(Note: Posts labeled Intake Pictures 1 and Intake Pictures 2 correspond with this long post and can be viewed or downloaded separately)
 
After a lull in my previous momentum, due to motivation, time, money and other factors, I went and made some significant progress towards getting our engine in a runnable condition (depending on how you define significant...)

   Most of my effort of late has been centered on the intake.. this is one area in which I had deferred any significant work because of various reasons, the first and foremost of which was that I was waiting on the Turretine Intake to become available, and therefore save a LOT of energy, time and perhaps even money with regards to making my own intake. Well.. I discovered that the Turrettine Intake, with its straight-out orientation, was bound to interfere with the turbocharger installation we are going to use. I checked with Bruce and he validated that he did not intend for his intake to be compatible with a turbocharger (at least a traditionally mounted turbo).

   So.. back to square one. I had a cleaning frenzy a few months back and got rid of all the engine parts that I didn't think I would need or be using (such as rusted iron housings, stock intake parts, etc...). So I literally had nothing to start with.. shame on me (and Chris was a little peeved that I had disposed of something prematurely - not the rusted housings, but the intake parts). After following all the traffic on ebay for a few weeks looking for a carbureated intake manifold that I could adapt to our needs, I realized the most economical way at this point to achieve success was to "roll my own". I ended up purchasing a stock 2nd gen lower intake manifold from one of the list members here for part of my plan, and cut it off a few inches above where it mates to the block. This provided me a "90 degree bend" that would use conventional stock intake gaskets and already had the right bolt pattern. The intake passageways were not quite round at this point, but that is not a problem in the long run. Pictures are in a separate post.

   Based on the measurements of those intake passageways, I chose runners that were 1 1/2" and 1 3/4" ID aluminum pipe/tubing. I obtained several pieces in 4 foot lengths that I could cut down to the desired length as the fabrication proceded. I originally figured that I would be having to fabricate the other end of the intake (that mates to the throttle body) our of fiberglass or aluminum or something.. I hadn't quite gotten there yet - one mountain to climb at a time. Well, I was doing some other stuff in the garage and happened across  an engine intake part that I did NOT know I still had - an upper intake manifold. I had a turbo 2nd gen UIM already attached to a throttle body in my junk pile, and its geometry did not lend itself to the type of install I wanted to do. This unexpected find was of a different type (perhaps from the normally aspirated junk core that Chris had given me a while back.. who knows) that would apparently work for what I had planned (runners over the top of the engine, TB on the plug side of the engine). I cut on it as much as I could with the dremel at home, and then took it up to the airport and used some of the tools there to finish the cut, leaving me with a remaining upper intake manifold that consisted of the initial plenums and the beginning of the runners (about 3-4" worth) that exited at an oblique angle. This would allow the runners to come in from the top "corner" and allow the TB to be mounted horizontally. Perfect!

   I came back home and began working on a stock throttle body to see what could be done to simplify/lighten it up. First off, I removed the SECOND butterfly pair from the secondary flow path. This leaves just the primary butterfly and one secondary butterfly. Drops a little weight and complexity. Next I removed what appeared to be throttle position sensors and any other instrumentation from the TB. These are not used on Tracy's ECU, so they are excess weight. I traced each of the 6 "nipples" (3 to a side) off the upper intake, through the black plastic spacer to where they emerge in the throttle body. Turns out TWO of them independently plumb the primary runner plenum, so this would be an excellent choice for the two independent tubing runs for the EC2. The upper deck is also plumbed by one of the six nipples, so an upper deck pressure (between the TB and turbo) is measurable.

   As of present, now all I have to do is bend and weld the runners. There will be a little creativity involved, because the runners will need to diverge at the oil fill point, then merge back together into the upper intake manifold just past this point. I intend to have a straight oil fill neck at the fill hole on the center side housing, so that oil can be checked and added all at the same access port. One issue that I will need to be VERY cognizant of is access for the spark plugs. I need to make sure that the intake/throttle body extends past  the plugs far enough that there will be adequate access to remove and replace the spark plugs. It would NOT be a good engineering approach to have to remove the intake to access the plugs. One other point is the matter of structural support: I intend to fab some runner supports on the aluminum tubing/runners that will take advantage of the bolt races on top of the rotor housings. Also, the motor mount studs on the plug side of the engine appear a good location to place some sort of pedestal mount  to support the Throttle body so that there are no flexing loads placed on the runners and tubing. Again, doing all this without making spark plug replacement a contorsionists nightmare will be the plan, but all of this appears to be easier than what I had staring me in the face: making the upper intake by hand.

   There are several features to the stock throttle body that make it attractive. The first is that there are separate butterflies for the primary and secondary runners. This allows airflow at low power settings to be channeled mostly through the primaries, increasing the flow velocity through the primaries. Given that Tracy's (and the stock) ECU "stage" or turn off the secondary injectors at low power settings, this would appear to enhance low speed/low power operation by allowing better mixing of the fuel  and ensuring the fuel charge is sucked in completely by a brisk primary airflow. The folks running ONE large TB lose the ability to divert airflow at low power to run through the primaries. This limits the low end of the operating spectrum and can result in higher minimum idle speeds. Another plus that I re-discovered today was that there are essentially TWO separate methods to actuate the throttle. I am presuming one is for the stock "cruise control" feature and the other for the traditional foot pedal. While I dont envision running two throttle cables, the ability exists. Given that if a throttle cable fails, the failure mode is for the throttle to close, a second throttle can be used to hold open the throttle if need be. Again, this may be overkill, but the ability to do so is built in to the TB. The other nice thing is, the contraption is already sized properly for the power we intend to make with this engine, so it takes some of the guesswork out of things.

Ok, the pictures are as follows:

The first series (Intake Pictures 1) are the upper intake manifold as cut. UIM1-4 show differing viewing angles of the upper intake manifold

The next picture series (Intake Pictures 2) shows the stock throttle body and its mating with the UIM. The first pic shows the removed parts beside the TB. The next two show the stock cutoff manifold attached to the TB with its black "spacer" ring in place.

Dave Staten