Power From the Pump Assembling a 14-71 Top Fuel Supercharger
Written by Randy Fish
Page 1 of 2
You've probably heard the term 're-stripping' a blower. THe Nylatron (black) strips seal the rotor to the housing and the tighter the tolerance, the cooler the air charge coming in. The Teflon (white) strips seal rotor-to-rotor. Here, Nate heats a Nylatron strip with a propane torch to soften it up.
Editor's note: Back in our March '07 issue, we showed you how a Top Fuel team mounts its Goodyear Eagle 2420 slicks on Weld Racing bead-loc wheels, and your comments were favorable. This time, we're giving you an inside look at how a massive 14-71 supercharger is assembled in the field, thanks to J.R. Todd and Dexter Tuttle's multi-national-event-winning Top Fuel team.
Years ago, all you could do to a 6-71 supercharger at the race track was change the pulley. If your blower was junk, you bolted on another one and then sent the dead player out for repairs later that week. In today's world of championship drag racing, a weak blower can be rebuilt and made race-ready in a little over an hour. Most teams keep anywhere from six to eight blowers ready to go, and at roughly $9,000 per copy (complete), we're betting a cabinet full of components like cases, rotors and gears helps the cost factor. However, maintaining the necessary inventory of race-ready blowers is as important as spare cranks, rods, pistons, blocks, and heads.
There are several keys to success when it comes to racing, but being self-sufficient goes a long way towards keeping a team at (or near) the top of its game. Most Pro teams have traveling machine shops, tire balancers, clutch surfacing machines, and much more. In order to compete in today's world, every component and system that occupies space on a race car needs constant maintenance, whether it be the ignition system, cylinder heads, clutch, rotating assembly, rearend, fuel system, or supercharger. Likewise, key personnel are assigned to perform these regular maintenance chores on a rotating basis.
With the level of competition we're seeing in the nitro classes, a 16-car Top Fuel field may only be separated by a little more than a tenth of a second. And when a car falls off in performance (on a clean run), the cause can sometimes be traced to the supercharger. Here in 2007, the stakes are too high to be bumped out of the top half of the field thanks to a weak blower, and strict maintenance can prevent that from happening. Here, we'll show you a 14-71 blower being re-stripped and rebuilt. For more information, you can contact any of the supercharger specialists listed in our source box. Now, let's show you how Dexter Tuttle's crew handles a normal blower build-up. DR
Sources:
Blower Drive Service 12140 Washington Blvd., Dept. DR Whittier, CA 90606 (562) 693-4302 www.blowerdriveservice.com
Cantrell Racing Products 2314 E. Laurel Lane, Dept. DR Phoenix, AZ 85028 (602) 918-4945
JEGS (800) 345-4545 www.jegs.com
Littlefield Blowers 1114 E. Kimberly, Dept. DR Anaheim, CA 92801 (714) 992-9292
Mooneyham Blowers 1935 W. 11th St., Unit N, Dept. DR Upland, CA 91786 (909) 985-4425
Performance Systems, Inc. (PSI) 6535 South Ash Avenue, Dept. DR Tempe, AZ 85283 (480) 820-6511 www.psisuperchergers.com
What we're looking at here is a brand-new PSI 14-71 magnesium supercharger housing. A bare case weighs in the neighborhood of 30 pounds, while a complete blower comes in at approximately 90 pounds.
The old phrase 'tight is right' applies here, as the strips are fitted into a machined receiver groove with extremely tight tolerances.
Once the strips are wrestled in place, they're checked, trimmed and ready for machining. The desired rotor-to-case tolerance is about 1/1,000-inch.
Rotor strips are commonly machined in a lathe, but this precision fixture has also become popular due to its portability. It locks the rotor in place, allowing it to spin freely, while an electric die grinder mounts below, sliding from one end of the rotor to the other, removing a prescribed amount of strip material throughout its travel. Shims are used to dial-in the amount of material being removed during each pass of the grinder. After the strips on each rotor are machined, the outside diameter is checked with a micrometer to verify if it's close to the desired tolerance.
