View Poll Results: Should I go with a 4.0 or a 3.5 in my F40?

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  • 4.0

    1 50.00%
  • 3.5

    1 50.00%
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Thread: 4.0 or 3.5? please read before voting

  1. #1
    Senior Member
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    Aug 2007
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    4.0 or 3.5? please read before voting

    Ok here are the facts, I have a 4.0 Aurora and have an Aurora IRL crank for it.

    The stock Aurora has a 84mm stroke and a 87mm bore
    The Irl motor has a 73.47mm stroke and a 93mm bore

    If I use the IRL crank in the stock 4.0 block I would need custom pistons and wind up with a 3.5 Aurora V8, 212 cu in.
    If I go with a 4.6 Northstar block with the IRL crank it will be a short stroke big bore 4.0, 242.48 cu in.
    If I go stock Aurora all the way it will be a 4.0, 242.69 cu in.

    Northstar block with the IRL crank would be the difference like building a 383 small block Chevy.
    400 block (4.125" bore) and a 350 crank (3.48" stroke), this would give less torque but rev quicker.
    350 block (4" bore") and the 400 crank (3.75" stroke), this gives a longer stroke, more torque, but not rev as quick.

    This motor is going to have twin TD05 Mitsubishi turbos from an Evo.
    Car should weigh around 2500 to 2600 lbs when done.
    A shorter stroke motor is normally better suited for a light weight car and longer stroke motors for heavier cars and trucks.

    The shorter stroke IRL crank should help it sound more like a real F-40, which is a 2,936cc with a 3.32" bore and a 2.74" stroke.
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  2. #2
    Moderator FunnyWheels's Avatar
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    Re: 4.0 or 3.5? please read before voting

    If I go with a 4.6 Northstar block with the IRL crank it will be a short stroke big bore 4.0, 242.48 cu in.They rev faster. like the destroked 327 resulting on a 302 small block chevy.

    Dave
    If you're not confused, you're not paying attention.

  3. #3
    Senior Member
    Join Date
    Feb 2005
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    742

    Re: 4.0 or 3.5? please read before voting

    Is this one of the 180 degree cranks like used in the IRL league race cars? If so, aren't you also going to have to have a counter crank? Second question, is where did you get it, and do they have another? I have a 93 NS sitting in my shop with less than 40k on the motor. I wanted one of those 180 degree cranks but didn't figure I could afford one, and or didn't figure I could build the engine!

    More info!!!

    Mike

    you do remember I am right down the road from you ........ right?

  4. #4
    Senior Member
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    195

    Re: 4.0 or 3.5? please read before voting

    This is a Bryant forged billet steel crank from Roush Racing's IRL racing team, they ran Aurora motors.
    It is not a 180 degree crank though, motor it came out of only had 112 test miles on it, also got the Carillo H beam rods from the same motor. I found a guy online that is an insurance salesman that went to an auction and bought a semi truck load of parts from Roush Racing. Every couple years they sell off all their parts for new.

  5. #5
    Moderator FunnyWheels's Avatar
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    Re: 4.0 or 3.5? please read before voting

    Quote Originally Posted by HTXtremes
    This is a Bryant forged billet steel crank from Roush Racing's IRL racing team, they ran Aurora motors.
    It is not a 180 degree crank though, motor it came out of only had 112 test miles on it, also got the Carillo H beam rods from the same motor. I found a guy online that is an insurance salesman that went to an auction and bought a semi truck load of parts from Roush Racing. Every couple years they sell off all their parts for new.
    Almost true about Roush selling off truck loads of parts.

    Roush Yates Racing is the name of the company. When they installed an new computer system to control their inventory, shop orders etc, they had about 8 million dollars of dead and obsolete parts clogging their warehouse store room. Only 42% were current production stuff so they took the accounting write down and began to implement a "lean supply chain" within their business. They now have the vendors deliver only what will be consumed in a day and carry no inventory. They do however sell used NASCAR parts to the public after they have been used a few seasons. They sell them on eBay. Roush Yates Racing made a presentation to our local APICS Chapter on the 11th of November 2008. That's where I got the information and a few billet motor mounts they made up the #99 Carl Edwards. I gave one to MacGyver with the hope he can find a place to put it on his build. They also had some signed pistons for door prizes but I was not the lucky recipient of one of those.
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    If you're not confused, you're not paying attention.

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