Try, for a moment, to comprehend a four-cylinder engine capable of achieving 4,000 hp at 55 psi turbo boost on nitromethane. It gets wild pretty fast. A single horsepower is defined as the ability to lift 550 lbs one foot in one second. Bob Norwood's 4,000-hp Turbo-Fuel Max-4 powerplant can lift 2.2 million lbs--1,100 tons--a foot in one second. This is about the weight of a 50-car freight train, but then again, the Max-4 has as much power as a railway locomotive. Another way to look at 4,000 hp is that the Max-4 is capable of lifting one ton straight upward 1,100 feet in a single second. Try to comprehend an engine in which every power pulse--each putt--can lift 4.4 tons upward one foot in one second. This is the type of mayhem a 4.8-liter inline four is capable of when you force-feed it air at a rate of 200 lbs per minute and pump it full of nitromethane at a rate faster than you could dump it out of a bucket. No matter how you quantify it, this is the extreme edge of high-tech performance.
The Norwood Type R Funnycar body tilts up to reveal the twin-turbo/Fuel Max-4 engine. Lowe
With the Max-4 Turbo-Fuel Type R Funnycar, Dallas supercar builder Bob Norwood once again exhibits his well-known penchant for bringing a sledgehammer to a fly-swatting contest. The Type R drag car and Max-4 powerplant are designed to deliver 250 mph and 5.50-second quarter-mile performance on alcohol and nitromethane. The vehicle is designed around a narrowed Mark Williams tube-frame chassis with a narrowed one-piece composite "Integra Type R" body. At 286 cubic inches, the engine is clearly the largest non-aviation four-banger ever constructed in modern times.
"I had the technology," shrugs Norwood, who once did nitrous oxide scientific research and raced Top-Fuel Hemi dragsters with Dale Armstrong. "The Max-4 is half of what we already had in the Batten B-4 DOHC Chevy-Rat-type V8s. I decided to build a big four-banger with lots of cubic inches, good technology, really strong. I basically used a fuel-burning mentality for the block and the driveline and everything else."
The Type R's Max-4 engine is conceptually half of an Arias 500 cid Top-Fuel drag-racing V8, topped with an exotic triple-plug, four-valve-per-cylinder DOHC Batten Performance cylinder head. The engine is based on an immensely-strong aluminum block milled from solid billet without cooling passages--a mighty, solid-block dual-fuel powerplant designed to achieve 3,000 hp on 55 psi of twin-turbo boost, using nitromethane delivered in bulk via constant mechanical injection and trimmed with gigantic port electronic injectors.
The Acura is powered by super hybrid four-cylinder engine featuring a custom billet block
Norwood Type R Origins & Concept
"Nitromethane fuel," says Norwood, "produces extremely high specific power, meaning power produced per mass of intake air. Gasoline actually has more energy per gallon than nitro, but it requires enormous amounts of air to combust--about 12-15 times by weight--and getting air into an engine is always the trick. A pound of air in an engine will burn about an ounce of gasoline. That same pound of air will burn more than a half pound of nitromethane. Nitro is expensive ($800 a drum) and you use a lot of it--a Top Fuel run burns up $200 of nitro--but what's really expensive is how destructive nitromethane is to engines. Our Type R project grew out of the goal of building an import-style (turbo four-cylinder) nitro Fuel motor that did not self-destruct on a regular basis," says Norwood.
"The primary reason that Double-A Fuel cars blow up is due to the wet fuel mixture in the hat, blower & intake being ignited all at the same time, which produces tremendous expansion," says Norwood. "By eliminating this major class of explosion, we had the potential to eliminate large fire extinguishers, blowout panels and body re-enforcements, which are all heavy components. And, of course, to minimize the cost of replacing destroyed engines on a regular basis. We decided our powerplant should be a dry-airflow motor, with Fuel introduced to the intake tract less than 3-inches from the intake valve.
9/16 Donovan TFX ("Top Fuel Experimental") studs help hold the TFX billet main caps in pla
"Fuel cars also blow due to tremendous fuel contamination of the oil, which then is highly flammable. We figured we could minimize nitro poisoning the oil with a dual-fuel injection system, which burns alcohol for start-up, idling, burnout and staging, then switches to nitro for the run. The risk of contaminated oil burning is markedly reduced with only 5-6 seconds of running on nitro. We reduce the risk even further by the use of a three-stage dry sump oil system, which keeps Nitro-contaminated oil out of the engine, in a dry-sump tank. The dry sump system scavenges both oil and crankcase gases from the oil pan, head and turbocharging system.
Close up of the Max-4 block reveals machining to provide rod clearance on each side of the
"Running turbochargers," says Norwood. "Introduces the problem of having enough boost to launch effectively at the starting line. But over the past few years, we have very successfully used nitrous injection to 'spank' up turbos so that they spool almost instantly. Nitrous works great with gasoline, and it works even better with nitro. Without tons of boost and load, nitromethane can be a dead fuel, but nitrous oxide is a very fast oxidizer.
"We decided to build a 5-liter four-cylinder block of solid aluminum using TFX Top Fuel main caps. This gives the same bottom end strength as the top fuel cars with the added bonus of just one rod on each throw and the torsional rigidity of a shorter crankshaft."
Bob Norwood lowers the Rody billet crank in to the Max-4 and turns it in preparation for f
Norwood purchased a funny car chassis kit from Mark Williams. This kit has all the major 'bends' done and is a well-thought-out system. They also used the Williams' front suspension A-frame kit, and narrowed the front end more than the standard set-up because of the narrow body.
Norwood joined up with the gang at Mastercraft Body Works to realize the car's body style. They lengthened an Acura Integra Type R body by 14 inches and narrowed the front by 22 inches and blocked off the doors to make a plug and then a high-temp mold to create Integra composite panels. Mastercraft painted the car, and Robert Opel did the airbrush work. With minor variations, Norwood can also build Honda RSX composite panels.
Max-4's Childs and Albert Hemi-style aluminum rod next to a competition Honda 2.2 rod and
As if anticipating the gestation of the Norwood Max-4, recent NHRA rules established new Pro classes for "Import Performance" eight, six and four-cylinder engines, all of which must use overhead camshaft designs. Pro Class V8-powered cars must weigh 2,350 lbs, use a production (cast) block, and utilize overhead cams. By contrast, four-cylinder vehicles need only weigh 1,750 lbs, and may utilize custom billet cylinder blocks.
Max-4 piston, rod, wrist pin, and rod cap. No pin-retainer is considered reliable enough i
Norwood Autocraft teamed up with Batten Performance and C&N Blocks to develop and manufacture the first batch of six Max-4 drag-racing blocks from heat-treated billet aluminum. Each block, carved from aluminum billet using five-axis CNC-milling equipment, was designed to weigh in below 100 lbs. Each Max-4 block is manufactured without cooling or oil drain-back passages from a $1,650 chunk of solid billet aluminum to big-block (7.4-liter) Chevrolet bore-center specifications. The Max-4 short block is designed for compatibility with a special 112 cc Norwood version of the Arias-type Batten Performance B4 cylinder head, and merges Batten, Norwood and C&N Blocks concepts.
Inserting the main-cap cross-bolts into the Max-4. Next generation Max-4 will have four-fa
Following the initial milling operations, each Max-4 block is blue-printed to the highest standards of precision machining for installation of radically strong Darton 4.5-inch-bore steel cylinder sleeves and a 4.5-inch stroke Rody ("row-die") crankshaft. The crank is supported by four-fastener, cross-bolted Donovan Top-Fuel-Experimental (TFX) center main caps. Norwood designed the main and rod journals to utilize Top Fuel Chrysler Hemi-type bearings, aluminum rods and main caps. Each Donovan center main cap is secured with two main studs and two cross-bolts.
In preparation for handling 4,000-hp worth of cylinder pressure, Norwood machinists drill and thread the block to accept huge 9/16x11-inch Donovan "TFX" head studs, which are tightened to 130 ft-lbs of torque. Also, these head studs extend deeply into the heart of the block.
Max-4 short block, ready for Batten B-4 Twin Cam 16-valve head installation. (Note Type R
Crank & Reciprocating Assembly
The Norwood Max-4 engine has a static compression ratio of 12:1 when fitted with JE flat-top forged "Top Fuel" pistons and standard B4 95cc combustion chambers. However, when fitted with larger 112cc chambers, dished pistons and shortened rods, the Max-4 has the ideal 7:1 compression ratio required for high-boost nitromethane drag racing.
Each Max-4 piston is equipped with a 0.017-inch L-shaped Dyks moly-coated top ring for both reduced weight and a wide cylinder contact surface. Each piston is fitted with a 1/16-inch Z-gap ductile-iron second ring and a conventional three-piece oil-control ring. Each piston is fitted with a full-floating Top-Fuel Childs and Albert Hemi aluminum connecting rod with cold-cycle cryogenic-treatment.
Each 9/16 x 11-inch Donovan TFX head stud received 130 lb/ft of torque.
Although Top Fuel V8 systems support the lower main bearings with a supplemental oiling system pressurized with a 3,000 psi CO2 tank, the Max-4's crank and bearings need only handle half the power with the same number of main caps. Therefore, a three-stage dry-sump oiling system provides 100 psi of lubrication to the Max-4, pumping fresh synthetic motor oil to the engine and turbos from a dry-sump tank vented through the frame of the vehicle. The dry-sump system directly scavenges oil and crankcase gases from all four corners of the cylinder head, the sump and both turbochargers.
Here we see the cam and follower atop the front valve and triple springs. We're talking 55
The Max-4 is equipped with a modified Batten Performance B-4 drag race cylinder head of the type designed to fit Arias Big-Block Chevy Rat-type blocks. This drag-race head is solid (without water-jacket cooling passages) and can only be used for short-duration drag racing. Each football-shaped B-4 four-valve pentroof combustion chamber is equipped with triple spark plugs for igniting the unimaginably dense air-fuel mixtures at 55 psi of boost with air-nitro ratios in the 1.75:1 range--meaning 40-percent of the charge mixture is fuel, as opposed to the seven percent you'd typically see in a gasoline-fuel powerplant.
Lowering and tightening the second cam box and studs on the Max-4.
The B-4 is equipped with four immense oval intake ports (1.560-inch high by 3.630-inch wide), which divide just upstream of each set of twin intake valve throats. Each port is capable of flowing 620 cfm at .550 lift. The intake ports direct charge mixtures almost directly into the combustion chambers with both swirl and tumble.
The included interior valve angles are 24-degrees intake, 26-degrees exhaust. The intake valves are 1.750 inches, the exhausts 1.500 inches. Eventually, Norwood plans to run coolant through the Max-4 head, though never in the head gasket area, thus maintaining a dry deck under all circumstances. Should the head ever "dance" up and down under the unimaginable combustion forces and pressures of 4,000 hp, it's--and will always be--impossible to get coolant in the oil.
Max-4 engine with cams and sprockets secured to the Batten B-4 head. Each camshaft provide
Camshafts & Drive System
The Max-4 is equipped with camshafts made from Norwood custom 8420 billet blanks that are copper-plated and hardened. Cam Motions roughs, hard-faces and grinds the cam to Turbo-Fuel specs of 265-degrees intake timing at .050 and 255-degrees on the exhaust side. Both cams are driven directly from the crankshaft with a single toothed 1.5-inch belt.
The Max-4 intake manifold consists of 5-inch straight tube primary runners, which blend from 3.5-inch ovals at the head end to round at the plenum end. The plenum is a 20-inch long round tube and tapers evenly from 5.5 to 4.5 inches. A 3.5-inch throttle body regulates intake air from a 3.5-inch feed pipe from twin turbochargers.
Max-4 Fuel System
Two gigantic Turbonetics Q-Trim ball-bearing turbos stand by to ingest burning nitrous exh
The Max-4's bulk fuel delivery system is organized in a way analogous to that of a Top-Fuel V8 Funny Car: The Max-4 system is based on a conventional constant-flow high-pressure nitro fuel system. Fuel pressure and flow is limited by the variable percentage of barrel-slits uncovered by the barrel in a nitro fuel barrel valve. Twin Down-Nozzles per cylinder--located in the head intake runners--provide the bulk of the nitromethane consumed during each 5-second, 250-mph drag run. Four huge electronic injectors located in the Max-4 intake manifold function analogously to the eight "Hat Nozzles" located on the plenum of a Top-Fuel V8 atop the supercharger just behind the gigantic throttle butterflies to provide the essential "wetness" required to lubricate the lobes of the Root-type blower and provide the fuel for idling. In the case of the Max-4, there's no need for fuel lubrication; the electronic "Hat Nozzles" provide additional computer-controlled fuel "trim" required to optimize the air-nitro mixture for maximum power and engine life, and to supply optimal amounts of nitro fuel for idle just prior to launch.
The downside of a Top-Fuel V8-type fuel delivery system is that these systems effectively provide for idle or wide-open throttle--and nothing in between. Starting, idling, burning out and then launching a 6,000-horse Top Fuel engine on nitro turns the oil into explosive "slop" that can be extremely dangerous, and is the most common reason for fires in a nitro-burning engine. Which is why the Max-4 starts, idles, burns out and backs up on E-80 ethanol (80-percent ethanol alcohol, 20 percent leaded VP-116 race gasoline), not nitro. It's only during the final idle just prior to launch that the driver switches over to nitro (or a specified combination of nitro-alcohol fueling). Essential to the key Norwood strategy of providing a solution for cost-effective ultra-high-output boosted-Fuel glamour-class "Import" drag racing by greatly reducing engine failures is a second set of high-flow electronic injectors designed to deliver E-80 ethanol under the control of an independent auxiliary M48 Motec engine management fully knowledgeable of the current status of the nitro delivery system. A Motec M8 calibrates the nitro-side electronic injectors and handles data acquisition. An electric Walbro inline fuel pump provides fuel for starting.
The Max-4's launch is fortified with port nitrous oxide/fuel injection, which provides a sudden scorching blast of power and heat that explodes the vehicle off the line and nearly instantly accelerates the giant twin turbochargers to full boost. It turns out high effective compression ratios in the combustion chamber are essential to efficiently and effectively producing prodigious amounts of power in a nitro motor (see sidebar); squeezing the required 1.75:1 air-fuel ratio hard in the combustion chamber is vital. Bottom line, combining nitrous injection with turbocharged nitromethane is a devastatingly effective recipe that unleashes the nitrogen-bonded hell of nitromethane's potential energy--in a hurry. The Max-4's E-80 ethanol fuel supply system makes use of an 8 gallon per minute Enderly in-line mechanical fuel pump driven directly off the exhaust camshaft. The pump, electronic injectors and pressure regulator, says Norwood, are capable of fueling more than 1,500 hp on E80. The alcohol system normally runs continuously, with the nitro system designed to come alive when it's time to go Postal. The intake cam directly drives a Waterman Red "Little Bertha" mechanical fuel pump driven to provide up to 40 gallons per minute of nitromethane to the staged-nitro system consisting of four electronic and eight constant-flow mechanical injectors. Depending on the jetting, the nitro delivery system can provide fuel for up to 4,500 hp. The Max-4 can go down the track on straight alcohol, straight nitro, or anything in between.
Force-Feeding The Max-4
The initial Max-4 turbo system employs twin Turbonetics turbochargers, which are coated by Norwood Autocraft. The turbos units have special giant compressor wheels able to move the extreme quantities of air required for more than 3,000 hp at 55-60 psi boost. These turbos have ceramic ball bearings and are coated to take the heat. Norwood also plans to test the Max-4 pressurized with a single gigantic Schwitzer turbocharger fitted with a 111mm Holset compressor wheel and housing components originally designed for large truck and railway locomotives.
But what do turbos do when you put all that burning hell spewing out of a nitro motor through a turbine section? "If you want to build a motor to make a lot of heat," says Norwood. "Use gasoline. Nitro doesn't burn as hot. Nitro's a 'dead' fuel with lower BTUs and much lower energy per gallon. I've made gasoline motors live with 1,900-degree exhaust heat. Nitro? It's just fuel. What's the EGT? I'd guess they run 1,300-1,400 degrees, but they typically have so much fuel burning in the headers of a blown-fuel engine, who can tell? Everybody thinks because there's a big flame coming out the exhaust it's gotta be real hot. That doesn't mean anything. The nitro just can't burn fast enough on a blown fuel motor. Why they're so loud is it's still burning when the exhaust valve opens. So they make a big bang and shoot fire out still burning."
"The big question mark," says Norwood. "Is that nobody knows what happens when you take a Fuel motor and get rid of the blower. People think blowers take away 1,000 hp from a Top Fuel crankshaft. I don't have to pay that penalty."
Stay tuned as we catch up with this ground breaking, ground shaking import in future issues.