Paxton’s Most Affordable Blower - Hot Rod Magazine

The Premise

Boost makes you godlike, letting you pick almost any power level you want. The downer is that guys fear the complexity and cost of adding a turbo or blower. Paxton solved that with the easiest and most affordable centrifugal huffer system we've seen: the Entry Level Universal Supercharger kit. For carbureted small-block Fords, these sell at Summit Racing for $2,359.95 in a satin finish (PN 1001864SL) or polished for $2,819.99 (PN 1001864SL-P). There are also setups for small- and big-block Mopars at slightly higher prices. With the promise of being the easiest boost-in-a-box kit yet, we had to check it out.

The Stuff

Paxton offers a number of carbureted small-block Ford kits with options to mount the blower on the driver or passenger side and with '85-style serpentine drive or with early V-belt setups. Those kits are spec'd with a full carburetor enclosure, but the new Entry Level kits hang the blower to the passenger side and use Paxton's new PowerHat carburetor bonnet that's vastly less expensive and easier to deal with than an enclosure. The blower included is the geardriven Novi 1200SL. The SL stands for self-lubricated, meaning the oiling for the supercharger comes from its internal reservoir and not from a pressure line that must be plumbed from the engine. This also eliminates the pesky-to-install return line to the oil pan.

The parts we used differ a bit from what's in the kit, as we had an older version of the early-Mustang package that places the blower on the driver side and uses a Novi 1200 that's not self-lubricated. However, we used the same pulley ratios and PowerHat and have no reason to believe that our results will differ from the new Entry Level package.

The Test

We did a simple A/B comparo of blown versus unblown power on the engine dyno using the 363ci small-block Ford built in last month's issue. It uses a Dart SHP block with a forged bottom end, a bore and stroke of 4.125x3.40, and Dart Pro 1, 195cc, as-cast cylinder heads. The compression ratio is 9.26:1, and the cam is a Comp Cams NX282 hydraulic roller with 232/244 degrees of duration at 0.050, 0.565/0.580 lift, and 114 degrees of lobe-separation angle (PN 35-560-8). We used Holley's Ultra HP 750-cfm carb and an MSD ignition and sealed the heads with Fel-Pro multilayer steel gaskets and ARP bolts. The tests were run on Rockett Brand 100-octane unleaded street gas. Interestingly, we tested both an Edelbrock Air-Gap dual-plane intake and an Edelbrock Victor Jr. single-plane.

The Results

The power charts (next page) tell the story: We gained about 250 hp and 160 lb-ft at peak and had massive power improvements at every point in the rpm curve. Duh.

In comparing the dual-plane Air-Gap intake with the single-plane Victor Jr., it was no surprise that, naturally aspirated, the dual-plane tromps below 5,000 rpm and the single-plane takes over at higher rpm. The same effect was seen when the engine was supercharged. The longer runners of the dual-plane blew the doors off the single-plane below 4,000 rpm, making as much as 35 extra lb-ft. The Air-Gap is stronger than the Victor Jr. all the way to 5,200 rpm, but the Victor never gets ahead by more than 10 or 12 hp. Our pick would be the Air-Gap. Paxton developed this kit for mildly hopped-up 289s and 302s and included pulleys estimated to deliver 7 to 8 pounds of boost around 5,500 rpm. Our Dart 363 has more displacement, which tends to reduce the boost reading, but we saw 7.4 psi at 5,500 rpm, right on Paxton's target. Our engine also carried more rpm (up to 6,600) than would be expected of a stock 289. Spinning the blower faster makes more boost, hence we saw 10 psi at 6,700 glorious rpm.

Conclusions

This is a mega-win for power and ease of installation and tuning. There are some things to consider, however. First, you'll need a quality electric fuel pump and a boost-referenced regulator. Here's why: The carburetor bonnet encloses the carb's vent tubes, inducing boost pressure in the float bowls. Any amount of boost effectively reduces fuel pressure at a rate of 1:1. Typical carbureted fuel pressure is 7 psi; if you add 7 psi of boost, the net pressure is 0. Therefore, fuel pressure needs to rise at the same rate as the boost, which is handled by a boost-referenced regulator (which is a fancy way of saying there's a hose that runs from the bonnet to the regulator). In our case, at a peak of 10 psi blower boost, the fuel pressure as measured at the regulator outlet was 17 psi. But in the float bowls, 17 psi of fuel pressure is reduced by the 10 psi of boost, creating a net fuel inlet pressure of 7 psi. This is critical to prevent lean-out under boost. We've run many carbureted blow-through setups from 700 to 1,100 hp using the Aeromotive A1000 fuel pump (PN 11101, $333.95 at Summit Racing) and the "R2D2" A1000 regulator (PN 13204, $163.95). That's a bypass-style regulator that will also require a return line to the tank. If you have lower power expectations, you could use something less hard-core.

Your other expense will be adding a blower bypass valve. This doohickey relieves blower pressure in circumstances in which the throttle is closed and engine rpm remains high, like when you lift while the trans is still in gear because you've panicked under newfound, brutal acceleration. Without the bypass, pressure can stack up against the blower vanes and cause badness. Paxton's least expensive option is PN 8D204000 ($245.00) and the mounting flange, PN 8D004-052 ($24.00).

The upgrades we just listed add up to $766.90. Add that to the price of a satin blower kit and you've got $3,126.85. That might be the end, or maybe not.

Another cost consideration is whether your existing carburetor is up to these antics. There's a lot of voodoo talk about blow-through carburetors, but we've found that an out-of-the-box Holley with adjustable air bleeds and without a choke tower can be tuned for boost levels up to 8 to 10 psi. Making it even easier is the Paxton PowerHat, which uses a diffusion element to reduce turbulence across the top of the carburetor. We've tested it three times, and we like it.

Then there's ignition timing, which must be retarded to safely run with boost, especially on pump gas. Our 363 made best naturally aspirated power at 36 degrees total lead, but we ran 27 degrees with the blower. The problem is that you can't just crank back the distributor if you have one with mechanical advance, because when you retard the total timing lead at high rpm, you'll reduce it by the same amount at idle. In our case, the change from 36 to 27 degrees retarded the total timing by 9 degrees. If we'd been idling at 15, it would now be 6 degrees, which is not groovy. You'll need to either limit your advance curve or invest in one of the electronic boost-retard boxes or, better, one of the newer boxes with a computer-programmable timing curve. MSD offers both.

How about your accessory drive? The passenger-side blower mounting creates no problems with a power-steering pump or a driver-side alternator. If you've got anything different, get ready to figure out some new brackets, belts, and pulleys. The last hidden cost is an O2 reader, which we highly recommend. Your carb will need to be jetted up significantly for the added power, and you can't do that without a way to data-log your air/fuel ratio, shooting for about 12.0:1 at WOT.

The kit's pulleys measure 3.7 inches on the blower and 6.88 at the crank for a ratio of 1.86:1. With the blower's internal step-up ratio of 3.54:1, you need to consider the maximum impeller speed of 52,000 rpm if your engine spins to 7,500 rpm. Those pulleys are for an eight-rib, serpentine-style belt. We've sworn off ribbed belts for blowers because they always slip, as ours did, requiring us to crank up the belt tension between pulls to get repeatable results. We ran a higher rpm and more boost than what was intended for this kit, both of which led to slip. A larger blower pulley would reduce boost (and power) and aid belt grip.

Bottom Line

We love this thing because it makes huge power that's always on tap, and it's one of the simplest blow-through setups. But like all blower installations, it will require a little fiddling before you're finished.