The XT intake is also tuned for an aggressive mid- and good top-end rpm range. Its shorter runners cannot deliver the low-range torque a big dual-plane carbureted intake or long runner EFI intakes such as the Performer RPM II do so well. Thus, it's optimized for relatively light street/strip cars--today's porky 4,000-pound Mustangs need not apply--with a bit of gear in the rearend.
On the other hand, the XT is not an all out racing intake for screaming 9,000-rpm small-blocks. That's what Victor Jr.'s are for. As Brent put it, "The XT is a tunnel ram with the throttle body in a convenient place for plumbing. If you wanted max power you'd have a pair of four-barrel throttle bodies on top of the plenum. But the [XT] runners are short enough that they won't be harmful at any conceivable rpm. The XT manifolds are capable of going to 7,000 or 7,500 rpm, and as they are, the XT are optimized for 6,500 or maybe 7,000 rpm."
Befitting a street/strip car, "the XT is more broad in its power. The Victor Jr. has one less turn for the air than this XT design, so ultimately the spider-type [Victor Jr.] would outflow the XT on top end. But the XT offers equal-length, more tuned runners, so the average will be better, with more area under the curve."
As Brent ran us through the XT's development, we realized there are two XT intake stories. The first is the standard how and why of its design, the second is the design and development process itself. This is one of the first intakes Edelbrock has developed entirely in a computer, including the manufacturing tooling, plus prototyped using plastic rapid prototyping parts. The result is the first XT intake cast in Edelbrock's foundry was nearly the first production part.
Brent started the XT's design by laying out the core, or inside of the manifold on his Pro Engineer software. At this point, "I paid attention to runner area and runner lengths," plus the important blend of the plenum into the runners. This aperture was made 2.8 square inches, with the runners slightly tapering to 2.05 square inches at the cylinder head end. "This is the only taper or change in cross-sectional area in the intake," said Brent.
"There is another [computer] file of the casting, which has all the bosses, the draft, so you can see all the parts, see the actual manifold," Brent explained as he moused over the XT's design on his computer monitor. "This is the second piece of the puzzle." Additionally, besides the core and casting files, there is a machining file that shows the intake after its trip through the CNC machine. "The core, the casting, the machined piece; these three files are joined into the "assembly." As you can see, it's starting to get pretty complex." And for a simple intake layout we had to agree as he rolled the stick figure XT intake around.
This assembly of Pro Engineer computer files was then imported to an existing file of a small-block Ford V-8. "This allows checking the distributor clearance and other crashes that may occur," Brent explained. "The throttle body was placed so you could get the cap and rotor out without touching the manifold. I checked the fuel rails, the cylinder head, the rocker cover rail... you can you get a wrench on the temp sensor with the valve cover on, you can line up the linkage for the throttle brackets..."
As Brent pointed out, when working with later-model cars the CAD files of the entire engine compartment are available from Ford, so the Edelbrock intake can be electronically verified in the car and under the hood before the first intake is ever made. Obviously this saves weeks of pattern making, casting, and redesign.
Finally, the multi-part computer file was sent to a Dimension 3D printer where the intake first took material form overnight as a plastic part. One computer step not taken with the XT intake was a CFD or Computational Fluid Dynamics analysis. This is where the intake's flow path has electronic air sucked through it by an electronic engine to arrive at a "video" of the air molecules racing through the intake. Edelbrock certainly has this capability--they showed us a fascinating CFD file from another intake--but the cumbersomely slow process (on less than supercomputer architectures anyway) was deemed unnecessary for the simple XT intake. This is, after all, not Edelbrock's first rodeo.
Insuring no lack of air to the crate engine is Edelbrock's newer 90mm throttle body. This is an evolutionary piece designed to iron out the installation wrinkles in previous throttle bodies while assuring adequate airflow. Highlights of the new 90 are it uses a Ford TPS and IAC valve for easy, familiar parts availability. And, Brent pointed out, "It has the left-side linkage, which is proper. You no longer have to use the right side linkage, which required snaking the throttle cable to the other side of the engine."
As an aside, Edelbrock has air intake elbows for fitting EFI to single-plane carbureted intakes and the new 90mm throttle body works on these elbows as well. "So, if he has a Victor EFI manifold and electronics, now he can run the Ford 90mm with the proper IAC and TPS," Brent said.
So, after all the computer design and prototyping, sometimes it still comes down to a little dirty work in the grinding booth during final development. By the time you read this the injector bosses were long ago slimmed down for production manifolds--something easily done when you own your own foundry--and the XT system should be on sale. When you step back and take it all in, the XT is a remarkable achievement for an aftermarket company. To design and build a complete, dedicated carburetor-replacement system is no mean feat, after all. And with this new intakes, the recently released E-Force supercharger, and continuing crate engines, the Big E is definitely in the hunt for Ford performance.
Tariff on the Ford version of the XT intake system was not set at our deadline. However, a Chevy version of the system is already on sale thus giving a good idea on Ford pricing because both systems include the same parts. For a complete Pro-Flo XT EFI Intake and System expect about a $3,300 price tag. This is a complete carburetor-to-EFI conversion kit and includes the XT intake manifold, fuel rails, injectors, distributor, XT ECU, Calibration Module, wiring harness, oxygen sensor, fuel pump, and small parts.
The XT intake manifold by itself should be $420, roughly. The XT cylinder head, dressed with valves and springs is just over $1,000. Edelbrock's existing 347 Ford crate engines, which are complete, with a single carburetor, start at about $9,600 so adding the XT upgrade means they'll certainly be over $10,000.