The contenders: an 1150 Dominator on a Weiand Team G race single-plane, the dual-quad tunn
Editor's Note: Several years ago, we published a story about a hot production-head 440 buildup, written by Steve Dulcich. When our buds at Car Craft found out, they assigned him to write a story on running intake setups on this motor. We asked Steve to retool the results for Mopar Muscle; we think you will find them very informative.
Back in 1999 we set out to see what kind of power could be extracted from a regular 440 using a set of ported stock heads. The idea was not big, mega horsepower, but to determine how much power we could get with the factory block, heads, and crank, while still keeping the cam short enough in duration that the engine would idle and drive. On the other hand, the mill would not simply be a stock-type grocery-getter. Perhaps the best term would be a super street engine. We detailed this build in the Mar. and May '99 issues of Mopar Muscle and ended up with a solid 587 hp at a modest 6,100 rpm when all was said and done. We also found this engine pulled a whopping 572 lbs.-ft. of torque at 4,900 rpm, which was very good for 452 cubes. In fact, with more than 500 lbs.-ft. across the entire range-from 3,500 to 6,100 (more than 400 lbs.-ft. showing at wide-open throttle at only 2,000 rpm)-man, did this thing make some torque!
Each test starts with partial pulls to check the mixture. The Westech dyno gives us calcul
Still, as good as those numbers looked, the combo was still somewhat raw. Mistake number one was in the accessory drive pulleys. Usually, dyno-testing at these power levels uses an electric water pump to minimize power-robbing drag. On this engine, we bolted on a set of stock C-Body pulleys, which overdrive the water pump to 145 percent of crank speed. For even more drag, we used a high-volume water pump. Before it was over, the water pressure at the resultant 10,000-rpm pump speed was blowing the pressure-relief valve on the dyno's cooling tower. It was like a second water brake mounted to the front of our engine-not good. We also discovered our ACCEL No. 137 spark plugs were too hot, and we didn't have a set of No. 134s on hand, so we had to run what we had.
But the biggest problem was probably the 1250 Holley Dominator carb, which we had calibrated for use on a dual-quad tunnel-ram. Running just one four-barrel on our Weiand Team G manifold, it was impossible to get the correct mixture without replacing the air bleeds. We didn't have the required air bleeds and ended up with No. 104 jets all around to compensate for the wrong air calibration. It was good enough to pull the numbers we got, but we knew the carb calibration and the other problems had left some power on the shelf.
We didn't make any changes to the basic combo we ran before, except this time we'd be prepared with the carb-tuning parts required to optimize the combo as required. In the meantime, we had to make a change to the water-pump system. While an electric pump would have been the easiest system to install, plus totally removing accessory power loss, we opted to retain a streetable belt-driven system. We dug through our pile of pulleys and found a small one to bolt on the crank, which we believe came off an old 215 Olds. It fit the 440 damper perfectly. Coupled with a small-block Mopar water pump pulley, which lined up, we ended up with a pulley ratio of about 1:1. We also changed to an OE A/C water pump, which offers less drag.
First out of the chute was the sleeper system, which would look at home on a tame street m
Every manifold tested was modified with port-matching, plenum work, and more. The racier m
Our numbers showed the Street Dominator induction was not quite enough for this wild 440.
While the last time around all we had was a miscalibrated 1250 Dominator, this time we came packing the goods. We would run three completely different inductions to see how they stack up. First up would be an 830-cfm HP-series 4150 Holley on a Holley Street Dominator intake, a combo that's as simple as it gets. Next, we'd run a Dominator carb as in our original configuration, sitting on a Weiand Team G single-plane. Unlike the last time, though, we'd run Holley's 1150-cfm version-like the 1250-one of Holley's HP-series Dominators. For the wild card, we ordered up a radical Weiand Hi-Ram dual-quad tunnel-ram and stacked a pair of 750-cfm 4150 double-pumpers on top of that. Westech's dyno has the advantage of being highly instrumented for gathering data on air/fuel ratio, meaning we'd get solid numbers to see where our fuel curves were, allowing precise calibrations to be made to each combo.
Our first test program was the Holley Street Dominator/830 double-pumper combo. Nothing real exotic, just an excellent single-plane and a classic Holley carb. Don't let that description fool you. The Street Dominator, though an older design, is consistently a top-performing manifold in dyno-testing and has long been one of the most successful race big-block intakes. The manifold was port-matched to the heads and received some minor radiusing of the runners' entrances to the plenum. Flow tests on this manifold show average flow of about 270 honest cfm (at 28-inch water), a good match to a well-ported set of 440 heads. The runner-to-runner flow distribution is unbelievably good. A good manifold out of the box with a fairly constant runner cross section, it's not a manifold that's easy to improve with additional porting-it's pretty well optimized as built.
Time to try something different. We hoisted our single-plane race manifold and 1150 Domina
The Holley 830 was almost exactly the size that a conventional cfm-to-cubic inch-to-rpm chart would recommend as optimal for our 440. Would it really be enough? Remember, these carb-sizing charts are based on a volumetric efficiency of 100 percent. Though most street engines never achieve these VE levels, our highly refined 440 was expected to come in at race VEs of more than 100 percent. The carb was out-of-the-box stock when we bolted it on, and a few partial pulls were performed to dial in the jetting. We could tell already that we had a healthy 440 on the dyno.
With the calibrations made, the hammer was dropped, and our first set of numbers were in: 600 hp at 6,300 rpm and 576 lbs.-ft. of torque at 4,900 rpm. Even with the most basic induction system, peak power was up 13 horses over our last dyno session with this engine. The fact that peak power was coming in 200 rpm higher than the last time showed that the miscalibrated Dominator we had used previously was off enough to significantly hurt power at high rpm levels. Torque came in at the same rpm as our old test and was up by 4 lbs.-ft. Crunching the dyno numbers, we found a vacuum level at the top of our pull reaching 1.8 inches of mercury, showing that the induction restricted airflow at higher rpm; in other words, 830 cfm wasn't enough. Volumetric efficiency was 103 percent in our baseline configuration, meaning our 440 was pulling 3 percent more air than its cylinders displace.
More airflow once again equaled more power. The big Dominator carb and Weiand manifold bum
The Holley Street Dominator was working well for what it was, but we thought added plenum volume would help feed our voracious 440. This manifold was designed to fit under most stock hoods, and though the runners are nicely shaped and very efficient, it is a relatively low design compared to high-profile race manifolds. This lower height limits the plenum volume. To add some capacity, a Wilson 1 1/4-inch open spacer was added under the carb. With just this change, peak power surged all the way to 621.2 hp at 6,200 rpm, while torque was up throughout the rpm range of the test. This was one of the biggest gains we'd ever seen with the addition of a spacer. The numbers backed up our result, with manifold vacuum down by as much as 0.4 inch of mercury, a significant reduction in induction restriction. The engine's air consumption, as recorded, increased by 21 cfm, and that's not chump change. VE was also way up-now at a racy 106.4 percent. To add some perspective, on milder 440 engines built to the 500hp level, adding a spacer on a Street Dominator usually shows nothing.
If the ultimate in single four-barrel capacity is what you're after, it's tough to beat the 4500-series Holley Dominators. While an 830 is a big carb, the 1,150-cfm Dominator we tested next was nearly 40 percent bigger. The new three-circuit HP-series Dominators have replaceable air bleeds for the idle, intermediate, and high-speed circuits, and are nearly infinitely tunable. The Dominator uses a specific manifold with a bigger flange, so a manifold change is required with this swap. We used the same Weiand Team G manifold that was run on this engine in our original stories.
Reference the usual carb-size charts and it would seem the big Dominator would be too much carb for our 440 combo. The large venturi size of such a big carb means lower air speed through the booster, and likewise a reduction in booster signal strength and atomization. To help counter this effect, we specified an annular booster version of the big Holley carb, which is much more sensitive to booster signal and a better atomizer than conventional Holley boosters. This all pays off with dividends lower in the rpm range, where air speed through the carb is low. For full-on, high-rpm drag use, it isn't an issue, but we wanted as broad a powerband as possible.
The wild card was our Weiand High Ram dual-quad tunnel-ram, with a brace of 750 annular di
The Weiand Team G manifold is a true-race single-plane available with either the 4150 or the Dominator 4500 base styles, and it is a much taller design than our baseline Holley intake. The runners have a larger cross section, and like most race manifolds, taper larger toward the plenum, which in turn is also generous in volume. Like the Holley manifold, the Team G was port-matched, though the plenum work was somewhat more intensive than that on the Holley intake. The mods were covered in detail in our original build-up article. No flow tests were conducted on the Weiand intake.
Since we had made some pretty impressive numbers with the Holley intake/spacer combo, we questioned whether more could be made from the induction. Bolting a manifold on a 440 is as easy as it gets, so we made the swap to see just what was there for the taking. Again, we ran some partial pulls to dial in the correct air/fuel ratio, then let it run for the numbers. With the Dominator induction, our 440 banged out a wild 646.2 horses at 6,400 rpm (a solid 25hp gain), extending the rpm range as well, with a 200-rpm higher peak; it liked the change. Torque busted out to more than 600 lbs.-ft., with a peak of 603.4 at 5,100 rpm, and VE was just a hair under 109 percent. Air consumption was up by another 21 cfm, meaning that the 440 was using the added capacity of the big Dominator.
Mr. Brule pulled the handles for our tunnel-ram show, and this iron-headed monster cranked
While there was a drop in low-end to the tune of 14 lbs.-ft. at 3,000 rpm, it was still churning out some serious low-end twist, with 475 lbs.-ft. at 3,000 rpm. By 3,500 rpm, the Dominator combo had outpowered the 4150 and never looked back. We could have further fine-tuned the low and intermediate circuits of the Dominator carb, but we were under time constraints. The dyno curve had already shown us what we were looking for: a 440 cranking power solidly in the mid-600hp range with a single four-barrel.
Tunnel-Ram with a Capital "T"
After hammering out the big numbers with our Dominator combo, could there possibly be anything left? We were packing dual-quads on a tunnel-ram to test those waters. Tunnel-rams were once considered the ultimate in induction, although they seem to have fallen by the wayside with the introduction of the current monster four-barrel intake and carb systems. What the tunnel-ram has always had going for it is outstanding mixture distribution, a nearly perfect runner approach into the cylinder heads, and the greatest design flexibility in terms of induction length and plenum volume. Think about it: Each runner has a fat Holley throttle plate swinging open like a trapdoor right above it. The large common plenum allows any runner to pull from a huge well of air-fuel mix, waiting to feed those hungry cubes. In layout, a tunnel-ram-equipped engine sees the end of the runner at the plenum as the end of the induction tract, as if the runner is just wide open to a world of air-fuel mix.
The factory '67 No. 915 heads featured extremely well-executed porting and 2.25-inch intak
We liked the theory, as well as the anti-contemporary approach, and ordered a Weiand Hi Ram. These tunnel-rams have been around for years: a two-piece manifold with tall runners and a large separate plenum. We looked it over out-of-the-box and decided it needed porting. The runners neck down in height at about the midpoint from the cylinder-head side, then transition to a large cross-section "D" shape at the plenum. We performed considerable porting, carefully measuring the point of minimum cross-sectional area and removing metal in that area. Access to any part of the runners is wide open for porting, with the top plenum removed. Later, we found this note on the Weiand Hi Ram in a Mopar Performance race manual, "For best performance, the Weiand ram should be ported out to the size of the port in the head." Guess we weren't the first to think of it. Finishing off the manifold mods, the ports were matched to gasket size, and the plenum-to-runner join was blended. We hoped it would work.
To top off our tunnel-ram, we went with a pair of No. 9379 Holley 750-cfm double-pumpers. These are traditional 4150-series Holley carbs, but they come with annular discharge booster venturis, which we specified for the same reasons as with the Dominator. All up, our tunnel-ram induction would give us 1,500 cfm of carb capacity. Would it add anything to the power bottom line, or would the engine just choke, spit, and sputter for lack of air velocity? We had a hunch it would be OK, with the Weiand manifold's long runners and ram effect. Despite conventional opinion, tunnel-rams can actually add substantially to the lower end of the power curve on high-output engines. Bolted onto our 440, the tunnel-ram looked serious, but we were after performance.
Again, we ran a few partial pulls to set the jetting and found the mixture way too fat. We pulled the jetting down three times in fairly large steps, arriving at No. 62 primary, No. 68 secondary for the final jetting from the stock No. 68 primary/No. 81 secondary jets. The difference between the primary and secondary jetting was because the primaries also had a power valve, making the mixture "square." The fact that the carbs needed to be jetted down so hard indicated that the booster signal was actually much better than we anticipated, pulling hard on the annular booster's discharge holes. These 4150 carbs don't have replaceable air bleeds, and though the fuel curve indicated a slight increase in the main air-bleed diameter would have been a benefit, it was close enough that we didn't want to drill the air bleeds.
With the jetting completed, it was time to whack it under load with a full pull. The tunnel-rammed 440 pulled cleanly all the way through the test range, belting out a fat 666.6 hp at 6,500 rpm and showing a massive 623.5 lbs.-ft. at 5,100 rpm. The tunnel-ram setup handily outpowered either of our single four-barrel inductions for high-output honors of the day.
Moreover, check out those torque figures. The 440 twisted out 513.3 lbs.-ft. at 3,000 rpm, by far the best low-end output of the inductions tested. The tunnel-ram shelled out 30 more lbs.-ft. than the 4150 and 37.5 lbs.-ft. more than the Dominator at the lowest rpm tested (which, by the way, was as low as the dyno would pull the engine down). Up top, the tunnel-ram outpowered the single 4150 by 66 horses and beat the Dominator setup by 20.4 horses as well, making it the power champ across the entire power curve.
Superflow 901 Dyno
|RPM||Test 1||Test 2||Test 3||Test 4|
Dyno Figures Superflow 901 Dyno
Test 1: Holley Street Dominator Intake; Holley 830-cfm Double-Pumper Carb
Test 2: The same as Test 1 but with 1 1/4-inch Wilson Spacer added
Test 3: Weiand Team G 4500 Intake; Holley 1,150-cfm Dominator Carb
Test 4: Weiand Hi Ram Tunnel-Ram Intake; Dual 750-cfm Double-Pumper Carbs
Superflow 901 Dyno
|RPM||Test 1||Test 2||Test 3||Test 4|
The short-block was relatively stock, but the Arias-forged 12.5:1 forged racing pistons an
Builder's Notes: 666hp Factory-Head 440
Getting 666 horses and 623 lbs.-ft. of torque from a .060-inch-over 440 without any juice, spray, or squeeze just doesn't happen by accident. Specific torque output best indicates an engine's power-producing efficiency, and our 440 produced 1.39 lbs.-ft. per cubic inch, a decent number for any engine, which is pretty tough to do with a set of non-welded factory iron heads. What it takes is a working balance of flow, valve action, and compression.
To get the flow, a set of No. 915 heads were selected, not for any higher flow potential (there isn't any), but to get the closed chamber configuration and reap the combustion efficiency of a quench head. How much of a benefit is there to the quench? Beyond some theoretical experiments conducted in the '30s at the Kettering Institute, as published by Taylor (MIT), we haven't seen it quantified. Though there really isn't a practical way to predict the benefit of the quench, we could easily test for flow.
The junkyard heads used in building this 440 received serious porting, but they weren't radically altered with welding, brazing, sleeving, or epoxy. Filling out the chambers, custom Manley valves were ordered in a large 2.25-inch intake diameter, with more conventional 1.81-inch exhausts. The intake seats were cut using a special 30-degree seat form on a Serdi seat and guide machine. To minimize shrouding with the large valves, the chamber was plunge-cut adjacent to the valve, well beyond the sealing surface of a stock gasket. Milodon copper gaskets were modified to match the chamber, and the bores were notched for a smooth transition from the chamber to the cylinder. Flow was improved to the tune of 25 percent more area under the entire flow curve (as opposed to just an increase in peak flow) on both the intake and the exhaust, with peak flow figures up by 34 percent. The heads moved air like a set of aftermarket race heads.
The short-block features a reground stock forged crank swinging Eagle H-beam rods and a 12.5:1 Arias piston with Total Seal Slant Gap Gapless rings. With a stock 3.75-inch stroke and a .060-inch overbore, the final displacement is 452 inches. The piston domes were massaged to break the sharp edges, and the spark plug reliefs radiused, which help flame travel with high-domed pistons and the big Mopar wedge's distant plug position. The final compression ratio calculated to 12.66:1 with a -.005-inch piston deck clearance and Milodon's .040-inch gasket. Milodon studs were used to secure the crank, along with their deep-sump tray, oil pump, 11/42-inch NPT pickup tube, and geardrive. The block's oil feed passages to the pump were massaged with a carbide bit in a die grinder.
Playing a big role in our final power production was having enough cam to get the job accomplished with the compression and flow we had. The cam and valvetrain were all Comp, using a custom solid roller, specing out at 260/258 degrees duration at .050-inch lift, run with Comp's 1.6:1 aluminum roller rockers, and Comp high-tech .080-inch wall pushrods. It's certainly a stout cam, but nowhere near the duration of a full-on drag-race cam. We covered the build in far greater detail when we first screwed it together. Want to build one just like it? Get the back issues and start wrenching.-Steve Dulcich