Kevin Peterson at JBA Headers is the wrench behind the carbureted and blown small-block. He designed the pistons, picked the cam specs, and put the TFS Street Heats together. His choice of valvetrain parts is certainly eclectic; the engine features 1.94x1.625-inch stainless steel Ferrea valves, 1.6x1.7:1 Crane Gold Race aluminum rockers, Isky valvesprings, Del West titanium retainers, Crane keepers, and Probe stud girdles.
Anyone needing proof that an A4 block is a good investment should consider this block has served numerous times on the dyno, track, and street, and is still up to more than 900 hp. The usual machine prep and freshen-up by JBA Racing Engines was all that was needed. Currently the bore measures 4.066 inches.
Petersons power plan called for simple engine internals, a really big cam, and really big boost. To make the desired 30 pounds of boost, this early Novi 2000 blower was selected from the JBA parts locker.
From any angle, the carbureted and supercharged combination has a distinctly individualistic look to it. The intake is a free-breathing Edelbrock Victor Jr., while the valve covers and dual breathers are dyno-only parts. In the Mustang, the engine wears an exhaust-driven crankcase evacuation system.
Another long-term player is this quality forged-steel Crower crank. As is normal for an internally balanced small Ford, plenty of heavy metal was necessary, but this has no doubt helped longevity. The stroke is 3.125 inches, for a displacement of 324 ci. Other internals include 5.350-inch-long Crower rods, Arias 8:1 reverse-dome pistons, B&B tool steel 0.120-inch wall wrist pins, and Total Seal piston rings. The oil pump is FRTs high-volume unit and the balancer is by BHJ. Its all sealed by a Canton drag race oil pan with windage tray.
One look at these massive lobes and you know something big is going on. Peterson went to Lunati for his solid roller cam, and didnt want to say much more than it comes close to 0.700 inch lift. The roller lifters are Isky parts because JBA has found they have superior needle bearings that seem to keep the usual destroyed-lifter-wheel/destroyed-engine phenomena at bay. An FRT double-row timing chain provides the drive.
Obviously the front engine dress is pure custom work. Peterson selected heavy, 1/2-inch thick, 7075 T-6 aluminum plates for the blower bracket. The water pump used in the car is a Deadenbear electric unit. Ignition is by a Holley Annihilator crank trigger. Interestingly, the timing is quite lazy; Peterson normally dynod the engine at 24 degrees total advance. He tried up to 30 degrees, but it made little more powermaybe 5 hpwhich wasnt worth the detonation risk. The distributor is a gutted 94-95 Mustang unitall it does is distribute the sparks. Peterson reports absolutely dead-nuts timing with no scatter.
As the supercharger draws through the carburetor, there is no need to do anything special with the float bowl vents. In fact, save for its taking 30 air correctors and 110 jets, the 1,250-cfm Holley HP Dominator carb is straight out of the box. It did want plenty of fuel, though. Peterson once resorted to making a test run with no jets in the carb at all to see if the engine wanted more VP C16 fuel. It did.
Scott Case, the R&D specialist and general TIG welding guru at JBA, did all the unique fabrication work. While there is nothing trick about the carburetor-to-supercharger plumbing, it seems to work just fine. Interestingly, during power pulls the evaporative cooling is powerful enough to form water droplets on the outside of the box just under the carb.
From the front, the blower belts dual manual tensioners are visible. All the blower drive hardware, including the pulleys and tensioners, are from Auto Specialties. This belt is 36 mm wide; Peterson is switching to a 50mm for more belt longevity. Hes only gotten 30 passes from the narrow belt at these power levels, as the drive forces shred the teeth right off the narrow belt. Hopefully the 50mm belt will do better.
To provide a stable carburetor mount, this detachable bracket was welded onto the left valve cover. Pulling the pin allows quickly removing the carburetor to access the rocker cover. With a mechanical roller cam, that access will be in demand for valve adjustment checks.
The fuel system is simple, as expected with a carburetor. An unnecessary complication turned out to be the nitrous solenoid and line running to the intake tube. This was plumbed to allow manual priming, as Peterson thought the engine would be difficult to start with the carburetor so remote from the intake manifold. It turns out that the engine starts right away, even when cold, so the priming system was removed after our photos were taken. Also removed was the bung on the discharge tube; it was designed for a pop-off valve, but with the throttles upstream of the blower, there is no need for the pop-off so the fitting was later removed.
One of the principal reasons for building this engine was to showcase Shorty headers in a big power application, hence the all-custom JBA headers. They feature 17/8-inch primary tubes, and are made from mild steel with ceramic coating. Obviously the supercharger and its huge boost provide the majority of the airflow in this engine, but it is still something to see a Shorty header around so much power.
With the 17/8-inch-diameter primary pipes, the standard Ford header bolt pattern was out of the question. The J302 bolt pattern was drilled and tapped into the heads. The sparkplug heat coverings over the Nology wires say something about the hellish temps formed in a 900hp engine.
One place the exhaust did prove a constraint was in collector and pipe diameter. Originally, the 3-inch collector Peterson is holding was tried but proved to cost 57 hp compared to the 31/2-inch collectors and tubing now on the engine. The engine was also provided with a custom 31/2-inch X-pipe on the dyno. Those collectors, by the way, are SPD-merged collectors. Peterson notes they could produce the same thing in-house, but it would take around 60 hours and SPD offers the collectors for around $250. It was quicker and less expensive to simply buy them.
Occasionally we come across something so differentyet which makes sensethat we know youll want a good look at it. When the folks at JBA Performance called and said they had a Novi-assisted small-block on the dyno, we thought that was nice. Then they said it was breathing through a carburetor, and we thought that was interesting. Then they said it made well over 900 hp, and we were there.
Actually, weve seen this block, crank, and rods before, running injection and powering J. Bittles Dominator project car. The A4 block and slightly stroked Crower crank and the TFS Street Heat cylinder heads have been from demo car to header development mule, and now to drag duty. The intended engine bay this time is in JBAs white 5.0 drag car, a West Coast machine that has made just a few outings to date, but were sure youll be seeing more of it soon.
The JBA drag car is aimed at promoting headers, of course, but not with an unlimited budget. Thus, JBA engine builder Kevin Peterson decided to bail on the original EFI plan in favor of the faster, easier carburetion concept. Plus, it would be something different. That has meant the somewhat seasoned engine internals, the use of an early Novi blower that was on hand, and the also-on-the-shelf Holley Dominator carburetor. The finished engine tuned easily, and has been reliable as sunrise on the dyno. Once jetted and timed, the engine started making 920 hp or thereabouts depending on the weather. When we stopped by for photos, it made 911 hp while we stood in the cell (Dont try this at home, kids!). Standing that close to such a banshee wail buzzed body parts we had forgotten we had.
The next step is to see how the rig works at the strip, an idea that has the normally exuberant J. Bittle a bit dry-lipped as he contemplates running low nines and eventually high eights. To see the details on why, check out the photos.