FormulaBoat

iTrader: (1)

Jimbo1367

why not go aftermarket? BTR? I would think using a spring designed for a lighter valve, on a heavier valve is asking for failure. Bite the bullet and buy aftermarket springs. It will be cheaper in the long run vs. fixing a dropped valve.

FormulaBoat

iTrader: (1)

Looks like I should be OK. From official GM released info on their websites, the stock L92/L94 is rated to 6000rpm as-is. The stock LS3 is rated to 6600rpm. The LS3 has a lot more spring pressure than the L92/4. So, using LS3 springs on an L92 valve train should easily extend the rated RPM operating window 100rpm or so to my 6100tpm target.

It is what I am going to go with, as I drive 22,000 miles a year, and don't want to be changing valve springs once a year. Going for stock LS3 430hp 100,000 - 150,000 mile durability setup, thanks.

cam

iTrader: (9)

I think you'll be fine at that RPM. I ran stock L92 valves over 7K for years with PAC 1518 until it slowed down. I had about 15k miles on the springs over many years and the intakes were totally soft and the exhausts were fine. I replaced with Psi1511ml and upgraded to LS3 intake valves, Barely run it since, no time. Setting up another now very similar to you I want to run stock LS3 blue springs and a mild cam for a truck. 6400 RPM is my upper limit, probably set the tune up for 6000RPM shifts though

Marc 85Z28

iTrader: (8)

I ran GMPP blue springs in my G8 with a LS7 cam swap and shifted at 6800-7000RPM depending upon the gear. I put just under 100K miles on that setup with no problems.

FormulaBoat

iTrader: (1)

Perfect info, thank you very much everybody. Exactly what I was looking for to have at least a small amount of confidence in what I am throwing together.

Just got the block back from the machine shop, and picked up a set of 823 heads, so time to go crazy on mail order to slam this together and put it in my Colorado. Machine shop local to me did an excellent job of re-sleeving 2 cracked cylinders on the damaged L92 block I picked up for $100. $600 total to do so including a very light decking, bore of all 8 holes to next size up, and kissing the main bearing bore tunnel with a ball hone to get rid of a few hang nails that were on it. I found replacement pistons for $200 a set on Rock Auto, so should be able to assemble a stock 430hp LS3 on a very reasonable budget.

L78steve

You didn't mention what lift your running. The blue springs are only good to .570 .

FormulaBoat

iTrader: (1)

warriorpluto

iTrader: (2)

If you already have the engine apart i would change the valves. Too many failures with l92 valves breaking

FormulaBoat

iTrader: (1)

Yep, thanks, good point. Doing that as well. I started with an L9H (L92) core, and building it up with a stock LS3 cam. Am checking valve part numbers now, but so far looking like LSA (stainless) intake 12605223, and inconel exhaust 12612427, GM part numbers, for max durability. Those are stock L92/LS3 valve head sizes. Not 100% sure on the material content of those part numbers, but that is what most information is reporting back.

Just got the block back from the machine shop. They did an amazing job pressing 2 new sleeves in. Looks 100% factory issued stock. So, she is going together as a new build from the ground up. New bores, pistons, lifters, cam, all of it.

Thanks again.

JakeFusion

iTrader: (7)

I'd look at some Comp 918 beehives... they'd clean up any harmonics and control the L92 valve a little better.