Suggestions of Mods.

I have an 03 z71 extended cab. 5.3L, 4" lift with 33" tires, the 5.3L isn't where i want it to be in the power range. I don't want to change my gear ratio's but i want to add power, mainly for pulling a 3500lb. trailer. Running 65-75 on the interstate, it will stay in 3-4 gear, because of the load, and i personally don't like seeing it run 3k rpm all the time. i usually get off the interstate and go back roads. I am thinking about a good head swap with a cam. I will eventually do a 6.0 conversion with full forged internals with a supercharger/turbo. but right now i just need something to get me by. Anyone know where to get a head and cam set up? or should i just go get the heads ported and polished?

A stock geared 5.3 with tires that tall that also has to pull a load is the problem. Lower it and take the big tires off and live with stock performance or mod it a bunch (including gears) to make up for the lift and big tires.

what is the stock axle gear ratios?

Not enough for that tire. Look at the G-codes in the glove box and we can tell you what ratio you have. It's probably 3.73.

well should i just do a LQ4 with forged internals swap now?

and a turbo for 33" tires and no gear ratio change...

even with the 6.0 with forged internals with good flowing heads won't be able to produce enough power with out an power adder?

Not with 33's and stock gears. IMO.

that is a shocker, my father-in-law has a 02 2500hd with the 6.0L and he has no problem pulling the trailer, i know he doesn't has teh tires, or maybe not even the gearing, but i wouldn't think it would matter that much.

Hah...really? There's a pretty big difference in a stock 6.0/4L80 and a stock 5.3/4L60 and add the tires and probably worse gearing and you have apples and oranges.

Forged internals make ZERO power they just hold high revving or forced induction stuff together better. What are good flowing heads is debatable. There needs to be a cam, converter, and gears to go along with a good flowing set of heads. Heavy, tall tires need a lot more of all that....especially gearing, to make a large enough improvement to justify the $$$..

i know forged internals don't make power, but i would put them in because eventually i will put around 15lbs of boost on it. and stock internals will not take that ever. i understand what your saying, i am just trying not to change my gear ratio because i do so much highway driving at high speeds, and i need the taller gears to keep my rpms low during them speeds. so a LQ4 with performance heads and cams, wouldn't give the power i need, most likely?

Power for what exact purpose I guess is the question.

With 33's your effective gear ratio (assuming 3.73 stock) is down near 3.23. You're lugging it on the highway as it is. It won't pull any worse or get worse loaded mileage with some 4.10's or 4.56's I'd bet considering the RPM range it's in now.

i wouldnt waste time and money modding the 5.3, just go for the 6.0 and build it for torque, swap out the gears youll get used too the higher rpms.

Sounds like you need a duramax.

yea i was wanting a diesel, but the additional cost is more than i had at the time.

IF you dont change your gears, you will never see the full potential of your truck. just as gas guzzler is saying, You are running over size tires and pullng a trailer. change to a 4.10 if you want to keep the tires you have. 4.56 if you want to go bigger. I have 33s and i pull a 3700 lbs car on top of the trailer. The first chance i get i am gonna regear. And as, prior stated, you will wear out your driveline and drivetrain faster.


Chris

so some 4.10's and a built 6.0 would be ok? i don't want any bigger tires except 35's. that is the max i would go.

for every inch you go up in tire size you drop .10 in gearing

so your truck has 342s and now you went up 4" in tires. so your gearing is basically 308s. i would do 430 gears and call it a day and not worry about any other mod besides a tune

ok thank you, that helps alot. i still have a lot of thinking to do, i am gonna go to 4.10s if not lower, and i am still trying to figure what to do about power...

You would be better off with 456 gears on 33. GM puts 410 gears in from the factory on the 5.3 Im driving a 2000 gmc 1500 with that set up and I use it to pull a 16 foot trailer and I use it to haul cars on and it works great. when it comes to pulling gearing is everything. gear swaps in your truck are easy and you can pick complete front and rear gear packages from randys ring and pinion for a good deal

Sorry to hack the tread but I'm confused. if I understand correctly numerically higher gears doesn't necessarily kill your gas mileage? I have 305/45/22 so I guess that's about a 30.5 in tire - stock 3:73 5.3/60e I'm turning 19-2k @ 70mph and avg 17.8 mpg should I consider changing gear ratios to obtain better mpgs?

Getting lower in number or higher in ratio used to be something people thought helped MPG but if you make the engine work too hard to haul the weight the MPG will suffer greatly. When I started in the dealers in the early 90's people bought 5.0's then realized the 5.7 got better mileage....

any recommendations on my set up?

I had the best luck with some performance mods for my four wheel drive the cold air kit exhaust and programmer got me just over 19 mpg on the high way with 3.73s and 33 inch all terrains

I have the k&n and exhaust. The only thing I 'm missing is the nelson tune!-soon to come.

Gears are the way to go for you at this point. It all about leverage.

I am in the same boat as you right now,
5.3 with 3.42 on 33's, not exactaly a tow pig but as soon as my kid is born and the wifey gives me the thumbs up my trucks getting 4.30's and a trutrac

35's 6.0l and 4.10 heres pulling upwards of 10k on a monthly basis. Not exactly great on gas, could probably stand to go to 4.56 since at my traveling speed is right around a shift point and it tends to work a lil harder than it should if i dont pay attention.

i decided to swap my gears to 4.10s or maybe a little more since i might start pulling a 29' boat, might go with 4.56s, but i am also going to put air bags on the rear axle to level the truck, any suggestions where to get the gears and bags?

Quote:

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Originally Posted by 03whitez71

i decided to swap my gears to 4.10s or maybe a little more since i might start pulling a 29' boat, might go with 4.56s, but i am also going to put air bags on the rear axle to level the truck, any suggestions where to get the gears and bags?

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I got my helper bags from summit. Get the ones with the air compressor and switch that mounts inside the cab. I can hook up to the trailer by letting all the air out of the bags, back up to the trailer and fill the bags and up it goes. I only wind up the jack to keep it from hitting the road.

Firestone Ride Rite, Coil Rite, Sport Rite 2178 - Firestone Electric Dual Air Command Systems - summitracing.com

Firestone Ride Rite, Coil Rite, Sport Rite 2320 - Firestone Sport-Rite Air Helper Spring Kits - summitracing.com

it says pressure sensor not included? anyone know where to get gears?