S3 performance valve springs
08-27-2013, 05:21 PM
#17
Former Vendor
I'm hoping that is not what I said....or gave the illusion of saying.
I've never fit a higher lift set of cams into an S3 engine....so although I can't tell you, for sure, what is going to happen, follow this logic:
The valve springs and retainers are the same in both an S3 and an S4. The spring seat, on the bottom, is thinner on the S3 than the S4, which means that there is less room from the retainer to the aluminum casting in an S3 head, not more!
I use the S3 spring seat in the S4 heads to get more room to allow the 944 spring to work.
It would logically seem that fitting the same spring in the S3 head (less available room) is going to be tough/impossible.
I've never fit a higher lift set of cams into an S3 engine....so although I can't tell you, for sure, what is going to happen, follow this logic:
The valve springs and retainers are the same in both an S3 and an S4. The spring seat, on the bottom, is thinner on the S3 than the S4, which means that there is less room from the retainer to the aluminum casting in an S3 head, not more!
I use the S3 spring seat in the S4 heads to get more room to allow the 944 spring to work.
It would logically seem that fitting the same spring in the S3 head (less available room) is going to be tough/impossible.
Is there enough material in the casting of the head to allow one to machine a pocket to gain the necessary clearance ?
08-27-2013, 05:51 PM
#18
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The S3 and S4 valve springs are the same, the top retainers are the same, the valve locks are the same. The S3 spring base 1,5mm in height, the S4 ditto 4,5mm. The S4 valves are 2,5mm longer. The distance from the tip of the valve stem down to the bottom of the valve spring pocket is different, 1,4mm (in) and 1,3mm (ex) more for the S4.
Ake
Ake
08-27-2013, 07:04 PM
#19
Former Sponsor
Haven't had to go down this path.
There are other springs to choose from.
One of the problems with the Lindsey Racing spring was....dimensional. The coils of the spring did not fit freely over the retainer or the spring seat. (The ID of the coil was smaller than the OD of the spring seat or retainer.)
"Spreading" or forcing coils over something too big always does the same thing to spring steel....the spring will break......100% of the time. Hell, springs will break when the two radiuses of the spring and the retainer interfere.
Valve springs are very critical, highly stressed pieces. Race engines "fight" valve spring issues, all the time. Some drag race engines only retain the valve springs for one pass down the 1/4 mile....and they are then trashed.
But when one starts with something that doesn't even "fit" for the application, there is absolutely no chance of them working.
09-10-2013, 10:11 AM
#20
Thread Starter
a little update.
had the shop try out a 944S2 spring set. seat pressures were good, fit was good.
used the S3 spring seats, no shims.
Intake- 60 before coil bind
Exhaust- 50 before coil bind
from what i understand 60 is good, 50 is.. meh, will work fine, but its a little on the small side.
had the shop try out a 944S2 spring set. seat pressures were good, fit was good.
used the S3 spring seats, no shims.
Intake- 60 before coil bind
Exhaust- 50 before coil bind
from what i understand 60 is good, 50 is.. meh, will work fine, but its a little on the small side.
03-12-2014, 11:56 PM
#24
When I am testing the springs I have, the "coil bind" is confusing because the springs are not compressing with all coils evenly spaced.
Are we looking for coil bind in ANY of the coils, yes?
Are we looking for coil bind in ANY of the coils, yes?
03-13-2014, 03:04 AM
#26
Archive Gatekeeper
Rennlist Member
Rennlist Member
Definition of coil bind is when _all_ the coils are touching and the spring is no longer a spring.
Junk 928S4 spring, some coils touching, but not in coil bind:
Same spring in coil bind:
Junk 928S4 spring, some coils touching, but not in coil bind:
Same spring in coil bind:
03-13-2014, 11:52 AM
#28
Looks like I was doing it wrong the first time.
03-13-2014, 11:53 AM
#29