Stock bottom end: What'll break first?
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Stock bottom end: What'll break first? Hey, this might/ probably has been answered but I cant seem to find anything...
Background:
I'm getting a used 12 bolt with 4.11s and in the 1/4 mile ill be a little above 6K RPM (redline), i could stay in 4th and run it up to 6,400 rpm give or take, or shift into 5th (time wise roll through the finish)
*What will be the first part to break on a SI LS1 and at what RPM will it break?
*Second part/ RPM?
*Third part/ RPM?
THANKS
EDIT: What parts will break on to stock motor, top end, bottom end, anything
Background:
I'm getting a used 12 bolt with 4.11s and in the 1/4 mile ill be a little above 6K RPM (redline), i could stay in 4th and run it up to 6,400 rpm give or take, or shift into 5th (time wise roll through the finish)
*What will be the first part to break on a SI LS1 and at what RPM will it break?
*Second part/ RPM?
*Third part/ RPM?
THANKS
EDIT: What parts will break on to stock motor, top end, bottom end, anything
Last edited by greatskiiiier; Dec 19, 2008 at 03:47 PM.
Do you have valvesprings/pushrods? 6400 is only 200rpm more than stock rev limit, you shouldnt have a problem. A pushrod will let go before anything else. Stock bottom end is pretty reliable.
One of my old motors dropped a valve and broke a piston, which broke another rod @ 6800. The rod is still connected to the crank and turns freely, with stock rod bolts still. I raced it like that shifting @ 6800 for 2 years, cam only car. i'd say bottom end on what you want to do will be fine forever
One of my old motors dropped a valve and broke a piston, which broke another rod @ 6800. The rod is still connected to the crank and turns freely, with stock rod bolts still. I raced it like that shifting @ 6800 for 2 years, cam only car. i'd say bottom end on what you want to do will be fine forever
If the top end is good for high rpm say ~6,800 to 7,000 rpm, the weak link is often the 97-00 stock rod bolts. They will last for a while over 6,500 rpm and usually last for a long time under 6,500 rpm.
If your not exceeding 6250rpm, then i would say pushrod first. The stock springs tend to float when you start pushing a higher rpm above the limiter, that second. Third is rod bolts like posted above. Having a t56, your more likely to bend you 3-4 fork before you bust a rod bolt if you have a stock t56. Just my .02
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bottom end can take a beating, even though running the stock cam out to 6400 RPM isnt going to do so much. maybe shifting at 5500 rpm and going in thru 5th would be better. im not sure but power drops sharply after 5500 and like was said springs will start to float.
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I agree with that.
How much power are we talikng about? RPMs(6500+) can snap a rod bolt pretty quick with little power but if you are keeping it in the low rpms then you will need 500+whp to break anything in the bottom end. There are a million different ways to kill a motor, you could lean out hard with 300hp and destroy a forged motor. I say screw it though and just drive it til it breaks
