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C6 Corvette Z06 Sports Flat-Plane Crank LS7: Video

Ford Motor Company made waves in 2015 when they introduced the Mustang GT350 with a 5.2-liter flat-plane crank V8 under the hood. Unlike the majority of American V8s, which have historically contained a cross-plane setup, Ford took a page from the Italians’ book on how to make big power. By utilizing a 180 degree flat-plane crank, an engine is able to breathe significantly better, and in turn produce more horsepower. The other key side effect of using a flat-planer? Lots of revs. The Voodoo motor screams all the way to 8,250 RPM before reaching fuel cut-off, significantly higher than the 7,000+ RPM redline of the 5.0-liter Coyote V8 on which the Voodoo motor is based.

You may be asking yourself why more American companies haven’t used flat-plane crankshafts, considering they are so beneficial to performance. Thankfully for the rest of us, this C6 Corvette Z06 owner decided to find out for himself what a flat-plane crank LS7 would be like. The answer? Quite different than a cross-plane motor.

2013 Corvette 427 Convertible LS7 V8

The stock LS7 is a 7.0-liter variant of General Motors’ fourth generation small-block V8. Built by hand in Wixom, Michigan, the LS7 has a reputation for being a bit of a monster that was only found in the C6 Corvette Z06, 427 Convertible, and fifth-generation Camaro Z/28. When looking at the numbers this engine produces, that reputation comes as no surprise: 505 horsepower at 6,100 RPM and 470 pound-feet of torque at 4,800 RPM are stout figures. Rip out that factory supplied cross-plane crank and stuff in a new flat-plane unit, and those numbers are surely going to be even more impressive.

The change in firing order, as necessitated by switching to a flat-plane crank, results in a new soundtrack for the LS7 in the Corvette Z06 as well. Gone is the traditional American muscle howl, replaced by a more exotic sounding exhaust note. The rev limiter has seemingly increased as well, however the owner hasn’t made that information available. Upon finishing the short clip, we had only two questions: how much does this cost? And with this around, who needs a Voodoo?

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Comments

  1. The LS7 was also standard equipment in the 2013 Corvette 427 Convertible. A total of 2552 were produced, all with manual transmission.

    Ford also hand builds the 5.2L Voodoo engine in Romeo, MI. Kudos to Ford for spending the money and developing a special engine for a low volume car like the GT350/GT350R. Highly unlikely the GM would do it these days.

    Reply
    1. Rumours out there say that the C8 may have one.

      This one sounds like a bag of marbles inside a tin can though.

      Reply
  2. I really don’t like the sound of the flat plane firing order. Though I don’t really care for the old 302 H.O. Ford firing order of the LS motors either. I always think fox body Mustang when I hear an LS. Even changing the sparkplugs on my 5.3 reminded me of the old Ford 302. One bank of plugs was slanted backwards, the other forwards. I understand the flat plane and the firing order, I understand the change in firing order on the 97 and up ‘smallblock’ LS, I just don’t like the way either sound.

    The 18436572 firing order sounded beautiful in the old smallblocks and bigblocks with the standard crank. I really wish GM/Chevrolet wouldn’t have changed it.

    Reply
  3. Sounds like a non VTEC Civic with a Pepboys catback.

    Too bad, because I like a well done flatplane V8. Maybe They should have taken a page from Ford engineers and changed the firing order and tuned the exhaust to add a little base in that LS7’s voice.

    Reply
  4. The flat-plane crank necessitates a change in firing order? I thought it was the other way around. I thought better breathing was accomplished by a change in firing order and that necessitated the flat-plane crank. No?

    Reply
    1. The firing order is simply the sequence in when each spark plug ignites the charge in the cylinder. Subsequently the the firing order can be whatever the engineers design it to be. On a flat plane crank the firing order traditionally mimics two banks of 4 cylinders firing in sequence exactly opposite the cylinder last fired vs a traditional 90 degree cross plane crank v8 which has a firing order that ignites on the opposite bank as well but not always opposite of the last cylinder fired.

      For instance a the original small-block Chevy has a firing order of :

      LSx’ s vs old small block’s
      1-8 1-8
      7-2 4-3
      6-5 6-5
      4-3 7-2

      Ford’s Coyote v8 (current OHC 5.0) VS VooDoo 5.2L V8 (GT350 flatplane)
      1-5 1-5
      4-8 4-8
      3-7 6-3
      2-6 7-2

      As you can see they have different firing orders between all four. I remember reading during the intro of the GT350 that the engineers intentionally designed the car with that firing order to eliminate some of the “exotic” sound out of the exhaust note and ensure the car wasn’t too far from the traditional American V8 sound customers were used to. They also did it to try and minimize NVH since the 5.2 Voodoo V8 is fairly large compared to the traditionally 2-3L+ flat plane V8s from Europe.

      Reply
      1. Correction my Ford Coyote vs Voodooo was swapped, the proper order is below:

        1-5 1-5
        4-8 4-8
        6-3 3-7
        7-2 2-6

        Reply
        1. Those firing orders look correct. The Voodoo is the only one that fires on the opposite bank for every successive firing. The LSx: #3 is followed by #1, same bank and adjacent. The SB: #5 is followed by #7, again on the same bank and adjacent. The Coyote: #8 is followed by #6, also on the same bank though not adjacent. I think you can’t get opposite bank firing on every successive firing with a cross-plane crank.

          Read more: http://gmauthority.com/blog/2018/09/c6-corvette-z06-sports-flat-plane-crank-ls7-video/#ixzz5RxERXRJ1

          Reply
  5. Those firing orders look correct. The Voodoo is the only one that fires on the opposite bank for every successive firing. The LSx: #3 is followed by #1, same bank and adjacent. The SB: #5 is followed by #7, again on the same bank and adjacent. The Coyote: #8 is followed by #6, also on the same bank though not adjacent. I think you can’t get opposite bank firing on every successive firing with a cross-plane crank.

    Reply

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