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  • I need valve spring info help please.

    I have the scheider vavle spring set which as Jason has said has a closed seat pressure of roughly 110lbs

    Do any of you guys know of a formula in figuring out what the spring pressure in relation to the RPM's would be? I've heard rumors that the Schneider springs are capable of reving to 10k rpm's but this of course depends on you cam grind also. I've tried google searching with no avail.

    Basicly I'm trying to find out high I wrap the valve train. I can take the bottom end to 8500rpms but not too sure bout the vavle train.
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

  • #2
    Hmm, nobody yet huh?

    How about this. With the stock springs being 54lbs and being able to rev to 7k on stock cams then do you think it would be "ok" for springs of OVER double the pressure (110lbs) to wrap up an additional 1.5k on an aftermarket cam?

    That seem feasible right?

    It would just be nice to be at least 90% sure is all. :?
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

    Comment


    • #3
      i remember reading the same thing. but i cannot remember where it was.

      you run stiffer springs so your valves do not float at the upper rpm levels. as long as your cam can handle the rpm i don't see why not.

      SATAN wrote: Hmm, nobody yet huh?

      How about this. With the stock springs being 54lbs and being able to rev to 7k on stock cams then do you think it would be "ok" for springs of OVER double the pressure (110lbs) to wrap up an additional 1.5k on an aftermarket cam?

      That seem feasible right?

      It would just be nice to be at least 90% sure is all. :?

      Comment


      • #4
        [quote]84z31 wrote: i remember reading the same thing. but i cannot remember where it was.

        you run stiffer springs so your valves do not float at the upper rpm levels. as long as your cam can handle the rpm i don't see why not.

        Originally posted by SATAN
        Hmm, nobody yet huh?

        How about this. With the stock springs being 54lbs and being able to rev to 7k on stock cams then do you think it would be "ok" for springs of OVER double the pressure (110lbs) to wrap up an additional 1.5k on an aftermarket cam?

        That seem feasible right?


        Well, its not the cam that I am worried about handling the RPM. Its the valve float. When you run a more aggressive cam the ramps on the lobes are more often than not, steeper. This has a tendancy to make the valve want to "jump" off of the cam. More so than a stock cam lobe. The durrability of the cam is not what concerns me.

        Its just kinda un-charted territory is all. And the people that have gone there dont really post on forums so.... I just want to be sure before I just crank up the redline and hope for the best. Thats why i'm looking for a formula or some way to find out.

        It would just be nice to be at least 90% sure is all. :?
        85 Z31 6.0 LSX turbo 766whp/792wtq
        04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

        Comment


        • #5
          SATAN wrote: Hmm, nobody yet huh?

          How about this. With the stock springs being 54lbs and being able to rev to 7k on stock cams then do you think it would be "ok" for springs of OVER double the pressure (110lbs) to wrap up an additional 1.5k on an aftermarket cam?

          That seem feasible right?

          It would just be nice to be at least 90% sure is all. :?
          Yes. 110lbs is probably a gross amount of overkill on seat pressure. The open spec is also very high compared to stock. You will be at piston speeds over 4000FPM well before you hit 8K though, so the bottom end (specifically the rods) is the only thing I would bother questioning. Calculate the inertial loads you're getting with stock stroke at that kind of RPM, even with lightened pistons and rods.

          Comment


          • #6
            [quote]Jason84NA2T wrote:
            Originally posted by SATAN
            Hmm, nobody yet huh?

            How about this. With the stock springs being 54lbs and being able to rev to 7k on stock cams then do you think it would be "ok" for springs of OVER double the pressure (110lbs) to wrap up an additional 1.5k on an aftermarket cam?

            That seem feasible right?

            It would just be nice to be at least 90% sure is all. :?
            Yes. 110lbs is probably a gross amount of overkill on seat pressure. The open spec is also very high compared to stock. You will be at piston speeds over 4000FPM well before you hit 8K though, so the bottom end (specifically the rods) is the only thing I would bother questioning. Calculate the inertial loads you're getting with stock stroke at that kind of RPM, even with lightened pistons and rods.
            Well I only think that I can run the 8500rpm on the bottom end because this is what Eagle recomends as the max safe rpm limit which equals out to be 4632.5 FPM. I'm willing to bet they say that is the safe point after testing them and watching them fail about 1k or 2k higher than that though or however much higher. I'm sure Eagle structural integrity is beyond that of a normal modern rod that is NOT designed to travel faster than the 4000FPM. If I wanted to stay at the 4000FPM mark though you are correct I would need to stay at about 7340rpm multiplied by 3.27" stroke devided by 6 which would equal 4000.3 FPM. (for those that dont want to do the math)

            However now I have to take into consideration the weight of the pistons like you mentioned. BUT considering that JE are some of the lightest pistons in the forged industry I have a feeling that it will be ok. Still want to make sure though before I destroy an engine from ignorance or from being to lazy to find out 100%. ops:

            But , back on topic. I would think that the valve train would handle at least the 8500 but again just want to be sure is all.
            85 Z31 6.0 LSX turbo 766whp/792wtq
            04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

            Comment


            • #7
              Well, once it is built, i would like to hear it up to 8500.

              And set it as my cell phone ringtone

              Terrible idea putting those wheels on...

              Comment


              • #8
                MrwassmanNA2T wrote: Well, once it is built, i would like to hear it up to 8500.

                And set it as my cell phone ringtone
                It is built. Just gotta break it in which is proving to be pretty hard in CO lately. with 2 feet of snow and all.
                85 Z31 6.0 LSX turbo 766whp/792wtq
                04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

                Comment


                • #9

                  Comment


                  • #10
                    Yo Satan - Since your ass is snowed in the more northern Part of the Rocky Moutains that I love and you can't do shite..hehehe.(talked to some buddies up their and they're not loving it).

                    I'm looking @ the same set of Valve springs and I'm going with Ti retainers, I wonder if the JWT set has any inherint advantages over the schnieders??? I just want the *best* within reason if I'm gonna spend this much on a freaking interference engine! As for reving, I think 9K would be a reasonable redline with Carillo rods and BRC pistons but we'll c if my engine is making real power @ 9k. All the kids nowdays wanna redline to 10K but how many are making any power @ that RPM even if they acomplished said redline.


                    As for your pistons, Do those JE's even have the proper valve cuts for the SOHC VG or are they the shelf pistons for the VG30DETT??
                    Ucked Fup!!!

                    Comment


                    • #11
                      VG36ET wrote: Yo Satan - Since your ass is snowed in the more northern Part of the Rocky Moutains that I love and you can't do shite..hehehe.(talked to some buddies up their and they're not loving it).

                      I'm looking @ the same set of Valve springs and I'm going with Ti retainers, I wonder if the JWT set has any inherint advantages over the schnieders??? I just want the *best* within reason if I'm gonna spend this much on a freaking interference engine! As for reving, I think 9K would be a reasonable redline with Carillo rods and BRC pistons but we'll c if my engine is making real power @ 9k. All the kids nowdays wanna redline to 10K but how many are making any power @ that RPM even if they acomplished said redline.


                      As for your pistons, Do those JE's even have the proper valve cuts for the SOHC VG or are they the shelf pistons for the VG30DETT??
                      They are the off the shelf pistons. I'm not too concerned.

                      Carillo rods and BRC pistons are good for taking a beating but what is the tensile strength of that rod? It can handle the compressive loads sure but what about the rod being torn apart from the high rpms?

                      Are you wondering about the JWT springs being better than the Schneider springs or the retainers? Schneider didnt make retainers for my engine when I bought my cams. not sure that they do now either.

                      The seat pressure on the Schneider springs is 110lbs closed and 240lbs at .500" of lift. the JWT spring offer a mere 61lbs and 71lbs if you use the stock nissan inner spring. JWT springs suck they are a whopping 7lbs more than the stock setup. Even JWT coupled with the nissan inner spring sucks. That and you have to use a shim with the JWT springs.

                      Schneider uses two springs to help with spring surge or in other words to fight the resonate frequency of the spring itself.

                      zmech- I gotta give them a call anyways as soon as they open to see what can be done about my cams being out of spec as far as they are. I appriciate the offer though.
                      85 Z31 6.0 LSX turbo 766whp/792wtq
                      04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

                      Comment


                      • #12
                        SATAN wrote: The seat pressure on the Schneider springs is 110lbs closed and 240lbs at .500" of lift. the JWT spring offer a mere 61lbs and 71lbs if you use the stock nissan inner spring. JWT springs suck they are a whopping 7lbs more than the stock setup. Even JWT coupled with the nissan inner spring sucks. That and you have to use a shim with the JWT springs.

                        Schneider uses two springs to help with spring surge or in other words to fight the resonate frequency of the spring itself.
                        Let's say you disregard piston speed and inertial load (I could calculate it again but with my combination I was seeing astronomical numbers above 7500rpm)... just for the sake of discussion.

                        I think you're not paying attention to the "harmonic tuned" aspect of the JWT springs. Double spring setups are needed to fight the dramatic rate drop you get when you hit a spring's resonant frequency, as you obviously know. If you tune the spring frequency to be outside of the operating frequency range of the valvetrain/engine then you don't need as much seat pressure and open pressure from spring rate because the resonant frequencies that make those pressures necessesary are not encountered. If you ask Jim about this he will give you a lot of talk about the work they had to do to develop those springs (to justify the additional cost). FYI the JWT shims replace the stock shims (which are thicker), while schneider uses the stock shims, and popping a stock shim under the JWT spring and shim will mean a higher seat pressure yet and I don't believe you would hit coil bind until over .500" valve lift even shimmed.

                        I'm not by any means saying that JWT springs are better than schneiders, but they (JWT) will insist they are.

                        I believe 'Ken in AZ' ran good condition stock valve springs with a similar grind, to 7K RPM without valve float. I have spun my engine (JWT springs) to 7500rpm with 270-62H grind cams. My pistons have no valve reliefs and are simple dish style in 8.5:1 compression. The only concerns I have about that kind of sustained RPM are:
                        1. the oil pump; volume and integrity
                        2. the CAS/distributor; relating to ignition precision

                        You obviously dont have a problem with the second one as you are using a hall effect sensor and coilpacks, right? But how about the oil pump? How about water pump cavitation? How about throwing rotor windings into the stator on your alternator? How about the clutch disc lining? I could go on like this, but who really knows? Fact is you're one of the very few people to actually bother investing enough time and money into a SOHC VG to actually make it live up to its potiential, and you may be the only one here to find out.

                        Comment


                        • #13
                          Jason84NA2T wrote: I think you're not paying attention to the "harmonic tuned" aspect of the JWT springs. Double spring setups are needed to fight the dramatic rate drop you get when you hit a spring's resonant frequency, as you obviously know. If you tune the spring frequency to be outside of the operating frequency range of the valvetrain/engine then you don't need as much seat pressure and open pressure from spring rate because the resonant frequencies that make those pressures necessesary are not encountered.
                          This is from that web site I posted up a while ago.

                          "The frequency that sends a valve spring into
                          surge does not have to be the exact resonate
                          frequency of the spring. A frequency 1/2 or 2 times
                          the frequency can aggravate it also, so building a
                          spring that has the resonate frequency higher than
                          the rpm range of the engine is not always an option,
                          so other means must be taken to dampen the
                          vibrations."

                          So just because they engineer the spring to resonate at say 10k rpm (which most would never hit in a SOHC VG) Doesnt mean that 5k rpm wouldnt get it to start resonating.

                          So when Jim shoves crap down your throat about how great his shop is and how great they are, keep in mind its only natural to talk great about yourself. I am truely NOT impressed with JWT due to the fact that they have been slipping lately. Meaning they have not improved much as of late. I used to think they were the shit AND they used to be the shit! Not anymore.

                          You said that I am one of the only ones that is going this far, so far. That is the scary part because I am not made of money so for me to "guess" at somthing could be a costly mistake on my part. Assumtion is the mother of all fuck-ups ops:

                          You also bring up good points about the oil pump not to mention wrapping it up that high would most likley foam the oil also. As for the cavitation in the water pump from it spinning that fast, that was somthing I completely over looked. Just didnt even think about it until you mentioned it. But, thats why I post about these things here. An engine is a complex machine to improve on. This is why car companies have TEAMS of engineers not just ONE. So I do appriciate the input.
                          85 Z31 6.0 LSX turbo 766whp/792wtq
                          04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

                          Comment


                          • #14
                            remember they make a special oil pump (nismo?) for high revving engines..

                            http://www.courtesyparts.com/Merchant2/ ... 9996-V1010

                            pretty cheap too! :lol:

                            you can do an electric water pump or some type of underdrive pulley for that cavitation crap you guys were talking about . but im sure you already knew that...

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                            • #15
                              i have revved mine to at least 8k w/o total distruction. sch stage I cams and sch springs. stock n/a motor.

                              i didn`t mean to do this, throttle stuck when racing

                              Exercising my constitutional right to be awesome

                              1.5.2. Podium winning cars do NOT need to be running at the checkered flag
                              good thing....

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