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Technical Highest e85 static compression ratio?

Discussion in 'The Hokey Ass Message Board' started by Hoonigan, Feb 13, 2015.

  1. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    whats the highest static CR youve seen someone run on the corn juice? i'm aiming for something pretty high on NA big block.
     
  2. grego31
    Joined: Aug 28, 2006
    Posts: 451

    grego31
    Member
    from Sac, CA

    I have read you can go as high as 15 to 1 but it is also has a lot to do with the cam specs, overlap and duration. Plus depending on fuel delivery, injected or carbed and the type of spark delivery and power. I talked to Esslinger about a e85 4 cylinder build and we talked a crazy 17 to 1 but it had to run perfect or boom!
    Talk to some cam companies to get some ideas.
    Good luck

    Posted using the Full Custom H.A.M.B. App!
     
  3. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    I was thinking around 15-16:1 static CR. forged pistons obviously, MLS HG, and head studs. non-vacuum electronic distributor, and possibly thermal coated pistons/combustion chambers.

    also planning on running dual 650-900cfm 4150 double pumpers on a tunnel ram
     
    Last edited: Feb 14, 2015
  4. stimpy
    Joined: Apr 16, 2006
    Posts: 3,546

    stimpy

    check your e-85 supply first to make sure its e-85 , as around here out of the pump e-85 can go down in the winter months to help it evaporate when its cold out ( can go down to 70 legally per EPA ) , and it screws up the octane ratings , and also double check the octane ratings as some are only labeled RON not RON/MON which is about 96 octane . not the 106 some people are saying .
     
    tylercrawford likes this.
  5. indyjps
    Joined: Feb 21, 2007
    Posts: 5,377

    indyjps
    Member

    Agree, E85 is inconsistent, the mix can change by season and station.
     
  6. Dan Timberlake
    Joined: Apr 28, 2010
    Posts: 1,549

    Dan Timberlake
    Member

    consistent squish quench of 0.04" can be a significant detonation suppressant.
    If the Big Block is a Chevy under 454 isn't the dome to achieve high compression ratios kind of ugly? Creating lots of crevices and pockets in the nether regions?
    " thermal coated pistons/combustion chambers."
    I think thermal coatings keep the heat in the chamber, reducing the acceptable compression ratios.
     
  7. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,855

    Mike51Merc
    Member

    OK, so this is definitely an OT question, but since E85 is pretty well OT, here goes:
    How do the manufacturers design/set up dual fuel engines? Are there variable compression scenarios?
     
  8. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,565

    gimpyshotrods
    ALLIANCE MEMBER

    Gasoline compression. Fuel sensor, vairiable ignition and injector timing.

    Not the best of ANY world.
     
  9. stimpy
    Joined: Apr 16, 2006
    Posts: 3,546

    stimpy

    don't forget the O2 sensors too ,
     
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,565

    gimpyshotrods
    ALLIANCE MEMBER

    Well, all 17, or so, sensors. All of which are OT here.
     

  11. Lots of computer efi voodoo.
     
  12. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    true, but its an booze fuel more then a petro. So its latent heat of evaporation creates a higher working octane rating then just a ron/mon motor test, especially when you really open up the taps. you can run alot richer mixture then even normal calcs for e85 gains say is optimum because it evaporates so readily and doesnt kill power right away with an overly rich condition.

    I also plan on running a near/around 300/300 adv. duration cam, making the dynamic compression less then the static compression.
     
  13. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    true, but if im really worried i can buy it from vp for about $10/gal
     
  14. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    its a big block blue oval 385 family

    the dome is a 14cc, im not exactly sure how intrusive that is going to be with how the combustion chamber in the head is, but it will have plenty of qench area at about .030" or less depending on what piston/head clearance i can get away with.

    the thing with thermal coatings is that it keeps the parts from over heating and turning into essentially glow plugs. the pistons i think would probably be more beneficial to coat then the combustion chambers because of the sharp edges around the cuts for the valve reliefs in the dome of the piston.
     
    Last edited: Feb 14, 2015
  15. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    these engines are not optimized for e85, they just can run on it by increasing duty cycle (like instantly changing jet sizes) and advancing ignition timing via a flex fuel sensor. also their fuel pumps/injectors/rails/soft lines are usually made of a different material from the standard fan-fair
     
  16. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    usually on the high end about 4, and they are only there usually to measure cat efficiency, they usually have nothing to do with the tuning of the engine at anything other the cruise (and cant operate in the range of e85 anyway).

    some cars will have wideband o2 or a lambda sensor, these can be used for feedback tuning but are seldom seen on normal passenger cars (usually high perf versions, hellcat, gt500, zl1 camo, etc...)
     
  17. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    its very simple really. im just going carb on this because its going to be a gasser style car with dual quads on a tunnel ram.
     
  18. tylercrawford
    Joined: Jan 30, 2011
    Posts: 726

    tylercrawford
    Member
    from Buford, GA
    1. S.F.C.C.

    OT all over the place . . . :D

    I know of one guy pushing the limits of a "street car" n/a wise. 408" LSX engine in a fox, is running right at 13.5:1 with a healthy solid roller on e85. Makes over 500rwhp with a t56.

    Not sure if that helps or not.
     
  19. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    seems a bit low for a lsx NA on e85, the reverse cooling system and alloy heads along with modern combustion chamber design should have alot higher safe limit. Hell car craft was at 12.5:1 on their stock iron headed 454 they built lol.

    this car is going to be pretty far from a "street car" but i'll still drive it down the road to fill it up at the station
     
  20. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,565

    gimpyshotrods
    ALLIANCE MEMBER

    Crankshaft position sensor, camshaft position sensor, coolant temperature sensor, manifold temperature sensor, Oxygen sensor, throttle position sensor (or drive-by-wire pedal), manifold absolute position sensor, fuel sensor, fuel pressure sensor, mass airflow sensor, knock sensor, transmission input speed sensor, shifter position sender, vehicle speed sensor.

    That's more than 4. And they are all off-topic.

    To answer your first question, 15.5:1.
     
  21. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    4 o2 sensors as referring to the initially statement. most vehicles dont run all of those sensors listed. for example usually do not run an map sensor and maf sensor together or a intake air temp sensor and maf sensor (as most mafs have internal temp sensors, and thats how they work anyway by calculating volume by temp change over a wire filament) not every car runs knock sensor(s) (very few do really), not all run cam and crank sensors together, almost no cars use fuel pressure sensors, and whats is a "fuel" sensor?

    15.5:1 with what cam? more overlap will decrease the working/dynamic compression and with the overlap of a 300/300adv cam it should be a bit lower.
     
  22. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    and speaking of e85, does anyone know how to modify 4160 style carbs for it? quickfuel provides kits for billet metering blocks and gasket/rebuild kits to convert a 4150, but no one sells a 4160 kit reasonably.
     
  23. tylercrawford
    Joined: Jan 30, 2011
    Posts: 726

    tylercrawford
    Member
    from Buford, GA
    1. S.F.C.C.

    This was back in either 2009 or 2010 . . . he was the first person I knew with an lsx block.

    I messaged him on FB and he said the shop that built the shortblock kept it at 13.5:1 because of the e85 in our area being all over the place and PTV clearance was minimal, normally they would have been another point or two higher at for a max effort N/A ls engine on e85.

    He didn't have the dyno graph on his computer but it made right at 590rwhp and 550rwtq. So "over 500rwhp" was close . . . :D
     
  24. stimpy
    Joined: Apr 16, 2006
    Posts: 3,546

    stimpy

    at $10 a gallon your better off using the VP race fuels as you will burn less and can control the mixture better unless your using the "voodoo" of a computer to control it . the only thing good about alky is its slow burn torque and not as touchy as gas in fueling because of the rich mixture .
     
  25. stimpy
    Joined: Apr 16, 2006
    Posts: 3,546

    stimpy

    the
    [/QUOTE]

    the BAnk 1 o2 sensor is still used for tuning and running just on a different MAP during closed loop other than cruise , it will still read the O2 output just its adjusted for the ethanol portion of the mix because of the lower readings .
     
  26. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    booze fuel runs the engine much cooler than recycled dinosaurs. every 8-9*f drop in intake temp is worth about 1 usable octane point
     
    Ned Ludd likes this.
  27. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    the engine will only run in closed loop with o2 feed back at cruise because narrow band sensors read only 14-15:1 afr. used for cruising steady states only. as soon as you dip in the throttle it disregards them and calculates fuel via manifold pressure and temp (speed density) or incoming air mass (mass air flow in lb/min or gram/sec)
     
  28. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    PTV clearance is the one thing im worried about with this engine, but the heads have the valves tucked way up in the combustion chamber. cutting the head down and ~.600-.650" of lift is going to make it a little close regardless me thinks haha.

    any idea what the displacement was of the LS machine? i'll be at 473ci after the engine is built which im sure is bigger then the ls engine and i'll be running around 325-350cfm on the intake holes.
     
  29. I'd build it at 17-1, blow the heads right off the son-of-a-bitch, then add a couple extra head gaskets the next time I built it.
     
  30. Hoonigan
    Joined: Feb 10, 2015
    Posts: 35

    Hoonigan

    well I was going to go with the thinnest HG Cometic offers to start with (.027) and back it off to larger ones if i have problems or decide to juice it later in its life. I honestly dont think it will be a HG eater with head studs, proper RA finishes on the head and block, and very thin MLS HGs
     

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