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OPR Top End Engine Kit (87-93 5.0L)

Market Price $2,249.99 You Save 11% ($250.00)
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$1,999.99 (kit)

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  • Item 99941
  • MPN# 99941

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    Features & Details

    • Bolt on More Horsepower
    • Complete Top End Kit
    • Improves Air Flow Over Original GT-40 Heads
    • Lightweight Aluminum Construction
    • Includes GT40X Heads, XE264HR Stage I Camshaft and Typhoon Intake Manifold
    • Fits 1987-1993 5.0L Mustangs
    More Power. Increase the horsepower and torque output of your push rod 5.0L engine with an OPR Top End Engine Kit from AmericanMuscle that includes Ford Racing Turbo-Swirl GT40X Aluminum Heads. This Top End Engine Kit will greatly improve airflow over the original stock design allowing you to bolt-on over 65 more rear wheel horsepower.

    Kit Includes. This Top End Engine Kit includes Ford Racing Turbo-Swirl GT40X Aluminum Heads, Comp Cams Xtreme Energy XE264HR Stage I Camshaft, Typhoon Intake Manifold, Aluminum Valve Covers, Magnum Double Roller Timing Chain Set, ARP High Performance Series Head Bolt Kit, and a Ford Racing Engine Gasket Kit.

    GT40X Aluminum Heads. Made from high quality 356-T6 aluminum castings, these Ford Racing GT-40X heads have an intake port volume of 178cc allowing for an intake flow of approximately 240 cfm at .550" lift (at 28" of H20) and an exhaust port volume of 62cc allowing for an exhaust flow of approximately 170 cfm at .500" lift (at 28" of H20). Machined for 1.94" Intake and 1.54" exhaust valve diameters.

    Xtreme Energy Stage I Camshaft. This Comp Cams Xtreme Energy Hydraulic roller lifter cam is a good replacement upgrade for the High Output (HO) 5.0 that was featured in the later Foxbody Mustangs for mild street performance gains. Perfect for bolt on modifications to make good overall power with a smooth idle without sacrificing daily drive-ability. 

    Typhoon Intake Manifold. Completed in a natural satin finish this aluminum Professional Products Typhoon Intake Manifold will allow your Pony to breath much easier with no loss of low end torque. A 70mm Throttle Body is recommended for optimum performance of your 5.0 Mustang.

    Application. This OPR Top End Engine Kit is designed for use on the 1987 to 1993 Mustangs equipped with the iconic 5.0L V8 engine, including the LX 5.0, GT and SVT Cobra models.

    Fitment: 1987 1988 1989 1990 1991 1992 1993 Details

    What's in the Box
    • (2) Ford Racing Turbo-Swirl GT40X Aluminum Head
    • (1) Comp Cams Xtreme Energy XE264HR Stage I Camshaft
    • (1) Professional Products Satin Typhoon Intake Manifold
    • (1) Upper to lower intake gasket
    • (1) Upper plenum to intake gasket
    • (2) Canton Aluminum Valve Covers
    • (1) Filler Cap
    • (1) Comp Cams Crank Sprocket
    • (1) Comp Cams Camshaft Gear
    • (1) Comp Cams Timing Chain
    • (20) ARP Bolts
    • (20) ARP Washers
    • Ford Racing Complete Engine Gasket Kit
    Installation Info
    Will it fit my Mustang?
    • GT - 87, 88, 89, 90, 91, 92, 93
    • LX - 87, 88, 89, 90, 91, 92, 93

    Customer Photos (2) Submit Your Photo

    View All 2 Photos

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    26 Questions / 7 Answers

    Ask a Question

    will the 19lbs injectors work with this kit?


    • 19lb injectors will work just fine. You would gain max performance with a adjustable fuel press. reg.


    Show 1 more answer Helpful (7)

    about how much horsepower can i expect from this kit


    • The heads alone will yield 65+. All the parts are used help each other and you can expect about 90 rwhp or more


    Helpful (4)

    I bought top end kit. my 92 gt is stock will it work with the current throttle body and current distributor?


    • The OPR Top End Engine Kit will work with your factory distributor. A 70mm Throttle Body is recommended for optimum performance of your 5.0 Mustang.


    Helpful (1)

    will this system work with my 94 5.0?


    • The OPR Top End Engine Kit can be used with 94-95 5.0's But would require different valve covers from what is included, and would also require a throttle body adapter.

      Rob D

    Helpful (1)

    Are the valve springs on the gt40x heads strong enough to with stand the aggressive ramp rates of the XE264HR cam?


    • The valve springs will be able to withstand the rates of the XE264HR cams without issues.


    Helpful (1)

    Do these heads have 58 or 64 çc chambers


    • They have 64cc chambers


    Helpful (1)

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    Customer Reviews (5) Write a Review

    Overall Rating 4.2

    out of 5 stars

    Installation Time:Weekend

    Installation Cost:$250-$500

    • Performance Gain 4.4 4.4
    • Fit 4.2 4.2

    • 4/5

      Installation Time: Weekend

      May 14, 2015

      More Power for you, Stang

      I purchased this exact kit for my Mustang GT 89, which was completely stock. It works perfect with the stock pistons. I put new exhaust with Long tube headers with flow masters. Sounds Awesome. Along with that I purchased 1.7 rockers, lifters, push rods, and spark plug wires 9mm all Ford Racing, also has upgraded alternator to130 amps, 70mm throttle body paired with MAF, cold air intake and a MSD distributor has stock injectors. The car also has a Bama Chip onboard as well. As for the build there were some issues with gaskets that were miss matched and some nuts and bolts that did not match as I thought they would. I'm not sure of the new horse power but it has a lot of new Ponies in the stable, and they love to run... Some things to note, I drive this car almost daily. It has over 10k miles on it since the rebuild. I changed the oil frequently for the first 5k miles. I'm now using lucus oil stabilizer. Wow! I notice a difference. I forgot to mention that the hood now sits on top of the air intake Manifold, does not hinder performance but I know it's rubbing.


      Year: 1989 Submodel: GT Margate, FL

      Helpful (8)

    • 5/5

      Installation Time: Full Day

      May 20, 2016

      Make real power

      nothing beats a turbo for power, but be sure to up grade your braking system to be able to get it stopped, also sold here


      Year: 1992 Submodel: GT

      Helpful (6)

    • 4/5

      Installation Time: Weekend

      June 12, 2013

      overall good kit

      the only thing this kit doesn't include are the studs for the rocker arms. other than that, this kit is pretty good.


      Year: 1988 Submodel: Other Queens, NY, USA

      Helpful (3)

    • 4/5

      Installation Time: Weekend

      September 20, 2013

      nice power gain

      nice power gains for the buck.I would recomend this kit for someone on a budget and looking some nice power gains.


      Year: 1987 Submodel: GT Prince Edward Island, Canada

      Helpful (1)

    • 4/5

      Installation Time: Shop Install

      Installation Cost: $250-$500

      August 08, 2013

      great kit but needs few things added

      great kit i have yet to run it but you will need rocker arm studs and smog plugs which are threaded inserts they should provide in the kit rocker arms were like $50 and the inserts i had to get off another site for $10 but besides that my mechanic and I had easy time doing the install.


      Year: 1990 Submodel: GT Brownsville, PA, USA

      Helpful (1)

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