the plug.  Firstly hooking up the power supply drew less than .01 amps.  This is good as things are not overheating.  Throttle closed was about .010 V.  Throttle opening saw a nice smooth increase in voltage to about 4.9 or so fully open.  I think the ford computer will readjust to small differences in wide open and full closed as there is bound to be a 5% or so variability in one part to the next.  Anyway another short test of the car will see if I am matching closely enough.  Use of this TPS will make the assembly neater by requiring less fabrication.

The TPS slides down a flat blade that becomes the throttle shaft.  You can see the secondary throttle plate blade which is similar.  You also get a spare TPS with this throttle body as the Secondaries have an identical position sensor that will not be used.

I used a hot air gun to soften the air box in the vicinity of the small copper 90's that will feed hot egr to the manifold.  This gave them about 3/8-1/2 inch clearance on the airbox. Pic 19.

I found an ABS coupling for flat drain pipe at Lowes.  I cut a piece of this 1/8 inch materialtoseal the unneded end of the airbox intake. Pic 20.

Pic 24-25-26-27

Air Intake Box is ready for glue. I put a cut down 4 inch plastic intake under the Aluminum intake to add strength and to fill the bottom two corners where the Aluminum intake flange lacked material. A couple of holes are left and will be filled with the 3M 4220 plastic mender. Also visible in this shot are the two islands that used to support the Suzuki air filter that will not be used. Left over is a gap. This will be filled with the plastic mender from the back and then smoothed over on the front. Surfaces must be scuffed and treated with an ABS primer which I bought at Lowe's. This will dry leaving surface tacky. The glue and primer are best used outdoors.Here is a picture after the glue up and a report on the glue. The 3M 4220 plastic mender comes in two large syringes. The 3M tool to squirt these is about $75 and is a good investement for a body shop. I cut two equal length dowels and used a standard caulk gun to push on the syringes. I sealed the two long seams along side the trumpets with one long smooth nice looking bead from the outside of the case using one of the self mixing tips. I smoothed the inside with my finger. This is really about all the time you have with this glue. Less than a minute before it starts to set up.
I used a second self mixing tip for the air inlet. I put a bead of sealer under the 4 inch plastic flange and on top of the plastic flange followed by the aluminum inlet and then four screws. I just barely got them tight before it all turned into a brick.
With the tips used up I then mixed the glue on a piece of heavy polyethylene. It is very liquid when it comes out, mixes and starts to stiffen very quickly. I applied it like putty to the inside of the plastic flange to smooth the air transition into the box. This worked OK but was not very smooth when I finished. I sanded it smooth and rounded off the corners. I sands and feels like a hard rubber when cured. The outside looks very much like the previous photo. Not much mess there.
It may be that Suzuki offers replacement trumpets at a reasonable price. This will allow some length and diameter tuning. Mine are a bit large in diameter, so maybe they are from the 1000 cc bike.
You might think this is a lot of work on an airbox until you price one from an aftermarket supplier.

This will probably be a long topic so as not to dilute the other content of the Journal so check back every couple of weeks.  There may be more photos and progress in the topic above.

Thread on FocalJet.com on this project.

John

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