KJ Jones Senior Technical Editor
August 1, 2009
Photos By: KJ Jones
Rocco Acerrio of A.R.E. Performance and Machine gives Racecraft's all-new fabricated 9-inch rearend housing a final cleaning before setting Strange Engineering's pro-geared, spooled third member in place.

Quickly bringing you up to speed on our latest full-fledged project, Boss 340 is an engine and race-car effort that we've been working on and covering here in the magazine for the last two years. This summary is more for those of you who are new to the mag. From this point forward, we hope you'll visit our website or consult past issues for the full lowdown on this exciting effort.

The engine side of the project centers on a Probe Industries-built bullet that features Ford Racing Performance Parts' 8.2-deck Boss 302 block as its foundation. The block is filled with forged rotating internals from Probe, Comp Cams' solid-roller bumpstick and valvetrain components, and is topped with Wilson Manifolds' Boss 302 single-plane EFI intake manifold (a custom piece derived from CHI's 302 intake manifold), 1,130-cfm throttle body, and Air Flow Dynamics' canted-valve, Cleveland-style aluminum cylinder heads.

Before removing our '90 Mustang LX's 8.8 rear and suspension pieces, Rocco uses a measuring tool to determine exactly how much angle the factory housing's upper-control-arm mounts create when the arms are installed. We measured 16 degrees of angle on each double-adjustable arm, and we'll use this as a baseline for positioning Racecraft's tubular arms in the fabricated 9-inch rear.

We're not aware of any other late-model Mustang magazine that has built this type of radical stroker (which, by the way, roared to the tune of 8,500 rpm on an engine dyno and put nearly 600 all-motor horses at the flywheel while doing so) for dyno testing or some other purpose. As you can imagine, our other purpose is installing the Boss engine in a Mustang. So when Editor Steve Turner asked what type of 'Stang it's going in, the answer came quickly and easily: We will use the '90 LX mentioned earlier in this report and build a drag-race Mustang, also named Boss 340.

That's the quick-and-dirty synopsis. Additional details to bring you up to date can be found in our intro story, "Here We Go Again," in the May '09 issue of 5.0 Mustang & Super Fords-and also in "Frontal Assault," our June '09 issue's play-by-play coverage of Boss 340's front-suspension upgrade, which actually is the precursor to this month's topic-the 'Stang's rear suspension.

Yes, we're ready to bring up the rear, so to speak. In this effort, we replace the project Mustang's original hind quarters-consisting of an 8.8 rear, adjustable upper control arms, stock lowers, and no brakes-with Racecraft's all-new, totally insane fabricated 9-inch rearend housing, as well as pairs of tubular upper/lower arms and an adjustable antiroll bar. Complementing Racecraft's collection are bulletproof rearend innards such as pro gears, a Pro Iron third member, 35-spline axles, and a spool, along with coilover shocks and drag-spec brakes, all from Strange Engineering.

In drag racing, being able to use all of a Mustang's rear-wheel horsepower is a major concern for any driver who wants his Pony to cover the distance as quickly as possible. Efficiently putting power on the pavement is key, but it also becomes more-and-more challenging when large amounts of horsepower are involved. Our intention is to run Boss 340 on a 10.5-inch-wide slick (with and without nitrous oxide), while kickin' and stickin' a McLeod twin-disc clutch and Liberty pro-shifted, four-speed transmission, which is somewhat similar to the way competitors in our NMRA Real Street class get it done

Keep in mind the importance of putting power on the ground on racing surfaces that typically vary between good, marginal, or really bad at different tracks on the PSCA circuit. During the summer, temperatures on the West Coast can sometimes top 110 degrees and wreak havoc on the 1,320. As such, the need for our project ride to have a strong, tunable rearend and suspension is critical if we want Boss 340 to perform like it should.

The following photos and captions provide a deeper look at our car's new, super-stout Racecraft/Strange rearend apparatus, with installation by Rocco and Tony Acerrio of A.R.E. Performance and Machine in Simi Valley, California. Check this out!

Weights And Measures
We explained in our Boss 340 introduction ("Here We Go Again, May '09 p. 60) that we really want to keep the 'Stang from becoming a super heavyweight. Our objective is to hopefully keep weight (with the driver) to between 3,100 and 3,250 pounds as opposed to the 3,500 pounds that our T-top '86 notchback carries, so don't be surprised if you hear reports that your tech editor is eating more salads instead of steaks, and doing whatever else may be necessary for achieving our lightweight goal.

We're using a set of Proform Parts' cool digital vehicle scales (PN 67650; $729.95) to keep tabs on the Boss' weight gains and losses. Available through Summit Racing Equipment, the scale system is all-inclusive-pads, 20-foot data cables, screen, carrying case-completely portable, capable of calculating weight-per-individual-wheel values as well as total vehicle weight (and front/rear percentage weights) for any vehicle weighing up to 5,000 pounds, and most importantly, accurate to within 0.1 of 1 percent.

We'll be lowering Boss 340 on the Proform pads throughout the remainder of the project. For now, the idea is to see how heavy she gets-or how light she stays. However, once the Mustang is race ready, the scales will play a bigger role as they'll be used extensively when we make chassis and suspension adjustments on the Boss.