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Chevy Small Block Part 22 - PT. 22: Horsepower Is King!

The Right Combinations Are The Key

By Mike Petralia

Old Fashioned Power
Right after the blower test we moved back to making power the old-fashioned way, on the motor. We had been wanting to try out Edelbrock's Victor Jr. heads and intake manifold for quite a while by now, but were hesitant because DM might not be capable of using that much air. But, we felt that maybe if we ordered the smaller combustion chamber heads and equipped DM with one of COMP Cams' newest Xtreme Energy Street Roller camshafts and the latest, mightily-efficient Demon carburetor, we just might be able to squeeze off 500 ponies! So we asked the guys at Speed-O-Motive to install the new components and strap it onto their new DTS dyno.

The results were spectacular! A true 500hp street bruiser that looked and sounded every bit the part (DM Part 19-T34). Also, just for giggles, we were curious what difference running hydraulic roller lifters on this new solid roller cam would make and we learned quite a bit from that test alone. Specifically, that in this case, running hydraulic roller lifters on solid roller cams really doesn't make much of a difference. We gained some mid-range power running the solid rollers, but lost it all back around the top end, probably because the hydraulic roller lifters actually made the cam act "bigger" since they run at zero lash, so average power was a wash.

We do feel however, that if the cam we'd used had been just a bit larger, the HR lifters wouldn't have kept up so well. That's because bigger cams make more power at higher rpms and that's where HR lifters can begin to suffer. You really need to fine-tune the valve train to make a HR spin that high. As it was, we had no trouble revving to 6,600 rpm with the HR lifters. But the motor was like a switch at that point and it practically turned off if we tried to push it above 6,600. Ironically, the power curve was all finished by then anyways, so more rpm was a moot point. And it still didn't rev any higher after we installed the SR lifters either!

DM Part 20-T35 was all about sealing. We've known Total Seals' gapless top rings have been out for quite a while now, but hadn't seen anyone using them in a true street engine yet. Well, we wanted to try and the results were outstanding, especially considering that the gapless rings only cost about $100 more than standard set we replaced. More power and torque was made at almost all points, except at the very top end of the curve, which surprised us. A call to Total Seal after the test explained the problem. "You coulda' done better," they told us. "If you had increased the high-speed air bleeds in your carb, leaning out the top end of the fuel curve, you wouldn't have lost the power up there.

Our testing has shown gapless rings pull more vacuum at higher rpm and therefore will also pull more fuel causing the engine to run rich at the top end." A review of DM's fuel curve confirmed this to some extent, but we didn't see a huge difference in the Lambda Air/Fuel readings from low to high rpm, so we never thought to change the air bleeds. Also, Total Seal recommended running less ignition advance with gapless rings, because they claim peak cylinder pressure comes just a bit sooner and therefore the combustion process begins that much quicker. Unfortunately, the engine was off the dyno before we could test either of these theories. But, we trust the information from Total Seal and have no reason to doubt its validity.

DM Part 19-Test 34:
355 cid, 10:1 cr, 4.030-bore 4-bolt Motown block, 3.48-stroke Lunati crank, 5.7-inch Lunati rods, Edelbrock Victor Jr. heads (64cc chambers, 215cc runners, 2.08" intake valves, 1.60" exhaust valves), Victor Jr. intake, Mighty Demon 650 carb, COMP Cams XR280R solid roller camshaft (242/248 @ .050, 280/286 adv, .600/.606 lift w/ COMP 1.6:1 rockers, 110 LS), COMP solid roller lifters lashed at 0.016-intake and 0.018-exhaust, 38 degrees total ignition advance.

The Biggest And Baddest Yet
Once the Total Seal rings gave us extra power, we began believing that more could truly be better in this case. So, after a lengthy phone call spent convincing Edelbrock to let us try their big, Super Victor racing manifold with an even larger COMP Cams solid roller, we went back to Speed-O-Motive's dyno to see if we could break the 550hp barrier. Well...we didn't lose any power and DM certainly made more power than it did the month before, but the results were a far cry from spectacular this time. After swapping the cam, intake, and carburetor, we only saw a 13hp increase and 14 ft-lb of extra torque (see: DM Part 21-T35 vs. T36.

By Mike Petralia
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