4.8 predictions
11-02-2015, 08:42 PM
#1
4.8 predictions A while back I posted about my stock long block 4.8 making 300 rwhp It ended up running mid 8s in the 1/8 NA. I'm putting a set of ported and welded 241s on it this month. The chambers are welded in so that they are shaped kinda like an 8. The compression ratio should be about 10.5 - 11 to one with 53 cc chambers. I have a brand new Cheatr V2 cam already. I know this cam wasn't meant for this engine but what kind of tq curve might I end up with if I use it? It's 219/230 117.5 LSA. I'm going to have a gt45 on the car next month too. It seems like the 117.5 LSA would be good with a turbo but the duration seems like a lot for this little engine. Any thoughts?
11-03-2015, 09:29 AM
#3
TECH Addict
The stock cast manifolds aren't much of a consideration given that you have a gt45 going on it in the near future.
I think that cam is obnoxious for a 4.8L, and I'm almost tempted to say that the stock 190/191 cam might be better, especially with the turbo. The 219/230 cam appears to be a rectangle port cam, as well. All that exhaust bias would be great if you were using a positive displacement blower, but not so much with a turbo.
Plus, 241's already have a pretty strong exhaust to intake flow ratio. They don't need any help from the cam in the exhaust duration. With those heads, and the 4.8L displacement, I would be looking at something like Martin's truck cam, 206/206 .560/.540 114+4, or a turbo specific cam designed for the 4.8/5.3 engine(s).
I think that cam is obnoxious for a 4.8L, and I'm almost tempted to say that the stock 190/191 cam might be better, especially with the turbo. The 219/230 cam appears to be a rectangle port cam, as well. All that exhaust bias would be great if you were using a positive displacement blower, but not so much with a turbo.
Plus, 241's already have a pretty strong exhaust to intake flow ratio. They don't need any help from the cam in the exhaust duration. With those heads, and the 4.8L displacement, I would be looking at something like Martin's truck cam, 206/206 .560/.540 114+4, or a turbo specific cam designed for the 4.8/5.3 engine(s).