What is the REAL rev limit for LS! engines?
08-23-2009, 10:13 PM
#1
Drifting
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What is the REAL rev limit for LS! engines?
We all know the factory sets our rev limiter to around 6000. What is real rev limit for a stock LS1 engine. When is she gonna blow???
08-23-2009, 10:29 PM
#2
Pro
every motor is different -
While idling -
floor it and when you hear a knocking sound, or worse (NO SOUND) ... you know you found it
OR
While Driving -
try shifting into 1st at 75 mph and let the clutch out, about 15,000 RPMs should be about right
ps - the above drivers are (NOT) professionals - don't try this at home unless huge amounts of cash is accessible
While idling -
floor it and when you hear a knocking sound, or worse (NO SOUND) ... you know you found it
OR
While Driving -
try shifting into 1st at 75 mph and let the clutch out, about 15,000 RPMs should be about right
ps - the above drivers are (NOT) professionals - don't try this at home unless huge amounts of cash is accessible
08-24-2009, 10:32 AM
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Don't know about you, but when my car showed the shift light (manual tranny), I did just that. 
08-25-2009, 04:08 PM
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08-25-2009, 05:48 PM
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08-25-2009, 05:53 PM
#11
Le Mans Master
08-25-2009, 05:58 PM
#12
Racer
I have mine set at 7200rpm. I usually shift at around 7k and run it up that high even time im at the track. Cant see the motor taking much more than that and i feel im on borrowed time as it is! I will be changing rod bolts soon.
08-25-2009, 06:05 PM
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08-25-2009, 09:14 PM
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My current limt is set at 6800, turned down a little 7k just scared me alot. I shift at the track (Drag race) at 6300 current setup flattens out at 62ish. When my motor was stock I turned 6500 many times...
08-26-2009, 02:14 AM
#19
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The time you lose in the shift could be lessened by making up for it in RPMs. If you shift later before you hit the rev-limiter, (assuming you're driving a manual) you will see higher RPMs on the return which will equal out to a higher point of the power band.
08-26-2009, 07:13 AM
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one of the things with too high a red line is valve float. Valves do not completely close and power is lost.
with the Stock LS1 and LS1 springs the current red line
with the LS6, stock cam and springs the engine was tested at 6900 rpms for 100 continuous hours and no problems.
with the LS1 or LS6 could run high red lines with the proper valve train.
the other thing is the LS6 as well as the Fast manifolds were designed for peek HP at 6300 rpms, and peak torque at 4800 rpms.
Dont remember the source
One could push that peek hp up slightly with a tighter LSA cam, 110-108. or even to 106 to push the peak hp up close to 6900 rpms. Is it worth it as the engine will loose low end.
Yes as one person mentioned above many times leaving the car in 4th and running the rpms up vs shifting to 5th only to downshift 75 ft latter has its advantages.
my redline is 6750 with peek hp at 6300. and I shift at 6600-6500. Having a few extra rpms above peek hp can help. When you do shift, in most cases the engine will drop 1500 rpms and then pull up to peek hp again.
To my understanding to run high redline and rpms, keeping the valve train as light as possible, an valve lift under .600 even well under .600 extends valve train life.
Most of the high rpms engines 6800-7300 rpms use the GM cup cam, or the engines that I am aware of.
239/251 570/570 106LSA
with the Stock LS1 and LS1 springs the current red line
with the LS6, stock cam and springs the engine was tested at 6900 rpms for 100 continuous hours and no problems.
with the LS1 or LS6 could run high red lines with the proper valve train.
the other thing is the LS6 as well as the Fast manifolds were designed for peek HP at 6300 rpms, and peak torque at 4800 rpms.
FAST LSX90 restricts the peak RPM to 6300. Set up a cam for a 7200 peak, and guess what, it still peaks at 6300 because of the manifold. It'll carry the power out to 7200, but you don't gain much. The difference is, you lose a lot before 5k RPM because the cam is not designed for low RPMs. Also, every single LS1 has peak torque at 4800rpm. That's because of manifold design. Work with the manifold, not against it.
One could push that peek hp up slightly with a tighter LSA cam, 110-108. or even to 106 to push the peak hp up close to 6900 rpms. Is it worth it as the engine will loose low end.
Yes as one person mentioned above many times leaving the car in 4th and running the rpms up vs shifting to 5th only to downshift 75 ft latter has its advantages.
my redline is 6750 with peek hp at 6300. and I shift at 6600-6500. Having a few extra rpms above peek hp can help. When you do shift, in most cases the engine will drop 1500 rpms and then pull up to peek hp again.
To my understanding to run high redline and rpms, keeping the valve train as light as possible, an valve lift under .600 even well under .600 extends valve train life.
Most of the high rpms engines 6800-7300 rpms use the GM cup cam, or the engines that I am aware of.
239/251 570/570 106LSA
Last edited by AU N EGL; 08-26-2009 at 07:15 AM.
