Hib Halverson's Big Block From Hell Series

Hib Halverson's Big Block From Hell Series

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Part 4 ... Dynamometer Decadence

by Hib Halverson

Now, you get to see if what you've been reading for the last four months actually works. The Edelbrock Research and Development Facility's dynamometer cell Number Two and its Super Flow SF901 fully-computerized "dyno" is the site of Big-Block from Hell activity this month. Simply stated: this engine is one nasty rat motor!


Edelbrock Test Engineer, Robert Jung, began preparations by bolting on a McLeod Mini-Super Starter (p/n 810152). This gear reduction unit produces increased torque but is smaller and 10-pounds lighter than a stock starter. Its mounting accommodates both 153 and 168 tooth flywheels and, speaking of the devil, we also used a McLeod aluminum flywheel. Part of the Street Twin, dual-disc clutch assembly (p/n 63109027) we'll install later; the flywheel weighs a scant 12.5 pounds. A light flywheel is not a problem with this motor's prodigious (trust me, you'll see!) low-end torque. In fact, it will help the engine rev quicker. The flywheel was balanced back in Part One (7/90 Vette) along with the rest of the engine internals by Evans Speed Equipment.

The 454fH uses a Chevrolet HD, magnetic trigger distributor (p/n 1111263). No longer listed in the Chevrolet Power book; at this writing, it is still available though dealers. (author's note: the HD distributor is no longer available and our current choice is a distributor by MSD) We chose this "early-HD" unit for its stout, cast iron construction; ball bearing equipped shaft; Corvette tachometer drive and high quality trigger signal. Equipped for use with reverse rotation, gear driven camshafts, to work with our chain drive cam; we changed the distributor gear. Additionally, the -263 has a distributor rotor phasing problem. A rotor is out of phase if, when the ignition trigger event occurs, the rotor tip is not in proper alignment with the contacts inside the distributor cap. This is common to most original equipment (OE) '64-'74 magnetic trigger (transistor ignition) distributors and exists because of the electrical characteristics of the OE ignition amplifier of that period. When amplifiers of contemporary design are used; the rotor phase problem rears its ugly head and the engine may misfire above 5000 rpm under load. The solution is an MSD Cap-a-Dapt kit (p/n 8420) which has an adjustable rotor to correct phasing. Further discussion of rotor phasing is not possible due to space limitations however, an excellent description is in MSD's "Tech Bulletin #104" which is free for the asking by calling their customer service department.

The -263 distributor is quite expensive and perhaps out of reach for some. Four alternatives exist: 1) a standard rotation unit (p/n 1111267) similar to the -263 but without ball bearings or 2) any good used OE '64-'74 T/ign. distributor. Either of these units should be checked for rotor phasing and may need the Cap-a-Dapt. Also available are 3) MSD's own mag. trigger, tach. drive distributor (p/n 8458) or 4) one of several aftermarket mag. trigger conversion kits for OE point-type distributors. We suggest the kit (p/n 112114) made by Stinger Ignitions.

For break-in and our first wide open throttle (WOT) dyno "pull", we ran the -263 on its factory mechanical advance curve which, interestingly, is very conservative. Full advance is not reached until 4000 rpm. The rest of the ignition system, part of Edelbrock's dyno, consisted of an MSD-6A (p/n 6200), multiple spark, capacitive discharge (CD) ignition amplifier and an MSD Blaster 2 (p/n 8202) coil.

Robert Jung filled the crankcase with eight quarts of Red Line Synthetic, 15W-40 Break In Oil. "Regular" synthetic oil is not acceptable for break-in because its lubrication qualities are so good that piston rings take a very long time to seat and, in some cases, will not seat at all. Red Line Break-In oil is unique in the synthetic oil market in that it offers race engine builders the benefits of synthetic oil while allowing the rings to seat. Jung pressurized the oiling system with a B&B Performance Oil Pump Primer (p/n 6510) that fills the oil passages feeding the lifters as well as those feeding bearings. He installed the distributor and, to make starting easily, static timed it with 20 degrees initial advance.

Because of the steady state, high load operation characteristic of dyno testing, a very cold spark plug heat range must be used. Jung's assistant, Matt Compton screwed in a set of NGK V-Power Racing, heat range nine plugs (p/n R5674-9). Gaps were .035-in. Then he added MSD Heat Guarded Heli-Core ignition wires (p/n 31778). Fitted with quartz fiber jackets to resist heat radiated by exhaust headers, these helically-wound, induction-supression wires reduce "ignition noise" generated by the engine and eliminate inductive crossfire between plug wires. It used to be that any resistance-supression wire would take the ignition buzz out of your radio. Nowadays with stereos approaching home component systems in sophistication and sound quality, cellular telephones and digital engine controls; ignition noise is more of a problem and requires more of a solution: Heli-Core.

A last inspection of the engine and the dyno cell door was closed. With Robert Jung at the controls, after four months of hard work on the part of the Edelbrock "Fun Team"; it was now finally time for that moment of truthÉ

The First Fire Up

Fuel pump and ignition on, hit the starter button on the Super Flow console and the 454 from Hell thundered to life. Ah yes, the joyful noise of four hundred sixty cubic inches of Mark IV Chevrolet! Ya gotta love it!

With oil pressure at 80 p.s.i., engine speed was raised to about 2000 rpm and the timing was retarded slightly. Robert turned the dyno controls over to Matt and he began 20 minutes of no-load operation to break-in the camshaft. This requires no extended period of cranking to start, no low rpm operation and at least 20-minutes at 2000. Neglect that procedure and you may buy a new cam. After the first 20 minutes, the engine was run another 40 at light load between 2000-2500 rpm for ring seating. If you are breaking in your new engine in the car; run the engine at 2000 in neutral for the first 20 minutes then drive it for 40, keeping engine speed between 2000-2500 rpm as much as possible and avoiding any rapid acceleration or steep hills.

At the end of the hour, Matt shut off the engine, drained the oil and inspected the removable screen that is part of the Super Flow's oil filtering system. Significant mettalic particles there would be indicative of internal problems. A small amount of contamination (a little metal, lint, silicone particles) is acceptable however as, no matter how clean one is in the assembly process, foreign matter is left inside the engine. It ends up in the oil and finally gets trapped in the screen.

Matt pulled the valve covers for a visual inspection. The only problem he found was number one exhaust rocker interfering slightly with the oil trap that is welded to the underside of the valve cover. A slight modification to the cover with a Ford Adjusting Tool (hammer) fixed this problem. The covers went back on and the engine was filled with eight quarts of the good stuff this timeÉ10W-40 Red Line Synthetic Oil.

Running Hard

The Big-Block from Hell was fired up again and warmed. Once water and oil temperature reached 180¡F , it was run up to 4000 rpm and the ignition timing was set at 38¡. After a three partial-load runs to get a "feel" for the engine, Robert Jung was ready to stomp on the loud pedal.

Before Super Flow introduced their 900 series units, a dynamometer test had the operator manually adjusting engine speed and dyno load such that the engine was operating with wide open throttle (WOT) at a specific rpm. Once the engine was "stabilized"; the operator took visual readings of the various data he wanted to study and recorded them on paper. Needless to say, if many types of data are required in 500 rpm steps; this could be time consuming and hard on the engine.

The beauty of the Super Flow dyno is that its computer can be programmed to run the "step test" and record all engine data simultaneously. All the operator must do is stabilize the engine at the lowest rpm step of the test then activate the SF901 program and computer software takes control of throttle opening and load adjustment. The engine is accelerated and load is increased to each step and held for 1-2 seconds while data is recorded. Typically, dyno test results are corrected for temperature and air pressure of 60¡F and 29.92 inches of mercury. The SF901 does that automatically, also.

For the first BBfH WOT test, Robert Jung programmed 500 rpm steps from 2500-6000 rpm. He increased speed and load until the engine was at 2500 rpm WOT, put the SF901 into automatic and we listened as the engine went from a low-end growl to a high rpm wail! Data now recorded, the program reduced the engine to idle. We all crowded around the SF901 terminal, read the information then broke out in smiles and high fives. The bottom line?

The Edelbrock 454 produced 464 horsepower at 5000 rpm and 497 pound/feet of torque at 4500 rpm. What's better is this engine will be downright decadent on the street! It's torque curve is above 440 lb/ft from 2500-5500 rpm! Remember folks, this is with a hydraulic lifter camshaft of only moderate potency, low-performance heads and one carburetorÉnow, that's a Big-Block from Hell!

The 1407 four-barrel is calibrated well for an engine such as ours. Brake specific fuel consumption is a measure of how efficiently the engine is using fuel. Right out of the box, in the 3500-5500 rpm range, the 1407 had the engine running with a BSFC of 0.45-0..49É0.48-0.52 is considered ideal. Lastly volumetric efficiency near the torque and power peaks was 90.5-93.3%. That tells us that the unfair advantage comes with using Edelbrock's "Total Power Package" concept of matched parts. The Torker 2-O intake manifold, the Torker-Plus camshaft and the 1407 all work together to provide a substantial performance increase. The other major player in the high VE figures is the cylinder head work by Mark DeGroff.

Going Digital

Some of the engine efficiency of late model Corvettes comes with digital control of the ignition advance curve. Edelbrock's newest product, the System II Ignition Computer, applies this technology to cars not originally equipped with digital engine controls. Next month we'll have an in-depth article on System II so, I'll only briefly discuss its designÉI am really more interested in its effect on the BBfH's engine. (author's note: the Edelbrock Ignition Computer is no longer available.)

The Ignition Computer is similar to the electronic control module (ECM) used on '80-'90 cars. It contains a computer chip programmed with eight ignition advance curves, one of which the user selects according to his engine configuration. The Ignition Computer has an automatic detonation avoidance feature equivalent in function to the electronic spark control (ESC) used on the new cars. Lastly, it has a built-in, user-adjustable rev limiter.

Features of "S2" that increase power, torque, drivability, fuel economy and durability are: 1) control of the ignition advance curve more precise than that available with mechanical means. 2) curves that are impossible with mechanical advance mechanisms 3) ESC that allows the engine to be run with optimum timing virtually all the time. The few cases where this optimum timing causes detonation, the ESC software temporarily retards timing until detonation ceases and 4) the rev limiter which prevents engine damage due to overspeed.

Many types of ignition amplifiers can be used with the Ignition Computer. On a big block generating more than one horsepower per cubic inch, I suggest an MSD-6A along with the System II Ignition Controller, a signal processing device necessary for use with CD ignition amplifiers.

Although one of the eight S2 curves is ideal for most any street high performance engine, in the interest of gathering data for further research and development of the product line; the Edelbrock people decided to program a special ignition curve into the chip for this engine. Determining the ideal advance curve requires an hour or so of mean best timing tests (MBT). The engine is run at 2000, 3000 and 4000 rpm. At each of these engine speeds, loads necessary to hold WOT, 4, 10 and 14 inches of manifold vacuum are set. In each of those 12 tests; timing is varied in two degree increments. The range in WOT tests is 30¡-44¡ and for part-throttle tests is 30¡-52¡. The advance figure that generates the best torque number is then put into the curve. From the MBT data, Doug Moody of Edelbrock's Electronics Department programmed our chip.

Moody installed the chip with "Curve 3A" (to differentiate from "standard" Curve Three on which 3A is based) into the Ignition Computer. The engine was fired and warmed after which Robert Jung ran a step test. Using System II with 3A, our best score was 472 hp.@5000rpm and 502 lb/ft. @4500 rpm.

To a "max numbers" type, the increase at WOT due to System II is, admittedly, not real impressive. However, at part throttle you get the full benefit of digital control of the ignition curve. To simulate one type of part throttle operation (a mild passing maneuver, travel up a slight grade or moderate acceleration typical of around town cruising) Robert Jung set the SF901 up to load the engine at 2500 rpm with 6 inches of manifold vacuum then put it on an automatic, 300 rpm per second acceleration test. Interestingly, in the range of 2500-4000 rpm, where, during everyday driving, most people will operate an engine like this; torque increased. At 2500 and 3000 rpm, we saw 10 lb/ft. more. Additionally at both those speeds and, to a lesser extent, the rest of the 2500-4000 range; less fuel was used to generate more horsepower. At 2500 the saving was 1.1 pounds of fuel per hour and at 3250 it was 4.0 lb/hr.

System II certainly has an effect on efficiency of the BBfH. In Part Five of this series after the engine is in the car; we will do further drivability testing to evaluate the effect of ESC, and check fuel mileage.

Something New

Just after we finished up reviewing S2, Vic Edelbrock himself walked in the dyno room with the latest Edelbrock manifold: a brand new, aluminum, in-line, dual-four barrel unit for Big Block low-performance heads. This unit was the first one made off production tooling and the Big Block from Hell was its first test. We were running so late with this article that some dyno testing was done after our photo deadline so, we don't have a picture of this piece.

Matt Compton bolted on this new dual-plane, medium-rise unit, known only as the "C66", then installed two, 600 cfm, Edelbrock four-barrels (p/n 1406). A non-progressive linkage was added, the fuel lines were hooked up and it was time to run the bi-quad 454 from Hell (bq454fH??). Admittedly, I was skeptical of the C66 as the in-line, 2x4 manifolds of 20-years ago were much more show that go.

The Edelbrock C66, however, got my attention. During another wailing 2500-6000 rpm step test the engine made 479 hp@5000 rpm and 514 lb/ft. torque at 4500 rpm andÉget this!Étorque was above 460 lbs/ft from 2500 to 5000 rpm. Awesome motor eh? ButÉthere's more.

454fH Gets the Squeeze

Nitrous Oxide injection is a cost effective way of gaining short duration power and torque increases with street high performance and racing engines. On the compression stroke, once temperature reaches 415¡F, nitrous oxide (N2O) breaks down into nitrogen and, most importantly, oxygen. If extra fuel is added along with the nitrous, more power is produced. The amount of increase is controlled by removable jets in the nitrous and fuel feed lines. The system is controlled by two solenoid-operated valves.

Nitrous Oxide Systems, Inc. (NOS) is one of the largest manufacturers of nitrous oxide injection hardware. We invited them to come to Edelbrock and install one of their "Cheater" systems on the Big-Block from Hell. Bill James of NOS' Technical Department installed the Cheater system, which injects nitrous oxide and extra fuel through "spay bars" mounted in an adaptor plate that goes between the carburetor and manifold.

As the NOS Cheater Kit is intended for use with one carburetor, we removed the C66 and replaced it with the Torker 2-O and the Edelbrock 1408 used previously. To run nitrous on the dyno, Bill James connected the adaptor plate to a pair of NOS Power Shot solenoids, hooked them to the nitrous oxide cylinder and the Super Flow 901's fuel system then, to trigger the solenoids, added a temporary electric circuit operated by a button. To run a nitrous unit such as this, a good ignition amplifier like the MSD-6A is necessary and spark plug gaps must be closed up to .025-.030. in.

There is no question that nitrous is very successful in adding power and torque. We ran two tests. The first was with NOS' "Stage One" jetting and a special "nitrous" curve in the System II chip. Typically, nitrous oxide injection should be run with the timing retarded six degrees. Stage One jetting on 92 octane fuel got us 567 hp@ 5000 rpm and 627 lb/ft. torque at 4000 rpm.

With our second nitrous test, we went for broke. Since we'd spent all that money and effort equipping the Big-Block from Hell with premium parts; we decided to give our BME pistons, Crowerods, Chevy LS7 crank and four-bolt mains a real work out and use maximum jetting. The NOS Cheater with max. jetting is an aggressive system as far as nitrous oxide injection units go and can not be used safely with on an engine that lacks forged pistons. Additionally, since nitrous increases cylinder pressure and max. jetting increases it greatly; octane rating of the fuel must be increased to eliminate detonation.

Robert Jung filled the dyno cell's fuel tank with a mix of 92 octane unleaded and Trick 106 octane leaded racing fuel giving us about 99 octane. He fired the engine, warmed it and ran another step test. Yea, buddy, we're having fun now! We made 600hp@5000 and 672lb/ft. @ 4000ÉOuch!!.

The nitrous oxide injected, Edelbrock 454 is one potent powerplant!

Where Now?

We are going to take a few months off to allow us to regroup, then we'll be back with the Big-Block from Hell in a Winter 1991 issue of Vette. At that point, the Edelbrock "Fun Team" will reinstall the engine into the '71 Coupe discussed in Part One of the series.

I would like to thank the major sponsors of this project: Vic Edelbrock and all those at Edelbrock Corporation's R&D Facility, the Chevrolet Raceshop, Bill Miller Engineering, Crower Cams and Equipment Co and Mark DeGroff's Cylinder Head Service and Machine Shop. Additionally, many associate sponsors provided invaluable assistance and their names and addresses have been listed below and in source "boxes" that accompanied the previous three parts of this series. If you build your own Big-Block from Hell consider all of these manufacturers as I have tested their products and, as you've read, published the results.


Autotronic Controls Corp. (MSD)
1490 Henry Brennan Dr.
El Paso, TX 79936
B&B Performance
29752 Banderas
Rancho Santa Margarita, CA 92688
Edelbrock Corporation
2700 California St.
Torrance, CA 90503
GM Performance Parts
(see your local dealer)
Evans Speed Equipment
2550 Seaman St.
South El Monte, CA 91733
NGK Spark Plugs, USA.
6 Whatney
Irvine CA 92618
Nitrous Oxide Systems (NOS)
5930 Lakeshore Dr.
Cypress, CA 90630
Red Line Synthetic Oil
6100 Egret Court
Benicia CA 94510

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