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RPM limits.....

This is a discussion on RPM limits..... within the Internal Engine forums, part of the LSx Technical Help Section category; Ok I'm looking to get this question answered for a friend of mine... What would you trust a stock rotating ...

  1. #1
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    RPM limits.....

    Ok I'm looking to get this question answered for a friend of mine... What would you trust a stock rotating assy out of a '99 ls1 from a T/A to spin too? If you need any info on the motor let me know.... Thanks in advance!!

  2. #2
    cutting and welding mark21742's Avatar
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    Quote Originally Posted by F-BodyBlur View Post
    Ok I'm looking to get this question answered for a friend of mine... What would you trust a stock rotating assy out of a '99 ls1 from a T/A to spin too? If you need any info on the motor let me know.... Thanks in advance!!
    more than likely unless you go completely outragious the valve train will max out before the lower end.

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    cutting and welding mark21742's Avatar
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    hugger orange
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    here is a thread from awhile back, hope it helpshttp://www.ls1.com/forums/showthread.php?t=10843

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    Junior Member Khaotic's Avatar
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    max out

    Mark21742 has it right valve train will max out before bottom end, in most cases on a dyno you will see the stock cam max out around 5200rpm

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    Valve train has already been upgraded along with the cam. Problem is that the motor is still pulling hard at 6100 rpms and he is shifting before is powerband is done

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    Firebird Encyclopedia 9T8W66's Avatar
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    Early `97-99 LS1's have weaker rod bolts so I wouldn't go much past 6500 rpm.
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    cutting and welding mark21742's Avatar
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    Quote Originally Posted by 9T8W66 View Post
    Early `97-99 LS1's have weaker rod bolts so I wouldn't go much past 6500 rpm.
    If i'm right these are still the weak point on the newer motors too...but nothing a set of ARP bolts cant fix

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    Firebird Encyclopedia 9T8W66's Avatar
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    Quote Originally Posted by mark21742 View Post
    If i'm right these are still the weak point on the newer motors too...but nothing a set of ARP bolts cant fix
    From my Understanding there was a Rod bolt change after some ASA Engines were having problems so GM changed how they were manufactured. And starting in `01 (or maybe earlier) All engines had the Better Rod Bolts.
    I do Agree though Put some ARP's on and be done with it.

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    Thanks for the help guys

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    TunedbyFrost.com Tuner Frost's Avatar
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    the 98 rod bolts are considered to be the weakest year-wise. From 99-up I will let them spin as high as about 6800 if the setup dictates, but no need to spin it past where it is making power. Honestly, your post lacks much of what is needed to answer your question though. You would get better answers if you had more detail.

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    Quote Originally Posted by Frost View Post
    the 98 rod bolts are considered to be the weakest year-wise. From 99-up I will let them spin as high as about 6800 if the setup dictates, but no need to spin it past where it is making power. Honestly, your post lacks much of what is needed to answer your question though. You would get better answers if you had more detail.
    Let me know what you want to know or need to know. I'm new to LSx motors and GM in general... I've been a Ford guy for years and decided to try something different.

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    TunedbyFrost.com Tuner Frost's Avatar
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    Are you asking what a particular setup should spin to, or just what is the max RPM you can get away with spinning a stock rotating assembly?

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    cutting and welding mark21742's Avatar
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    Quote Originally Posted by Frost View Post
    Are you asking what a particular setup should spin to, or just what is the max RPM you can get away with spinning a stock rotating assembly?
    sounds to me like he is asking what a stock one would spin to

  14. #14
    TunedbyFrost.com Tuner Frost's Avatar
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    stock rotating assembly after 98: 6800 for safety
    stock rotating assembly with ARP rod bolts: 7200 for safety
    stock valvetrain: floats around 6200ish

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    Quote Originally Posted by Frost View Post
    stock rotating assembly after 98: 6800 for safety
    stock rotating assembly with ARP rod bolts: 7200 for safety
    stock valvetrain: floats around 6200ish
    Thanks!!! This is all I needed to know. We've already replaced the ENTIRE valve train with the proper parts to hold up to the rpm we are wanting to spin

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    Senior Member INMY01TA's Avatar
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    Rev limiter on my 01 is set to 7,000. I like to live on the edge.

  17. #17
    I don't sell out! blackSS01's Avatar
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    Am I the only one that spins mine to just 5,200 rpms. Going any higher, doesn't help the SOTP Dyno to me.
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    I raced my 99 all the time and spun it to 7400 w/ comp cam and comp springs.Way past the point were it made any power,but it didn't seem to care, took motor apart after 45,000 very,very hard miles,proubly 20,000 race miles, and everything looked great(wish i would have left it together). Dont be afraid to spin that thing up, find out what it likes goin through the traps. sometimes runing a steeper rear gear to help 60' times and let it hang its tongue out going through the lights will net you better times.

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    Senior Member INMY01TA's Avatar
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    Quote Originally Posted by blackSS01 View Post
    Am I the only one that spins mine to just 5,200 rpms. Going any higher, doesn't help the SOTP Dyno to me.
    Ya take it to a track and see how it does shifting at 5,200.

  20. #20
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    Quote Originally Posted by blackSS01 View Post
    Am I the only one that spins mine to just 5,200 rpms. Going any higher, doesn't help the SOTP Dyno to me.
    yes, you are the only one. this is exactly why SOTP is the world's worst dyno:

    your body cannot sense certain things, like temperature. you can feel a room temperature piece of metal and it feels cool because of its high thermal conductivity and low specific heat, then feel a room temperature wooden dowel and it feels like "room temperature." but they are both actually room temperature. your body simply is not a good judge of some things.

    it also cannot sense speed; it can only sense changes in speed. there are two different measurements that deal with changing speed: acceleration and momentum. acceleration is purely the rate of change of the velocity. your body cannot detect this with any accuracy. what you experience when your car accelerates is the change in momentum. in a heavy vehicle, you feel more "acceleration" than in a light one. ride in my car and it will feel slower than a bolt-ons F-body. it's lighter enough that its momentum changes less rapidly than does the heavier F-body. but change in momentum does not have a direct correlation to the car's acceleration. hence, my lightweight car whips a similarly-modded F-body by quite a lot.

    i don't know if i made that clear enough, but if you tell me you don't understand i'll come up with another way to explain it. SOTP = for the lose.

    better: not just peak HP, but use area under the curve. plot your shift points onto your dyno sheet, and take area under curve. that's why shorter gears often net faster cars in the 1/4, and top end power rules there as well. InTeGrAtIoN . . . AHHH calculus!!!!! run!
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