Is there a diference between a 3.2 986 and 3.4 996 head?
03-06-2012, 05:45 PM
#2
Three Wheelin'
The heads are different part numbers, so chances are no.
I think there are some differences such as AOS holes, etc as well.
edit: Jake gives us the scoop down below!
I think there are some differences such as AOS holes, etc as well.
edit: Jake gives us the scoop down below!
Last edited by logray; 03-06-2012 at 09:45 PM.
03-06-2012, 05:54 PM
#3
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I'm looking for a 4-6 so that wouldn't matter about the AOS, correct?
I know part numbers will differ due to different chassis codes. I thought the only difference was the stroke and not the bore. Do you not know anyone that has tried to do this?
I've read that the differences between the 3.6 and 3.4 996 is the cam carrier location points and the fact that it uses different cams and cam gearing.
I know part numbers will differ due to different chassis codes. I thought the only difference was the stroke and not the bore. Do you not know anyone that has tried to do this?
I've read that the differences between the 3.6 and 3.4 996 is the cam carrier location points and the fact that it uses different cams and cam gearing.
03-06-2012, 08:01 PM
#5
Former Vendor
I carry out this type of interchange frequently. I have included an interchange table in my assembly manual that should answer most questions.
Combustion chamber variances of 3cc are the biggest difference in the two heads as long as both are from the same era. Both engines must be "5 chain" to allow this to happen easily. There were no 3 chain 3.4 engines, and all were 5 chain. The 3.2 heads will increase the compression ratio of the engine due to their smaller chambers. The 3.2 and 3.4 share the exact same camshafts and the only difference between the 2 internally is the bore size, CR and intake arrangement.
It is possible to install 3 chain heads on a 5 chain engine and 5 cain heads on a 3 chain engine, according to what the combo is you are shooting for.. Hell, I have even used a 2.5 Boxster crank inside a 3.8 liter 997 crankcase for a short stroke, Big Bore HI RPM beast.
3.6 heads have vane cell adjusters for their vario cam + cam arrangement and NONE of these parts are interchangeable with the earlier engines to include the camshafts.
Its all in the combo.
Combustion chamber variances of 3cc are the biggest difference in the two heads as long as both are from the same era. Both engines must be "5 chain" to allow this to happen easily. There were no 3 chain 3.4 engines, and all were 5 chain. The 3.2 heads will increase the compression ratio of the engine due to their smaller chambers. The 3.2 and 3.4 share the exact same camshafts and the only difference between the 2 internally is the bore size, CR and intake arrangement.
It is possible to install 3 chain heads on a 5 chain engine and 5 cain heads on a 3 chain engine, according to what the combo is you are shooting for.. Hell, I have even used a 2.5 Boxster crank inside a 3.8 liter 997 crankcase for a short stroke, Big Bore HI RPM beast.
3.6 heads have vane cell adjusters for their vario cam + cam arrangement and NONE of these parts are interchangeable with the earlier engines to include the camshafts.
Its all in the combo.
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03-06-2012, 11:33 PM
#8
Drifting
Heck of a crack in that head. Not sure if that one would be fixable. Looks like it started at the spring seat and missed the spark plug chase then ran to the expansion plug chase. What cylinder is that?
03-08-2012, 11:15 PM
#10
Three Wheelin'
I carry out this type of interchange frequently. I have included an interchange table in my assembly manual that should answer most questions.
Combustion chamber variances of 3cc are the biggest difference in the two heads as long as both are from the same era. Both engines must be "5 chain" to allow this to happen easily. There were no 3 chain 3.4 engines, and all were 5 chain. The 3.2 heads will increase the compression ratio of the engine due to their smaller chambers. The 3.2 and 3.4 share the exact same camshafts and the only difference between the 2 internally is the bore size, CR and intake arrangement.
It is possible to install 3 chain heads on a 5 chain engine and 5 cain heads on a 3 chain engine, according to what the combo is you are shooting for.. Hell, I have even used a 2.5 Boxster crank inside a 3.8 liter 997 crankcase for a short stroke, Big Bore HI RPM beast.
3.6 heads have vane cell adjusters for their vario cam + cam arrangement and NONE of these parts are interchangeable with the earlier engines to include the camshafts.
Its all in the combo.
Combustion chamber variances of 3cc are the biggest difference in the two heads as long as both are from the same era. Both engines must be "5 chain" to allow this to happen easily. There were no 3 chain 3.4 engines, and all were 5 chain. The 3.2 heads will increase the compression ratio of the engine due to their smaller chambers. The 3.2 and 3.4 share the exact same camshafts and the only difference between the 2 internally is the bore size, CR and intake arrangement.
It is possible to install 3 chain heads on a 5 chain engine and 5 cain heads on a 3 chain engine, according to what the combo is you are shooting for.. Hell, I have even used a 2.5 Boxster crank inside a 3.8 liter 997 crankcase for a short stroke, Big Bore HI RPM beast.
3.6 heads have vane cell adjusters for their vario cam + cam arrangement and NONE of these parts are interchangeable with the earlier engines to include the camshafts.
Its all in the combo.
03-09-2012, 12:53 PM
#11
Former Vendor
Actually, thats a "good crack" because it doesn't extend to either the intake or exhaust valve spring seat... Those are the easier ones to "fix". We have never had a crack recur after our repairs.
