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will a 993 crank and rods fit right into my 3.0 case?

will a 993 crank and rods fit right into my 3.0 case? As I have stated in teh past, i am getting the displacement madness for my planned rebuidl and I want to know if a 993 crank will fit right into my 3.0 case.

my understanding is it should...am I right?

i know on the 3.2 many suggest replacing the rod bolts with new...anyhtign about the stock 993 crank and rod setup that folks like to get modded?

I know I will need custom pistons, but other than that, will I be ok?
Old 11-30-2004, 06:59 PM
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Are you going to use 3.0 barrels and pistons or 100mm??

Michael
Old 11-30-2004, 07:11 PM
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I have 95mm 3.2 cylinders that I will be getting bored to 98mm and nickie plated. I beleive the 993 crank will fit in resulting a 3.5 motor.

I have not yet decided if I will be going high compression, hot cams, and carbs or low compression, supercharger, and EFI.
Old 11-30-2004, 07:38 PM
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I am under the impression that the 3.6 crank will fit however I wonder whether there may be some issues with the rods.

I am sure that someone must have already done this modification

Try a search and see what comes up.

I will ask one of my guys whether it works.


Michael
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Old 11-30-2004, 07:48 PM
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I believe I asked this same question a few weeks ago. Henry said that he had done this combo at their shop (Supertech) and it didn't work out. The rod length is too short resulting in excessive piston side loading and the motor would'nt rpm. Made all kinds of torque at low RPM but it just didn't work.

It's my understanding that Andail builds this set-up and still promotes it although Henry said that he's seen a few explode repeatedly.
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Old 12-01-2004, 09:39 AM
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If the factory uses 3.6 crank and 100mm barrels and pistons one wouldn't think that the smaller bore would result in to short a rod length??

Hopefully Henry from supertec will give us his views on why the combo won't work

Michael
Old 12-01-2004, 02:44 PM
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The rod length is shorter (I'm certain) in a 3.2 resulting in a not-so-favorable rod/stroke ratio. Given the same bore/stroke, as you shorten the connecting rod you will move the torque curve to a much lower rpm and increase frictional rotation by increased rod angle and piston side-loading.
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Old 12-01-2004, 02:57 PM
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Below is a result I found from one of Henry's old posts on this topic.


We built the engine you're talking about back in the early 90s. It produced huge torque but no rpm. In fact it blew 2nd gear right off the main shaft (early 915). We encounter some clearance problems and because of the excessive rod angularity that makes piston side loading an issue we gave up on this spec for our performance engines. These cranks are designed to run with a dual mass flywheel and a harmonic balancer and without them balance also becomes an issue.
We just took apart a turbo engine built by Andial with a 3.6 (76.4 x 100) crank. This engine has exploded at least 3 times so we removed the crank and reconfigured the engine in an attempt to keep this engine alive. We'll let you know how the new configurations



I would have thought you could keep the same rod length and had a shorter piston
My 2 cents worth

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Old 12-01-2004, 03:02 PM
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A possibilty: Use the 3.6 connecting rods and have the pistons custom made with the proper wrist pin location. Down side of this may be that to locate the pin where it needs to be will put the pin boss up in the oil ring land area.

I believe there is a mathmatical formula for calculating optimum piston pin location, distance from the pin centerline to the crown, skirt length for a given bore/stroke/rod length combination. Also the pin location has great effect on the pistons' leverage (amount of work exerted) on the crankshaft.
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Old 12-04-2004, 08:11 AM
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