ACURA NSX TWIN TURBOCHARGER

The ACURA NSXTWINTURBOSYSTEMfrom the Bell Engineering Group, Inc. (BEGI) brings to the NSXperformance enthusiast a whole new dimension of engineering, sophistication and value,

The perceptive/demanding buyer will be asking questions about the depth of engineering,experience and quality of design prior to deciding if the system meets his/her needs. Thisdocument is an overview of those questions and the engineering involved.

If one is not an expert in the facets of turbocharging and other performance systems, a guideto what aspects of these systems to look for and their respective significance is a handy tool.For example, a water injector is a disastrous part and fuel controls are crucial. This paper canoffer some degree of guidance on those matters.

Any given performance system has several areas that need inspection before a judgement canbe rendered as to the quality of its design. These individual areas are: power, safety, response,quality, fun, economy, durability, and price. These items are discussed in the following pages.

There are key features that create power safely. These features are critical to the long termreliability of a turbo/supercharger system and more importantly, its host engine. It isessential thatthe prospective buyer examine these features of any performance system before determiningthat a particular system meets his/her long term requirements.

The three features that must be under absolute control at all times are:

1. Temperature of the air entering the engine. "Thecharge temperature"

2. Correct air fuel ratio under all operationalconditions.

3. Margin of safety on knock (ping, detonation).

WHY THETURBO

Turbo machinery science has advanced to a performance and durability level approximately30 years ahead of any form of supercharging. This is reflected in many areas; there are 96 turboengine vehicles in production today, there are only three supercharged vehicles. The slowestten turbo vehicles average faster than all the supercharged vehicles. No major road raceanywhere in the world has been won by a supercharged vehicle in the past 38 years.Turbocharged vehicles have won perhaps 5000 races in that period of time.

CHARGE COOLING

Heat makes detonation and detonation leads to engine damage. Therefore, charge coolingis one of the most urgent requirements of a successful system.

An example of requirement number one can best be illustrated by comparing our turbosystemwith the Paxton and Vortech based supercharger systems.

BELL ENGINEERING GROUP, INC.Legal for sale or use in California only on racing vehicles whi::h may never be used upon a highway

ECONOMY.,

Although perhaps of lesser'importance, any turbosystem will effect economy less than anysupercharger system. The supercharger system suffers the power loss of always driving theblower, even when boost is not wanted. Thislossiscalled a parasitic loss.The new turbo in theBell Engineering system has the interesting characteristic of far lessback pressure in the exhaustthan any other turbo. The Bell Engineering system will thus have the least effect on economy.

LAG

Lag isthe time delay between applying throttle and achieving useful boost. Representative lagrates can be depicted by the following chart:

RPM MAX BOOSTAT TIMETO MAX BOOSTTHATRPM

Paxton styleClassic turboBell Engr turbo

POWER

300030002200

2.55.05.0

1.0 Sec1.0Sec.25 Sec

Fun isfurther a function of power. The power output of our twin turbo is390 bhp. It can generallybe accepted that the most powerful unit has one element of fun in excess of the others.

To acquire a further feel for the actual performance of a vehicle without driving it, it is oftenhelpful to compare the acceleration rates with other known vehicles with similar pound perhorsepower ratings. Our twin turbo system will produce equal or faster 0 to 60 acceleration ratesthan some other interesting well known automobiles. Road & Track magazine publishes a roadtest summary in each issue offering excellent comparison data.

Fun isa also a function of smooth driveability. Our system does not change the stock driveabilityquality of the NSX.

LOW ENDAND MID-RANGETORQUE

The BEGIturbo will make more boost at just 2000 rpm than the Paxton/Vortech style can at 7000rpm, and more than the classic turbo can at 3000 rpm. It is a relatively simple calculation toshow that the BEGI system can accelerate as hard in 4th gear at 3000 rpm as thePaxton/Vortech based unit can in 3rd gear at any rpm. It is reasonable to suggest that the lowend and mid-range torque superiority of the BellEngineering system isnot just somewhat better,rather, it is orders of magnitude better.

Conclusion: The Bell Engineering turbosystem will oner a greater degree of fun than any otherform or brand of power improvement system.

11723 WARFIELD SAN ANTONIO TX 210-349-6515Legal for sale or use in California only on racing vehicles whi.::h may never be used upon a highway

BHP2&0

200

150

100

50

POWER, BHP

_ STOCK

~ CARTECH

EZ2:l PAXTON

~ ROOTS

EBB BELL ENG. GROU

c=J BBR TURBO

Although often stated in writing that the Paxton and Vortech style superchargers produce lessintake charge heat than a turbo, the claim iscompletely false. Simple temperature probes canprove it in minutes, The Paxton style blower will raise the charge temperature at 5 psi boost byapproximately 70 degrees f. No intercooler ispresent in any Paxton or Vortech based systemto reduce those 70+ degrees, The turbosystem we offer will raise the charge temperature only55 degrees at the same boost, Our system, however, utilizestwo intercoolers that remove 90%of the heat put in by the turbos, Thusthe air charge entering the engine isup approximately 10degrees over ambient with the BEGIsystem,whereas the Paxton and Vortech style systemswillreceive the full 70+ dose. Clearly, these systemscreate heat levels over sixtimes greater thanour twin turbosystem. It isinteresting that the designersof the lessthermally efficient superchargersystems choose not to use charge cooling yet they clearly need it the most.

The extreme ne~d for high quality charge cooling has been met by BEG!.No others have tried,

AIR FUELRATIOS

Supplying fuel in proper proportion to the air when operating under boost has proven to be thesingular most difficult facet of turbo/supercharging, We have solved this problem by driving thefuel pressure up as the boost rises,

The BEGIsystem will keep the air/fuel ratios correct under all operational conditions.

With respect to emissions,economy, reliability and driveability, it isour opinion that the enginemanagement electronics should not be altered in any way,

MARGIN OF SAFETY

Clearly a system that will deliver performance as aovertised must have a margin of safety. This

11723 WARFIELD SAN ANTONIO TX 210-349-6515Legal for sale or use in California only on racing vehicles which may never be used upon a highway

margin refers to the boost pressure point at which detonation will occur relative to theadvertised boost setting. If a given system runs7 psi boost and will not encounter detonationuntil 9 psi, it can be called 0.margin of 2 psi. If it does not have a margin it cannot be operatedas advertised. The margin is created by the heat and fuel controls designed into the system,versusthe boost at which it operates.

The BEGINSXSYSTEMwill offer an adequate and proper margin of safety.

FUN

There existsa group of features and parameters that combine to create a truly fun car to drive.Obviously power and smooth driveability are two of these. When specifically discussingdriveability of a turbo/supercharged engine the desirability of an early onset of boost iscommonly viewed as critical. Low speed boost capability isalso an indication of the speed atwhich the system can respond in the normal driving rpm ranges. It isvery interesting to note theextreme fallacy of the lore stating that superchargers such asthe Paxton produce more low endboost than turbochargers. Thisisexactly the opposite of correct. Thefollowing graph representsthe boost rise rate of all known systems.

a73 ••. 5

RPM X 1000a1o

1

BOOST PSIIS

3

:2

- BEOI -+- VORTECH'PAXTON ~ CLASSIC TURBO

The rate of boost risedepicted by this graph iscorrect. Obviously the rate of boost riseof theclassic turbo isfar faster than the Paxton/Vortech stylesupercharger. The rate of riseisyet fasterfor the new technology of the BEGIsystem.Thereason turbos gain boost faster than Paxton styleblowers isthe simple fact that they can change speeds relative to the crankshaft. A turbo canchange speed from 5,000 rpm to 75,000 rpm without changing engine speed. At a constantengine speed, a supercharger cannot change 1 rpm.

BELL ENGINEERING GROUP, INC.Legal for sale or use in California only on racing vehicles whi:;h may never be used upon a highway

We feel it is fair to suggest that more automotive fun than a Bell Engineering Twin Turboequipped NSXwill be near.~mpossibleto find.

PERFORMANCE

On road performance as measured by the vari-corn VC-200 yielded the following data:

Power; bhpTorque; Ib-fto to 60; sec1/4 Mile: timeVelocity

BEGITWINTURBO

3903054.4/4,812.8113

STOCK

2702255,914,499,0

These performance numbers were recorded with a stock engine, One of the BEGIdesignobjectives was to provide substantial performance with an unmodified engine, Although ourobjective was clearly achieved, we were mindful of 1he adventurer that may want performancein excess of that available from the stock engine. Thus, the design we have created isexpandable in the performance envelope to provide virtually any power rating consistent withengine preparation.

INSTALlATION

The ease of installation should only be a seriousconcern if the buyer does not do hisown work,Sublet expenses can add up to significant numbers,but hobby/fun time for the diy'er should notbe of concern, if kept within reasonable bounds, BEGIstrongly urges the buyer with modestmechanical ability to tackle the job himself, save the install labor costs, and learn the systemwhile assembling it. There isno rocket science here, and no specific turbo experience required.Thisisa simple systemto install,It isestimated that th,~firsttime inexperienced installercan installthe BEGIsystem in as few as twelve hours.

Twenty years of experience has clearly shown that the pride of ownership will make the diy'era generally better installer than the time clock conscious professional technician, Pride andsuccess are in the details and the owner tends to do details well.

QUALITY

The essence of quality isthe ability to function well and maintain an attractive appearance formany years, The details of quality run from material selection, craftsmanship, choice ofturbo/super charger, surface coatings, to fits and finishes,

The BEGIsystem feature stainlesssteel construction on all hot components and all intake sideitems are powder coated.

No body work modifications are required.

Quality extends to instructional material and service after the sale, as well.

BELL ENGINEERING GROUP, INC.Legal for sale or use in California only on racing vehicles which may never be used upon a highway

We would be delighted to have any quality aspect of our system compared in detail with thatof any other system.

SUMMARY

It should be obvious that we feel our systemscompare favorably with all aspects of all others.We invite discussion,debate, argument if necessary, third party review, an all competitors run-off, or any other means of comparison.

Bell Engineering Group, Inc. represents twenty years of applied turbosystem design andengineering. We are confident we offer the highest science available today in performancesystemsfor your ACURA NSX.

Installations available at our shop for $700.Pleasecall for an appointment.

BellEngineering offers a pickup and delivery service nation wide for the cost of airfare and fuelonly.

California air resources board exemption order application pending.

System price: $7,850

11723 WARFIELD SAN ANTONIO TX 210-349-6515Legal for sale or use in California only on racing vehicles whi,:::h may never be used upon a highway

MA~AZINE COMMENTARY

Over the past twenty-two years Bell Engineering Group Inc, formerlyknown as Cartech Inc. has enjoyed more than eighty magazine featurearticles. Collected here are just a few of the comments.Motor Trend Rick Titus re Cartech Supra Turbo: "Quality exceedsthat of OEM." "A Toyota Supra Turbo that goes ballistic." IIClean,well planned installations." "Sets new standards for aftermarketengineering. II

Automobile Magazine Barry Winfield, re Cartech Miata Turbo:"It streaks down the road with a vehemence that is totallyunexpected from one of these friendly little sports cars."Autoweek Bill Lovell, on Cartech's RX-7 Turbo: "It looks morefactory than the factory." "Two seconds faster than the factoryturbo." --- "Peace brother."

Car Craft C. Van Tune about our Mustang 5:0 turbo: "Theengineering magic behind this potent pony comes from Cartech of SanAntonio."Road & Track Andrew Bornhop re the Mustang turbo: "Founded byformer racer Corky Bell, San Antonio based Cartech has blossomedinto a leading aftermarket turbo technology firm." "Think about177mph for a moment,. fairly quick is an understatement."Turbo & High Tech Performance Jeff Hartman on the Twin Turbo NSX:"The boost gauge swings instantly toward five psi and the outsideworld begins to blur. The NSX now has the horsepower to play hardball in the big leagues."Rotary Rocket Magazine Dick Turner about the Cartech TurbochargedRX-7: "Corky,·Bell is a brilliant engineer who is dedicated togetting the job done without a lot of fuss or bother." "To set therecord straight, I've probably driven 500 RX-7's with every type ofgo fast gadget you can imagine. I can promise you this, the CartechRX-7 is the fastest car of its type I have ever driven."Road & Track Ted West on the Honda CRX Turbo: "No other way to putit, pretty wonderful. II"Corky Bell, be proud."Automobile Magazine William Jeanes,"Turbocharging is Cartech' s specialty,well."

on the Cartech Supra:they do it carefully and

Turbo & High Tech"With the pedal tofive psi boost atlarger engine than

Jeff Hartman, on the AerodynejCartech Miata:the metal, the Aerocharger instantly made over1000 rpm." "You might think it had simply a

stock, since there is no detectable turbo lag."

HORSEPOWER, ACCELLERATION, AND POWER TO WEIGHT RATIOSREVISED 4-1-91

PERFORMANCE COMPARISON CHART - DATA GATHERED FROMCARTECH T~STING AND MAGAZINE ROAD TESTS

VEHICLE BHP WEIGHT 0-60 1/4 MILE LBS/BHP

Acura Legend 4dr-1988 151Alfa Romeo GTV-6-1988 154Alfa Twin turbo GTV-6 230Aston Martin V-8 Vantage 300Audi 5000CS Turbo 4X4-1988 158BMW 320i 108BMW 320i CARTECH TURBO 210BMW 318i 101BMW 318i CARTECH TURBO 195BMW 325es 121BMW 325es CARTECH TURBO 228BMW 325is 167BMW 325i CARTECH TURBO 283BMW 535i 182BMW 535i CARTECH TURBO 341BMW 635csi 182BMW 635csi CARTECH TURBO 360BMW 735i 1823MW 735i CARTECH TURBO 3413uick Grand National 2453uick GN CARTECH UPGRADE 293~amaro IROC Z28 5.7L 240~orvette 240:orvette "Callaway Turbo" 345:hrysler Omni GLH Turbo 146:hrysler "Shelby GLH" 175)atsun 280ZX Factory Turbo 180~80ZX Turbo CARTECH UPGRADE 274)atsun 280Z 155:80Z CARTECH TURBO EFI 265:80Z CARTECH TURBO (w/carbs) 29080Z CARTECH MAX (w/carbs) 400+OOZX Stock turbo 200OOZX Turbo CARTECH MAX EFT. 384OOZX Twin Turbo 300OOZX TWIN TURBO MAX EFFORT 475eTomaso Pantera GTS 350errarl F40 478errari Testarossa 380ord Mustang LX 5.0L 225USTANG,CARTECH LEVEL I 325USTANG,CARTECH LEVEL II 425ARTECH TWIN TURBO (modified) -ord T-Bird Turbo W/IC 190ARTECH T-Bird Max Effort 330Jnda CRXsi 16V 108Jnda CRXsi CARTECH TURBO 175~guar V-12 XJS 262

307728753030411033512710274524502500272327782805285532303265338034453540360533493365329532163280223724833160320029653010300530053265330034503450325024253500314031903220

33803410211521604040

8.18.56.26.88.39.06.211. 66.29.05.98.25.77.95.38.55.39.16.56.05.36.75.85.08.16.77.86.18.15.95.44.97.44.96.74.65.53.95.36.05.03.3

8.55.58.96.38.8

16.416.414.515.316.416.814.118.314.316.714.016.013.716.113.616.313.016.714.614.513.815.214.413.716.315.315.814.116.114.013.712.915.713.215.012.814.011. 513.415.012.911. 6

16.413.717.114.616.7

20.418.313.213.721.225.113.024.312.822.512.216.810.117.79.7

18.59.6

19.410.613.711. 513.713.49.5

15.314.219.211.719.111. 410.47.5

16.38.5N/AN/A9.3N/A9.2

13.910.07.6

17.810.319.612.315.4

HORSEPOWER, ACCELLERATION, AND POWER TO WEIGHT RATIOSREVISED 4-1-91

~amborghini Countach 5000S 455*(*note; inconsistant power vs

~otus Esprit Turbo SE . 2641aserati Bi-Turbo E 2051azda Miata 116:artech Miata Turbo 1851azda RX-7 GSL (79-85 12A) 101~X-7 CARTECH TURBO 12A 235~X-7 CARTECH TURBO 13Bported 3401azda RX-7 GSL-SE (84-85) 135~X-7 GSL-SE CARTECH TURBO 2631azda RX-7 Sport (86-87) 146~X-7 86-88 CARTECH TURBO 2701azda RX-7 Turbo II 182~X7 TurboII CARTECH LEVEL I 258~X7 TurboII CARTECH LEVEL II 3151azda 626 Turbo 120)26 Turbo CARTECH UPGRADE 1501ercedes 2.3-16 1671ercedes 560 SEC 2381erkur XR4Ti 175(R4Ti CARTECH UPGRADE 2371itsubishi Starion ESI-R 176)ontiac Trans-Am (5.7. TPI) 210)orsche 911 214)orsche 928S 316)orsche 911 Turbo 282)orschejRuff 930 Turbo 369)orsche 944 147)orsche 944 Turbo 217;aab Turbo 16V 160'oyota Supra 82-86 2.81iter 161;upra 2.8 CARTECH TURBO 270'oyota Supra 86.5up 3.01iter 200;upra 3.0 CARTECH TURBO 315;upra Factory Turbo 3.01iter 230;upra CARTECH UPGRD.LEVEL I 333;upra CARTECH UPGRD LEVEL II 362;upra CARTECH UPGRD LEV. III 392

3280 4.2acceleration )2975 4.72910 6.32205 9.72240 6.32350 9.92400 5.52400 4.52550 8.52600 5.72805 8.52855 5.12850 6.62865 5.42870 5.12640 7.82655 6.93010 7.83890 7.02920 7.92935 6.23087 8.33435 7.92756 5.73549 6.32976 5.02905 4.72780 8.22992 6.02910 8.63045 8.73045 6.13460 8.33495 5.33522 6.83517 5.83520 5.33530 5.0

13.7

13.315.017.414.717.413.712.816.413.916.513.415.213.813.316.015.116.215.516.014.616.216.114.314.713.413.316.114.616.516.814.816.213.815.014.313.913.6

7.2

NjA14.219.012.123.310.27.1

18.59.9

19.210.615.711.19.1

22.017.718.016.317.212.417.516.412.911.210.57.9

18.913.818.221.811. 317.311.115.310.69.79.0

****NOTE: ALL TIMES ARE TRACTION DEPENDENT****