Performance parts = MPG gain?

[Arctic-Rodz]

From what i've had before on my 2008 Sierra i would say yes.

is that also true for 4x4 lifted vehicles?

I've had my tahoe now for about 1 year and im getting the itch for more power.

I already have a K&N CAI, Borla pro XS muffler and custom HP tune.
I already have LS1 e fans with Nelson harness going in soon and 4.56 gears.

Im debating on adding long tubes with a cat-less y pipe. Maybe 243 heads and im not so sure on a cam.

I had my 08 sierra with a bunch of go fast parts and i was getting about 22-23MPG highway.

Im not expecting that on my lifted Z71 Tahoe, but can i also expect improvements in MPG as my 08 did?

 

[WildBill]

from the way I see it, anything you do to increase power requires more fuel, which equals worse miles. I would think the 4.56s would kill mpg, but i suppose it just balances out the 35s.

I've got no expierence on big motor mods on these trucks, but i would expect a mpg loss. Good luck though.

 

[Arctic-Rodz]

true, more power requires more fuel (but at more throttle) having more power doenst mean worse fuel economy.

i had, K&N CAI, long tubes, cat less y, pulleys, borla, 3000 circle d verter, custom HP tune, 4/7 drop on 22" wheels and i was getting 14-15mpg city and 22-23 highway on my 08 2wd sierra ext cab.

Granted, it was (im sure) lighter than my Z71 Tahoe. im just wondering if MPG would improve on my heavy ass truck if i give it a similar treatment. id hope to see 14city and maybe 17-18 highway?? is it POSSIBLE!!??

I dont think id put a converter on it though, that hurts city MPG

 

[WildBill]

If it helps you mileage, ill copy your setup! I sure would like more that 13-14 combined, lol. Keep us informed.

 

[Arctic-Rodz]

LS1 e fans will be going in next week followed by 4.56's. Ill post what results from the mods.

wish me luck!

 

[FBO Z71]

If you are planning on going that far into modding I would look into getting your stock intake port ans polished or an ls6 intake. With an ls6 intake on the dyno I showed about 13rwhp more than stock. A buddy of mine had his stock one p&p and saw almost the equivalent gains

 

[Arctic-Rodz]

ive heard the NNBS intakes flow just as good as LS6 intakes, but more torque since its for a truck.

Anyone know if there is a difference from the NBS to the NNBS intake??

Ive thought about swapping to the 243 (LS6-truck) heads too, i know those are way better than the stock NBS heads

 

[ATL]

im assuming the nnbs still has a 5.3? i know nothing about those, but the new 6.2L motors flow like crazy. the 6.2 uses a different port size and shape than the 5.3 and 6.0 heads tho. but you could just swap the heads on as well and use the matching setup. Those motors use the L92 heads and depending who you ask, they flow 300-320 cfm.

 

[BeaverGod]

i had an 09 5.3 1500 lifted on 35s with 4.10 gears. the main thing that will hurt you is the 4 speed tranny. with my set up i was getting 1 mpg shy of stock mileage and had plenty of power. with the 4.56's youll be running slightly higher rpm but you wont have as much throttle. i wouldnt imagine there would be much argument for 4.56 gears hurting your mileage as far as gear swaps go (theres pretty much only two scenarios 4.10 or 4.56). with lifted vehicles the best way to feel more power is to regear plain and simple. i think youd be surprised by the throttle response the gear swap will make

good luck

BG