Quote:
Originally Posted by Jim_PA
Yes, but I think you could make the mileage close enough that it shouldn't be a deciding factor. My build should be in the 390-400 range, and with an overdrive, I'm confident I could easily get 17-18 with it.
I also take into consideration that my 04 yukon has averaged 14.5 MPG over the last 4 or 5 tanks of gas. I've never seen more than 17-18 MPG on a highway trip with it. I realize it weighs about 800lbs more than my truck does.
I'm not anti LSx. I think it's a cool thing to do, and if 5 years ago when I started with nothing under the hood and had it been as economical and common as it is now, I would have considered it. But IMO, the entire requirements bill for an LSx swap over-complicates things, and would make back-yard tuning and diagnosing problems less more difficult than staying "old school"...
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I agree with what you are doing. I see 17.5 mpg regularly in my 06 SWB 2wd and that is at 80mph highway and beating it around town. I have seen 19.5 mpg when I do strictly highway at 65mph and under. I am 4200lbs curb weight I believe. I am surprised you get such poor gas mileage from your 04. My brother in laws 02 4 door 4wd gets 21mpg average. He drives like a grandma.
When I see guys pull off the 5.3 swap at $1500 complete with doing all the labor themselves I find it hard not to be an advocate. I also see my friends tune their FI motorcycles from their laptops on a regular basis, so I can't agree with your backyard tuning, but I can agree it may not be for you. I can tune my truck with several products out their that cost as little as $200 (I think, been awhile since I looked at the handheld stuff) so you don't even need a laptop if you maintain the data port with the factory computer.
That is where I am coming from. Plus you can than add heads, cam, etc.. to get you into 400-500hp territory.
I looked into supercharging my 5.3 and I was told my stock motor puts down 220-230hp at the wheels and with a magnacharger would be about 450hp at the tires (with a 3 year warranty). I spoke to another tuner who said I would be better off with a centrifugal blower that would net me well over 500hp at the tires and that they had a GTO with an LS2 stock block with water injection at almost 750hp at the wheels and there wasn't any issues with reliability. That also makes me an advocate for the newer gen stuff.