valve spring sizing and boost
valve spring sizing and boost I have a 224/224 .580/.580 lift cam and run 15psi. I broke one of my old dual PSI springs and am going to buy new ones.
Will the comp 918s work fine? I know they would with out boost. But is that 15# going to matter?
any other recomendations if they dont work?
thanks.
Will the comp 918s work fine? I know they would with out boost. But is that 15# going to matter?
any other recomendations if they dont work?
thanks.
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Joined: Jan 2004
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From: Castro Valley, CA
I just went to the Patriot Gold duals and it helped me solve some problems above 4500 rpm... re-tuned, at 11 psi or so, I made 30 more rwhp and rwtq. I'm glad I did it. The cam is nothing special: 224/224/114, 0.588.
I had the same problems and switched to the Patriot springs.
http://www.ls1speed.com/catagory.cfm...in%20/%20Heads
http://www.ls1speed.com/catagory.cfm...in%20/%20Heads
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Joined: Apr 2002
Posts: 1,755
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From: Cincinnati, Ohio
Since upgrading from a T-trim to a YSi I have been trying to work out high RPM mis-fires (I have 918's). I thought I had it solved when I raised the MAF Hz to 16000 (couldn't hardly get past 6000 until I did this). I go right up to the 6800 rev limit now but it still is doing weird things up top. I think I'm going to be switching to the Patriot duals.
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Originally Posted by pwrtrip75
I have a 224/224 .580/.580 lift cam and run 15psi. I broke one of my old dual PSI springs and am going to buy new ones.
Will the comp 918s work fine? I know they would with out boost. But is that 15# going to matter?
any other recomendations if they dont work?
thanks.
Will the comp 918s work fine? I know they would with out boost. But is that 15# going to matter?
any other recomendations if they dont work?
thanks.
If you are running a maximum of 15lbs of boost and your heads have 1.94inch intake valves (for example). Your springs would require an extra around 45-50lbs (theoretically) of additional pressure from the spring to control your valve motions while under full boost. Not having that additional spring pressure MAY cause your valve to not fully close against the seat. This CAN be catastrophic...
A spring like the COMP 918 would be able to control the cam you are running in most N/A instances.
COMP 26918
130@1.800"
333@1.150"
So,adding the additional poundage required due to boost you can figure on using a spring in the 380 @1.15 range.
Springs that should work for you:
CompCams 26921 Springs;
O.D.: 1.300
I.D.: 0.655
Seat Load: 135
Open Load: 400
Coil Bind: 1.040
Rate (lbs./in.): 408
Patriot Gold Springs;
O.D.: 1.290"
I.D.: .675"
Seat Load: 140
Open Load: 380
Coil Bind: 1.090"
Rate (lbs./in.): ???
Of the two the patriots are cheaper and have a great track record. I have also heard nothing bad about the 921s but they are pricey.
Either of those springs will offer you a bit of "working room" with the cam/boost combination you have.Well, that is assuming you have a valve size near 1.94in anyway...
The figures I've presented as your requirements are not exact,they are rough estimates of what you would need on the more extreme end but you should have ZERO problems with either the 921 or Patriot Gold spring.
I hope that helps.
Last edited by Cheatin' Chad; Jun 8, 2007 at 07:19 PM.
how would 918s fare with 8psi and a 228/228 .588 .588 115LSA cam. Would they hold 10psi? Is it vital to swap to ti retainers or any of that? my 317 heads came assembled with stock stuff but still new.
Originally Posted by JAvenger007
how would 918s fare with 8psi and a 228/228 .588 .588 115LSA cam. Would they hold 10psi? Is it vital to swap to ti retainers or any of that? my 317 heads came assembled with stock stuff but still new.
Losing weight in your retainers,locks,and valves will reduce demands on the springs. All things being the same you will improve valve control for a given spring rate by reducing "sprung" weight.
To give you exact figures I'd need to know your intake valve size,camshaft specifics,etc. If you do a rough estimate based on the information I provided earlier you will be able to get yourself in the ballpark.
Based on the information provided (and assuming on everything else) I would say you are probably marginal.I believe It is better to err on the side of caution concerning valve control.
My car:
Crane 832's at 17 psi, 700rwhp or so
Comp 921's at 18-21psi, 746rwhp or so
ETP Springs at 24-26 psi, 867rwhp or so
My Crane 832's worked very well until I went to more camshaft (went from 230/236 to 236/246).
Crane 832's at 17 psi, 700rwhp or so
Comp 921's at 18-21psi, 746rwhp or so
ETP Springs at 24-26 psi, 867rwhp or so
My Crane 832's worked very well until I went to more camshaft (went from 230/236 to 236/246).
Originally Posted by Pro Stock John
My car:
Crane 832's at 17 psi, 700rwhp or so
Comp 921's at 18-21psi, 746rwhp or so
ETP Springs at 24-26 psi, 867rwhp or so
My Crane 832's worked very well until I went to more camshaft (went from 230/236 to 236/246).
Crane 832's at 17 psi, 700rwhp or so
Comp 921's at 18-21psi, 746rwhp or so
ETP Springs at 24-26 psi, 867rwhp or so
My Crane 832's worked very well until I went to more camshaft (went from 230/236 to 236/246).
