Should I replace my crankshaft? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 01-25-2013, 03:36 PM   #1
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Default Should I replace my crankshaft?

My engine is a 1991 b6 made after VIN 209XXX, it has 175K miles (280 000kilometers), has always been running smooth, no pulley wobble or anything weird. Its been boosting 9lbs for 4 years and I've been going to many track day events since even before that so it has suffered a lot of abuse. I'm currently gathering the parts to rebuild it with forged internals etc... aiming at 300whp and still planning on going to track days. On most forums and posts that I've checked out they say that this crank is really tough but still... I'd like to have some opinions on this.
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Old 01-25-2013, 04:12 PM   #2
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Show us your crank and let us decide.
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Old 01-25-2013, 05:23 PM   #3
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Aside from the stroker crank that FM uses in their 2 liter kits, I can't recall ever hearing of anyone using an aftermarket crank in a B6 or BP engine. While the stock rods are a notorious weak point, the stock cranks seem to be good for upwards of 400 HP reliably.
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Old 01-25-2013, 05:36 PM   #4
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With the cost of good 1.8 blocks why waste money on replacing a 1.6 crank?

Run the 1.6 till the pistons fly through the hood, meanwhile build a 1.8 ready to swap in.
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Old 01-25-2013, 07:09 PM   #5
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+1, run the 1.6 until it grenades and build a 1.8 on the side.
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Old 01-26-2013, 02:28 AM   #6
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I don't think I've ever heard of anyone busting a stock crank.

OP, you know the stock crank in the b6/bp is forged, right?

Edit: Yes, swap in a 1.8. Sell me your non-SNC 1.6 block.
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Old 01-26-2013, 04:44 PM   #7
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thanks for the info, that's one less thing to worry about!
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