Holley is easily one of the most iconic brands in all of racing. It has to be right up there with Ford, Chevrolet, and Earnhardt. Even now that NASCAR’s Sprint Cup Series has ditched carburetors in favor of very expensive fuel-injection systems, the sanctioning body still turned to Holley to manufacture and supply the throttle bodies.
Of course, carburetors are still the only way to go in practically every other class of stock car racing. That, however, doesn’t mean that Holley doesn’t have competition. Companies like VDL, Braswell, and AED do a lot of work tuning Holley carbs, but they also produce a lot of components, and even complete carbs, of their own.
A few years ago, Holley seriously upgraded its 4150 series carburetors with the HP lineup. And now it has done it again with the Ultra HP carbs. There are tons of new features, but the most striking of all is the all-aluminum construction. Not only do they look good, but by switching to aluminum, Holley’s engineers were able to cut the weight of each carburetor from 12 to 7 pounds. And any racer will be happy to cut 5 pounds of weight high above the car’s center of gravity where the carburetor sits.
In addition, you can also get an Ultra HP with a hard anodized coating. Again, while it looks good, the true value for racers is elsewhere. The hard anodizing helps keep chemicals, track grit, and mud from attacking the carburetor’s surface. Not only are they easier to clean, they are also more durable for good service season after season.
Of course, that’s all nice, but the Ultra HP carbs are at least $100 more than standard HP carbs. So the question becomes whether all those changes are worthwhile. The only way to find out for sure was to do a shootout between the two carbs, and Holley’s Bill Tichenor encouraged us to do just that. His confidence in the new Ultra HP line of carbs spurred us on, so we brought two carburetors to the shops of race engine builder Automotive Specialists. Owner Keith Dorton had the engine we thought would put any carburetor to the test: a high-rpm, high-horsepower SB2.
The carbs we tested were a 950-cfm Holley HP (PN 0-80496-1) and a 950-cfm Ultra HP (PN 0-80805BK), which is essentially the next generation in the 4150 series lineage. We won’t spoil the surprise here, but needless to say the Ultra HP is a very impressive carburetor by any standard. The Ultra HPs are well thought out from top to bottom, and we expect that they will become the new standard in open classes like Super Late Models, where teams can use any carburetor they think will give them the best advantage.
Holley recently introduced the new Ultra HP series of racing carburetors with lots of new features. But is new really better? We put the new Ultra HP to the test to find out.
Holley HP vs Holley Ultra HP
||Ultra HP 950
By the Numbers
In a test, the only thing that really matters is the hard numbers. Here are the results on the dyno with the standard HP 950-cfm carburetor and the Holley Ultra HP 950-carb. As you can see, the HP carb not only produced better peak numbers, but was also better all the way across the board for both torque and horsepower. On the racetrack, there is no downside.
Holley’s new Ultra HP carbs...
Holley’s new Ultra HP carbs feature many major upgrades over the standard HP carbs, but the only thing that matters is if it will help you on the racetrack.
1 The standard throttle linkage...
1 The standard throttle linkage uses a bend rod. To control the rate the secondaries open, you have to bend or straighten the rod.
2 The Ultra HP uses a threaded...
2 The Ultra HP uses a threaded rod as a secondary throttle linkage, which makes it a lot easier to tune. Also notice the knurled knob to make quick idle adjustments easier.
3 One of the first steps...
3 One of the first steps we took was to carry both carburetors to the UTI NASCAR Technical Institute in Mooresville, North Carolina, and have one of the advanced classes run both across the flow bench. We flowed both at 23 inches of water (different from Holley’s testing, so they won’t hit the same cfm numbers) and found that the standard HP flowed 1,044 cfm while the Ultra HP flowed 1,139—which is an improvement of 9 percent.
4 The biggest reason (but...
4 The biggest reason (but not the only one) for the improvement in flow is the fact that the original HP (left) has venturis that measure 1.380 inches, while the venturis on the Ultra HP (right) measure in at 1.604 inches.
5 A lot of attention has...
5 A lot of attention has been paid to the fact that the Ultra’s billet aluminum base plate (right) which eliminates the annoying habit of the cast plates to crack and break at the carburetor studs when they are over tightened. But notice that the bolt holes on the four corners are slotted. This makes the carb a direct bolt-on with both standard and Dominator-style intake manifolds.
6 Not only are the billet...
6 Not only are the billet metering blocks more precise than a cast block can ever be, but every fuel circuit is also fully adjustable. No more drilling necessary.
7 This feature won’t make...
7 This feature won’t make you faster, but it will make jet changes a lot less annoying. A new feature with the Ultra carbs is this built-in drain plug in both float bowls.
8 The float bowls for the...
8 The float bowls for the Ultra carb is 20 percent larger to reduce the chances of fuel starvation, and in addition you can also see the internal baffling inside the bowl on the right designed to reduce fuel aeration and slosh for more consistent operation.
9 Up top, the air bleeds...
9 Up top, the air bleeds have been repositioned further away from the venturis to reduce disruption to the flow of air into the carburetor. You can also see the attention to detail involved in the new-style squirter screws, which Holley’s engineers found is less disruptive to airflow than the old style Phillips head screws.
10 Finally, we like that...
10 Finally, we like that the Ultra carbs (right) now have capped and sealed the primary throttle shaft to keep it from binding up front the intrusion of dirt and debris.
11 Our test engine is a Chevy...
11 Our test engine is a Chevy SB2 built by Keith Dorton of Automotive Specialists.
12 First up was the Holley...
12 First up was the Holley HP 950 carb. Dorton has raced and won with these carburetors for years, and this one performed exactly as he expected. On the SB2, it produced peaks of 512.5 lb-ft of torque and 785.6 hp.
13 Meanwhile, the Ultra HP...
13 Meanwhile, the Ultra HP carburetor outperformed its older brother considerably. The peaks stayed at the same location in the rpm range, but the Ultra HP bumped the numbers up to 527.7 for torque and 824.1 for horsepower.
14 Not only were the peak...
14 Not only were the peak numbers better, but the Ultra HP produced more horsepower and torque throughout the rpm range by a significant margin. The difference only grew as the rpm’s increased.