Approval Details

Valid E.O.

Validity

This Executive Order approved the specified parts on on October 24, 1991.
As of Wednesday, October 16th, 2019 this Executive Order has not been overturned or superceeded.

Approved Parts

Part NumberModels
303Y-S0, 303Y-DAO 388Y-S0, 354Y-1987-1992 GM vehicles powered by a closed-loop 400-454 CID engine

This Executive Order may be listed as:
  • C.A.R.B.E.O. D-200-5
  • Executive Order 200-5 / D200-5
  • ARB # D-200-5
  • Executive Order No: D-200-5
  • C.A.R.B. No. D-200-5
  • Resolution D-200-5
For Free CARB Executive Order Status verification, email an image of the device Executive Order label as well as the Year/Make/Model and Test Group # of the vehicle to [email protected]

Download: Executive Order D-200-5 PDF

D-200-5 Document:



                                                  (Page 1 of ?)

                            State of Californta
                            AlR RESOURCES BOARB

                          EXECUTIVE ORDER D—20G0—5
                 Relating to Exemptions Under Section 27156
                            of the Yehicle Code

                         DOuUG THORLEY HEADERS, INC.
                                HEADER SYSTEM
{P/N‘s 303Y—50. 303Y—DAO, 388Y—50, 354¢—50, 354Y—0A0, 392Y—50 AND 399Y—50)

Pursuant to the authority vested in the Air Resources Board by Section 27156
of the Vehicle Code; and            —

Pursuant to the authority vested in the undersigned by Sections 39515 and
39516 of the Health and Safety Code and Executive Order G—45—5;

I1T IS ORDERED AND RESOLYVED: That the installatiton of the Doug Thorley
Headers, P/N‘s 303Y—S0, 303Y—DAND, 388¥—50, 3544—S50, 354Y—DAO, 392Y—S0 and
399Y—50, manufactured by Doug Thorley Headers, Inc. of 1561 Commerce Street,
Corona, CA 91720 has been found not to reduce the effectiveness of the
applicable vehicle pollution control system and, therefore, is exempt from
the prohibitions of Section 27156 of the Vehicle Code for 1987—1992 model—      .
year General Motors vehicles powered by a closed—loop 6.6—7.4 liter {366§ ¥22°"°~   Y
C€10—454 CID) engine.

This Executive Order is valid provided that installation instructions for
this header system will not recommend tuning the vehicle to specifications
different from those submitted by Doug Thorley Headers, Inc.

Changes made to the design or operating conditions of the header system, as
exempt by the Air Resources Board, which adversely affect the performance of
a vehicle‘s pollution control system shall invalidate this Executive Order.

Marketing of this header system using any identification other than that
shown in this Executive Order or marketing of this header system for an
application other than those listed in this Executive Order shall be
prohibited unless prior approval is obtained from the Air Resources Board.
Exemption of the header system shall not be construed as exemption to sell,
offer for sale, or advertise any component of the kit as an individual
device.

This Executive Order does not constitute any opinion as to the effect the
use of this header system may have on any warranty sither expressed or
implied by the vehicle manufacturer.

THIS EXECUTIVE ORDER DOES NOT CONSTITUTE A CERTIFICATION, ACCREDITATION,
APPROVAL, OR ANY QOTHER TYPE OF ENDORSEMENT BY THE AIR RESOURCES BOARD OF
CLAIMS OF THE APPLICANT CONCERNING ANTI—POLLUTION BENEFITS OR ANY ALLEGED
BENEFITS OF DCUG THORLEY HEADERS, INC.*‘S HEADERS, P/N‘S 303Y—SG, 303Y—DAO,
388Y¥—50, 354Y—S50, 354Y—DA0, 392Y—SO AND 399Y—S0.


BOUG THORLEY HEADERS, INC.                        EXECUTIVE ORDER D—200—6
HEADER SYSTEM                                     (Page 2 of 2)



No claim of any kind, such as "Approved by the Air Resourcas Bsard" may be
made with respect to the action taken herein in any advertising or other
oral or written communicatiton.

Violation of any of the above conditions shall be grounds for
revocation of this order. The order may be revoked only after ten day
written notics of ifntention to revoke the order, in which period the holder
of the order may request in writing a hearing to contest the proposed
revocation. If a hearing is requested, it shall be held within ten days of
receipt of the request and the order may not be revoked until a
determination after hearing that grounds for revocatfon exist.

Executed at El Monte, California, this AA              October, 1991.


                                       R&.   &. Summerfiel
                                       Asststant Division Chief
                                       Mobile Source Division


                       State of California
                       AIR RESOURCES BOARD




      EVALUATION OF—BOUG THORLEY HEADERS, INC.‘S HEADER SYSTEM
           FOR EXEMPTION FROM THE PROHIBITIONS OF VEHICLE
CODE SECTION 27156 IN ACCORDANCE WITH SECTION 2222, TITLE 13, OF THE
                   CALIFORNIA CODE OF REGULATIONS




                            October 1981


                          State of California
                          AIR RESOURCES BOARD




         EVALUATION OF DOUG THORLEY HEADERS, INC.‘S HEADER SYSTEM
               FOR EXEMPTION FROM THE PROHIBITIONS OF VEKICLE
   cODE SECTION 27156 IN ACCORDANCE WITH SECTION 2222, TITLE 13, OF THE
                      CALIFORNIA CODE OF REGULATIONS




                                     by
                           Mobile Source Division
                            Statse of California
                            Air Resources Board
                            $528 Telstar Avenue
                          E1 Monte, CA 91731—2990



{This report has been reviewed by the staff of the California Air Resources
Board and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Air Resources
Board, nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.)


                                   SUMMARY



       Doug Thorley Headers, Inc., of 1561 Commerce Street, Corona, California

81720 has applised for an exemption from the prohibitions in Section 27156 of

the California Vehicle Code {YVC) for the Doug Thorley headers, P/N‘s 303Y—S0,

303Y—DA0, 388Y¥—50, 354Y—S0, 354Y—DA0, 392Y—S0 and 389Y¥—SQ.    These headers are

designed for installation on 1987—92 General Motors vehicles equipped with a

closed—loop 6.0—7.4 liter (366 CID—454 CID) engine.

       Based on the results from comparative exhaust emission tests performed

at an independent laboratory on a 1991 Chevrolet C2500 pick—up truck., the staff

concludes that Doug Thorley Headers, Inc.‘s headers, P/N‘s 303Y—SO0, 303Y—DA0,

388Y—S0, 354Y—50, 354Y—DA0, 392Y—S50 and 399Y¥Y—S50 will not adversely affect

exhaust emission from vehicles for which an exemption is requested.

       The staff recommends that Doug Thorley Headers, Inc. be granted an

exemption as requested and that Executive Order D—200—5 be issued.


                                                      Page Number



SUMMAR Y

CcONTENTS                                                  11

1.         INTRODUCTION

11.        CONCLUSION

II1I.       RECOMMENDATION

IV.        DEVICE DESCRIPTION

V.         HEADER SYSTEM EVALUATION AND OISCUSSION

APPENDIX

           APPENDIX A:    INSTALLATION INSTRUCTIONS




                                            11


               EVALUATION OF DOUG THORLEY HEADERS, INC.‘S HEADER SYSTEM
                     FOR EXEMPTIOGN FROM THE PROKHIBITIONS OF VEHICLE
        CcODE SECTION 27156 IN ACCORDANCE WITH SECTION 2222, TITLE 13, OF THE
                            CALIFORNIA CODE OF REGULATIONS




I.        INTROOUCTION

          Boug Thorley Headers, Inc. of 1561 Commerce Street, Corona, California

91720 has applied for an exemption from the prohibitions in Section 27156 of

the California Vehicle Code for the headers, P/N‘s 303Y—S50, 303Y—DAO, 388Y—S50,

354Y—SO, 354Y—DA0O, 392Y—SO and 399Y¢—S50.   These headers are designed for

installation on 1987—92 General Motors vehicles powered by a closed—loop 6.6—

7.4 liter {366 CID—454 CID) engine.

          Doug Thorley Headers, Inc. has submitted data from comparative emission

tests conducted on a 1991 Chevroltet €2500 pick—up truck at Milton Roy

 Laboratory, Orange, California.



 II.        ONCLUS   S

           Based on the results from comparative exhaust emission tests performed

 at Militon Roy Laboratory on a 1991 Chevrolet €2500 pick—up truck, the staff

 concludes that Doug Thorley Headers, Ihc.'s headers, P/N‘s 303Y—S0, 303Y¥—D0A0,

 388Y—S50, 354Y¥—S0, 354Y—DAO, 392Y—S0 and 399Y—50, will not adversely affect

 exhaust emissions from vehicles for which an exemption is requested.



 II1.      RECOMMENDATION

           The staff recommends that Doug Thorley Headers, Inc. be granted an

exemption for their headers, P/N‘s 303Y—S0, 303Y—DA0, 388Y—SO, 354Y—SC,



                                          —1—


354Y—DA0O, 392Y—S0 and 399Y—SQ, for installation on 1987—1992 model—year General

Motors vehicles powered by a closed—loop 6.6—7.4 liter {(366 CID—454 CIN0)

engine.    The staff also recommends that Executive Order D—200—5 be issued.



IV.       EVICE     DESCRIPTIO

          The Doug Thorley headers, P/N‘s 303Y—S0, 303Y—DA0, 388Y—S0, 354Y—50,

354Y—DAO, 392Y—S50 and 399Y—$0, are designed for installation on 1987—92 General

Motors vehtcles powered by a closed—loop 6.6—7.4 liter (366 CID—454 CIB) fuel

 injected engine.     As with the original equipment manufacturer‘s {OEM) exhaust

system, the function of Doug Thorlsey‘s header system is to route exhaust gases

through the header pipes from the two exhaust manifolds of the engine into a

 common pipe which then feeds to the catalytic converter.         Each cylinder has a

 1.75" diameter pipe that combines with the adjacent pipe into a 2" diameter

 pipe.    On each side of the engine, tfiese two 2" pipes combine into a 2.5"

 diameter pipe.      Finally, all the exhafist gases are then routed into a pipe

 which feeds into the pre—catalyst piping.

          The system operates in conjunction with the OEM computer controlied

 electronic port fuel injection and emission control systems already certified

 with the stock engine.          Installation of Doug Thorley exhaust system does not

 alter the OEM location of the oxygen sensor and the catalyst.          The tune—up

 specifications also remain the same.         Appendix A contains a sample of the

 installation instructions.


 V¥.     HEADER SYSTEM EVALUATION AND DTSCUSSTON

         A 1991 fGeneral Motors C2500 pick—up truck with a 7.4 liter (454 CID)

 fuel injectsed gasoline engins was used for the evaluation of the header P/N‘s

  303Y—$0, 303Y¥—DA0, 388Y¥—50, 354¥—50, 354Y—DA0, 392Y—50 and 399Y—S0.   The

  dynamometer inertia weight and loading used were 7000—lbs and 15.4—hp

  respectivaly.

         Comparative emissions tests conducted by Milton Roy Laboratory

  for Doug Thorley Headers, Inc. consisted of one Cold—Start CVS—75 emission test

  in the unmodified {baseline)} configuration, followed by one Cold—Start CVS—75

 emission test in the modified (header system installed) configuration.         The ARB

 did not perform tests to confirm the test results submitted by the applicant.

 A summary of the test results is shown below:


                          Exhaust Emissions Test Results
                      On A 1991 Chevrolet C2500 pick—up truck

_ Test               Exhaust Emissions {gm/mi)               .
  Mode               NMHC                CO                      NQx.

 Baseline             4178                6.619                  2.552
 Device               .552                7.2176                 2 .779
 Difference          +.074                +.657                  +.22]
 % Difference        +15.5%               +9.9%                  +8.9%


       The differences between the device emission test results and baseline

emission test results submitted by the applicant were within the allowed lHimits

of .1 gm/mile or 10 percent of baseline HC, 1.0 gm/mile or 15 percent of

baseline CO and .1 gm/mile or 10 percent of baseline NOx as specified in the

"Procedures for Exemption of Add—On and Modified Parts."        Based on the test

results, the staff concludes that the installation of the Doug Thorley headers,

P/NX‘s 303Y—SQ, 303Y¥—DA0, 388Y¥—50, 354Y—50, 354Y¥—DA0O, 392Y—S50 and 399Y¥—50 did

not have an adverse effect on exhaust éfiissions of the affected vehicles.           Doug

Thorley Headers, Inc. submitted all the required information and fulfilled the

requirements for exemption.


Appendix


                             DOUL riiomiry HEHNDER
                                         ParRtif3IG3¥ & 303Y¥—S0
            CHEVROLET/CMC         Pick—ups, Suburbans, Blazers:                           1973—1905           2464vD
                  CLass     "A"   MOTORROMERS:       19785—1985S           396~—427—454             HEugine
 when the enclosed instructions are followed precisely you will £f ind                                                         the
                                                                                                                        O‘,'l{.:r —
 instaliation of your headers to be relatively simple.    We canmnot
 ecmphasize of adnering strictly to this proven approuch.
  NOTE:       Installation of headers for vehicles equipped with emissi ons
            control devices          and/or       catalytic converters                  imust be inade                 in   accord—
            ance    with    government       rbgulatlonu         pertaining             to    emissions                standargd:an.
   Due to restricted room in the engine compartinent, your headers may Come
  closse to certain body and chassis components   This is a normal contlition
  for an installation of this type.    WARNING: MAKE sURE YOU MAVE ENOUGIH
  CLEARANCE AROUND          BRAKE,    FUEL    &    ELECTRICAL         LINES,        RTC.        ln     some      c ascs
  it may be necessary to relocate                   those iteims which miqght be adver.ALJ.Y
  affectoed by exhaust heat.
  1.     Disconnect battery cable to avoid damage                          to vehilcle elcciric alo sys tom.
  2.     Raise front of vehicle approx. 24" and support with jack                           s ta nds .
         WARNING : DO NOF RELY ON BUMPER JACKS FOR SUPPOIWTII
  3J.—   Remove spark plugs, hecadpipes, and oil fllter.    lt is not ne cessaury
         to remove clutch linkage or front drive shaft on vehicles so equipped .
         It may be necessary to lift the engine from its mounts to rsInOV O
         the stock manifolds ‘and to install the loeft side header.
  4..    Loosen starter motor, but do not remove.     Remove dipstick tu ba .
, 5.     Clean accumulation of carbon from exhaust port gasket surfacCuGd .
  656.   Place headers into position from the underside of the vehicl @, using
         the gaskets and hardware provided,    We strongly recommend th e use
         of high—temp silicone gasket sealer between the header and t hbe gaskeL.
         Start all header bolts.   Re—install dipstictck and oil filter, ctCe.
  7.—    Tighten all bolts securely.    It is important that on the hea der flanigs
         you start with the center bolts and work your way outward.      Re—tightoen
         bolts    to starter,       motor mounts,         ctc.
         NOTE:—    All engines are not mounted exactly the same at the f actory
                   and is sometimes necessary to shift the moutor from si de £o
                   side    to   obtain maximum clearanco.                     If    motor mounts                ure         wOoLn
                or broken, they should be replaced at this time.
   8.    Attach reducer adapters to header collectors and attach to ©>yxhausdL
         systen by clamping or welding.
   9.    After completion of the oentire systom, start the engine and chook
         for leaks.  After the engine has run for approx. 204 iminutes, i —
           tighten    all header bolts            ({approx.      35   ft/lbs}).
                                                          Headar bolls shoul d
         be inspected periodically for tightness  in order to prevent gqaslket
         damage and leakage.
   Due to varying conditions in different gceographieal arecas, we strongly
   recommend having your engine re—tuncdad after the installation of hcaders .
    This   will    assure    that    you reccoive      the maxilmuin increase                     scavenging                 in
  performance and cconomy.      It may be notcd that due to the incroused
   scavenging effcect: of FTri—Y headers, that your air—fucel mixture uaund/or
   timing may roequire modAification.
                                                                                                     PHK          :/
     ut LEGaLk FOR        SALE Ol USEH     LR CA ON       POLLUTIGOGH CONTROLLEL
                                 )t{Si\JC * 1501 CnlflflNefi ..‘A
            DOUG T}{O} YY f‘“";‘\l                                C(.)H‘na.;, C‘f". v1720 \71” 7_,') Tmi‘r\fr' 5/ i) ?j:
                                                    A—"



Document Created: 2005-09-01 12:45:01
Document Modified: 2005-09-01 12:45:01

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