SUPER SUCKER...IS IT FOR REAL?

[Corzette]

Race Tech article: Ne w-age Carb Spacers

 

A couple of years ago, I wrote a column on carburetor spacers in which I discussed how spacers worked, how they can be used to tune a given combination, and what materials are used in spacer construction. From my experience and from what most racers already know, there usually isn't much power in a spacer. Oh, you might find a horsepower or two in some cases, and you can move the power band around a bit and help distribution in other cases, but for the most part, there isn't much extra grunt available from a spacer, or is there?

 

Fast forward a few months to the 1999 PRI Show. Joe Petelle of HVH was manning a little piece of a booth shared with his pals from Porta-Tree. The folks in the booth handed me a one-inch-tall carb spacer with the simple words "Try it."

 

Joe Petelle and his son, Keith, own HVH, or High Velocity Heads. HVH may not be well known in drag racing, but it's another story in Winston Cup, where they ported heads and manifolds for Chevy and Ford teams from 1980 to 1992. In addition, HVH designed a series of intake manifolds for Brodix and created the layout for the Canfield big-block Chevrolet head. Currently, they primarily build carb spacers, but they also do limited amounts of custom work for short-track applications and drag race cars (yes, they work on NHRA Stockers, iron heads, and basically anything that flows air).

 

The HVH Super Sucker that I picked up at the PRI Show languished on my desk for months before it was moved to my work bench, where it languished for many more months. Finally, I slipped it into my camera bag on a trip to Speed Way Testing in Richmond, B.C.

 

While talking to John Heida of Speed Way Testing about his SF901 Dyno installation (a rather nice installation, by the way), I opened my camera bag and tossed the spacer to John with the simple instructions "Try it."

 

 

Heida knows his way around cylinder-head and manifold flow, and we scrutinized the Super Sucker. Sure, it was made from a very composite material, and it was a one-inch-tall version. And, yes, the top side (carburetor mount side) looked like any other four-hole spacer for a standard Holley flange. But the bottom (intake manifold side) was far different than anything we had seen before. I think independently we came up with the same assessment: It's different, but it's a carb spacer. It might be worth a horsepower or two. It's probably nothing more than a tuning aid.

 

Nothing more came from all this until a few days ago, when the fax machine in my office began spewing paper. Out came a couple of dyno-pull results from Speed Way Testing. The results from those tests were remarkable.

 

The engine in question was a relatively mild 355-cid small-block Chevy with a set of small-valve heads that Heida had reworked. If you check the engine's volumetric efficiency against the brake specific, you'll find that the engine is a pretty efficient piece. Data was corrected for 29.92 inches Hg, 60-degree F dry air. The tests were done in a conventional A-B-A format (for the sake of simplicity, I haven't included the final backup test; it matches the first test exactly). Here are the baseline test results:

 

rpm torque horsepower

5,000 402.8 383.5

5,100 401.8 390.2

5,200 397.3 393.4

5,300 400.6 404.3

5,400 393.7 404.8

5,500 390.0 408.4

5,600 386.2 411.8

5,700 380.6 413.1

5,800 375.6 414.8

5,900 376.2 422.6

6,000 370.7 423.5

6,100 366.4 425.6

6,200 362.8 428.3

6,300 359.3 431.0

6,400 352.8 429.9

6,500 349.4 432.4

 

Peak in baseline configuration was 432.4 horsepower at 6,500 rpm.

Maximum torque was 402.8 foot-pounds at 5,000 rpm.

 

The second test duplicated the first with only the one-inch-tall HVH Super Sucker carburetor spacer added. Results follow:

 

rpm torque horsepower

5,000 413.2 393.4

5,100 405.3 393.6

5,200 398.8 394.9

5,300 402.1 405.8

5,400 396.9 408.1

5,500 390.4 408.8

5,600 387.2 412.9

5,700 379.8 412.2

5,800 377.1 416.4

5,900 378.6 425.3

6,000 372.6 425.7

6,100 370.9 430.8

6,200 369.0 435.6

6,300 367.3 440.6

6,400 367.1 447.3

6,500 353.7 437.7

 

As you can see, the small-block peaked at 447.3 horsepower at 6,400 rpm, and the maximum torque of 413.2 foot-pounds occurred at 5,000 rpm. In comparing peaks, the Super Sucker added 14.9 horsepower and 10.4 foot-pounds of torque (again at peak).

 

There go the assumptions. In theory, the two-inch model should have made even more power. So how in the world does this thing work?

 

I asked that of Keith Petelle of High Velocity Heads. He said, "These spacers work, obviously, by helping the fuel distribution. If you look at the bottom of the spacer, you'll see that the shape is different [in comparison to other spacers]. We wanted to improve the feeding of the outside runners on a single four-barrel manifold. The design picks up the air speed and gives it a specific direction. Finally, the plastic composite material insulates the carburetor.

 

Plenty of people are skeptical. Many people will think that if they spend big money on a hand-fabricated intake manifold, they don't need a spacer. We've had some racers with very powerful engines see major gains. We've had some used on Comp engines. The spacers don't discriminate between expensive, high-horsepower engines and low-cost, low-horsepower engines. They work equally well on either small-displacement engines or big ones. We typically see power increases in the range you found. We've seen more, but it really does depend on the engine and the type of manifold used."

 

Currently, HVH spacers are made from solid plastic composite stock on Haas CNC mill equipment. The company offers one-inch- and two-inch-tall four-hole spacers for 4150 Holley carburetors, one-inch- and two-inch-tall four-hole spacers for Holley Dominator carburetors, open one-inch-tall spacers for Holley 4412 carburetors, and one-inch-tall two-hole spacers for Holley 4412 carburetors.

 

The spacers aren't cheap at a price range between $85 and $105 (racer's net), but they do provide cheap power, and in a well-sorted engine, 15 horsepower for 85 bucks can be considered a bargain.

 

My preconceived notions were definitely wrong: There is power to be gained from a carb spacer, but it takes a special configuration like the one used on the Super Sucker to make it happen.

 

[grumpyvette]

spacers add plenum volum and a more gradual change in direction to the air flow which tends to lower the airflow speed very slightly but boost the air fuel mixture time . each engine will require testing to see which combo is best.as a general rule any engine that runs much better with a spacers is seeing a restriction in the runners and/or plenum and might be better off with a differant intake or port work, spacers are a tuneing aid not generally a huge help in making hp unless your combo is restricted in its air flow or needs that extra height to aid the fuel air mix time. If they see a gain like that , changing intakes or doing port work would most likey further boost the power curve, its NOT that the spacers "MADE POWER" its that the intake in use was COSTING POWER WITH OUT THE SPACER DUE TO A FLOW RESTRICTION

that 14.9 hp represents a 3% peak differance, a change easilly bettered with a bit of port work and a differant intake design

the differance the spacer made was that the tq at the higher rpms held up better, a sure sign that the cylinder fill efficiency was slightly better, while the spacer obviously helped a swap to a better intake would more than likely improve things even more.

as an example I rarely see spacers help on a correctly ported edelbrock super vic single plane intake because they flow exceptionally well but I comonly see the dual plane rpm style intakes on radical engines benifit at the upper rpm ranges simply BECAUSE the dual plane intakes design is not meant to operate at that rpm level efficiently so the spacers extra plenum volum helps, but keep in mind that its normally a trade off... the spacers normally hurt low rpm /off idle tq

 

NOTICE THE DATA STARTS AT 5000RPM, BELOW THAT THE SPACER MORE THAN LIKELY HURT TQ ..always ask WHY was the data not from idle to engine red line on any dyno info thats only showing results over 1500rpm???????

[SleeperZ]

So much for running a stock hood huh?

[Guest Anonymous]

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[jap tin]

You should have run a 3rd test without the spacer A B A . A dyno operator is like a good bookkeeper, tell me what you want.

[Guest LightHeaded2ozKB]

This is a random question but has anyone ever uesd wood spacers. I hear they transfer very little head. Any on know if this is true?

[Guest Anonymous]

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[Drax240z]

Here is a quick list of materials and their relative thermal conductivities. Remember, even though a material has a low thermal conductivity, that may not make it suitable for a carb spacer. (air for example! ) Make sure that whatever material you use has mechanical properties suitable for the task, is fuel resistant, and has a flash point well higher than the surrounding areas temperatures.

 

MATERIAL CONDUCTIVITY ("k")

Copper 2712.00

Aluminum (6061) 1160.00

Aluminum (5052) 960.00

Lead 245.00

Stainless Steel (316) 113.00

Glass 5.00

Polyester FRP (hand laid) .48

Polyethylene Foam .43

Wood (dry) .33

Polyester FRP (pultruded) .31

Glass Wool .29

Polystyrene (expanded) .28

Cork Board .27

Polystyrene (extruded) .21

PVC (Klegecell) .21

Polyurethane Foam .17

Air .16

BARRIER Ultra-R .02

Total Vacuum .004

 

Oh, and phenolics have very low thermal conductivities, depending on what materials they are doped with. (could be graphite, glass, wood, etc) So a paper/phenolic is probably in the AREA of 0.33. (and honestly I can't remember what the american units are for thermal conductivity)

[Guest Anonymous]

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[Drax240z]

How many stickers does that entail? Oh and how bit is the exhaust tip? I guess it depends what site you scour for information.