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.

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

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?

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.

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

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

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

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

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

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.

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.

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.

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.