How much do you guys rev?

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  • SATAN
    SATAN
    Senior Member
    • 6782
    #31
    jjewell wrote: some have talked about the heads and intake being the rpm bottleneck. what is safe for the factory bottom end? 7500-8000? what would it take to have a solid 7500rpm shift point?
    I would say safe for a stock vg30 bottom end is 7500 max sustained. this will give you a piston speed of 4087.5 FPM.

    piston speed in feet per minute = stroke in inches x rpm/6

    generally the piston on a modern stock(OEM internals) engine should not move faster than around 4000 feet per minute. So ive read.

    To have a solid 7500 shift point would require porting, cams and springs. Maybe not REQUIRE cams but…
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20… underway for summertime daily driver.
  • jjewell
    jjewell
    Senior Member
    • 402
    #32
    [quote]SATAN wrote:
    Originally posted by jjewell
    some have talked about the heads and intake being the rpm bottleneck. what is safe for the factory bottom end? 7500-8000? what would it take to have a solid 7500rpm shift point?
    I would say safe for a stock vg30 bottom end is 7500 max sustained. this will give you a piston speed of 4087.5 FPM.

    piston speed in feet per minute = stroke in inches x rpm/6

    generally the piston on a modern stock(OEM internals) engine should not move faster than around 4000 feet per minute. So ive read.

    To have a solid 7500 shift point would require porting, cams and springs. Maybe not REQUIRE cams but…
    i'm already in the process of building a set of heads this winter. the only things i haven't gotten yet are the cams and valve springs, i just need to figure out which grind i want to use. as far as springs go i think i'm going to use the scheider outers with new factory nissan inners.


    boost. does a body good!
  • SATAN
    SATAN
    Senior Member
    • 6782
    #33
    [quote]jjewell wrote: [quote=SATAN]
    Originally posted by jjewell
    some have talked about the heads and intake being the rpm bottleneck. what is safe for the factory bottom end? 7500-8000? what would it take to have a solid 7500rpm shift point?
    I would say safe for a stock vg30 bottom end is 7500 max sustained. this will give you a piston speed of 4087.5 FPM.

    piston speed in feet per minute = stroke in inches x rpm/6

    generally the piston on a modern stock(OEM internals) engine should not move faster than around 4000 feet per minute. So ive read.

    To have a solid 7500 shift point would require porting, cams and springs. Maybe not REQUIRE cams but…

    i'm already in the process of building a set of heads this winter. the only things i haven't gotten yet are the cams and valve springs, i just need to figure out which grind i want to use. as far as springs go i think i'm going to use the scheider outers with new factory nissan inners.
    Can you buy the schneider springs without the inners? If not why would you pull the inners and use stock inners? That would lower the pressure
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20… underway for summertime daily driver.
  • jjewell
    jjewell
    Senior Member
    • 402
    #34
    [quote]SATAN wrote: [quote=jjewell][quote=SATAN]
    Originally posted by jjewell
    some have talked about the heads and intake being the rpm bottleneck. what is safe for the factory bottom end? 7500-8000? what would it take to have a solid 7500rpm shift point?
    I would say safe for a stock vg30 bottom end is 7500 max sustained. this will give you a piston speed of 4087.5 FPM.

    piston speed in feet per minute = stroke in inches x rpm/6

    generally the piston on a modern stock(OEM internals) engine should not move faster than around 4000 feet per minute. So ive read.

    To have a solid 7500 shift point would require porting, cams and springs. Maybe not REQUIRE cams but…

    i'm already in the process of building a set of heads this winter. the only things i haven't gotten yet are the cams and valve springs, i just need to figure out which grind i want to use. as far as springs go i think i'm going to use the scheider outers with new factory nissan inners.
    Can you buy the schneider springs without the inners? If not why would you pull the inners and use stock inners? That would lower the pressure
    i thought the schneider springs were only the outer if it's a set with both i won't split it up. i haven't done a whole lot of research on this yet so i still have some things to figure out.


    boost. does a body good!
  • Elliott
    Elliott
    Senior Member
    • 103
    #35
    The Schneider springs are both inner and outer. You're probably thinking of the JWT springs, which are outer only.
    Attached Files
    • 20140807_141234.jpg (90.5 KB)
    • insideintake.jpg (94.1 KB)
    • toppieces.jpg (91.3 KB)
    • toppieces2.jpg (96.2 KB)
  • JK
    JK
    Senior Member
    • 117
    #36
    Things that affect how far you can spin the engine would be piston speed (ring flutter), and crank flex at high rev's and even the journal size on the crank. But the weakest link on this engine is the valve train. With the correct valve springs (read: nose pressure on cam) this engine should mechanically be able to spin to 7500-8000.

    That being said what will prevent you from reaching these numbers is airflow, or in other words, the car is to heavy and the hp is not adequate. On a NA the heads don't flow enough air and you have a severe plenum restriction.
    On the turbo, just pump up the boost, if you got it, and deal with the plenum restriction. Peak HP should reach ~7300+ for shifting points above 7500.
    For those with deep pockets (none of us here) it is called 'destructive testing'. lower the gearing and spin it till she yields.
    Speaking for us cheap bastards, we can just sit back and wait until Satan tells us what breaks first. Just my opinion of course.
  • Steve88t
    Steve88t
    Senior Member
    • 1337
    #37
    JK wrote: For those with deep pockets (none of us here) it is called 'destructive testing'. lower the gearing and spin it till she yields.
    Obso did just that a few years ago. Lets say it was over 8k for some time before letting go. I would like to see a stock engine with cams/springs turned up till it wont go any further.
    http://z31performance.com/forum/viewtopic.php?f=5&t=147
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