onfire

iTrader: (17)

How far can you take the stock crank with a built bottom end. If you added forged pistons, rods, hd bearings,etc and balanced everything how nitrous friendly would it be?? OK to 600rwhp???TIA

bigSS

I recall that 600rwhp is about the limit of the stock crank. I personally wouldn't exceed 600.

y2khawk

iTrader: (5)

[quote]Originally posted by bigSS:
<strong>I recall that 600rwhp is about the limit of the stock crank. I personally wouldn't exceed 600.</strong><hr></blockquote>

I presonally haven't seen/heard of anyone breaking a crank yet.

Should know how mine has held up journal wise when it comes apart in a month or so.

I'm not planning on anything but a stock crank for my buildup, 800+ RWHP is the goal

Crazyquik

RPM level would make a difference as well wouldn't it? I'd suspect the crank would hold up better at 600 rwhp@6500 rpm vs 600 rwhp@8000 rpm.

J.

Ted J

iTrader: (4)

[quote]Originally posted by y2khawk:
<strong>I presonally haven't seen/heard of anyone breaking a crank yet.
</strong><hr></blockquote>

Breadking the crank aside, what about the crank flexing under high loads and that robbing some ponies?

I don't know how strong the stock crank is but I recall hearing some people talking about it's not always if the crank breaks or not but rather if it's flexing. Just a thought though.

Ted

Nick Agostino

We have made over 700rwhp through a t-400 and 9inch on slicks, about 750rwhp in an M6!! The engine was torn down and checked for any kind of failure, none was found. We put it back together and its still running strong.

One of the last things to worry about in the Ls1

onfire

iTrader: (17)

Thanks for all of the responses. Also, a special thanks to Nick for some "hands on" feedback....it's great to get some feedback from a tuner! It's time to make some hp decisions now. <img src="gr_grin.gif" border="0">

[ January 18, 2002: Message edited by: onfire ]</p>

ls1fun

Someone (99Redhawk) actually blew his motor up on nitrous and disintegrated some pistons and bent all the rods. The crank held up! <img src="gr_eek2.gif" border="0">

Bad Habit Bird

iTrader: (12)

99redhawk was making 650 rwhp on the dyno with his n2o setup. Actually the day he blew his motor up he went to the track wanting to blow his motor up, just some FYI <img src="gr_images/icons/wink.gif" border="0">

bigSS

Ok, its it RWHP that matters, or is it RWTQ?? And I would also like to know more about RPMs too.

LS1derfull

Crazy Quick, you are right about cranks. Here are some more facts:RPM kills crank more than power going thru it does, this is mostly because of the exhaust stroke doesnt have much resistance to piston and rod as they come up and change direction. Think of this as like hyper extending your arm from its socket. Also cranks break from flexing,(and vibrations also)GM uses nodular iron crank for ls1, this is not all bad, iron doesnt flex as easy as steel which this rigidity is irons positive, now steel can handle flexing better with out breaking thats why its preffered in racing. I cryoaged a 400 small block cast crank
that put out 636hp, shifted motor at 8000 rpm in a bracket race car for many years. When i finally retired that crank it was cracked, but it ran that way and never failed. GM tightened LS1 bearing clearances in end of 2000 this improves crank strength by leaving less room for flex.
I know this is a lot of reading but i hope it helps some people.