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2.7 to 3.0 conversion

Will swapping a 3.0 liter 944S2 or 968 crankshaft into a 2.7 liter 944 engine with no other modifications (no changes to con rods or pistons) result in a 3.0 liter eight valve engine? Would there be any problems, such as changes to the compression ratio or con rod incompatibility, resulting from this modification? TIA MF
Old 09-05-2004, 05:58 AM
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the wrist pins on the 3.0L are in a different location...so you'll need to change pistons for clearance
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Early '85 944
Old 09-05-2004, 08:55 AM
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I think you get a lower compression like 8:1, Im not sure, Also you need to start thinking about Air and fuel flow and ratios now that the engine will want more
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1986 951, Stock for now.
]87 924S Gaurds red- SOLD after 11 years of ownership
Old 09-05-2004, 10:19 PM
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Just think, though...lower compression means more boost. You'll obviously have to find a T-88 to strap on the block...
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Old 09-05-2004, 10:34 PM
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its a NA, anyways screw the turbo, slap a supercharger on her and run like 10-12psi and have balls all the time
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1986 951, Stock for now.
]87 924S Gaurds red- SOLD after 11 years of ownership
Old 09-05-2004, 10:40 PM
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screw it...T-88 + supercharger...best of both ends of the powerband...
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Old 09-05-2004, 10:45 PM
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HAHAHAHA ok t-88+SC+100hp shot nitrous. Now Im happy
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1986 951, Stock for now.
]87 924S Gaurds red- SOLD after 11 years of ownership
Old 09-05-2004, 10:48 PM
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I can already imagine not being able to see the engine due to the manifolds, supercharger, turbo scrolls, and a huge blue bottle (you know it's GOT to be HUGE)...
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Old 09-05-2004, 10:55 PM
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No no, DUEL TANKS, 2 20lbs nitrous tanks, with custom paint, HEHEHEHEHEHE
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1986 951, Stock for now.
]87 924S Gaurds red- SOLD after 11 years of ownership
Old 09-05-2004, 10:58 PM
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Re: Re: 2.7 to 3.0 conversion

Quote:
Originally posted by FR Wilk
You will have 4.5mm more piston travel in each direction.
This is what I was concerned about...I was not sure if the specs of the 3 liter crank increased the stroke by displacing the stroke downward only - per FR Wilk, it does not. So, if I go with aftermarket (Pauter, Carillo or whatever) 4.5 mm shorter con rods, will I then be OK in terms of piston coming even with the cylinder top, and of course still have 3 liters of displacement? And if I want to lower the compression ratio a bit, what length connecting rods will be best to draw the piston down a bit into the cylinder, for use with a forced induction intake?

Exploring this a bit, and feel free to jump in and correct me where I'm getting goofy: displacement is derived by bore x stroke. Stroke will remain constant regardless of the con rod length, the length merely dictates where in the cylinder the stroke is taking place.

Since it sounds like the 3 liter crank creates an additional 9 total mm of travel, like FR Wilk says, I need to get rid of 4.5 mm of travel to take care of the overage at the top. However - is there a table or some area in the shop manual that can help me compute how much length I can further reduce the connecting rod length by to arrive at say 8.5:1 to 9.0:1 CR? I would guess this can be done with nothing more than simple math.

Also, with the wrist pin issue stated by carsontc: I wonder if aftermarket con rods can address this issue without springing for new pistons. I would like to stick with the stock pistons since it is a low mile engine and I don't want to take a chance on having to visit the machine shop for lapping or worse, I would like to make this a home garage project if possible. TIA MF
Old 09-06-2004, 05:38 AM
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Wow, markford where are you located, I will be rebuilding my 924S engine this winter and have been thinking about the same things as you, since most of the questions you are asking are not traveled by most of the people on this forum I would try calling some of the race engine build companies, they have done this and know what you will need. Here are some sites, you can e-mail then and ask.

http://www.jmengines.com/index.htm

http://www.ebsracing.com/water.html

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Old 09-06-2004, 11:39 AM
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