Under size crankshaft

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speedmaster
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Under size crankshaft

Postby speedmaster » Tue Mar 03, 2015 1:34 am

I was told undersized crankshaft performs better than standard size. Anyone can correct me?

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Re: Under size crankshaft

Postby totta crolla » Tue Mar 03, 2015 1:57 am

speedmaster wrote:I was told undersized crankshaft performs better than standard size. Anyone can correct me?

The person who told you, what was their explanation ?

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Re: Under size crankshaft

Postby speedmaster » Tue Mar 03, 2015 2:00 am

totta crolla wrote:
speedmaster wrote:I was told undersized crankshaft performs better than standard size. Anyone can correct me?

The person who told you, what was their explanation ?

It said they work like a stroker kit

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Re: Under size crankshaft

Postby Rogue-AE95 » Tue Mar 03, 2015 6:33 am

Undersize, as in the crank's journals (main & rod) were ground and micropolished? That wouldn't change the stroke, it would just require thicker bearings for the mains and rods.
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Re: Under size crankshaft

Postby yoshimitsuspeed » Tue Mar 03, 2015 8:00 am

It is possible to grind a crank with the rod journals off center to give it more stroke but that is not standard procedure. Normally they will be grinding on the rod journal centerline keeping an identical stroke and just reducing the diameter of the journal.

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Re: Under size crankshaft

Postby allencr » Tue Mar 03, 2015 8:28 am

speedmaster wrote:I was told undersized crankshaft performs better than standard size. Anyone can correct me?
It said they work like a stroker kit


WHY CAN'T ANYONE WRITE NO, it's either just ignorance or 100% BS!
Theoretically - less surface area = less drag, also = more heat, also some bearing manufacturers don't use a larger steel shell and/or base metals and only build up the softer outer layer for their OS bearing, weaking it.

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speedmaster
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Re: Under size crankshaft

Postby speedmaster » Tue Mar 03, 2015 2:00 pm

Possibility and No.

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Re: Under size crankshaft

Postby THE_ENTHUSIAST » Thu Mar 12, 2015 11:16 pm

Are you referring to using an early 40mm crank? Then to a degree yes!!

The 40mm (early 3rib) crankshaft is approx 700g's lighter and has been argued to be slightly better in some mild street builds. less friction vs. 42mm. I would also assume less friction/drag meant less heat. Also both cranks are 77mm stroke. So that wouldn't change.

If you're talking about regrinding a 42mm crank to 40mm in an offset. You'd only gain 1mm extra stroke. A waste of time and money since the advent of the 7age.

Read here for more info -http://www.billzilla.org/4agstock2.htm

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Re: Under size crankshaft

Postby speedmaster » Sun Mar 15, 2015 7:57 am

THE_ENTHUSIAST wrote:Are you referring to using an early 40mm crank? Then to a degree yes!!

The 40mm (early 3rib) crankshaft is approx 700g's lighter and has been argued to be slightly better in some mild street builds. less friction vs. 42mm. I would also assume less friction/drag meant less heat. Also both cranks are 77mm stroke. So that wouldn't change.

If you're talking about regrinding a 42mm crank to 40mm in an offset. You'd only gain 1mm extra stroke. A waste of time and money since the advent of the 7age.

Read here for more info -http://www.billzilla.org/4agstock2.htm



the answer i want, thanks