If you want mpg and rpm then go 4.8l with 799 heads and a decent cam and t56. My old C5 z06 Vette would pull 30mpg+ all day long. 4cylinders sound cool good on paper but after it’s said and done it will feel like a turd, sound like a turd and get worse fuel economy then you would have thought. you can make allot more reliable power that will actually be worth the money it costs to build it with an ls.

 

you spelled "706 heads cut .035" weird

 

Idk lol I’ve never even pulled a set of ls heads. I thought the 243/799’s flowed allot better and had bigger valves. I have 706’s on my Tahoe and 862’s on the other 5.3 I bought for my S-10.

 

Flow is only part of the equation

While its true that flow helps increase economy, same reason turbo's get better highway MPG; increase VE for a given engine speed- its more better to have high compression when shooting for economy. Higher combustion heat= better thermal efficiency. Less energy is wasted heating a larger space. So assume that at 3k rpm the 706 and 799 pull in ~5% the same amount of air, 706 will turn more of that explosion into moving the piston vs heating the larger, less compressed chamber of the 799

Dan and I were talking about this earlier actually. If I could build the "ultimate" mpg LS I would put truck heads and flat tops on the biggest motor I could find, deshroud the valves, run a 205 t stat and tune it to run 15.2-15.5 down the highway on premium

To this date, I wouldn't pick the 243/799's for anything making power in the idle-5k range that was smaller than a 6.0

 

That makes sense to me. The big thing I’ve found for fuel economy on a full size trucks are aero drag and driving habits more then anything. Drafting semi trucks usually picks me up somewhere in the 3-4 mpg range vs Highway driving with no one in front of me. If I was gonna build something for fuel economy it definitely wouldn’t be a full size truck though lol. My insight got 80mpg round trip an hour each way on i5 with hyper miling techniques with just the Gas engine no integrated motor assist from the hybrid crap. Really miss that car. I need to find another one to store for a future build before they are extinct. They only made 17k of the first gen insights from 99-06.

 

Not much of an update but finally washed the Tahoe. Also replaced the drivers lower seat cover as it was starting to get warn. Got this one off eBay and it fits and feels great. Only paid $25 shipped for it. Also got my z71 lower front valance finally and wow what a difference it made in appearance.

 

got some used 295/70/17 hankooks for the burborator today for a steal from my buddy chuy at martinez tires. Looks way better. Seemed to rub on the first turn but hasn’t since then lol. Looks 100x better in my opinion. Got the wheels for free from a dude on offer up and the tires were $200 mounted and balanced and are probably 40-50% tread left. They actually drive a lot better then the old tires did too which I wasn’t expecting. I’m sure I can sell the stock wheels and tires for 200 ish to cover the new setup.

 

Both trucks look great! I wish I could find a cheap 4x4 NBS down here that actually runs and drives. I don’t even need more than first and second gear for golf cart duties.

 

Thanks man. The burban was a steal. Needs some interior love but I just picked up some 2nd row seats from a 04 Tahoe lt because they will fold flat without having to pull the head rests and they look allot less methy. Unfortunately the brackets are a little different, front bolt holes line up, rears are off set over like 1-2” and sit a little higher. I’ll jurry rig something up to make it work. Also dan I was just reading through your thread last night and saw the pictures of your driveway to your place. Looks pretty bad *** man.

 

Crappy interior would be fine for my intended purposes, the doors would be coming off anyway but, I can't be driving around in no meth mobile. Thanks! I love my driveway I'm glad I didn't have to pay for all the rock and crushed asphalt because whoever did it must have spent a fortune. If they hadn't done the driveways it would be straight sugar sand and impossible to get to the house lol.