[Black1972]

I posted this yesterday with no responses maybe someone can help today? I have a blown big block that is going in to my 1972 Chevelle. I didn't see the need to dyno it when it was done but often wonder what the power numbers are since often I see people advertising four digit figures on pump gas and find them hard to believe. This is what I have : 454 30 over speed pro dished fourged pistons ( l2453f30)7.68 to 1, eagle H beem rods and fourged crank, Comp cams complete solid roller kit (.652/.652 lift, 300/308 duration, 114 lobe seperation) chevy Iron open chamber/rect port heads (118cc cumbustion chamber, 325cc intake runner with 2.250 intake and 1.88 exhaust) 871 weiand blower running 1/1 about 10lbs of boost, with two holley hp750 blower carbs, timing set at 28 degrees, MSD pro billit distibutor, and a 6AL box. I think I have covered everything and can anyone tell me what to expect. Thanks

 

[Bomber '67]

Your engine is one that would particularly benefit from dialing in the tune. At least strap it down on an chassis dyno, or buy the Innovate LM1 and get your fuel curve and ignition sorted out. Blower engines will hate you if they go lean, but on the other end power suffers if they are run overly rich.

It is important to remember that the boost psi that you measure in the intake manifold is only a measure of the backed up flow behind the intake valves - but it is not a measure of actual air flow through the ports. Although many people still incorrectly believe that head flow on a supercharged engine is not all that important, it will be the flow capacity of your heads that determine your power level.

Your general specs should make in the 750 hp range. I'll bet that you could even run a couple more degrees of ignition advance on pump gas. I've built a centrifugally supercharged 468 in the past that made 753 hp at 10.5 psi of boost, and 482 hp with the belt off. Your engine is quite a bit different though. One of my friends just finished an 8-71 blown 540 that had more of everything; cam, heads, compression, etc. He went just over 900 hp at 7,000 rpm with 6 - 7 psi on pump gas.

Thomas