L92 head 427 makes 700HP n/a!
07-09-2008, 08:14 PM
#61
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OK did i miss a link here to your dyno graphs?
I am a avid user of epoxy to allow port sizing and shape changes, surface prep(cleaning) is #1 key to success and reliable epoxy use.
I am extremeli interested in what your #'s were above 6900 cause mi L92 402"
goes into seat bounce hysterics at 7000 rpm with similar sized Comp hydraulic roller and #26921 springs. I run a GMPP carbed intake and mi peak power is at 6900 so i have no room to shift past peak(a real problem with TH400 auto)
What valves and springs does this set up have and how high does it rev cleanly? TIA
I am a avid user of epoxy to allow port sizing and shape changes, surface prep(cleaning) is #1 key to success and reliable epoxy use.
I am extremeli interested in what your #'s were above 6900 cause mi L92 402"
goes into seat bounce hysterics at 7000 rpm with similar sized Comp hydraulic roller and #26921 springs. I run a GMPP carbed intake and mi peak power is at 6900 so i have no room to shift past peak(a real problem with TH400 auto)
What valves and springs does this set up have and how high does it rev cleanly? TIA
Brian
07-10-2008, 02:26 PM
#62
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I couldn't rev that engine past about 7100 as I used the customers' existing valve spring package. Based on more current testing, I would expect it would carry HP a long way (probably a 7500 or so shift point). You will need to run your 921 springs about .040-.050" from coil bind to get more revs out of your combo as well as switch to 3/8" pushrods. However, I wouldn't expect you will too much more RPM unless your cam is around .600" lift so that you will wind up with about 170 lbs. seat pressure @ 1.720" spring height. That should get you to about 75-7600 RPM capable.
Brian
Brian
Jeff
07-10-2008, 06:37 PM
#63
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I don't think you'll be able to run that much lift w/ the springs @ 1.740". My calculations for that spring (I just happen to be setting up a set right now on some L92's) is that they bind at 1.075" - allowing .040" to max lift, that's 1.115" - plus .660" for the cam (and I wouldn't expect you to lose any noticeable lift w/ stock geometry) puts you at 1.775" assembled height.
07-10-2008, 06:47 PM
#64
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Ferrea sells a dual spring combo that would work a little bit better for you... it has a part number S99100. It is made by PAC racing - I am using them right now in our test 454 w/ L92 heads and a .700"+ cam. With your cam being only .660" lift, you could set them up a little tighter than the ones I am running and since I have turned this engine 7100 already, they should work well for you. Ferrea lists them as requiring retainer p/n E12000 and spring seat SL1036 to complete the package. Hope this helps.
07-14-2008, 01:56 PM
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Ferrea sells a dual spring combo that would work a little bit better for you... it has a part number S99100. It is made by PAC racing - I am using them right now in our test 454 w/ L92 heads and a .700"+ cam. With your cam being only .660" lift, you could set them up a little tighter than the ones I am running and since I have turned this engine 7100 already, they should work well for you. Ferrea lists them as requiring retainer p/n E12000 and spring seat SL1036 to complete the package. Hope this helps.
07-18-2008, 09:08 PM
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07-29-2008, 06:21 PM
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Ferrea sells a dual spring combo that would work a little bit better for you... it has a part number S99100. It is made by PAC racing - I am using them right now in our test 454 w/ L92 heads and a .700"+ cam. With your cam being only .660" lift, you could set them up a little tighter than the ones I am running and since I have turned this engine 7100 already, they should work well for you. Ferrea lists them as requiring retainer p/n E12000 and spring seat SL1036 to complete the package. Hope this helps.
08-10-2008, 04:38 PM
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I bought and set these springs up on my motor but they are not close on tensions listed at set heights. I ran them anyway cause i had plenty of coil bind clearance to tighten them up to what i needed. I was shocked at how low they read at adv. settings. Any way with stock L-92 valves and Cadillac race hydraulic lifters, i spun it clean to 7500 with no trauma. I am racing this weekend so i will report how they handle 7500 thru the traps.
btw no damage suffered but it is unerving when it seems to seat bounce above 7000 making it pop thru the carb.
08-21-2008, 01:43 PM
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I couldn't rev that engine past about 7100 as I used the customers' existing valve spring package. Based on more current testing, I would expect it would carry HP a long way (probably a 7500 or so shift point). You will need to run your 921 springs about .040-.050" from coil bind to get more revs out of your combo as well as switch to 3/8" pushrods. However, I wouldn't expect you will too much more RPM unless your cam is around .600" lift so that you will wind up with about 170 lbs. seat pressure @ 1.720" spring height. That should get you to about 75-7600 RPM capable.
Brian
Brian
I feel i am experiencing seat bounce, since no loss of spring pressure occurs when this happens, even multiple times. Anyone?
08-21-2008, 02:16 PM
#79
Ok so you have exceeded 6900 rpm with L92 and hydraulic roller cam? I have not done that yet, im thinking thats where the weight of the valves(no titanium) and heavy hydraulic rollers lose control dynamically... anyone want to let me know if they are able to exceed 6900 and still make power?
I feel i am experiencing seat bounce, since no loss of spring pressure occurs when this happens, even multiple times. Anyone?
I feel i am experiencing seat bounce, since no loss of spring pressure occurs when this happens, even multiple times. Anyone?
08-21-2008, 03:33 PM
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Ok i am running Comp SP and RP solid roller lobes with GM Cadillac race hydraulic lifters. The lobes are 252* and 260*@.050"on a 111* LSA the rockers are stock and net lift is .660"/.647" My pushrods are .080" 5/16's My springs are the Ferrea duals with 170 seat and 480 open lbs. You really think thats enough spring to deflect these pushrods?
Last edited by LSwonderfull; 08-21-2008 at 04:08 PM.