300 hp @ 4000 rpm...can it be done?

Discussion in 'Chevy' started by TXFlyGuy, Aug 21, 2012.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Aug 21, 2012 #1

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,493
    Likes Received:
    436
    Location:
    Republic of Texas
    Here is a question for you "Hot Rodders"...can a 4.3 V6 be built to put out close to 300 hp at 4000 rpm? With the 1.71 PSRU I can't go over this limit with the 88" prop.
     
  2. Aug 21, 2012 #2

    TFF

    TFF

    TFF

    Well-Known Member

    Joined:
    Apr 28, 2010
    Messages:
    11,639
    Likes Received:
    3,269
    Location:
    Memphis, TN
    Probably not without turbo or supercharger. I would guess 200hp at that rpm.
     
  3. Aug 21, 2012 #3

    Toobuilder

    Toobuilder

    Toobuilder

    Well-Known Member

    Joined:
    Jan 20, 2010
    Messages:
    4,447
    Likes Received:
    3,246
    Location:
    Mojave, Ca
    I'm guessing you are looking to retain a "scale" prop?

    We've discussed it before, but a big inch LS series V8 should pull 300 HP at 3000 RPM direct drive. You certainly are not going to swing an 88 inch prop at that speed, but the 184 PSI BMEP required of a 430 inch LS is in the realm of possibility. Should end up comparable in weight to the V-6/PSRU combo as well.
     
  4. Aug 21, 2012 #4

    Detego

    Detego

    Detego

    Well-Known Member

    Joined:
    May 29, 2012
    Messages:
    470
    Likes Received:
    105
    Location:
    North America

    John Steere’s Supercharged Thunderbird

    "The engine is a 90-degree, 3.8-liter V-6 from a 1990 Thunderbird Super Coupe.
    It is supercharged by an Eaton blower and inter-cooled.
    The compression ratio is 8.2: 1 and the fuel is supplied by six fuel injectors.
    The engine is rated at 210 hp at 4000 rpm and delivers 315 lb-ft of torque at just 2600 rpm.

    Among other essentials such as a Northwest Aero Products 1.7:1 ratio cog belted propeller speed reduction unit (PSRU), this automobile engine conversion includes the standard automotive sensors, multi-port fuel injection system, and computer ignition systems, less the standard emissions junk. An emissions air pump (not standard in the car) was added to serve as a vacuum source for the flight instruments."


    [​IMG]

    08/08 - Hangar Talk - John Steere’s Supercharged Thunderbird Powered BD-4
     

    Attached Files:

  5. Aug 21, 2012 #5

    Lemans

    Lemans

    Lemans

    Well-Known Member

    Joined:
    Mar 23, 2008
    Messages:
    586
    Likes Received:
    99
    Location:
    Riemst Belgium
    You may expect 240hp@4000rpm for a normal aspirated 4-stroke 4.3 V6 if you if take your engine to an experienced engine engineer.
    This spreadsheet comes in handy...
    Up until now the spreadsheet has shown 'real world' figures.
     

    Attached Files:

  6. Aug 21, 2012 #6

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,493
    Likes Received:
    436
    Location:
    Republic of Texas
    Thank you! I cannot open this file...can you send it in a PDF?
     
  7. Aug 21, 2012 #7

    Detego

    Detego

    Detego

    Well-Known Member

    Joined:
    May 29, 2012
    Messages:
    470
    Likes Received:
    105
    Location:
    North America
  8. Aug 21, 2012 #8

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,493
    Likes Received:
    436
    Location:
    Republic of Texas
    Thanks! I ran numbers from 298 hp @ 4000 rpm to 258 hp @ 4000 rpm. We may bore & stroke this engine to 287 ci. This would be 3/4's of Chevy's famous 383 engine. The 4.3 V6 is a SBC minus two cylinders.
     
  9. Aug 27, 2012 #9
    I know people get an idea and want to stick with it, but look at it this way. An LS?
    V8 Chevy will weigh about the same as a cast iron 4.3 (262 cu in) V6.

    You will have to stress the V6 with higher rpms while a 415 cu in LS3 would basically
    loaf along and easily produce 300 hp way below 4000 rpms.

    You can purchase aluminum heads for the LS dirt cheap while aluminum heads for the 4.3 will cost you more than the basic engine. Personally I plan to use some LS1
    heads which should keep the air flow plenty fast (2700 rpms in my case). You can purchase 2 used LS1 heads for $100-$150 on ebay easily. This will also allow the use of the cheap and easy to find LS1 intake manifold if you inject it. I don't recommend the LS1 block because of thin cyl walls that don't allow much reboring.


    You might even be able to produce the 300hp at a lower engine rpm and slow prop speed even further.
    There is a shop on Ebay selling 415 stroker 8.5 to 1 compression ratio forged crank and pistons professionally machined and assembled short blocks for about $4200.
    Bolt the LS1 heads on with a factory GM parts intake and carburetor. Ignition system may take a little work......crank trigger maybe.

    The point is that you have a far more efficient engine design that is all aluminum and very strong, and it doesn't have to work hard to get the power. If you read anything about these engines you will see that power is rediculously easy to extract from them with just a few mods. Price for building and stroking an alum head V6 will be comparable and you will have a lot more harmonics to consider with the V6.

    Also, GM changed the firing order from the old 18436572 of the small block Chevy so that the engine produces less harmonics from the firing order.
     
  10. Aug 27, 2012 #10

    Toobuilder

    Toobuilder

    Toobuilder

    Well-Known Member

    Joined:
    Jan 20, 2010
    Messages:
    4,447
    Likes Received:
    3,246
    Location:
    Mojave, Ca
  11. Aug 30, 2012 #11

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,493
    Likes Received:
    436
    Location:
    Republic of Texas
    Yes, you are correct. But the problem is weight & overall dimensions. Our V6 is all aluminum, so it is lightweight. Plus we have a very well engineered and tested PSRU drive system that is lightweight as well. This V6 with the stroker kit will easily put out 300 hp @ 4,500 rpm. And it will loaf along at 2400 rpm cruise which is where the torque numbers are real good.

    As much as I would like to drop in a GM crate 350, it just will not work without major engineering issues being solved.
     
  12. Sep 6, 2012 #12
    xxxxxx
     
    Last edited by a moderator: Sep 7, 2012
  13. Sep 23, 2016 #13

    Armilite

    Armilite

    Armilite

    Well-Known Member

    Joined:
    Sep 6, 2011
    Messages:
    3,022
    Likes Received:
    244
    Location:
    AMES, IA USA
    While 4000rpms is not really working any of these Small Block Engines very Hard, there is No Substitute for Cubic Inches!

    262ci = 4293cc(4.3) at 4000rpms at Stock 90% = 182hp, at 95% = 192hp, at 100% = 202hp

    262ci = 4293cc(4.3) at 4000rpms at Turbo 4lbs of Boost = 257hp. At 75% Rpms = 3000rpms = 193hp

    262ci = 4293cc(4.3) at 4000rpms at Turbo 5lbs of Boost = 271hp. At 75% Rpms = 3000rpms = 203hp

    262ci = 4293cc(4.3) at 4000rpms at Turbo 6lbs of Boost = 285hp. At 75% Rpms = 3000rpms = 214hp

    262ci = 4293cc(4.3) at 4000rpms at Turbo 7lbs of Boost = 298hp. At 75% Rpms = 3000rpms = 224hp

    262ci = 4293cc(4.3) at 4000rpms at Turbo 8lbs of Boost = 312hp. At 75% Rpms = 3000rpms = 234hp

    =======================================================

    415ci(LS3) = 6801cc at 4000rpms at Stock 90% = 288hp, 95% = 304hp, 100% = 320hp (Without a Turbo).

    415ci(LS3) = 6801cc at 4000rpms at Turbo 2lbs of Boost = 364hp. At 75% Rpms = 3000rpms = 273hp

    415ci(LS3) = 6801cc at 4000rpms at Turbo 3lbs of Boost = 386hp. At 75% Rpms = 3000rpms = 289hp

    415ci(LS3) = 6801cc at 4000rpms at Turbo 4lbs of Boost = 407hp. At 75% Rpms = 3000rpms = 306hp

    415ci(LS3) = 6801cc at 4000rpms at Turbo 5lbs of Boost = 429hp. At 75% Rpms = 3000rpms = 322hp

    415ci(LS3) = 6801cc at 4000rpms at Turbo 6lbs of Boost = 451hp. At 75% Rpms = 3000rpms = 338hp

    415ci(LS3) = 6801cc at 4000rpms at Turbo 7lbs of Boost = 473hp. At 75% Rpms = 3000rpms = 355hp

    ========================================================

    427ci = 6997cc at 4000rpms at Stock 90% = 297hp, 95% = 313hp, 100% = 329hp (Without a Turbo).

    427ci = 6997cc at 4000rpms at Turbo 2lbs of Boost = 374hp. At 75% Rpms = 3000rpms = 281hp

    427ci = 6997cc at 4000rpms at Turbo 3lbs of Boost = 397hp. At 75% Rpms = 3000rpms = 298hp

    427ci = 6997cc at 4000rpms at Turbo 4lbs of Boost = 419hp. At 75% Rpms = 3000rpms = 314hp

    427ci = 6997cc at 4000rpms at Turbo 5lbs of Boost = 442hp. At 75% Rpms = 3000rpms = 331hp
     
  14. Sep 23, 2016 #14

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,493
    Likes Received:
    436
    Location:
    Republic of Texas
    As the engine of choice for the T-51D Mustang is now the LS3 6.2 V8, it will easily make 300hp at 4,000 rpm. And normally aspirated. Note that it makes 400 lbs of torque at the setting also.

    Of course, this is a sea level number.
     
  15. Sep 24, 2016 #15

    Winginit

    Winginit

    Winginit

    Well-Known Member

    Joined:
    Jun 13, 2016
    Messages:
    811
    Likes Received:
    242
    Location:
    x
    . Shush! Torq is a four letter word around here.:gig:
     
  16. Sep 24, 2016 #16

    blane.c

    blane.c

    blane.c

    Well-Known Member HBA Supporter

    Joined:
    Jun 27, 2015
    Messages:
    3,264
    Likes Received:
    559
    Location:
    capital district NY
    CUBIC INCHES
     
  17. Sep 24, 2016 #17

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,493
    Likes Received:
    436
    Location:
    Republic of Texas
    The LS3 6.2 is 376 cubes.
     
  18. Oct 16, 2016 #18

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,493
    Likes Received:
    436
    Location:
    Republic of Texas
    For those who have followed the thread on the Hot Cam, 300hp can be made at 3500rpm, with the LS3 V8.
     
  19. Oct 17, 2016 #19

    WonderousMountain

    WonderousMountain

    WonderousMountain

    Well-Known Member

    Joined:
    Apr 10, 2010
    Messages:
    1,853
    Likes Received:
    193
    Location:
    Clatsop, Or
    Okay, so uh,

    You're gonna need boost. Either more revs needed (a lot) or more cubes. You can turbo though, there's no law against it.
     
    Last edited: Oct 17, 2016
  20. Oct 18, 2016 #20

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,493
    Likes Received:
    436
    Location:
    Republic of Texas
    Please read post #18.
     

Share This Page

arrow_white