'09 4.8

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Sep 28, 2008 | 07:27 PM

#11

viciousknid

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From: Dover, Oklahoma

I'm going to say tune and maybe exhaust changed. Has anyone checked the cam specs?

Other than that I'd say they used a different dyno.

Sep 28, 2008 | 10:41 PM

#12

SlvrSierra4.8

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From: Houston, TX

Quote:

Originally Posted by InchUp

I know the newer 4.8's and 5.3L's have been getting the 243's, but then what else changed? Bolting on a set of 243's with stock pistons would actually lose compression, since the 5.3L heads have smaller chambers than the 243's. So if compression is up, but 243's are on...what changed? What kind of pistons?

243's w/ new pistons were used and the stock CR was maintained as far as I know. Not sure on the new piston specs?

Sep 29, 2008 | 05:46 PM

#13

sickREDsierra

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From: Mobile, AL

bla bla bla.

anybody notice the new 4.8's got e-fans ? my 2007 4.8 had 862 heads, same as older models... but i think the efans free'd up the 20 bhp you are noticing.

it damn sure wasnt in the tune. torque management was more ridiculous than i have ever felt. that was my first goal, getting rid of that ****!

BTW the rating on the 4.8 went to 295 bhp in 2007

you just noticed it for the 2009... but like i say, the earlier motors had manual fans running off the water pump pulley.

Sep 29, 2008 | 05:52 PM

#14

BlackGMC

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From: Fort Worth - TX

I think the changes are 243's, efans (as compared to <05), different intake and larger TB... The tuning is completely different on the NNBS, if you have ever seen one they don't have any of the regular tables...