Stroking a 944...
10-07-2003, 02:21 AM
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I've been in Chevy engines since I was about this tall, and I'm now into my first Posche engine. Stroking a BowTie is easy, and I have little knowledge on stroking Porsches. Different crank (longer throw of 3.0) will require shorter rods (from the 3.0) so your pistons don't try to push the head off the block. You'll have to wait for some other info on the pistons, I'm not sure if the wristpin locations are the same (distance from wristpin to the top of the piston). But defintely, 3.0 crank will have to either the 3.0 rods or custom rods made. Lots of guys have done/are doing that conversion here.
10-07-2003, 04:09 PM
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is the crank and rods the only difference? What is the bore on the 2.5, 2.7 and 3.0?
A 3.0 crank in a 2.5 would be a lot cheaper than finding a 3.0.
What about valve clearance?
A 3.0 crank in a 2.5 would be a lot cheaper than finding a 3.0.
What about valve clearance?
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10-07-2003, 04:47 PM
#8
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Re: Stroking a 944...
Originally posted by JediAgent
Whats the possibility of just stroking a 944?
Whats the possibility of just stroking a 944?
10-07-2003, 05:39 PM
#9
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2.5l = 100mm bore x 78.9mm stroke
2.7l = 104mm bore x 78.9mm stroke
2.8l = 100mm bore x 87.8mm stroke
3.0l = 104mm bore x 87.8mm stroke
You can stroke a 2.5L motor, you just need a S2 or 968 3.0L crank and rods. This will give you the 2.8l option above (by the way, the 2.8 was never offered by the factory).
I'm not sure the specifics of compression ratios and any machine work needed, but I imagine it's pretty simple. This is a pretty popular upgrade on turbos.
On a side note, I'm 90% sure that this was done on my motor. The package of reciepts I got from the previous owner included one for about $5000 for "new rods & crankshaft". It also has a dyno slip thrown in showing 200rwhp. I can't get any more info than that however as the previous owner (who only had it one year) knew nothing about the car from before when he got it. If so, would I be the only one with a 2.8L N/A? It would also make my car quite the sleeper as the engine looks bone stock... Any ideas on how to check, short of pulling the engine apart?
2.7l = 104mm bore x 78.9mm stroke
2.8l = 100mm bore x 87.8mm stroke
3.0l = 104mm bore x 87.8mm stroke
You can stroke a 2.5L motor, you just need a S2 or 968 3.0L crank and rods. This will give you the 2.8l option above (by the way, the 2.8 was never offered by the factory).
I'm not sure the specifics of compression ratios and any machine work needed, but I imagine it's pretty simple. This is a pretty popular upgrade on turbos.
On a side note, I'm 90% sure that this was done on my motor. The package of reciepts I got from the previous owner included one for about $5000 for "new rods & crankshaft". It also has a dyno slip thrown in showing 200rwhp. I can't get any more info than that however as the previous owner (who only had it one year) knew nothing about the car from before when he got it. If so, would I be the only one with a 2.8L N/A? It would also make my car quite the sleeper as the engine looks bone stock... Any ideas on how to check, short of pulling the engine apart?
10-07-2003, 07:42 PM
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Or you could try doing what some of us 928 owners are doing....
Ordering a custom length stroke crankshaft from Scat Industry. We use the 968 pistons (increases bore from 100 to 104 mm) and using SBC rods (5.75 inch in length) along with a 95 mm stroke crank, we get the motor displacement up to 6.5L.
Might be worth investigating the possibility of getting Scat to make some crankshafts for the 944 bunch. Ours cost ~$3K apiece so be warned.
Ordering a custom length stroke crankshaft from Scat Industry. We use the 968 pistons (increases bore from 100 to 104 mm) and using SBC rods (5.75 inch in length) along with a 95 mm stroke crank, we get the motor displacement up to 6.5L.
Might be worth investigating the possibility of getting Scat to make some crankshafts for the 944 bunch. Ours cost ~$3K apiece so be warned.
10-07-2003, 09:08 PM
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Anyone here who has actually done this?
Im the kinda guy that would come across a some 3.0L crank and rods and then take my engine apart to see if they will fit...
...it might be better to ask someone who has done it if those two things are the only difference.
Im the kinda guy that would come across a some 3.0L crank and rods and then take my engine apart to see if they will fit...
...it might be better to ask someone who has done it if those two things are the only difference.
