Bbc509+twin gt45

Discussion in 'Superchargers, Turbos, Nitrous' started by stepside, Apr 27, 2016.

  1. stepside

    stepside Well-Known Member

    Hi gearheads
    I started collecting parts for turbo project
    I have two china gt45 turbos which I am going to use

    Turbo wheel diameters are 70mm compressor and 77/88 turbine
    what do you think how high i can rev 509 motor with these turbos and 10psi boost
    My combo
    509 bbc afr 305 heads 10,4 compression
    Dart tunnelram megasquirt2 efi
    2" headers 3,5" exhaust
    Air to water cooler
    I use e85 so compression is not a broblem
    I have custom hr cam that i try cam specs are 241/244 111lsa 650 lift
    I'll take pictures when i star the project
     
  2. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    Id suggest limiting the engine RPM to about 6400 rpm , max, due to very likely valve train control issues with a hydraulic roller cam, if you push much higher,E85 has about 30% less energy per gallon than petroleum race fuel, but you need to run about 35%-40% more fuel, so theres potentially a significant LOSS in mileage but a GAIN (if properly tuned) in over all power of near 5%-7% with E85 (obviously the turbo has the potential to boost power much higher than the fuel change alone)
    keep in mind the turbos will provide a good deal more mid and upper rpm potential torque due to the greater cylinder pressure the , E85 fuel could produce.
    you won,t need to spin a 509 BBC very high in the rpm band to get the power youll want.
    keep in mind ethanol is HYGROSCOPIC
    adjective

    1.
    absorbing or attracting moisture from the air.


    and as such it tends to both cause and aggravate corrosion issues, so youll generally have to add a corrosion inhibitor too the fuel or have a small secondary fuel tank you use to run the engine on pure race gas until it heats up and one you switch too 2-3 minutes before the engines turned off so the fuel lines and pump, filters etc, and generally youll want to add an upper cylinder lube additive to e85 plus change your oil more frequently if the engines nor driven almost daily , so parts washed with e85 don,t degrade over time as the E85 tends to accumulate moisture rapidly in storage

    http://garage.grumpysperformance.co...ne-running-a-turbo-s-on-e85.10990/#post-48881
     
    stepside likes this.
  3. stepside

    stepside Well-Known Member

    I m not concerned about the valvetrain
    I'm more concerned backpressure and that na cam
    I think peak power is 6200-6400 with that cam and 10psi boost
    I wrote an email to mike jones , and he suggested that the cam would work ok
    what you think of the size of the turbine wheel
    I have used e85 ten years and i have not nouticed any corrosion
     
  4. 87vette81big

    87vette81big Guest

    Turbo Boost & Supercharger Boost places greater loads on Valvetrain parts.
    Its not an Achilles Heal on Big Block Chevies because of the Very Large Intake Valve Face Diameter typical used.
    The Larger the Intake valve with Boost psi the Greater the loads on entire Valvetrain.
    Pie X Radius Squared.
    At least 20-30 pounds more seat pressures required than N/A.
     
    stepside likes this.
  5. stepside

    stepside Well-Known Member

    My seat pressures are 200lbs , i think that holds 10psi 6500rpm
    Na engine revs 7800 without valve float
     
  6. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    KEEP IN MIND THAT A TURBO ON BOOST IS SUPPLYING pressure behind the valve that offsets some spring seat pressure that the N/A engine does not have to deal with, lowering its effective seat pressure , a 2.30" intake valve has about 3.7 sq inches of area that intake runner boost works against to prevent or slow the valve seating so if theres 200 lbs of seat pressure, under boost youve effectively reduced that to about 165 lbs, while that might seem an insignificant loss in seat pressure its about a 18% loss and remember at 6400 rpm, the valves open and shut about 53 times a second, the 18% reduction in seat pressure will lower the engine rpm level where valve control loss starts to occur.
    keep in mind valve springs tend to loose tension, over time and its not rare for springs that were installed with 200 lb-250 lb seat pressure to measure significantly lower after a few months use!
    http://garage.grumpysperformance.com/index.php?threads/valve-springs.9613/#post-50534

    that bit of experience gained info might not seem critical but it could easily explain why the engine did not experience valve float issues when first tested but it does several months later!
    Id also point out that a 509 with its 4" stroke reaches 4500 fpm in piston speed at 6750 rpm, and 4500 fpm is considered by most engine builders as pushing the durability limits on a big block engine if long term durability is a concern.
    Id also point out that valve springs tend to loose tension and load rate as they age and stress on valve train parts is cumulative , as is wear on the bearings, and stress on rods and pistons, etc.,so the rpm range you could safely maintain when the engine was new will be reduced as the engine ages.
    your twin turbo big block has a great deal of power potential and will rather easily exceed 2 hp per cubic inch if correctly tuned but be aware that there are potential stress limitations
    [​IMG]

    [​IMG]
    http://garage.grumpysperformance.com/index.php?threads/redline.343/#post-1170

    this thread , and its sub-links may help your determine if the turbos you have match the application
    http://garage.grumpysperformance.com/index.php?threads/turbo-maps-and-related-turbo-info.1215/

    having a turbo map chart, for those turbos would help
    [​IMG]
     
    Last edited: May 20, 2017
  7. 87vette81big

    87vette81big Guest

    I am with Grumpy you have to watch Piston Speeds.
    But there are times you must push the Limits. Only scenerio present is Street Racing Hellcats.
    Pontiac 455 RA4 Power.
    Other than that no reason to push it real hard.
     
  8. stepside

    stepside Well-Known Member

    I tried , but I could not find compressor map
    I modified My intake
    image.jpg
    image.jpg
    image.jpg
    image.jpg Now transition to plenium is long and smooth
    I think i limit rpms to 6000
     
  9. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    CONGRATS on the custom work,
    ITs always nice to see guys do custom modifications to improve performance or over come the lack ,
    of over the counter parts matching their particular application!
    and I can,t begin to tell you how many times,
    Ive pointed out that having a welder and a drill press or milling machine.
    frees you up to do a whole lot more in the way of custom work,
    or allowing you to not be limited by what you see available in catalogs

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  10. stepside

    stepside Well-Known Member

    Hi
    I've been driving a few hundred miles nowThe car works well except it gets valve float first and second gear over 6500 rpm
    I have to put stiffer valve springs
    Current combo is
    509 bbc
    10.4 comp
    241\244 111lsa hr cam
    305 afr heads
    Dart tunnelram
    1 7\8 stainless headers
    Two gt 45 turbos
    Two inter coolers
    4l80e transmission 11" converter
    3.5"stainless exhaust
    3.42\1 gears
    View attachment 8452 FB_IMG_1494181614911.jpg FB_IMG_1494181622813.jpg FB_IMG_1494181630073.jpg FB_IMG_1494181640767.jpg FB_IMG_1494181663085.jpg FB_IMG_1494181698877.jpg FB_IMG_1494181708756.jpg
    20170507_193820.jpg
    20170507_193913.jpg
    20170507_193938.jpg
     
    Last edited: May 7, 2017
    Strictly Attitude likes this.
  11. stepside

    stepside Well-Known Member

  12. Loves302Chevy

    Loves302Chevy "One test is worth a thousand expert opinions."

    This guy can fabricate!!! Nice to see something other than store bought bolt-ons.
     
    stepside likes this.
  13. stepside

    stepside Well-Known Member

    I did calculations if i use 10 psi boost i have to raise the spring pressures 20-30 lbs, i think the morel lifters will take it
    Spring pressures are now 200 lbs
     
  14. stepside

    stepside Well-Known Member

    I measured the spring pressures, they were 40 lbs down, grumpy was right.
    I need 220 lbs of springs but it's pretty much pressure for hydraulic roller
    Especially since the car is my daily drive now
     
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  15. stepside

    stepside Well-Known Member

    Hi gearheads
    Cutlass was my daily driver last summer it worked great ,few pases in local 1/8 mile street race, no traction but only one drag race supra was 0.01 sec faster
    Then cutlass couth on fire when my girl frend was in grosery store
    I didint do anything for the car whole winter ,now i got the inspiration and started to wor the car
    New hood, engine bay wiring ,hoses radiator,and intercooler
    Car is now ready for paintjob
    I post more pictures when i start painting received_1078374288928876.jpeg IMG_20180710_101217.jpg IMG_20180829_120724.jpg
     
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  16. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    Poor Drivers fender got Hot.
     
  17. Indycars

    Indycars Administrator Staff Member

    Nice to see it restored instead of sending it to the junk yard!

    BTW, do they have junk yards where you live?
     
  18. stepside

    stepside Well-Known Member

    I sand plasted that fender ,heat didint bend the fender
    Yes we have big junk yard here ,
    I go once a week at the junk yard,some times good finds, tools ,old machine parts
    ,cars in the yard are usualy newer but if i need oil cooler ,radiator fan or that kind of parts i go there
    Some times farmers bring old stuf in the yard i found 39 ford front axle and brakes
     
  19. Strictly Attitude

    Strictly Attitude solid fixture here in the forum

    Sweet look forward to seeing it back in shape team A-body
     
    Maniacmechanic1 likes this.
  20. stepside

    stepside Well-Known Member

    Primer IMG_20180830_160230.jpg IMG_20180830_190455.jpg IMG_20180830_190509.jpg
    [​IMG]
    [​IMG]
     
    Last edited by a moderator: Aug 30, 2018
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