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3.0 L crank in a 2.5 L engine?

I was wondering if its possible to install a 3.0 Lt crankshaft in a 2.5 Lt engine? I have heard that it can be done, but what needs to be changed and what is the end displacement?
Cheers
Graham

Old 10-02-2004, 03:52 PM
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You would end up with a 2.7 as I recall.

Exactly what porsche used to make their 2.7.



but a 3L crank will set you back a minimun of $1,000
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Old 10-02-2004, 04:32 PM
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umm...the 2.7L has the 2.5 crank but 104mm pistons
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Old 10-02-2004, 04:51 PM
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Quote:
Originally posted by carsontc
umm...the 2.7L has the 2.5 crank but 104mm pistons
No, the 2.7 liter has a 104mm STROKE, not bore. The bore is the same as the 2.5 litre cars at 78.9mm.

The 3.0 has a 104mm stroke with an 87.8 mm bore.

The 3.0 is essentially a bored out 2.7, though I'm not entirely sure that the bore center spacing is the same.

Aaron
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Old 10-02-2004, 11:07 PM
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Quote:
Originally posted by ae1969
Exactly what porsche used to make their 2.7
are we talking about the '89 944 2.7L ?

3.0L have 87.8 mm Stroke
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Last edited by carsontc; 10-03-2004 at 04:32 AM..
Old 10-03-2004, 04:25 AM
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What kind of performance gain can you expect from all that work? Seems like us 944 owners are constantly searching for the "holy grail" of speed.. I have been caught up in that myself..But now that I'm seeing boxsters with 11K on the odometer for 25K I'm begining to think it might be better to just buy one and ditch my 44...
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Old 10-03-2004, 06:00 AM
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Quote:
Originally posted by AaronM
No, the 2.7 liter has a 104mm STROKE, not bore. The bore is the same as the 2.5 litre cars at 78.9mm.

The 3.0 has a 104mm stroke with an 87.8 mm bore.

The 3.0 is essentially a bored out 2.7, though I'm not entirely sure that the bore center spacing is the same.

Aaron
Bzzzzt!

Wrong answer...

The 3.0 L engine and the 2.7 L (89 944NA) share the same 104 mm bore. The 3.0 has the longer stroke. The 2.7 shares the same crankshaft as the 2.5 L, and, consequently, the shorter stroke.

The bore center spacing is the same for the 104 mm bore and the 100 mm bore.

You could look it up!

gb
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Old 10-03-2004, 06:40 AM
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Quote:
Originally posted by 944 Ecology
Bzzzzt!

Wrong answer...

The 3.0 L engine and the 2.7 L (89 944NA) share the same 104 mm bore. The 3.0 has the longer stroke. The 2.7 shares the same crankshaft as the 2.5 L, and, consequently, the shorter stroke.

The bore center spacing is the same for the 104 mm bore and the 100 mm bore.

You could look it up!

gb
I did look it up. But I see where I got it wrong, the site I looked it up on lists the dimensions as "Stroke/Bore" instead of the usual "Bore/Stroke". I should have been coherent enough to realise that these engines couldn't be that undersquare, but everyone has his off days.

http://www.petting-zoo.net/~gkm/944.html

Quick question now, will a 3 litre crank drop into a 2.7 litre engine? I realise that going from a 2.7 litre 8v engine to the 3.0 crank would not yield as much power gain as a true 3.0 since you wouldn't also get the 16v heads, but would that grank swap be do-able without major modification?

Aaron
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Old 10-03-2004, 08:57 AM
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Yes, you can put a 3L crank in a 2.7L 89 NA, but you will also need (at a minimum) new pistons and connecting rods...

This should result in your having a 3L 8V NA motor... I would estimate the power to be about 180-190, depending on compression ratio...

gb
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Old 10-03-2004, 09:09 AM
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So then the answer to my original question about putting the 3 Lt crank in a 1985 1/2 2.5 Lt block is......? So it can't be done without changing the pistons and rods? Is it possible to bore it out, change the crank, pistons and rods and make it a NA 3.0 Lt 8v?
Old 10-03-2004, 09:45 AM
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I don't believe that you will be able to bore the 100 mm cylinder out to 104 mm without compromising the strength of the cylinder walls.

Of course, that may not stop you from trying... You would be the first person I know of to do it.

YMMV

gb
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Old 10-03-2004, 10:41 AM
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Use the search key man!!!!!!!!, A few weeks ago this was all over the forum. First a 3.0L crank is like 1500 used, SO its alot of money for approx 20hp. After getting rods the price will be up there. Also If I where you I would not stroke the engine, stroking increase pistons speeds wich can be very bad. If you wanna play like that then do what ferrari does, big bores small strokes= high rev, good power. If your gonna bore it out you need to have steel sleeves pressed into the cyclinders and then bore them out, It all can be done but its alot of money and labor. Your better off just buying a full 3.0L or 2.7L engine and droping it into your 944
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Old 10-03-2004, 11:37 AM
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As FRWilk pointed out in another thread about this, you have 4mm more travel in each direction (hence the new pistons and con-rods), but would you have to get the 3.0 oil pan as well or will the 2.5 unit work?

I, for one, would like to build a 3.0..or drop one in, but then you need the wiring harness, too.

On a releated side note, does anyone know if you can get aftermarket pistons coated with that AuSl(?) stuff that the factory units are coated with? I'd like a set of lighter, higher compression pistons...
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Old 10-03-2004, 03:08 PM
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The short answer is yes, you can use a 3.0L crank in a 2.5L motor. What you will end up with is a 2.8L motor. This is exactly what Powerhaus ( http://www.powerhaus.com/ ) uses for their 2.8L conversion.
Old 10-03-2004, 03:10 PM
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I have been looking and it is very hard and alot of money to find pistons aftermarket pistons that have a higher CR and that are coated, most will drop in a set of EURO pistons or drop in steel sleeves and get a set of sweet JE pistons.

http://www.importperformanceparts.net/imports/pek-porsche.html
http://www.lindseyracing.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Code=944PISTONPISTONS
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Old 10-03-2004, 08:42 PM
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so are you folks saying that all you need to bring a 944 2.5 up to 2.8 liters is install a crankshaft from the S2?
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Old 10-03-2004, 09:07 PM
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No, you need to install a 3.0 crank, and get different pistons/connection rods
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Old 10-03-2004, 09:10 PM
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Wow! There's a whole bunch of crap info flying around in here! ...some of which got straightened out. Thanks for the effort you guys.
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Old 02-04-2013, 07:44 PM
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Quote:
Originally Posted by 944 Ecology View Post
Bzzzzt!

Wrong answer...

The 3.0 L engine and the 2.7 L (89 944NA) share the same 104 mm bore. The 3.0 has the longer stroke. The 2.7 shares the same crankshaft as the 2.5 L, and, consequently, the shorter stroke.

The bore center spacing is the same for the 104 mm bore and the 100 mm bore.

You could look it up!

gb

So, in theory, you could fit a 3 litre block with the 2.7 litre 8v head to make a 3 litre 8v?

Why would anyone want to do this? Because the regs in the race series I race in preclude me having a 16v engine in a car that was originally 8v (in this case a 924S)
Old 10-12-2015, 03:31 AM
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3.0 liter crank in a 2.5 liter block, with offset grinds...and a little more work.

Refresh951** l** Porsche 944** l** Porsche 951** l** Shawn Deal

Old 10-12-2015, 07:05 AM
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