Power Limits for Aluminum Block and Cast Crankshaft

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  1. #1

    Default Power Limits for Aluminum Block and Cast Crankshaft

    Not a new topic, but what is the current thinking on the power (and/or RPM) limits for a Teksid aluminum block, and for a cast crankshaft? My 2V set-up includes these two components along with a big bore (3.700") kit and forged rods and pistons. I'm planning to upgrade cylinder heads and positive-displacement supercharger to make more power. The current assembly has done fine at 470 crank HP, but I want to move up to about 650. Rev limiter is set at 6500 RPM, and that will not change. This is primarily a street car, but it does go to the drag strip occasionally. Am I asking for trouble?

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    Senior Member Array smashedheadcat's Avatar
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    I would not count on the teksid block in its current condition (3.7 bore) to hold 700rwhp. I honestly wouldn't really feel good about it with any boost. While opening up the bore unshrouds valves and adds cubic inches, you have to thin the sleeves (weaken the block) to get it. I bet the cast crank will survive longer than the block will.

  4. #3

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    Thanks for the input. This Teksid block was bored out and resleeved for the larger diameter pistons, so I think the sleeve thickness is the same as stock.

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    Senior Member Array smashedheadcat's Avatar
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    That may be the case, but the meat that supports the sleeves has also been thinned. I am sure the block will hold together for awhile, but I would never consider it bulletproof.

  7. #5

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    To add to Josh's cautionary comments you will experience challenges sealing up a 3.700 bore that you will not experience with a 3.552 bore. In supercharged form, unless you are running a class where the extra inches might be helpful, the smaller displacement 4.6L version of the engine is a better choice.

    If you are running very high power in a very fast class the 4.6L version of the engine is the only choice. I would give considerable thought to replacing the cast crank, it is unsuitable for a supercharged high output engine. The Teksid block is good for several times more power than you are planning on — if it is standard bore.

    You will need some good rods, like the Manley H-Beams and good pistons. The Gibtec pistons you can find elsewhere on the site are original Modmotor only design done in SolidWorks for supercharged ModMotors. They are not warmed over n/a pistons masquerading as blower pistons. They are the real deal and they are custom billets, available in 0.001" increments for any bore size you want. They also cost less than any of the quality alternatives out there. Search on Gibtec or check out the Articles section of the site.


    Ed

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