The Fastest Little Sports Car in Utah: Bill Gordon’s 20-valve Norwood MR2 Turbo

 

 

Bonneville can be one mean, unforgiving bitch.

 

There are legions of good racers who have tilted at the Windmills of a Land Speed Record many times and never come out on top.  There are competent racers who have gone to the Utah Salt Flats every year for decades and never set a Land Speed Record.

 

Going fast requires a TON of power.  Air resistance goes nuts with speed, increasing exponentially as the cube of the increase in speed.  Air resistance over 120 mph becomes extreme, which is the speed at which a human body free-falling through the air (prior to pulling the ripcord!) reaches terminal velocity and will not fall any faster.  If you could go 100 mph on, say, 80 horsepower, to double speed to 200 mph requires 640 horsepower!  If you could go 150 mph on, say, 210 horsepower, doubling speed to 300 mph requires 1680 horsepower!

 

Once you’re making a ton of power, you typically need to run hard for a relatively long time--minutes rather than seconds like a drag car.  And then you need to run again within four hours, with the car in the meantime locked in impound where certain repairs are impossible.  Mechanical parts flogged to the limit over the required 4-7 miles of super high speed running take a terrible pounding, and thermal loading can increase to fatal levels as the minutes tick by.  Melt-downs are endemic to salt-flat racing.

 

And then there is the question of tuning.  Truly fast cars have virtually no good way to test at design speed at full power until they actually arrive on the desolate dead-level salt flats 100 miles west of Salt Lake City.  Where can you run a car flat-out at 200-300 mph for 4-7 miles without lifting the throttle except at Bonneville?  For many competitors, Salt Flat racing is more akin to an R&D and tuning nightmare than a race.

 

For one thing, the air is thin at Bonneville, because the altitude is over 4300 feet.  This means the atmosphere is less than 90 percent as thick as the air at sea level.  Normally-aspirated engines lose about 3-percent of their power for every 1,000 feet of altitude, but there’s also the double-whammy that tuning that worked well at sea level in California may be rich (or lean!) at Bonneville, even if you’re fuel-injected and turbocharged.  It’s a fact of life that sanctioning bodies typically force you to use “event fuel”, very high octane stuff that may have different specific gravity and energy content from what your engine’s used to.

 

Even very fast well-tuned cars can run into very bad luck:  The salt surface can change radically, depending on the weather.  Tires that worked well for dry salt may be all wrong when the salt is wet from a sudden rain storm.  Cross-winds mess with your handling and aerodynamics—on occasion catastrophically.

 

Bonneville is not for the faint of heart.

 

 

Dr. Bill Gordon was an owner-racer looking for the right project car that could go fast enough to take a shot at a Land Speed Record without the task becoming a Manhattan Project. Gordon’s “Other Car” was the “World’s Fastest Ferrari,” a Norwood-Autocraft 300-mph Ferrari 308 with 288-GTO body panels and a 500-inch Twin-turbo big block V8 that had already proven itself the fastest sports car on the planet by making easy work of 250 mph.  This time, psychologist Gordon was looking for something the kids at his Fairhill School could get involved with and “own.”  Something that could make a difference in the lives of some bright kids who struggled with learning disabilities like dyslexia.  A project that was difficult but not impossible.  Expensive but not too expensive.  So he went to Bob Norwood.

 

Bob Norwood was a Dallas-based supertuner, Ferrari hotrodder and speed freak of long standing who, in addition to building Gordon’s Top-Gun 8.2-liter 288 Ferrari, had years before captured the 3.0-liter naturally-aspirated Land Speed Record with a stock-displacement 308 Ferrari.  He still owned that record more than 15 years later.  Norwood was a Bonneville veteran who had also built streamliners and other exotic speed vehicles and raced many times at the desolate salt flats flanked by mountains 100 miles west of Salt Lake city that are the remnants of prehistoric Lake Bonneville and provide up to 15 miles of runway for vehicles trying to go very fast.

 

Norwood was enthusiastic about managing Gordon’s project and acting as crew chief at Bonneville, immediately suggested acquiring a Toyota MR2 Turbo.  This was no coincidence.  Norwood had already proven the power potential of the MR2 Turbo’s 3S-GTE powerplant, deriving output approaching 600 horsepower on gasoline from a heavily modified MR2 for Sport Compact Car magazine’s Project MR2 street car in ‘97 and ‘98.  Norwood had followed that up by building 3S-GTE powerplants with power approaching 900-hp!  The MR2’s four-cylinder 2.0L 86mm x 86mm engine size was eminently suitable for a run at the various smaller-displacement Bonneville classes in the 1.0-2.5 liter size.  Besides big power potential, a 1991+ MR2 has the kind of good aerodynamics that are de rigueur at Bonneville.  The MR2, referred to by some as the “Poor Man’s Supercar,” looks a lot like a Ferrari 308, and Norwood knew the aero would be good over the mid-engine four-banger.  Actually, quite a few men who were not poor had dumped money into MR2s, proving it capable of perhaps the highest streetable specific power of any production “Import Performance” powerplant.  Norwood needed a wildly powerful MR2, so he went to James Patterson.

 

James Patterson was a former Norwood Autocraft exotic engine builder who had recently bought Norwood’s engine-building, Ferrari and exotic car service, and super-high-output performance-upgrades business, and was still based out of the same building in Dallas as Norwood Autocraft, which now focused exclusively on complete exotic-car construction, custom engine-management system design, and chassis dyno tuning.  Patterson volunteered to have the new company—Norwood Performance—build a super-high output MR2 engine and modify an MR2 to make it capable of “safely” exceeding 200 mph.

 

The day Gordon wrote a check and found himself the proud owner of a 1991 MR2 Turbo, the Land Speed Records for stock-body 1.5L and 1.0L sports cars were 142 and zero mph.

 

 

In Quest of the World’s Fastest MR2

 

The MR2 project kicked off informally the day Gordon bought a ’91 MR2 Turbo for less than $10K and shipped it over to Norwood’s Dallas supercar shop conveniently close to the Fairhill School in Dallas where Gordon and a small team of kids from the school could, on occasion, watch the car go together and even potentially help out.

 

In spite of the excellent possibilities of the 2.0L 3S-GTE motor, Norwood quickly decided to discard the 2.0L motor and work with an exotic 1.6L Japanese-only 20-valve 4AG powerplant, complete with individual-cylinder throttlebodies, five valves per cylinder, and computer-controlled variable intake-cam phasing.   This motor could straightforwardly be de-stroked to 1.49 and .99 liters in a quest for the 1.5L (H-class) and 1.0L (I-Class) Blown GT and Blown Modified Sports classes at the salt flats.

 

 

The main point of using Toyota’s smaller exotic 20-valve 4AG powerplant was that it was smaller to start and could more easily be further reduced in size compared to the 3S-GTE MR2 powerplant, an iron-block phenomenon built strong as an artillery piece that had been run at super-stock power levels by everyone from high-school dropouts to Pikes Peak racers like Millen.  However, the 4AG motor appeared more problematic over 600 horsepower than the 3S-GTE, and James Patterson and the Norwood Performance techs would have their work cut out prepping the little motor to survive at such extreme power levels.

 

However, the breathing of the 5-valve-per cylinder head was already phenomenal (though not necessarily better than the 4-valve 3S-GTE except at partial valve lift when the valve circumference is more important than the total full-open valve area).  Okay, the production 20-valve 4AG motor ran out of cam way below the stock redline at something like 6,000 RPMs, but custom cams could easily fix that problem.  In fact, the race engine that would power Gordon’s MR2 Turbo in a quest for FOUR Land Speed Records in supercharged Bonneville classes used a stock 20-valve head with nothing more than a fresh valve job and very good super-high-speed valve springs and retainers.

 

 

Breathing 22,000 Times Per Minute

 

With a goal of an 11,000 RPM redline, each valve must open and close 92 times a second.  With this in mind, the Norwood team installed a set of serious valve springs designed to resist 45 psi boost against closed intake valves and control float at extreme RPM via closed spring pressure of 85 psi and open pressure of 145 psi at .300 lift.

 

In the quest for super-high RPM performance, the Norwood team next installed extremely high-lift, long duration cams capable of producing power deep into the 10,000 RPM range, and simultaneously modified the stock variable valve timing system for better performance at high RPM.  Toyota’s variable Cam Phasing system on the 4AG 20-valve uses hydraulic oil pressure inside a diagonally-splined cam sprocket on the intake cam under computer control to force it to move on its sprocket relative to the exhaust cam, thus increasing valve overlap for better efficiency at high engine speeds.  Norwood Performance altered cam timing from the stock minus-five degrees initial + 15 to 17-degrees initial + 15, with total advance limited via a custom positive-stop set-screw at 26 degrees combined intake cam advance.

 

 

Living to Tell

 

Norwood Performance equipped the 4AG powerplant with standard and non-standard super-duty custom parts and anti-failure countermeasures.  These included lightweight Pauter connecting rods designed to survive extreme tension forces on the rod bolts of up to 180,000 pounds at 11,000 RPMs, a Norwood Performance custom crank-girdle to reinforce the main bearing caps and keep them from “walking” under heavy load at high-RPM, a custom Rody 43XX billet-steel crankshaft, and a set of 3.200-inch bore custom super-duty forged JE pistons.  The billet crank had stroke reduced from 3.025-inches to 2.830.  Displacement shrank from 1.6 to 1.5 Liters.

 

In a somewhat controversial move, Norwood Performance set initial static compression ratio at 9:1—high for an engine designed to gobble as much as 45 psi turbo boost.  There was a good reason:  On the way to supercharged glory, Norwood figured to take a backhand swipe at a Land Speed Record in the naturally-aspirated H Class—just for fun and to provide a relatively safe venue for a teenage student driver from the Fairhill School who would represent all Fairhill students at the salt flats.  High static compression helps a naturally-aspirated engine rev fast and hard; the final effective compression ratio would be a function of the complex interaction between static compression ratio, cam timing, and boost pressure.

 

To improve lubrication, provide hood clearance and keep weight as low as possible, Norwood and crew tilted the engine forward and fabricated a custom steel oil pan--and installed a multi-stage dry-sump oiling system to improve crankcase aerodynamics and keep flying oil and windage from slowing down the crank at speeds up to 11K RPMs.  Norwood’s team simultaneously reworked the engine and trans mounts to raise the little 4AG engine and tranny 3.5 inches in order to bring the back of the car down close to the salt while maintaining good suspension geometry.  The decreased engine height and Powertrain relocation enabled the team to lower the MR2 body for minimal clearance above the salt with greatly decreased drag. 

 

 

Engine Management and Boost

 

Norwood Performance techs converted the 4AG engine for turbocharging by constructing a stainless-steel header system made from equal-length mandrel-bent tubing and 304 stainless flanges.  They installed a Turbonetics T04 turbocharger with P-trim compressor and T-61-trim turbine, with the turbine housing A/R ratio set at .81.  The team installed a Turbonetics Racegate with the goal of limiting boost to 40 psi.

 

Norwood selected a Motec M8 engine system to manage the engine and installed sensors and actuators for direct-fire ignition, using monster 1,700 cc/min injectors capable of fueling at least 150-hp per cylinder at 85 psi fuel pressure.  Norwood’s team installed an electro-pneumatic actuator that could regulate boost under Motec control by pulse-modulating the wastegate manifold pressure reference to provide pre-programmed and cockpit-selectable boost pressures ranging from a nominal 20 psi anywhere on to blow-up.  Twin in-tank and in-line high-pressure electric fuel pumps supplied fuel.

 

To withstand the enormous thermal and mechanical loading of long-duration Speed-Record runs, the Norwood team built a trunk-mounted air-water intercooler cooled with water routed through a large heat-sink tank which was cooled by a heat-exchanger built from a converted MR2 A/C condenser unit mounted ahead of the radiator.

 

 

The Bonneville MR2 Comes Together

 

The Norwood team rebuilt the stock MR2 transaxle.  To get power to the ground, they installed a five-inch single-disc carbon clutch of the type no longer legal on an Indycar.  The team installed a Tilton Super-starter with a matching small ring gear, and fitted the engine with a miniature Denso alternator.

 

Meanwhile, the Norwood-Gordon-Fairhill team completely gutted the interior of the 1991 MR2 Turbo to remove weight, installing the required full roll cage, fire-control systems, and driver’s race seat.  Along the way, they removed all unnecessary electro-mechanical equipment, including the heater, the A/C system and plumbing, and no less than five computers which the stock MR2 Turbo uses handle chores such as cruise control, anti-theft, electric power-steering, anti-lock brakes, and so on.  The team removed the rear anti-roll bar, which they considered dead-weight on the Salt Flats.  Safety equipment included an 11-lb fire-system, aluminum race seat, Diest five-point harness, and a window net.

 

Externally, the Norwood race team removed the MR2’s rear wing, and installed mandatory spoiling rails on the roof to keep the car from trying to fly if it turns sideways, and a roof-flap that pops up in the wind if the car spins backward to cut the air and spoil all lift.

 

Bob Norwood mapped the Motec engine management system on the Norwood Autocraft Dynojet chassis dynamometer, providing fuel and ignition calibration data at breakpoints from vacuum to 50 psi boost.  Unfortunately, it was impossible to load the engine to the extent it would encounter at Bonneville when driving the weight of the car across the salt against the enormous air-resistance of speeds above 150 mph.  Some of the numbers at certain engine loads where guesses that were not possible to achieve in the Dallas shop.  On the dyno, the Toyota 4AG engine managed to achieve at least 34 psi boost on the dyno in the relatively thick barometric pressure of Dallas, Texas, 600 feet above seal level.

 

In ready-to-rumble trim, the car weighed in at 2400 pounds.

 

 

Y2k:  A 1.5L Land Speed Record.  Or Bust

 

 

In 1999, a team campaigning an Alfa Romeo Guilette Spyder had set the 1.5L blown modified sports (H/BMS) record at 140 mph with the supercharged Alfa Romeo. 

 

The Alfa guys were back in 2000 when the MR2 and its crew of Norwood professionals and Gordon and the Fairhill school kids arrived at Bonneville.  The Alfa team batted first in the forced-induction H Class, and immediately pushed the record up to 152 mph.

 

A young driver from the Fairhill School, newly licensed, had previously done his best to run the MR2 very fast in practice runs on the salt, but the MR2 proved tricky enough to drive that it quickly became clear that any serious safe attempt at a record would require the skills of someone more experienced.  Owner Bill Gordon test-drove the short-wheelbase MR2, which he found “busy” at high speed without an anti-roll bar.  Gordon drove the MR2 and but then decided to turn over the wheel to Norwood driver Tom Stephens.

 

Stephens was an experienced racer with a resume that included setting track records in the Norwood Doom and Doom II Porsche racers on various road courses. Stephens had also successfully driven Norwood Ferrari and Porsche race cars in various road-course and drag racing events around the country.  Stephens had quickly proved his ability to drive fast on the salt and set a 250 mph Land Speed Record in the glamour AA/MS class that distinguishes the fastest sports car on the planet, the 8.2 liter Norwood-Gordon twin-turbo Ferrari 288-GTO conversion.

 

Stephens suited up and took the wheel of the MR2 in the summer of 2000.

 

“On our first run out of the trailer,” says Norwood, “the MR2 went 205 mph.  We heard some people had trouble believing our car could be legal; you’re not supposed to pound the record by 70 miles per hour.”

 

The Norwood car went into impound where you get four hours to fix any problems and make the required backup run whereby your official speed is considered to be the lesser of the two maximum speeds attained in runs over the same best measured mile of the course. 

 

The Alfa Team stood by helplessly watching as their hours-old speed record stretched its wings and prepared to fly the coop to faster territory.  But in the meantime, the Norwood team had its own troubles.

 

“We immediately knew there was a problem from the way the MR2 cranked,” says Norwood.  “The Event Fuel ran lean in the 1.5L 20-valve motor even though it ran rich in the big car [8.2L Ferrari].”  The Motec datalog showed exhaust gas temperature had jumped to 1970 in the number three cylinder, just as driver Stephens lifted the throttle at the end of the last mile.  The other three cylinders peaked at 1930, 1910, 1915, and clearly were not damaged.

                                                                                                                          

“We pulled the head in about an hour,” says Norwood, “and saw that the number three cylinder had been torched between the two exhaust valves, with a great big path cut through the head down to the piston.  That was it, the head was totaled.”

 

At this point it was clearly out of the question that Norwood’s team could make the four-hour impound limit.  Assuming the engine could be fixed, the team would have to start over.

                                                  

“Fortunately we had a spare 20-valve head,” says Norwood.  “In the meantime, the Alfa crew was still complaining our engine couldn’t be legal size given our results that were fifty mph faster than what they had done.  We’re certified engine builders and are automatically assumed to know the engine size and be honest about it.  But since we were already tearing down the top end, we invited the officials over to measure bore and stroke.”  The officials decided the powerplant was precisely legal at 98 cubic inches.

 

“Unfortunately,” say Norwood, “the spare head had never been on the block.  I had to drill it out for the huge head studs we were using in the block.  With a hand drill.  Which took three hours and nearly wrecked my arms.”

 

At this point, Patternson and built up the new head with the high-RPM valve springs and retainers, while Norwood worked on replacing the melted piston in the short block.  “I used Muriatic acid to remove aluminum stuck to the cylinder walls,” says Norwood, “then prepped the cylinder wall with Scotch Brite.  Everything worked out perfectly except for this one quarter-sized spot five-thousandths deep burned into the cylinder wall which we couldn’t fix.”

 

With the engine finally mechanically sound, the exhausted Norwood team buttoned up the engine and car and went back to their hotel for the night.

 

 

Gasoline and Salt

 

 

In the morning, the Norwood teams arrived back at the Salt to discover the supercharged Alfa Team had given up and departed.

 

Meanwhile, Norwood had other concerns besides the competition or lack thereof.  In the current state of tune, the MR2 had already eaten one of its pistons.  It was clear from overnight datalog analysis that the engine system had certain problems.  For one thing, the air-water intercooler had not proven sufficiently effective at the extreme power levels the engine had actually developed at Bonneville in high gear with 30 psi boost against a wall of air resistance at 205 mph.  Air temperature had been rising from 60-degrees in the lower gears to 210 degrees—hot!—as the water reservoir heat-soaked during a run.

 

“I knew I had to do something to the engine to ‘safe it up’ a bit,” says Norwood.

 

A compounding problem was that the fuel pressure was insufficiently high to fuel the enormous dynamic range of an engine which idled like a tiny economy car and then rose up on its hind legs and peaked at over 600 horsepower at high RPM.  The combination of over 150 horses per cylinder and RPM so extreme that the engine made 92 power pulses per second at max speed left very little time available to squirt fuel into the engine even with the largest available injectors operating at 100-percent duty-cycle.

 

Another problem was boost creep:  The Norwood team had equipped the MR2 with a huge Turbonetics Racegate wastegate and an electronic wastegate controller under Motec control, but the car developed so much power, that even at 4300 feet above sea level the wastegate could not bypass enough exhaust gases to effectively limit boost, which went out of sight when the engine was really loaded at high speed.  “The engine just went crazy with boost, went nuts,” says Norwood, “and the wastegate couldn’t control it.”

 

The team installed a Kenne Bell Boost-A-Pump on the second high-pressure fuel pump to overdrive the motor with boosted voltage.  Norwood recalibrated the on-board computer for 90 psi fuel pressure with safe, rich mixtures.

 

The Norwood team then began a series of high-speed runs designed to simultaneously go faster and optimize engine tuning parameters:  The car ran 160.  With leaner tuning 180.  With leaner tuning 195, then 200, then 205, then 207.

 

“I finally got to the point where it had a perfect map in it,” says Norwood, “and just about that time the motor started to show a little blow-by.  On the last day it was slowing down.  We went out to try and bump the record at bit more, but now it wouldn’t quite run 200.  I suspect the rings got tired of running on that ratty low spot, and started ragging out the rings.  Or maybe the engine just didn’t like running all that boost.”

 

However, by the time the Norwood team was finished, the final and slowest run of the Norwood Gordon Fairhill MR2 had established a new Land Speed Record of 199 mph, almost 50 miles per hour faster than the number two Alfa sports car.

 

Gordon, Norwood, Stephens, and the entire Norwood Team of professionals and Fairhill School kids had realized the dream of setting a Land Speed Record a fraction of a mile per hour below 200.

 

 

 

The MR2 Goes Small:  2001 1.0L Engine

 

When the year 2000 rolled over to 2001, the Land Speed Records for the 1.0-liter supercharged I-Class were 70 mph in I/GT and zero in I/BMS (no one had ever even competed in the I-Class blown modified sports with a one-liter engine).

 

In the new year, the Norwood team set about to reduce the displacement of the ’91 MR2 Turbo in order to murder both supercharged I-Class records.

 

Norwood Performance ordered up a new billet-steel Rody crankshaft with reduced stroke that decreased the 1.6L Toyota 20-valve 4AG engine from the 1.49 liter displacement that had qualified it for the H Class in 2000.  With only a hair over one inch of stroke, the new engine would now displace just 999 cc’s.

 

The Norwood Team was immediately forced to install smaller injectors in the tiny powerplant in order that injection pulsewidth was long enough to be sufficiently repeatable that the engine would idle adequately with its bike-sized displacement.

 

In the meantime, Norwood’s crew had changed turbochargers on the mini-4AG engine and reconstructed the air-water intercooler to make it considerably more effective at controlling inlet air temperature than it had been on the 1.5L version of the engine in 2000.  A Turbonetics turbo was selected with the goal of making a maximum 45 psi boost and power possible equal to that of the 1.5L motor.

 

Other 2001 changes included the Norwood team re-installing a stock rear sway bar on the MR2 to take some of the roll out of the car for speeds over 200 mph.  “I would never have thought roll would be an issue on the salt,” says driver Stephens, “but it was.  In 2001, the MR2 wasn’t as much of a handful to drive because horsepower was down.  However, boost now came in later with a huge rush at higher RPM compared to the 1.5L version of the car.”

 

“We added a lot more boost to the 1.0L motor,” says Norwood.  “If you look at the dyno sheets, the engine has BIG power at 6,500, big power on up into the 9,500-10,000 range, then it goes down a bit.  The sweet spot’s between 6,500 and 10K.  I had assumed power would be much higher if we ran way up there above 10K, but the engine is happy between 6,500 and 10,000, it works there, and we have a good gear combination for that range.  So we left it alone.”

 

Norwood knew that if the MR2 could maintain 45 psi boost throughout the RPM range, the tiny 1.0L engine could push the car to 200 mph, even with only 65-percent the displacement available when the car had attained 207.

 

In the end, scheduling considerations limited the amount of time available for extensively testing the MR2 with its new mini-motor prior to the late-summer 2001 trip to the Salt, but the engine had definitely proven itself capable of at least 450-hp on Norwood’s Dynojet chassis dynamometer.

 

On an ominous note, on the dyno, the car encountered anomalous operating conditions at high load that seemed to demand better ignition at extreme boost.  The Norwood team installed four MSD 6-series igniter boxes to energize the four direct coils of the 4AG motor, ripped off some R&D dynoruns, and headed for the salt.

 

 

The 1.0 LSR

 

Salt Conditions were nearly perfect for the first time in years when the Norwood Team arrived at Bonneville with the 1.0-liter MR2 in 2001.  Good salt would improve high-speed stability for all competitors, but it was especially good for the short-wheelbase MR2.  With the sway bar in place on the Norwood MR2, Stephens decided the car was a “real dream” to drive.

 

It was not a real dream to launch.  The engine had such small displacement, light reciprocating weight, and poor low-end torque that it would stall under all conditions from a dead stop without special countermeasures.  Stephens’ de facto launch method quickly became to rev it hard to 4,000 and massively slip the 5-inch carbon clutch to get the car moving.  Once RPM moved into the “sweet spot” above 6,000 rpms, power would come on hard and the car would accelerate very well to 10,000—in the first few gears.  In the bright sun against the dead-level bleached-white salt with the only frame of reference distant mountains, there was little sensation of speed other than the increasing wind noise and the diving and shuddering of the short-wheelbase car on rough spots of the cement-like salt surface as speed increased beyond 100 mph.

 

The car immediately set a Land Speed Record in the I/GT class the first day out at 132 mph, and the Norwood Team proceeded with plans to push the envelope as far as possible.

 

But, as usual on the salt flats, there was trouble.  Manifold pressure became maddeningly unstable as speed increased into the 150-mph range.  Stephens would hear the engine surging, with power moving up and down in 4th and 5th gear.  He wondered if something mechanical might be opening and closing.  To eliminate the possibility the wastegate was fluttering, the Norwood crew removed it, to no avail.

 

In the end, the Norwood team was forced into an exhaustive on-site R&D effort that made use of the only testing regime possible on the salt flats, a lengthy series of high speed runs:  Wait in the interminable line of race cars queued up for the next high-speed run.  Make the next experimental run with one or maybe a few parameters changed.  Tow the MR2 back to the pit area to analyze the results and data.  Huddle to decide what’s next.  Execute the changes as fast as possible and then back in line as fast as possible.

 

Crew Chief Norwood set about methodically to achieve a good, stable state of tune.  But after converting the Motec from throttle-position to Manifold Absolute Pressure-based air-fuel tables and touching up the ignition and air-fuel Maps such that engine management was theoretically perfect under all boost conditions, the instability only became WORSE.

 

Eventually, Norwood realized that the program had a design flaw.  It was encountering a wall of air resistance approaching 150 that required extremely high boost in order for the tiny engine to develop sufficient power to push through.  And there was the rub:  The engine was so small that the boost pressure ratios required in the realm of the lower air-flow ranges in 4th and 5th gears to achieve the necessary power levels to accelerate were so high that the operating point on the turbocharger’s compressor map had crossed over the surge-line into an unstable realm.  The MR2 would proceed quickly through the first several gears with no problems, but when it was time for the shift into high gear, air resistance was so extreme that boost would build to 345 KPA as relatively low engine air-flow, the engine would push the car hard against the wall of air resistance, the car would start to accelerate hard, and suddenly a pressure wave would surge backward through the centrifugal compressor of the turbocharger and boost would crash back to 265 KPA boost.  The situation was a little like trying to launch a car missing first gear or an offshore boat potentially capable of very high speed that didn’t have the power needed in the range required to get it up on plane.

 

Stephens and Norwood tried a range of strategies to avoid the fatal turbo surge.  Reducing the boost pressure to 22 psi via adjustments to the electronic wastegate avoided surge, but then the car didn’t have the power to exceed 150 mph.  Stephens tried slipping the clutch during the transition from 4th and 5th gear, but at higher rpm the problem only got worse.  “You’re spinning the turbo faster,” says Norwood, “and you’re already up against the surge line.  It gets worse.  We had a good turbo, but we had the wrong unit or possibly needed compound turbocharging [the first turbo blowing into the second such that neither encounters extreme pressure ratios at low air-flow].”

 

The upside of the new engine setup was that everything else was working very well.  The new intercooler exhibited outstanding thermal efficiency.  The car’s high-speed controllability was excellent.  In spite of the turbo surge, the car managed to achieve a one-way high-water-mark of 165-mph over a two-mile stretch.

 

And the MR2 had achieved outstanding results.  With the best efforts of the Norwood crew, the MR2 set I-Class two-way records in Blown GT and Modified Sports classes at 152 mph.  Two records had, indeed, been murdered, one by 82 mph, the other by 152 mph!

 

Not bad for a tiny engine smaller than many motorcycles that was pushing a production sports car over 2,000 pounds.

 

The Future

 

Clearly there is an upside available when the Norwood crew returns to the salt in 2002 with the 999 cc MR2.   This summer, the car will again run in Class I/GT and I/MS 1.0, in the later with the body altered to eliminate the notch above the MR2’s rear mid-engine.  Following the summer’s fun at the salt, Gordon hopes to sell the car along with both the H-and I-class motors.

 

Bob Norwood firmly believes both I and H records are “soft” and can be raised further.  And, of course, there’s the potential for using the car as a platform to attack 2.0 and 2.5 Classes with the 3S-GTE motor—or perhaps even the 3.0 class with a bolt-in Toyota 3VZ-FE or 1MZ-FE 4-cam 3.0L V6!


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