Tom Naegele and Jimmy LaRocca of LaRocca's Performance (Old Bridge Township, New Jersey) both agreed that 520 rwhp (600 flywheel) is about the limit if you want the engine to last. Our 331 is certainly capable of making much more power simply by turning up the boost or changing the cam and intake manifold to a more supercharged-specific application. However, we intend to keep our pony completely streetable and have no intention (at this time) of installing a rollbar, so we don't see the need to push the envelope. And 500 lb-ft of torque is a lot of power to put down to the asphalt and a task not easily accomplished. With a clear vision of what we wanted to do, we set about swapping in the new engine.
We were still using the stock camshaft in the old engine because of piston-to-valve clearance, but with the DSS pistons we were able to sling in a performance bumpstick. We chose the Comp Cams XE274HR hydraulic roller, which features an advertised duration of 274 degrees intake, 282 degrees exhaust, and duration at .050 is 224 degrees intake, 232 degrees exhaust. Gross valve lift is .555-inch intake/.565-inch exhaust and the lobe separation is 112 degrees.
It's designed for an rpm range of 2,200-6,200 rpm and it is the same cam that Richard Holdener used in his "Ultimate Guide to Cylinder Heads" article (November 2003). His combination was a 10.25:1 compression 331 and our Brodix ST 5.0R heads came directly from the engine dyno test. With a carburetor, the combination made 434 hp and 437 lb-ft of torque.
It's not necessarily the best blower camshaft, but we went with Holdener's theory that the best supercharged engines are maximized in naturally aspirated form. This allows you to use less boost to attain the same or better performance. Plus Richard has run the same camshaft in his street car for quite a bit of time and was happy with its drivability and performance. That meant a lot to us since ours is primarily a street car.
When you get to this power level, you'll find that there are a lot of ancillary items that need to be replaced with better pieces. Even at stock power levels, the factory engine mounts are easily taxed and if your ride is a high-miler like ours, chances are they're completely shot. We called up Holcomb Motorsports in Lumberton, North Carolina, to get a set of Energy Suspension polyurethane mounts. We wanted them to be strong, but we didn't want to resort to a solid mount.
Holcomb also provided us with a new harmonic balancer/dampener. The Engine Works piece is made by Romac and is SFI approved. Our stock balancer was still holding together, but with the considerable investment in the short-block, we didn't want to skimp here.
Another item that we decided to upgrade was the bellhousing. Holcomb shipped us a Lakewood blowproof steel housing that is also SFI approved. It's a little overkill for our "street car," but you can't powershift without your ankles.
The oil pressure sending unit...
The oil pressure sending unit must be reused, and we'll also be using the stock oil pump pickup. You'll also need a new pilot bearing/bushing.
DSS includes a new cam plate,...
DSS includes a new cam plate, as well as dowel pins for the cylinder heads.
Here you can see the DSS reverse...
Here you can see the DSS reverse dome low-compression piston. We opted for the O-ringed block to make sure we keep the cylinder pressure where it needs to be.
Note how the DSS main support...
Note how the DSS main support girdle is clearanced for the connecting rods. All bolts are triple checked to ensure your motor is ready to go when you receive it.
For our camshaft, we chose...
For our camshaft, we chose a Comp Cams XE274HR grind. This exact cam (PN 35-518-8, $234.95) was used with our Brodix heads in our "Ultimate Guide to Cylinder Heads" (MM&FF November 2003) and produced 434 hp in a naturally aspirated 331-inch engine.
We had only logged 140-some...
We had only logged 140-some miles on the Comp Cams double roller timing chain that we installed when we swapped the Brodix heads on, so we reused it.
We also reused our ARP head...
We also reused our ARP head studs. For head gaskets, we chose the factory graphite pieces. According to Tom Naegele at DSS, they've seen great power had with graphite or Cometic gaskets. Obviously the SuperPro Bullet's straight deck and O-rings help keep everything in its place.
The Brodix M2 ST5.0R heads...
The Brodix M2 ST5.0R heads were installed and torqued to 80 ft-lb. We let them sit for 30 minutes and then backed them off and retorqued them to 85 ft-lb. to make sure there was no more stretch.