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    Thread: 400 vs 377

    1. #1
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      Oct 2005
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      New Washington, IN
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      400 vs 377

      I have a 400 block rady to go, but no rotating assembly.

      I can build a 377 with the same parts for about $200 less than if I go 400.

      Car is a fun protouring car, 6 speed manual, weighs 3200lbs.

      I know they say there is no replacement for displacement, but also here people argue over the rev capabilities of the destroked and its desirability for a car of my nature.

      Thoughts?

      1971 Camaro 427 in waiting
      1988 C1500 Daily Driver
      1955 Bel Air, blown BBC street car


    2. #2
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      bowling green,ky
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      if you want to spin it then 377, 400 will be rpm limited, but lots of torque down low. i know, ive blown up 2 of them.

    3. #3
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      I guess then I am asking, for a pro touring car with a 6 speed and 3200lb curb weight what would be better?
      1971 Camaro 427 in waiting
      1988 C1500 Daily Driver
      1955 Bel Air, blown BBC street car

    4. #4
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      The 377, a big bore, short stroke engine is my definition of cool...if you're considering it then you must have the same appreciation for the unique-ness.

      The rpm ability of the engine is more determined by what your valvetrain can handle, not really the stroke of the engine. Since both engines can be made to rev as high as the valvetrain wants to go, there is no replacement for displacement (as much as I hate to admit it sometimes).

      If you want the engine to have wicked throttle response and rev quickly, get an aluminum flywheel. Revs and throttle response seem to be generated through compression and minimizing inertia...not engine stroke so much.

      That said, my vote is for the 377!
      Steven

      1968 Camaro: Project "TRACKDAY"

      Latest Track Weekend Video

      Build in Progress

    5. #5
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      Either engine would have 10.5:1-11:1 compression.

      Both would have solid roller cams, similer speced as recommended, both would have heads in the 200-210 size.

      The thing is, which would be better for my use?

      Looking at a 2000-6500 powerband.

      AS stated, manual 6 speed trans with a 3.23-3.42 gear ratio, so the motor must be able to lug around under 2000 rpms.

      That makes me think the 400 would be a better choice.
      1971 Camaro 427 in waiting
      1988 C1500 Daily Driver
      1955 Bel Air, blown BBC street car

    6. #6
      Join Date
      Feb 2007
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      USA, TN
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      They will both spin the same properly setup. What you have to ask yourself is what cam and heads are you using and what RPM do you want to make power. If you want to spin the moter to 6500 RPM and you have small heads, stay with the 377. If you have big heads, go with the 400. The 377 will be soggy down low with the big heads.

    7. #7
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      As stated, max rpm 6500.

      Heads will be 210-225 intake runner size.
      1971 Camaro 427 in waiting
      1988 C1500 Daily Driver
      1955 Bel Air, blown BBC street car

    8. #8
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      I'm building a .040 over 400 for my '77 Camaro. With your gearing you might like the torque of the 400 better. I'm building a pretty mild motor, but I'm expecting close to 400 lbs. ft. of torque from before 2000 rpm on up. It should be a fun car when it's done.
      Allen Ortega
      Meanstreets Performance Fabrication

      ---------------------------------------

      Vegetarians are the reason for global warming

    9. #9
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      This goes back to the arguement about rod/stroke ratio. By design, the 377 is more efficient and can handle more abuse vs. the 400 in upper RPM's. This is because the long stroke of a 400 crank demands shorter rods-this puts more stress on the block (cylinder wall loading) and you are also more likely to wipe out a rod bearing because of the angle the rod moves in relationship to crank stroke. As for valvetrain weight, a 400 crank is HEAVY-so this is more inertia moving down the cylinder wall after combustion has occured. This adds to the harmonics which because of the long stroke, will limit RPM ceiling all else being equal so no, 400's will not spin as easily as a 377 will. Big bore, short stroke equates to a quick reacting valvetrain...a big plus with a forced induction motor to be sure and with a 5 or 6 speed where the first gears are fairly steep, this imo is the better way to go. It's better to grab traction and haul ass than it is to give off a smoke show. My choice would be a 377 hands down over a 400...or a 406 by the time you're done. If nothing else, reliability would win out in the end.
      "...if at first you don't succeed, try again.
      If you still don't succeed, then quit-no sense being a damn fool about it..."
      -W.C. Fields

      HARNESSWORX
      (formerly gmachinz)

    10. #10
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      That arguement makes a lot of sense.

      So, would a 377 (actually 380, as block is .040" over.
      With a 6" rod, be best?
      1971 Camaro 427 in waiting
      1988 C1500 Daily Driver
      1955 Bel Air, blown BBC street car

    11. #11
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      I have a 377 (.030 over) with 6" rods, lightweight Scat crank, Victor Jr heads (215cc intake runners) and a rather big circle track cam (266 duration at .050) and love it. The torque down low is pretty good for the cam size and a Z/28 crossram on it. A 406 would have more torque, but it's hard enough to get the 377 to hook in 1st and 2nd gear.
      2018 Cruze LT Hatchback
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      2003 GSX750F Katana

    12. #12
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      Sounds like a good set up, a bit more cam than I was thinking.

      What do you use this in?
      1971 Camaro 427 in waiting
      1988 C1500 Daily Driver
      1955 Bel Air, blown BBC street car

    13. #13
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      I go with 6.2 Scat rods-JE makes pistons with raised ring lands for this type of setup. Since this scenario focuses on a fast rotating assembly, focus more on airflow velocity vs. sheer volume when it comes to your heads. Port design is critical. Reducing piston speed by going with a long rod is key to engine longevity.
      "...if at first you don't succeed, try again.
      If you still don't succeed, then quit-no sense being a damn fool about it..."
      -W.C. Fields

      HARNESSWORX
      (formerly gmachinz)

    14. #14
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      Quote Originally Posted by Johnny Blaze View Post
      Sounds like a good set up, a bit more cam than I was thinking.

      What do you use this in?
      It was in my 67 El Camino that I autocrossed and drove on the street. The cam was a bit much for the street. It's now going into an 81 Camaro which is being turned into a dedicated autocross car. The El Camino has a 94 LT1 in it now, just not running yet. I have a Richmond 5 speed (4+1) behind it, same trans behind the 377.

      A 377 is basically a 350 that's been bored out. With the right cam, it will produce good torque, just not quite as much as the 400. But it does like to rev, which makes it just plain fun.
      2018 Cruze LT Hatchback
      2003 Suburban 2500 8.1L
      1975 MGB Roadster
      2003 GSX750F Katana

    15. #15
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      Quote Originally Posted by H2Ogbodies View Post
      I go with 6.2 Scat rods-JE makes pistons with raised ring lands for this type of setup. Since this scenario focuses on a fast rotating assembly, focus more on airflow velocity vs. sheer volume when it comes to your heads. Port design is critical. Reducing piston speed by going with a long rod is key to engine longevity.
      Aside from pretenting that rod/stroke ratio is important, don't you think you're overthinking a 6500rpm engine?

      OP,
      A 377 would be hand cuffed by the parameters you've layed out. 2000- 6500rpm at 10.5:1 is VERY tame and you would see none of the benefits of a shorter stroke (assuming you believe there are benefits). Take the extra cubes and enjoy them.
      1967 #s RS

    16. #16
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      Well, all I have to start with is a bare block, so I figured I would weigh my options.
      Also, as stated the 377 would actually be about $200 cheaper. My thought was the "faster reving motor" would be better paired with the 6 speed. But I do not know as I have never built such a combo.

      A little loss of torque would only help with traction issues on the street.

      Thanks
      1971 Camaro 427 in waiting
      1988 C1500 Daily Driver
      1955 Bel Air, blown BBC street car

    17. #17
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      At the performance level you're talking about, the engine isn't going to rev any faster do to the 1/4 reduction in stroke. In reality you're going to accelerate slower at all rpms from the loss of 30ci.
      1967 #s RS

    18. #18
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      Quote Originally Posted by wendell View Post
      A 377 would be hand cuffed by the parameters you've layed out. 2000- 6500rpm at 10.5:1 is VERY tame and you would see none of the benefits of a shorter stroke (assuming you believe there are benefits). Take the extra cubes and enjoy them.
      I think I agree. I thought the primary reason to go 377 is to build a high revver (7500+), which means high valvetrain $$ - no?
      Scott from NJ.

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    19. #19
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      The only real reason to build a 377 is if you're racing in a class that limits the CID. In that case, you'd build the largest engine you're allowed and building using the largest bore possible.
      1967 #s RS

    20. #20
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      do the 400 if you are stopping at 6500rpm, and consider a hyd roller. The solid roller does make more HP, but it's typically for higher rpm applications and higher pressure angles, I run one, and after losing a few lifters on a high lift 358 mech roller over the years, I almost wish I gave up some HP for the reliability and maint. free aspects of the hyd roller.
      1968 Camaro RS/SS, LS7 with Katech mods, T56 Magnum, C6Z06 Brakes
      1968 Camaro RS Convertible project LS3/480hp/4L70E
      1962 Corvette 327-340hp stock
      1972 Corvette LT1 Stock
      2006 Corvette Z06
      2011 Corvette GS convertible


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