SteveJewels

LS3 red line is 6,600 RPM. What would need to be changed to be able to spin it to 7,000 or 7,200 RPM?

Z28SteveA4

iTrader: (16)

Are you talking about spinning a stock ls3 higher then 6600 rpms? I’m guessing an automatic?

SteveJewels

Yes, it is a 2010 Corvette. Originally an A6 trans but it was changed to a fully built 4L65/70e.

KW Baraka

iTrader: (7)

Better than stock valve springs will allow you to spin the engine higher.

But it's pointless because you won't be making more power. HP levels with the stock cam falls off by 6000 rpms.

KW

SteveJewels

Z28SteveA4

iTrader: (16)

So you have that cam installed already?? Any other mods done to the engine?

SteveJewels

Yes, that cam is in.

Trunnion kit and springs. I did not have the cam and springs installed so I don't know what they are.

I have a set of Yella Terra Ultralite twin shaft rockers to install. If there is something else to improve the valve train I might do it when I change the rockers. I am thinking about having the heads ported but I will probably wait on that.

Che70velle

iTrader: (6)

You do not need To port the heads. LS3 castings flow mega air and don’t need ported except in extreme max-effort builds. Your thread topic asks what limits RPM? RPM is limited by airflow and /or a rev-limiter device. That’s it. Get the air in the cylinder, and get it out of the cylinder. 7k rpm isn’t a big deal these days in the pushrod world. Valves have to be controlled with the correct springs...this is a must...and you’ll need a camshaft capable of getting it there. The LS3 intake manifold is very good in raw form, but there are porting and radius rod mods that help it a lot. The intake tract in front of the manifold needs to be as restriction free as possible, and a 102mm throttle body will help also. Nothing wrong with the latest version of YT rockers, just make sure your springs are specced for the addition nose weight from the YT’s. It’s roughly 10 grams...I’ve weighed them.
Are you looking for a power goal, or do you just want to turn rpm regardless?

SteveJewels

@Chev70elle

Thanks for the helpful reply.

The card for my cam is in post #5.

Not necessarily looking to make a specific number. As long as I am opening it up to replace the rockers I wanted to see if there was anything else I should do. I plan to rebuild the bottom end next year with forged internals and want the heads, valve train and intake to go with it. If there is something relatively easy to do while I am in there and it will let me spin the engine safely, higher or not, I may do it.

I didn't have the cam installed, bought it that way, so I don't know what the springs are. I assume they went with what Comp Cams recommended for that cam. I sent Comp Cams an email asking what the recommended spring rate would be.

I will port the intake and open the mouth to accommodate a Soler TB opened up to 102 mm and do the rod mod. I have a plan for reinforcing the intake manifold after removing the pillars since I am running a CSC.

I would not have know about the additional nose weight of the YT Ultralite rockers. It would never have occurred to me. Thanks!

How much additional spring rate is needed to compensate for that?

Che70velle

iTrader: (6)

Are you planning on living at 7k, as in a mile event or similar, or just an occasional blast to 7k? The truth is, your stock bottom end is tough. Currently, the latest stock bottom end LS3 record is something well north of 8k, and iirc 825ish hp. So unless your building a land speed record type build, the forged bottom end isn’t really necessary. I can’t say I’ve ever seen a build that was built for rpm, without a certain hp goal.
Your in a pickle per say, not knowing what valve spring you have. Pull a cover and let us know if the springs are beehive or duals. If beehive, are they colored? If duals, maybe a name or part number on a retainer. Again, 7k isn’t crazy these days, just depends if you want to blip to 7k or live there.

rpturbo

iTrader: (47)

I wouldn't call it a pickle, but I get what is being said. If it were mine, I'd just buy and swap the springs, retainers and keepers. The small cost of new springs and keepers vs possible trashing a LS3 is a no brainier. Besides, valve springs have a life span. They loose seat pressure and control after events. They are not as easily trashed as they once were, but on a track car, it's best practice to replace the springs every year or 2, depending on use, rpm ect. JMO

SteveJewels

I won't be living at 7k, probably not there very often. My avatar is from the previous owner. I am looking more for insurance, to know that I that I can turn it up with impunity if I want to.

825ish WHP? Not for me, not on a sbe. I want to build a forged bottom end but I don't what to have to build a forged bottom end. If I can run it a year or two on the sbe, that would be just fine.

I am hoping I can do as you say and identify the springs by sight. Worst case I can pull one and measure it. Might not be a bad idea anyway. I would rather wait until I get some head work done to the the spring and do valves at the same time.

Thanks @Che70velle ! and @rpturbo !

Darth_V8r

iTrader: (4)

Is that like - I want you to WANT to wear thirty pieces of flare....

TurboBuick6

iTrader: (2)

Cam, Springs, Pushrods and a trunion kit. Nothing else is needed internally. Sell the rockers and use those funds for the previous parts you don not have, if any.

Bob570

There's no reason to build the bottom end unless you plan on spinning it to the moon, plan on adding a LOT of boost, or you want to increase displacement. From a reliability standpoint, all you need to spin to 7k is the right valve spring and you're set.

ddnspider

iTrader: (26)

Yessssssssss. I'm going to need you to move your office down to the basement.

grubinski

Part of my unofficial mentoring of younger guys before I retired was to make sure they watched this movie. Some of the younger generation are unaware of it. That won't do. :-)

ddnspider

iTrader: (26)

I can't tell you how many people, even corporate managers haven't seen it. It should pretty much be required watching when you are hired.

Darth_V8r

iTrader: (4)

I'm gonna need you to come in on Saturday.... i won't be here. You'll be here, but I won't be here.... Thanks..... insert fistpump

ddnspider

iTrader: (26)

I can do this all day.