by John Baechtel

George Poteet's Speed Demon is back on the salt again for the 2017 SCTA Speed Week. The Speed Demon had accumulated a grand total of 39 runs over 400 mph. Most of those runs and records were posted prior to the 2014 crash that destroyed the original Speed Demon. The all new Speed Demon returned in 2016. It immediately resumed its dominance at the 2016 Bonneville Speed Week by setting top speed of the meet with a 442.099-mph blast and a new 416.511-mph B/Blown Fuel Streamliner class record that secured the Hot Rod Magazine Top Speed Trophy for the 6th year in a row. For the 2017 Speed Demon engine builder Kenny Duttweiler is departing from his traditional small block ware to construct a 441-cubic inch LS -based powerplant to attack the A/Blown Fuel Streamliner record that currently stands at 409.986 mph. He could get there with a traditional small block, but he liked the potential of Dart’s new LS head and he decided to try it for this SCTA class. Poteet owns the B, C, D and F Blown Fuel Streamliner records and he is intent on taking the A record in 2017. Spoiler alert. The effort was successful in every respect.

The impetus behind Poteet and Duttweiler's decision to attack the A/Blown Fuel record is twofold. Poteet wanted to secure another record and the A record was not yet a part of his inventory. But he didn't have any engines large enough to fit the class. The A engine class at Bonneville specifies 440 to 500.99 cubic inches. Duttweiler knew he could build another small block to that spec, but he was so impressed with Dart's new LS cylinder head when he saw it at the PRI Show, he decided to build an LS engine for the A class and save the lower displacement small blocks to attack FIA records at Mike Cook's FIA Bonneville Shootout. In keeping with his long standing philosophy of running minimal displacement to avoid traction issues caused by higher torque, large displacement engines, Duttweiler chose to fit the engine at the very bottom of the A/Blown fuel class with the smallest allowable engine at 441 cubic engines. He prefers to employ the torque control the smaller engine offers and then modulate it with traction control and boost management where the ECM makes decisions based on wheel speed and manifold pressure.

His reasoning is straightforward and purely logical. In a highly imperfect traction environment, big blocks with a lot of displacement are traction limited because they make too much torque. While they offer high power potential, they have more limited acceleration potential because they easily overcome the tires, particularly on a two-wheel drive vehicle driving only the rear wheels. A single smaller displacement engine is more favorably biased toward traction management and is easily boosted to big power once the car meets the traction requirement for acceleration and begins to feel the increased resistance of aerodynamic drag. This new LS engine still attempts to accommodate Duttweiler's small displacement concept by configuring the absolute smallest displacement legal for the class.

Designed for maximum competition requirements, Dart's 10° LS head was just what Doctor Kenny ordered. It features raised Pro Stock oval ports, canted valves, and highly efficient, kidney-shaped wedge style combustion chambers. The Race Series 10° LS head departs from traditional LS heads in that the intake and exhaust valve locations for each cylinder are reversed, a key standard feature for maximum power wedge engines. The intake port volume here is 368cc on the CNC version. Flow numbers specified at 1.00-inch lift are 456 CFM intake and 316 CFM exhaust. The chamber volume is 57cc and Kenny special orders beryllium copper alloy seat inserts. The part number for a bare head is DRT-11081050

Duttweiler used the Dart LS Next tough compacted-graphite-iron block because he can't take a chance on the cylinders moving around under the cylinder pressure generated by very high boost pressures. The block incorporates Dart's best features including, priority main oiling, siamesed cylinder bores with extra thick walls, cylinders extended .375” at the bottom, extra thick decks ensure reliable head gasket seal, blind head bolt holes, scalloped water jackets increase flow around cylinders, clearance for 4.100” stroke w/ steel rods and splayed outer bolts on middle main caps.

A key factor in the decision to use the LS engine in a big block class is the engine's narrow architecture which fits in the Speed Demon chassis that was originally built around small block Chevy dimensions. A big block would never fit and Duttweiler calls this engine a big block in a small block wrapper. Dart’s new LS block offers up to 9.450-inch deck-height or 9.950-inch with a .388-inch raised cam tunnel. This makes room for the 4.060-inch-stroke Crower crank that provides the necessary displacement increase. Gen-I race blocks come no higher than 9.300 inches. Duttweiler special-ordered the new block with Ford Cleveland-sized, 2.75-inch main journals that provide the desired journal overlap to withstand the high power level. This block also comes with 1/2-inch main studs to help provide superior clamping force and a very rigid structure for the rotating assembly. The blocks are machined to accept fully counterweighted crankshafts.

Duttweiler uses extra heavy duty Crower race cranks in all the Speed Demon engines. He prefers their precision machining and sturdy reliability. The longer stroke requires a lot of heavy metal Mallory slugs to achieve proper balance. The crank comes with center counterweights and all the counterweights are knife edged to reduce oil drag.

Over time, Duttweiler has developed a list of trusted components he believes are essential to the task. All the Speed Demon engines use Diamond pistons because they provide the material and design strength he requires for engines boosted up to 60 psi; not for 5 or 6 seconds on a drag strip, but for more than 22 seconds at WOT on a 5-mile track.

The Diamond pistons in the Speed Demon engines are extremely tough with heavy duty thrust surfaces, thick decks and reinforced pin bosses to take the abnormal abuse. They have never disappointed even when enduring massive amounts of boost. The compression ratio with the Dart aluminum cylinder heads is nominally set at 9:1. The H13 tool steel piston pins feature a DLC (diamond like coating) and a .220-inch wall thickness. The pistons come fully treated with Diamond’s hard anodized coating and skirt treatment. The whole piston is coated and there is virtually no scuffing after repeated abuse.

The gas ported pistons for the LS engine feature precision ring grooves that accept 2-piece Total Seal .043 gapless top rings that are diamond coated with a special infusion process. The second ring is a .043-inch Napier style and the oil groove accepts a standard tension, 1/8-inch ring. The valve reliefs are pre-forged and present no interference problems as the valve sizes, angles and placement in the Dart cylinder heads are known factors.

The Ferrea valves include 2.300-inch titanium intakes and 1.600-inch Inconel exhausts. The Inconel alloy exhaust valves are required to deal with the extreme exhaust heat generated by the high boost turbocharged application. The valves are secured with Titanium retainers and 10-degree locks. PAC springs deliver the control necessary to run over 9000 rpm for long periods at high boost. The Jesel steel rockers and guided lifters accommodate offset Trend Performance pushrods to gain clearance around the large intake ports. A critical component of valve train stability is the Jesel steel mounting bar (see photo above) that ties the valvetrain together in one very rigid and inflexible structure, thereby ensuring rock solid valve motion and control.

To make 2900+ horsepower requires about 4500lbs./hr of fuel through the engine. That's handled by a pair of Seimens 225 lb. fuel injectors for each cylinder, augmented in each runner by a mechanical injector controlled by the MoTeC ECU. At about 85% duty cycle, the electronic injectors max out and encounter a slow decay in flow. At this point (about 35 pounds of boost) the ECU turns on the mechanical injectors. The mechanical injectors have a high enough flow rate that the ECU can then throttle back the electronic injectors with a specified tune table that reduces the pulse width to a more easily sustainable flow rate. With the MoTeC, they can drive both the Seimens injectors on each runner with a single driver and enable the mechanical system for the necessary supplemental fuel trim. That much fuel flow requires a robust fuel delivery system. A cable-driven 19/gpm pusher pump, gravity fed from the rear mounted fuel cell provides the necessary flow to feed the sixteen fuel injectors and the supplemental mechanical injectors. It also requires a powerful ignition source. According to Kenny, you are trying to fire almost a full intake port full of fuel every cycle with a .013 plug gap. It takes a lot of energy to burn that mixture and they have settled on a 250 Mj M&W ignition system with a MoTeC engine management system.

Another highly critical component of the Speed Demon's robust fuel delivery system is Aeromotive's Ultra-High Flow EFI Regulator for belt drive and hex drive fuel pumps. It is designed for engines making up to 4,000 HP on gasoline and is compatible with gasoline and the methanol fuel used by the Speed Demon. It is adjustable from 40-100 PSI fuel pressure and it references Vacuum/Boost on a 1:1 ratio.

The regulator's performance must be spot on accurate and consistent to ensure a constant fuel supply at the correct pressure as manifold pressure is being throttled. Its job is actually easier under full boost and full power because fuel flow stabilizes. When the engine is operating under traction control the fuel demand is constantly changing, requiring a fast acting regulator to keep up.

The Speed Demon Racing Team has won the Hot Rod Magazine Bonneville Top Speed Trophy for the last seven consecutive Speed Week events. That extraordinary record is due to George Poteet, Ken Duttweiler, Crew Chief Steve Watt and, in very large measure, the relentlessly hard working crew, aptly named the Men in Black in 2016 by a novice reporter whose intended slight resulted in the coveted shirts proudly worn by the Demon record assault team.

As of Speed Week 2017 Poteet has penetrated the rare air of 400 mph speeds a total of 43 times. That is very close to, and in fact, may well be more times than everyone else combined. He owns almost the entire top half of the Blown Fuel Streamliner class at Bonneville. Chassis dimensions will likely prevent the Demon from ever challenging the AA class record because the small block and LS engines cannot be built to 500 cubic inches. But there's no need. All of the Speed Demon's lower class records except one already exceed the standing AA record.

The Speed Demon is not an anomaly. Its performance is too consistent to be labeled a lucky shot, yet it flies in the face of convention where all-wheel drive and big block or multi-engine power are thought to enjoy significant advantages. Kenny Duttweiler's thoughtful approach to torque-managed small block power and rear wheel drive may soon deliver the first piston powered 450 mph speed record.

Well, lookie there. They're already on their way. The same day we posted this story, George and the Speed Demon team qualified against the 409.986 mph A/Blown Fuel Streamliner record they were seeking with a 418.168 mph average through the 5th mile and a 431.512 mph exit speed. Less than twenty-four hours later George shredded a tire going into 6th gear, but that didn't prevent him from running a 428.874 mph record run to claim the new record. Pending certification by the tech team that puts the new A-record at 423.521 mph.

And we just showed you how they did it.

Driver: George Poteet
Crew Chief: Steve Watt
Engine by Kenny Duttweiler
MoTec tuning by Shane Tecklenburg
And wrenching by the always fabulous, Men in Black
Track Photos by Chris Raschke, ARP

In the video above, Tuner Shane Tecklenberg, rigged the onboard data feed so it would show George the engine bay during this run. Note at the end it shows an engine fire caused by a leaky valve cover gasket. George observed the fire and put it out with the onboard fire system while completing the run. These guys leave nothing to chance.