Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 37

Thread: F-head high altitude head?

  1. #21
    Senior Member
    Join Date
    Jan 2015
    Location
    E OK
    Posts
    484
    How the octane rating is determined has changed over the years as well.
    Jeff
    '51 CJ3A
    '47 CJ2A

  2. #22
    Super Moderator gmwillys's Avatar
    Join Date
    Aug 2017
    Location
    Alabama
    Posts
    3,734
    That is a very interesting chart Bmorgil.

  3. #23
    Super Moderator bmorgil's Avatar
    Join Date
    Dec 2018
    Location
    Northwestern Ohio
    Posts
    3,761
    It really does show the evolution of combustion technology. A GM "Gen V" L83 Engine has 11 to 1 compression and runs on 87 octane fuel with 32 degrees of ignition timing. That is just Wow!

  4. #24
    Senior Member
    Join Date
    Jan 2015
    Location
    E OK
    Posts
    484
    I think the computer controlled electronic fuel injection systems have more to do with the ability to run low octane fuel in high compression engines. “By guess and by golly” was all it took in the past to get an old carbureted engine to run good. Now it’s all very precise.
    Jeff
    '51 CJ3A
    '47 CJ2A

  5. #25
    Super Moderator bmorgil's Avatar
    Join Date
    Dec 2018
    Location
    Northwestern Ohio
    Posts
    3,761
    Yes the precision of the fuel delivery is important but, you still see the best "all out" horsepower from a carburetor. As old as that design is, on the dyno a well tuned carb has been proven over and over to make the maximum power. We have now seen the latest design heads make awesome power, with a carburetor and 11 to 1 compression on 87 octane. The emulsification of the fuel and air mixed well and far ahead of time is the key. The other tell tale of the efficiency in the combustion chamber design is the total timing required. As the combustion chamber efficiency increases the amount of total timing required for complete combustion decreases. This is also a huge help in preventing detonation. A Gen 1 GM small block would usually make the best power approaching and sometimes exceeding 40 degrees of total timing. A modern GM LS doesn't need any more than 30 with racing engines running around 34 on race gas. The newest design combustion chambers combined with the precise timing and fuel control of injected computer controlled engines, provide the unbelievable "best of both worlds" we now see from autos. Great power, smooth drive-ability in all conditions, fuel economy and low pollution. Now keep in mind, if it does start to detonate on a computer controlled engine, it will adapt. Power will be reduced. On a non computer controlled engine, you may want to back that 11 to 1 down a bit just in case!
    Attached Images Attached Images
    Last edited by bmorgil; 04-17-2024 at 06:11 PM.

  6. #26
    Senior Member
    Join Date
    Jan 2015
    Location
    E OK
    Posts
    484
    Thanks for the extra info. I remember when we started switching to electronic ignition and EFI. I didn’t want any part of it but 235,000 miles on my current truck, my EFI boat motor and even my last motorcycle has made me a believer in the newer tech. I turn the key and it starts ready to drive. It’s bad when it screws up because no one knows how to troubleshoot what the computer doesn’t tell them in plain english. Fortunately, the issues show up a lot less often while needing a lot less maintenance to get there. Who would have thought 100,000 miles would be the normal spark plug change interval 40 years ago? I still get to do old school maintenance on flat fenders, lawnmowers, old 2-stroke boat motors, airplanes and the like.
    Jeff
    '51 CJ3A
    '47 CJ2A

  7. #27
    Senior Member 56willys's Avatar
    Join Date
    Jan 2023
    Location
    Northwestern PA.
    Posts
    311

    Insane Hurricane head!!

    This could solve all the problems with the 134! https://www.facebook.com/marketplace...lace_pdp_share Definetely looks tempting, maybe its a good thing i dont have 2 grand to spend right now. One could do some really neat stuff with this head though. It would be a fun thing to play with, and could have some crazy results.

    I dont know, i think Ham's 48 needs an aluminum head!!
    Last edited by 56willys; 05-24-2024 at 09:51 PM.

  8. #28
    Super Moderator gmwillys's Avatar
    Join Date
    Aug 2017
    Location
    Alabama
    Posts
    3,734
    7,500 rpm on the bottom end would definitely make for an oil pan failure. '56, your welds look a lot better than the ones on that intake.

  9. #29
    Senior Member 56willys's Avatar
    Join Date
    Jan 2023
    Location
    Northwestern PA.
    Posts
    311
    Quote Originally Posted by gmwillys View Post
    7,500 rpm on the bottom end would definitely make for an oil pan failure. '56, your welds look a lot better than the ones on that intake.
    It is sketchy that's for sure. I can just smell the rods twisting already. But hey, it was a cool experiment. And I appreciate you complement on my welds!

  10. #30
    Super Moderator bmorgil's Avatar
    Join Date
    Dec 2018
    Location
    Northwestern Ohio
    Posts
    3,761
    I have to agree gm, at nowhere near 7,500 rpm we can expect to see many holes in the oil pan! Very clear what to do with that cylinder head. Leave it on Facebook. Note its " Never been run, Outlaw status". I think someone is trying to recoup some costs on a bad mistake. Lets think about 7,500 rpm on a motor that only has one cam bearing...
    Last edited by bmorgil; 05-25-2024 at 06:19 AM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •