JAX04

iTrader: (17)

I was just curious,


Im wanting to keep my 4.8 crank (3.27" stroke) but i know the block needs some machine work, with that said, im guessing i can get it out to a 3.898 or even 3.905 and be ok.

But what about rods?? Ive yet to see any 6.275" LSx Rods listed anywhere,

Any help would be appreciate, hell if you have any other weird ideas for this crank and block, shoot them out their, its still up in the air.

Oh, its a turbocharged motor as well.

Thanks!

Kyle

chrisfrost

iTrader: (8)

I have no clue where You can get aftermarket rods for that engine but . The factory rods are good to 600-650 hp fairly safely . 1 thing good about the shorter stroke especially if You do bore it is a higher rod ratio which equalls more ignition timing without pre-ignition . There is a great article in Hot Rod magazine called "The 350 Chevy should have made" . You can go to Hot Rod and search that article and read it . 2 guys took a sm bl 400 , bored it .030 (4.155") and used a 307/327 crank (3.25" stroke) and ford 300 rods (6.209") making 352ci . They got JE to make pistons with wrist pin location higher on piston and used aluminum heads with 58cc chambers neting static comp of 11/1 They were able to advance timing 36deg total . With a quadrajet and stock cam and long tubes on a dyno 435 tq and 413hp on 92 octane , on 87 octane same tq with 412 hp without any signs of pre-ignition . I did a little computing and figured out what a 1st gen 350 with all those mods except the crank , rods and pistons and came up with 150 or 160 less hp and 150 less tq .

JAX04

iTrader: (17)

They used ford rods? thats interesting, lol. I have seen someone post that they used SBC 6.25" rods with stock compression height pistons. But thats it. I think it was Erik of HKE, id love he would chime in.

I really want to stick with this short stroke combo, just need to make it work.

RezinTexas

4.8 and 5.3 iron blocks are identical and can both be bored to 3.902"

JAX04

iTrader: (17)

Yes, im aware of this, lol.

I guess this post was more directed to different combos that i can make with the different pistons and different rods.

Darkman

iTrader: (2)

Accordng to Joseph Potak's book on LS engines the maximum bore for these motors (4.8L and 5.3L) is 3.910 inches.

JAX04

iTrader: (17)

Thank you for that. So does anyone know where to find a 6.275" rod?? or is their another Rod that will "WORK" with an off the shelf aftermarket piston?

Callies Performance

You are not going to find a steel rod that length, unless you have some one make you a custom rod $$$$$ Keep in mind, LS rods are on center and SBC / SBF rods are offset

JAX04

iTrader: (17)

Thanks for taking the time to talk with me on the phone Adam, I do appreciate it, seems like this endeavor is a waste of time now and i ought to ****** up a stock stroke crank and go to 347CID.

Ill keep you updated. thanks man!

Callies Performance

No problem, I will let you know if I come up with any other Ideas!

98SSClone

iTrader: (2)

Couldn't you use a regular LS series rod and a custom piston?

JAX04

iTrader: (17)

The idea was off the shelf parts. If i was trying to build a max effort type engine, that would be a viable option.


As it appears, unless someone else comes forth with more knowledge on teh subject, it doest look possible with "shelf" parts.

BattleSausage

iTrader: (3)

Use a 6.4 rod with an off the shelf JE forging @ 1.175 compression height for a 3.905 bore, deck the block .031 and use a thicker gasket. There are a bunch of combinations you can create if you do the math, especially if you know what chamber size you are using, etc. However, you would have to take into consideration the quench and what not. I haven't done any off the wall combos with the LS platform but I'm sure there are many options if you talk to a reputable builder. Btw, there are a bunch of people that are taking the iron 4.8/5.3 blocks far beyond 3.90X and still have plenty of meat left on the thrust side. Of course they are sonic checking their blocks, but most can go at least 3.950 & still have ~.18ish left on the thrust side from what others have reported.

chrisfrost

iTrader: (8)

There's a thread in this forum that the op bored 5.3l to 6.0l bore , sonic checked and says its still thicker than a .060 over gen1 sm bl 350 . Also one of the piston manufacturers I believe it was a Federal Mogul website I was looking at one day that has all their piston listed for all gm's , fords , mopar ....1 by 1 line by line all the important specs , bore , comp height , pin diameter , dish , flat , dome . You may be able to find a non LS piston that has what You're looking for .

tatersalad25

Im not sure but I think you could use the wiesco forged pistons for a 5.3 with a 1.3 compression height with lunatis 6.300 rods and make it work. Im not too sure on the math but I think its pretty close the only problem is that the lunatis are pretty expensive.