Just how good is this latest iteration of Holley’s big power carburetor?

The world outside of Holley Carburetor’s R&D department first saw the new Gen 3 Ultra ‘Super’ Dominator at the 2012 Carb shoot-out at Bo Laws Performance (BLP) in Orlando Florida. This was a gathering of about a dozen of the country’s top carb specialists. Despite an extreme level of competition the latest iteration of Holley’s #1 horsepower generator came literally within a hairs breadth of winning the shootout. Impressive yes, but even more so when you consider that this carb had not been dyno tested until 3 days before the start of the event.

Holley’s new ‘Super’ Dominators

Figure 1. Holley’s new ‘Super’ Dominators with their show quality finish, look every inch the part of a power producer. They are available from 950 to 1475 cfm in roughly 100 cfm increments. The question is ‘do they go as good as they look?

Four years or so on we hear many enthusiastic comments from top pro engine builders while negative comments amount to a light sprinkling. Having witnessed the original carb shootout tests it seemed time to see if this all translated into real world field gains.

Terry Walters and Jack Sain

Figure 2. Between them, Terry Walters (right) and Jack Sain (left) have better than a half century of dyno test experience. Their efforts here made this feature possible so our thanks go out to them.

The Test Engine

To produce meaningful results when testing a Dominator of almost any size the test engine needs to be reliable, repeatable and, most of all, powerful. The plan here was to test 4 carbs. Two were of known capability and two the Gen 3 Ultra Dominators. To truly optimize the calibrations (and that means main jets, air bleeds and, if required emulsion well jets) means a lot of work especially so when a major part of the optimization process involves stagger jetting. Obviously a stout race engine would be good but most shops are reluctant to use an expensive race engine for what could well approach a hundred pulls.

Fortunately ex ProStock racer Terry Walters of Terry Walters Precision Engines in Roanoke VA provided a very acceptable solution. Terry is, with GM’s blessing, currently testing modifications which could possibly find their way onto GM’s 572 big block crate motors. Part of the requirement for an engine sold out of GM’s performance division is that it must pass a 50 hours at peak power test.

Test motor is shown equipped with the GM intake. Even though this is a relatively low rise, installation friendly intake, it produces, in oval port form, excellent results on long blocks capable of 550 to 750 hp.

Figure 3. Here our test motor is shown equipped with the GM intake. Even though this is a relatively low rise, installation friendly intake, it produces, in oval port form, excellent results on long blocks capable of 550 to 750 hp.

Terry’s 572 dyno mule, at the time of our tests, had 141 hours on the dyno. But, in all respects other than the fact it made right on 800 horsepower, it was no premadonna race engine. To the contrary, it was a truly streetable 9.4/1 dyno mule with a 650 rpm idle. Best yet it ran on 87 octane fuel and that saved us a ton on fuel costs.

The Test Carbs

The plan here was to test 4 carbs. The baseline carb, because it is what the GM 572 street crate motors come with, was an electric choke, vacuum secondary equipped, 850 Holley #80531. This part number comes from Holley with calibrations targeting big block engines in and around 500 inches. As such it has a good track record for meeting the demands of a true street power plant, hence its baseline usage.

Figure 4. Our test carbs left to right. 850 vacuum secondary, 950 Ultra HP, 950 Ultra Dominator and 1050 Ultra Dominator.

Figure 4. Our test carbs left to right. 850 vacuum secondary, 950 Ultra HP, 950 Ultra Dominator and 1050 Ultra Dominator.

Next on the list was what is proving to be a thorough bred race carb – the 4150 series 950 Ultra HP. Ours was highly corrosion resistant ‘Hard Core Gray’ finish variant #80805HB but they can be had with a silver body together with red or black metering blocks and base plates. Terry Walters has considerable experience with these 950 Ultra HP carbs and speaks highly of them. He commented that if the cam is right for the rest of the engine spec these carbs will consistently deliver top results. For that reason we are using it as a yardstick by which to judge the Ultra Dominators which are also primarily a race carb.

The third test carb was a 950 Ultra Dominator. Going into this series of tests we knew it was going to be on the small side for our test engine. But here is the logic. The 4150 series 950 Ultra HP has, over the last few years, more than proven its capability to produce power. If the new 950 Ultra Dominator (#80901HB) could, with the same airflow, equal or even exceed the output shown by the 4150 series 950 Ultra then we could be almost certain that these new Gen 3 Ultra Dominators had what it took to be a top predator.

Last on the list was the 1050 Ultra Dominator (#80902BK). This was the carb that Holley’s engineers suggested would give us the best overall power curve keeping in mind our test engine would pull from a little over idle to 6300 rpm.

850 Baseline Results

Here is where you will probably need to start dodging back and forth between the text and the dyno results in the nearby chart and graphs. Check under the torque and hp columns headed ‘GM 850’ (850 carb – GM 88961161 single plane non-heated street/strip intake). Note our 87 octane burning 572,which would be happy in most truck applications, cranked out peaks of 738 lbs-ft and

Holley 850

Figure 5. Here is our baseline 850 as was used for the tests. The choke plate was removed to facilitate easier access to calibration elements but its removal does not affect airflow. Also a quick change vacuum diaphragm setup was used for a speedier setup of the vacuum secondary opening point.

756 hp. But, as good a showing as that may be for a pure street spec Holley carbed motor there is more, as Terry Walters was quick to point out. The calibrations of this street 850 are primarily for a heated street intake. Whereas this does not impinge on any ability to optimally calibrate jets it does impact the style of boosters best suited to the much cooler running intake such as the single plane GM intake used here. A cooler running intake requires a booster with greater atomization capabilities. Terry advice here is that if you use an 850 on an unheated intake then the regular dog leg boosters need to be converted to stepped dog leg items. He tells us that, from experience, swapping to a stepped dog leg will half the difference seen between a regular 850 and a race spec’ed 950. Equally important is the fact that all the gains are in terms of extra lbs-ft and show everywhere in the rpm range.

950 Ultra HP Test

The next tests (columns headed 950 GM) involved removing the 850 and substituting it for a 950 Ultra HP carb. This was run with and without a spacer but the best average output over the rpm range tested was without a spacer so these are the numbers used for our comparison.

Holley 950 Ultra HP

Figure 6. Given that the motor’s cam, head and displacement specs are compatible the 950 Ultra HP has proved a consistent top performer. Our tests here showed just such a trait.

As can be seen the 950 Ultra HP produced a very healthy gain. But numbers aside we need to consider that this is a street motor so low speed torque and drivability are important. A batch of tests designed to highlight any holes in the power curve found none. If the 950 Gen 3 Ultra Dominator could match or exceed the drivability and output given by the 950 Ultra HP then we can be near certain it has the right pedigree.

950 Super Dominator

Running the 950 Ultra Dominator required the use a spacer/adaptor to adapt the 4500 Dominator bolt pattern to the intake manifolds smaller 4150 bolt pattern. When a spacer was used with the 4150 style 950 Ultra HP a low speed torque reduction was seen that did not justify the small high rpm gain.

Once calibrated, our 950 Dominator and space/adapter combo was marginally down at lower rpm but marginally up at the top end in almost the same proportions to the 950 Ultra HP and spacer combo. If this 950 Ultra Dominator was doing what it was supposed to do then these results mirrored our expectations. Overall top end output rose by 11 horsepower.


Figure 7. Holley 950 Dominator Carburetor.

Figure 7. Holley 950 Dominator Carburetor.

Holley 950 Dominator Carburettor, in Battleship Grey.

Figure 8. Holley 950 Dominator Carburetor, in Battleship Grey.


1050 Ultra Dominator

Continuing out tests with the GM intake we found, after optimizing the 1050’s jetting, that peak torque and hp were virtually unchanged from that seen with the 950 Ultra Dominator. What did change however was that the 1050 was down a lb-ft or so below peak torque and up 1 to 7 lbs-ft above peak power. In other words it hung on better after peak power rpm. This was not unexpected and on the track would help performance by allowing the upshift to be made about 200 rpm later.

Holley 1050 Ultra Dominator Carburettor

Figure 9. Not only did this 1050 Ultra Dominator perform but also it was finished to show quality standards.

There was an expectation of greater output from the 1050 than was seen. However, there is a factor conspiring to limit the output regardless of how big a carb might have been installed. The GM manifold being used has a relatively short carb pad height which means sharper port turns both from the plenum and on into the head ports. This limits airflow between the carb and cylinder heads. Here, Terry Walters pointed out that although they had topped 800 horses on their street big block Chevy’s with a GM pattern intake and a 4150 carb such a manifold carb combo was right at its limit. Even though the 1050 had more flow capability the engine itself could not access it because the intake manifolds runners were fast becoming the limiting flow factor. Time then for a manifold change.

950 Dominator Plus Sniper

An intake manifold that has repeatedly shown strong results on the TWPE dyno is the Darin Morgan inspired Profiler ‘Sniper’ and ‘Sniper Jnr’. These race bred intakes are popular with the rear engine dragster guys because they work really well. Here one was pulled from the TWPE parts room and quickly port matched to the 325 cc runners of the Dart heads.

Profiler Sniper Jnr

Figure 10. In terms of performance capability this Profiler Sniper Jnr is a no compromise design and that virtually mandates the need for a high hood cowl or hood scope. That may be fine for the track but not so much for the street.

The dyno numbers demonstrate the validity, at this power level, of the factory 572 intake manifold being the cork in the induction system. At the lower rpm there was a small reduction in torque with the 950 Ultra Dominator on the Sniper Jnr. intake compared to the numbers produced on the GM intake. But at 3900 rpm the score was even and from there on up the 950 Dominator/Sniper Jnr. combo went on to make 7 lbs-ft more for peak torque and 14 more horsepower.

At this point the expectations for positive results using the 1050 were high.

1050 Ultra Dominator Plus Sniper Jnr

As it happened the jetting for the 1050 Dominator was close right from the first pull and the numbers seen went right by those so far recorded. After minor jetting changes the 1050 showed it’s worth and proved the selection of a 1050 by Holley’s engineers to be on the money. Below 4000 rpm we saw, from figures averaged over 5 pulls, just one lb-ft less torque and from 4000 up the 1050 was the best of the best. Peak torque was up by 14 lbs-ft and peak power up by 12 over the 950 Dominator and up 36 horses over the best seen with the 950 Ultra HP on the GM intake.


Though it had several hundred pulls the TWPE 87 octane friendly 572 endurance motor proved capable of virtually 800 hp given the intake capacity to feed its substantial appetite for air. Even though our test engine was a street spec motor both Gen 3 Ultra Dominators proved capable of delivering greater output with no apparent loss of drivability. This new offering from Holley seems to justify our unofficial description of ‘Super’ but don’t take our word for it. Terry Walters twenty plus years in ProStock has meant a close relationship with Dominator carbs. His thoughts here – “on a well speced engine these new Gen 3 Ultra Dominators perform as good as they look – and that is just great”.



So what makes the Ultra Dominator into a ‘Super’ Dominator?

As a starter the not so obvious overall design refinements consisting of better fuel sealing and float bowl fuel control. This may not seem much but it adds up. A centrally located drain plug makes fuel draining for a jet change more convenience with less fuel spillage. The billet metering blocks have just about everything adjustable by means of removable jets. Also jet extensions are stock on the rear float bowls.

Holley Rear float bowls have jet extensions as supplied.

Figure 13. The new metering blocks come equipped with just about everything a pro level racer would want to get the best from the engine. Rear float bowls have jet extensions as supplied.


Boosters are billet style items which produce much more consistent results as well as being more effective at signal generation. The support arms are also more aerodynamic. The main venturi and the bodies form to and from it, are redesigned for better airflow for a given size.
Also gone is the need to drill holes in the butterflies to set up the idle system when a big cam is used. Instead an adjustable idle air bypass system allows the calibration of the idle circuit air demand with the engine running.

Original Holley Dominator

Figure 14. Original Dominator left and the Gen 3 Ultra Dominator right. Notice the more aerodynamic shape of the new Dominators entry into the venturi. Also the billet booster (yellow arrow). An adjustment screw under the air filter securing stud thread ((blue arrow) controls the quantity of bypass idle air drawn through the hole (one for each venturi) indicated by the red arrow.


David Vizard.

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