Mojave

iTrader: (4)

The LT4 in my C4 exploded last month, and the entire bottom end is trashed. I'm working on putting together a new motor. I dropped my LT4 heads and intake off at Lloyd Elliot's to get fixed/ported. I was planning on freshening up a stock bottom end, and putting my top end on it.

What is the max safe RPM for a stock bottom end? I will have it balanced, with fresh bearings/rings/etc, hopefully with stock pistons/rods. ARP rod bolts and main bolts. The car will be used for road racing/auto-x, and will see extended times of WOT at high rpms. The front straight at my local track (Texas World Speeday) is close to 1/2 mile long, and I will be WOT above 4K rpms the entire time. My heads/cam package will peak about 6300 rpm, so shift at 6400 and rev limiter at 6500.

Is this too high? Anything else I should do to the bottom end to ensure a long and happy life?

matt94z

iTrader: (49)

With arp rod bolts, spin that that bitch as high as you want.

Revelation Z28

iTrader: (10)

as long as you have good pressure, and valve springs, i dont see why you cant go to 6500-6800. besides the rod bolts. how many liles are on the rotating assembly?

BOLO

iTrader: (40)

I remember talking to Geoff @ Thunder Racing over the phone about my LT1. He said even the stock bottomend is capable of spinning to 7000 rpm if tuned properly.
Right now my shift points are @6500 rpm,limiter set @6900. and still stockbottomend.
So, you shouldn't have any problem w/ your new set up. Good luck.

Mojave

iTrader: (4)

LE is picking the springs, but he said the springs are well up to the task of the cam he spec'ed, so they should be good. I have no idea how many miles are on the rotating assembly, but the machine shop will check everything out before putting it all back together.

Revelation Z28

iTrader: (10)

yea, with a set of rod bolts, a refreshed bottom end with good oil pressure will survive to 7000rpm.

3pnt4maro

iTrader: (2)

i went on the safe side when i tuned mine and set my shift points at 5800 rpm and the redline at 6000 and that was a bad idea...the setup i have spins through it way too fast and hits the rev limiter before the computer can shift the gear...so i need to bump mine up so i can make full use of the powerband..

gatorhead

iTrader: (4)

I don't see where the tune would have anything to do with the distortion of the rod caps and bearings. Thats what happens when you over rev and stack a bearing. The ARP hardware helps you out a great deal, but you have to keep in mind that the factory clearances are really tight and not much oil coats the bearings sooo.... if you can open them up a bit then I would tend to agree with the additional clearance and the ARP hardware you should be safe to 68-- RPM. That is the max I would ever push a non forged bottom end to, but thats just my .02.

speed_demon24

iTrader: (6)

If you are getting detonation it will have everything to do with that.

wrd1972

iTrader: (12)

Built right with decent components it will rev safely just shy of 7K RPM.

Razor_Blade

iTrader: (8)

Sounds like fun!

GIZMO

iTrader: (8)

I would suggest installing a set of light weight forged rods. I have had pretty good luck turning the stock rods to high rpm, but have also had them fail due to valvetrain failures. With forged rods I have only had to replace one rod, versus the entire short block.

Good Luck,

Daren

Mojave

iTrader: (4)

Thanks for all the info, guys. I need to get my short block to the machine shop and get it checked out before going any further.

gatorhead

iTrader: (4)

Touche'

I was referring more at the post stating with a proper tune being able to spin 7k. Aside from detonation issues I stand by what I posted up earlier.