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From: Lake Charles, LA

Hi all. Before I start, yes, I did use the search and came up with nothing. I�ve been wanting to do a rowdy 4.8 for a long time. I got my hands on a very nice specimen today and my mind is already spinning with ideas.

The first thing Hong I wanted to look into was forged internals. I can�t seem to find a forged crank for a 4.8. Does anyone know who makes one... or if anyone makes one? If there aren�t any to be had, or if there are but they�re insanely expensive, does anyone know what kind of power the stock 4.8 crank is good for and still maintain reliability? Thanks for your input.

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From: Central Cal.

Joined: Oct 2016

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From: Lake Charles, LA

I am thinking much more than that, like around 1000 at the crank. Obviously I�m not going to be driving it WOT at 1000 hp all day, but I want the capability. I also know this is much more easily done with displacement, but I want to use a 4.8 and most likely twins

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From: PNW

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From: Fredonia,WI

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From: Santa Ana, CA. USA

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From: Lake Charles, LA

Yes, I plan on making the power with twins and high rpm. It�ll be a little bit different powerband than my 545 build.

I have that article bookmarked on my computer and phone, lol. That�s what spurred this idea years ago. I know it�s been a long time since that came out. I was just curious if anyone made a forged crank for them. Sure the stock crank did it on a dyno, but how many times would it do it in a car before becoming a stain on the road?

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From: Lake Charles, LA

I�ll never turn down help, are these cranks you�re talking about for a 4.8 LS, or am I looking at getting a custom billet piece made? That would fall into the �extremely expensive� category. Before I went that route I�d just dismally use a 5.3 crank.

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From: Lake Charles, LA

Really I�m not looking for 1000 rwhp, probably closer to 800, but I figured that�s probably close to 1000 at the crank. In a sub 3000 lb street car that should make for a fun ride and not eat as much fuel as my 545

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From: Ohio

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From: Lake Charles, LA

Really? They that tough? I�m perfectly happy running the stock cast crank as long as it�ll hold the power. I figured the short stroke had to give it an edge. Should be interesting to see. Looks like I�ll just look at some good rods (Oliver) and pistons and start force feeding it.

Totally separate thought, but anyone know how they do with nitrous? That�s power, but it�s a different kind of power

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From: Fredonia,WI

thought they mentioned over sixty pulls in excess of 1000 horsepower
engine dynos are harder on the rotating assembly than an auto car

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From: Lake Charles, LA

Yup, they did over 60 pulls at 1000+ hp. I�ve had that article bookmarked for 7 years, lol. I�m not sure if I�d agree that dynos are harder on an engine. I used to have an engine dyno and it was wonderful for tuning, but there�s a lot of stuff that happens in the car that you can�t simulate with a dyno

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From: Lake Charles, LA

Also, the setup they used was for peak power. Twin 76�s probably wouldn�t be the best setup for a driver on a 4.8

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From: Santa Ana, CA. USA

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From: PNW

Its not that they�re �that tough� it�s that it�s a short stroke crank and this isn�t the 1950�s, technology has come a long way in not just manufacturing techniques but material quality as well. You�re not damaging the crank before you damage something else first.

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From: Lake Charles, LA

Just from what I�ve been reading that seems to be the case. It also looks like nobody makes an exact stock length rod, so I�ll either have to go with a 6.250 or 6.300, no biggie. I�m just curious to see how far down in the hole the pistons are stock. If they�re 0.025 or so then that�d be pretty cool. I could get some forged slugs with a small dish or use a different head to keep the compression where it needs to be.

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From: Ohio

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From: Lake Charles, LA

Well if that�s the case it looks like I�d be needing a custom piston. I�ve used JE/SRP in the past and been very happy with their quality. I just don�t see anything out there for aftermarket, stock length rods. Correct me if I�m wrong, but it looks like you�ve either got to go with a 6.250 or 6.300. I�ve been unable to find a 6.276� con rod.

I guess I could go with a 6.250 rod and have it about 0.020 in the hole and shave the head a bit to bring compression back, but I�m not a huge fan of that idea.

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From: Lake Charles, LA

Actually I just did the math and sinking the piston in 0.020� (using stock type piston with 6.250� rod) would yield a 9.12:1 CR vs the 9.64:1 stock CR. That�s not bad at all, and even a bit more turbo friendly. Still giving up some quench though.

FYI, that is all based on the assumption I use a head gasket with a 0.051� compressed thickness.