Which Springs?
05-07-2012, 09:03 AM
#1
Which Springs?
Okay so quick engine specs:
2005 LQ4
317 heads stock
7.4 hardened PR
Isky Tripple 12 cam
LS9 Head gasket
ARP Head Studs
76mm turbo
The big question is what spring do I use, I like the added insurance for the duals... but I don't know what spring pressure to shoot for especially since this isnt a high lift cam! Patriot Performance 8401-B ? or are the Extremes a better choice? Any suggestions? Thanks!
2005 LQ4
317 heads stock
7.4 hardened PR
Isky Tripple 12 cam
LS9 Head gasket
ARP Head Studs
76mm turbo
The big question is what spring do I use, I like the added insurance for the duals... but I don't know what spring pressure to shoot for especially since this isnt a high lift cam! Patriot Performance 8401-B ? or are the Extremes a better choice? Any suggestions? Thanks!
05-08-2012, 07:32 AM
#3
Not getting any feedback, so I looked up some older posts concerning Single vs. Dual Springs and looks like we have a winner...
Patriot Performance 8401:
Technical Specs:
Install Height: 1.800''
Max. Valve Spring Lift: 0.650''
Spring Pressure Closed: 135 lbs. @ 1.800''
Spring Pressure Open: 375 lbs. @ 1.150''
Coil Bind: 1.090''
Retainer Material: Titanium
They are drop in which are a plus, dual spring for a little extra insurance, and have great user reviews.. I know they have been used on a lot of motors out there, but they are new to me and Jeg's sells the whole kit for $256, pretty nice for duals with ti retainers!
With only 8-10lbs of boost I doubt I'll have worries of seat pressure, although just for the sake of this thread anyone who might look into a set of Valve Springs and what Seat Pressure to consider in relation to a Turbo/Supercharger build I found this in a thread from yellowbullet.com that might help:
The Crane Cams website used to state this;
"Selecting the proper valve spring for any performance engine is important; but it is critical to proper operation of supercharged engines. Consider the fact that when the engine is in a "boosted" condition, the supercharger (or turbocharger) is trying to blow the intake valve open. The boost pressure actually reduces the intake valve spring seat pressure. This is extremely critical on engines with hydraulic lash adjustment. Proper seat pressure (working through the rocker arm and pushrod) is necessary to keep the hydraulic lifter plunger centered in the lifter body to prevent "pump-up." If an engine has 2.25" dia. intake valves, there is 4 sq. inches of backside valve area. Now add 12 (psi) of boost pressure, and you have reduced your effective seat pressure by 48 lbs. (12 lbs/sq.in. X 4 sq. in.). If you started out with 120 lbs. of seat pressure (static), you now have 72 lbs. of operational seat pressure. There is no way that 72 lbs. of pressure is going to control a 2.25" valve! For street use, the answer is to select a tall, mild-rate spring that assembles at a high seat pressure, yet keeps the open pressure reasonable over the nose of the cam to assure long cam life. (For example; a great spring on a Big Block Chevrolet with a hydraulic roller and a supercharger is our #96879 spring, which will provide 169 lbs. at 1.880" seat and 432 lbs. at 1.280" open with a .600" net lift cam.) Exhaust valve seat pressure does not need to be raised significantly on supercharged engines. Racing applications with solid lash adjustment do not experience lifter "pump-up,” but still need the high seat pressure to prevent the valve from bouncing on return to the seat against the boost pressure. Consult our easy to use valve spring pressure chart at the back of our Valve Spring and Retainer catalog."
Entire thread at: BOOST & VALVE SPRING PRESSURE?? - Yellow Bullet Forums
Those guys run big motors with big boost but it still applies to us all I would think...
I'm seriously new to this so if any of the gurus on this site have anything to add chime in, this site could use a discussion on this topic.. and sorry if I missed it anywhere couldn't find much from searches
Patriot Performance 8401:
Technical Specs:
Install Height: 1.800''
Max. Valve Spring Lift: 0.650''
Spring Pressure Closed: 135 lbs. @ 1.800''
Spring Pressure Open: 375 lbs. @ 1.150''
Coil Bind: 1.090''
Retainer Material: Titanium
They are drop in which are a plus, dual spring for a little extra insurance, and have great user reviews.. I know they have been used on a lot of motors out there, but they are new to me and Jeg's sells the whole kit for $256, pretty nice for duals with ti retainers!
With only 8-10lbs of boost I doubt I'll have worries of seat pressure, although just for the sake of this thread anyone who might look into a set of Valve Springs and what Seat Pressure to consider in relation to a Turbo/Supercharger build I found this in a thread from yellowbullet.com that might help:
The Crane Cams website used to state this;
"Selecting the proper valve spring for any performance engine is important; but it is critical to proper operation of supercharged engines. Consider the fact that when the engine is in a "boosted" condition, the supercharger (or turbocharger) is trying to blow the intake valve open. The boost pressure actually reduces the intake valve spring seat pressure. This is extremely critical on engines with hydraulic lash adjustment. Proper seat pressure (working through the rocker arm and pushrod) is necessary to keep the hydraulic lifter plunger centered in the lifter body to prevent "pump-up." If an engine has 2.25" dia. intake valves, there is 4 sq. inches of backside valve area. Now add 12 (psi) of boost pressure, and you have reduced your effective seat pressure by 48 lbs. (12 lbs/sq.in. X 4 sq. in.). If you started out with 120 lbs. of seat pressure (static), you now have 72 lbs. of operational seat pressure. There is no way that 72 lbs. of pressure is going to control a 2.25" valve! For street use, the answer is to select a tall, mild-rate spring that assembles at a high seat pressure, yet keeps the open pressure reasonable over the nose of the cam to assure long cam life. (For example; a great spring on a Big Block Chevrolet with a hydraulic roller and a supercharger is our #96879 spring, which will provide 169 lbs. at 1.880" seat and 432 lbs. at 1.280" open with a .600" net lift cam.) Exhaust valve seat pressure does not need to be raised significantly on supercharged engines. Racing applications with solid lash adjustment do not experience lifter "pump-up,” but still need the high seat pressure to prevent the valve from bouncing on return to the seat against the boost pressure. Consult our easy to use valve spring pressure chart at the back of our Valve Spring and Retainer catalog."
Entire thread at: BOOST & VALVE SPRING PRESSURE?? - Yellow Bullet Forums
Those guys run big motors with big boost but it still applies to us all I would think...
I'm seriously new to this so if any of the gurus on this site have anything to add chime in, this site could use a discussion on this topic.. and sorry if I missed it anywhere couldn't find much from searches
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