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Thread: Unknown Internals 477 RWHP SBC Advice?

  1. #1

    Default Unknown Internals 477 RWHP SBC Advice?

    Long story short, I'm installing an XFlow on a 1969 Camaro built for high speed open road racing (Silver State Classic), with a goal of getting the car more streetable and better fuel economy for HPDEs. Here's a build thread of the wide-body conversion: https://lateral-g.net/forums/showthread.php4?t=45491

    I don't have a lot of information about the motor, but here is what I do know:
    • Build is from ~2004, and there are ~70 hours on the motor
    • 406" Dart Iron Block
    • Motor dynoed 477 hp and 451 ft lbs at the rear wheels through a T56 and 12-bolt with 4.30 gears with a Demon carb
    • Unknown compression (but it's high)
    • Unknown cam specs
    • Edelbrock Victor Junior Aluminum Heads
    • Edelbrock Air Gap Intake


    I'll be running as follows:
    • XFlow
    • HyperSpark
    • MSD 6AL
    • MSD Blaster Coil
    • Aeromotive Stealth 340 in a surge tank in an ATL fuel cell
    • Holley FPR/filter to a returnless AN-8 to the XFlow (59.5PSI)


    A few questions as I'm new to SBCs (coming from LS engines, Viper V10, and Ariel Atom K24s):
    1. Should I use 100oct or 91oct + Amsoil octane booster for learning? I run 91+booster on the street but 100oct for HPDEs.
    2. What should I do to the motor to prep for first start? I've pulled the plugs, sprayed fogging oil in the cylinders, and will spin the oil pump with my drill before firing.
    3. Any advice on where to set initial timing when I don't know the cam specs or compression?
    4. Right now, my tach is driven by the 6AL. Do I need to change that over to the XFlow tach out?

    Thanks! Jason

  2. #2

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    Good luck on getting answers to those questions if you don't know the cam specs or the compression ratio. Guess you'll just have to try something and see if it works. If the engine is on an engine stand, you can figure out the compression ratio pretty easily, but if it's in the car then you'll just have to guess. Cranking compression will give you a rough idea of where you're at. I'd leave the tach hooked up to the 6AL if that's working okay.

  3. #3

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    Thanks for the advice! I'll start with the tach off the 6AL and switch over to the Sniper if there's any problems or lag. I'm hoping that I can get the Sniper to self-tune well enough for idle and part throttle, then have a local tuner work on WOT fuel & timing on his dyno. Given how well you said your XFlow worked on your big engine, I hope to have similar results!

  4. #4

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    Pull the engine and actually degree the cam to find out the specs, and CC the heads to figure out compression ratio.

  5. #5
    Join Date
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    Default

    Quote Originally Posted by Widebody 69 View Post
    A few questions as I'm new to SBCs (coming from LS engines, Viper V10, and Ariel Atom K24s):
    1. Should I use 100oct or 91oct + Amsoil octane booster for learning? I run 91+booster on the street but 100oct for HPDEs.
    2. What should I do to the motor to prep for first start? I've pulled the plugs, sprayed fogging oil in the cylinders, and will spin the oil pump with my drill before firing.
    3. Any advice on where to set initial timing when I don't know the cam specs or compression?
    4. Right now, my tach is driven by the 6AL. Do I need to change that over to the XFlow tach out?

    Thanks! Jason
    1) You don't need race gas for this. I don't even know why compression ratio matters so much to anyone anyways. Put the race tune in the ECU if you wish and run the car. I'd use the 91 octane with Amsoil octane booster if you're worried. I'm a Amsoil dealer if you need some. The engine has 477 horsepower out of a 406 Dart Iron Block. It's not like it has 1000 horsepower naturally aspirated out of a 400 cubic inch engine. How high can the compression ratio be anyways.
    2) Check for oil and oil pressure.
    3) Set the initial timing for 20°.
    4) Since your doing the full HyperSpark setup, why not install it per the instructions and be done with it.

    Quote Originally Posted by JF74CHEVELLE View Post
    Pull the engine and actually degree the cam to find out the specs, and CC the heads to figure out compression ratio.
    This is hilarious.

  6. #6

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    Why is it hilarious? If I were him I’d want to know what I have. I must be Eddie Murphy!

  7. #7

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    Quote Originally Posted by JF74CHEVELLE View Post
    Why is it hilarious? If I were him I’d want to know what I have. I must be Eddie Murphy!
    I'd want to know too. Especially for extended WOT like the Silver State Classic. Compression, Cam Timing and fuel octane are most important. And besides, it not like it's hard to pull a engine on a '69 Camaro. I can pull the engine on my '69 Chevelle in less than a hour. Maybe a little longer now with all the extra wiring for the 1250 Super Sniper and all the extra sensors and wiring I added.

  8. #8

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    Quote Originally Posted by RPnova View Post
    1) You don't need race gas for this. I don't even know why compression ratio matters so much to anyone anyways. Put the race tune in the ECU if you wish and run the car. I'd use the 91 octane with Amsoil octane booster if you're worried. I'm a Amsoil dealer if you need some. The engine has 477 horsepower out of a 406 Dart Iron Block. It's not like it has 1000 horsepower naturally aspirated out of a 400 cubic inch engine. How high can the compression ratio be anyways.
    2) Check for oil and oil pressure.
    3) Set the initial timing for 20°.
    4) Since your doing the full HyperSpark setup, why not install it per the instructions and be done with it.
    What if it's 13.5:1 and setup for C16. How long do you think it would last on 91 octane and a Bottle of Octane Booster running mile after mile wide open?

  9. #9
    Join Date
    Apr 2019
    Location
    Florida
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    Quote Originally Posted by RPnova View Post
    1) You don't need race gas for this. I don't even know why compression ratio matters so much to anyone anyways. Put the race tune in the ECU if you wish and run the car. I'd use the 91 octane with Amsoil octane booster if you're worried. I'm a Amsoil dealer if you need some. The engine has 477 horsepower out of a 406 Dart Iron Block. It's not like it has 1000 horsepower naturally aspirated out of a 400 cubic inch engine. How high can the compression ratio be anyways.
    2) Check for oil and oil pressure.
    3) Set the initial timing for 20°.
    4) Since your doing the full HyperSpark setup, why not install it per the instructions and be done with it.
    Meh. Who cares about compression? Surprised you didn't tell him to run 87 and double up on the Amsoil since you're a dealer, LMAO. He needs to know his compression so he can optimize power through timing and fuel.
    Last edited by 1slow62; 09-17-2019 at 05:17 AM.
    Current Projects:
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    89 LX mustang

  10. #10
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    Oct 2017
    Location
    Los Angeles
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    Quote Originally Posted by djh61187 View Post
    What if it's 13.5:1 and setup for C16. How long do you think it would last on 91 octane and a Bottle of Octane Booster running mile after mile wide open?
    He said he runs 91 on the street plus octane booster and 100 octane for his races. Based on what he said, his engine will not blow up with 91, plus booster is safe for the street, and initial Learning.

    Quote Originally Posted by 1slow62 View Post
    Meh. Who cares about compression? Surprised you didn't tell him to run 87 and double up on the Amsoil since you're a dealer, LMAO. He needs to know his compression so he can optimize power through timing and fuel.
    He can always tune the engine by what the engine wants not what you think it needs. I still would not pull the engine. I'd limit my total timing to 28° to be a safe starting point. You'll just have to go slow, and not go full blast from the beginning.
    Last edited by RPnova; 09-17-2019 at 11:26 AM.

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