6.0 LQ9 vs 454 1986 k30 crew cab short bed questions

[DustyNova]

if i save up the cash wich would you reccomend swapping in? Id use a built700r4 tranny 373 or 410 gearing and i want to try and get 600hp 600tq out of the build in the end wich would Be better for a swap and wich would get the better mpg id use this kit for the 6.0 swap http://www.summitracing.com/parts/ed...cXEaAq-I8P8HAQ

the 6.0 is out of a 2003 Chevy 2500

[mongocanfly]

Personally I wouldn't even consider the 454..I would go with the LS..but wouldn't go carb..I would stay with the injection..the ls swap itself will cost more than just dropping in the 454..I think the 6.0 from the 03 2500 isn't a lq9 but is a lq4. If your wanting to build 600hp you don't need to worry about gas mileage..ha ha

[kalbert]

Lol... 600hp and 600ft-lbs out of a carb 6.0 that you want to drive on the street in a K30 and you're wanting to know what kind of fuel economy you can expect?

[Firebirdjones]

For that kind of power you'll likely be stroking that 6.0 and a really good set of heads. So you'll wind up with 402-408 cubes anyway. It's not going to be a gas mileage queen.
If you want to keep the fuel injection, things get pretty expensive. Stock truck intake won't get you to that power level, you'll want an LS6 or FAST setup. Either of those intakes will mean you'll be changing the front accessory drive setup too, as the truck drive setup doesn't work with either of those intakes. You'll either need a vette setup or an Fbody setup, or go completely aftermarket. Plus you'll be dealing with different fuel system requirements for an injected motor. Carb would be the cheaper and easier way to go, so it's really up to you and what your budget allows.

Even a 454 BBC would be pretty radical to reach those numbers. Mine made 640 HP and 612 torque on pump gas. But I had to use expensive AFR heads and a fairly radical custom roller cam to get it there. It likes a 3800 stall converter and 4.10 gears, it likes RPM. I street drive it all the time and find it very livable, could even daily drive if needed, but to most people it's pretty rambunctious. It would be much easier to stroke the 454 to hit numbers like this.

Sounds like you are wanting more of a fun street truck rather than something to haul and tow with.

I've went the other end of the spectrum as well. I've done the 6.0/4L60E swap in one truck, and my other pickup has it's stock 454. As far as towing and hauling goes, the 454 will run circles around the 6.0, especially on the hills. The 6.0 is hunting for gears and you have to mash the pedal pretty good to maintain speed, while the 454 just climbs without fuss, it just has more torque available under the curve where you need it for pulling. I like the 6.0, but for a work horse and all around usability of a good pickup, I'll take the 454.
Gas mileage is 2 fold. It depends on whether you have a good tuner on your hands. My 454 pickup with it's 400 turbo and 3.73's will get 14 mpg highway, empty. The carb and distributor are dialed in. My 6.0 swap with a 4L60E overdrive and 3.73's, tuned with HPtuner gets 17-18 mpg highway.
On the other hand my fathers 2002 6.0 with it's 4L80E with stock tune gets no better than 13 mpg no matter how he drives it, and his 2015 6.0 with it's new 6 speed auto gets just over 15 mpg highway, also stock tune.
Granted there is a lot left in the tune on these trucks and I think I could find a couple MPG with both of them if I dove into them with HPtuner, but as they sit, they really don't do any better than my old 454 pickup.

Just depends on what you want out of it. Gas mileage usually isn't all that great with any of these trucks though, they are heavy and you're pushing a brick through the wind.

[andrewmp6]

If you want mileage go diesel,But you gotta remember these trucks have the aerodynamics of a brick.I have seen diesel swap trucks get 20mpg but gas and 600hp 10mpg will be a good day if you keep your foot out of it.

[Firebirdjones]

I have a diesel as well. The mileage is decent when empty. My duramax will get 18 mpg or so without trying too hard. It's about 4 mpg better than my 454 on average. Pulling power is certainly better, which is why I bought it. It climbs the mountains around here pulling the trailer like it isn't even back there.

However the mileage while pulling doesn't impress me. I've pulled my 28 foot enclosed with my 1 ton 454 and with my duramax, both across country and loaded. My 454 would consistently get 10 mpg on fillups. The duramax last year pulling the same trailer across country only got 11 mpg on fillups.

What really killed it for me at the time is that last year diesel fuel averaged $4 a gallon across country and cost me over $1200 to go 3600 miles. Regular gas was in the $3.50 range for high test at that time. So in the end my 454 and the duramax would have been a wash towing across country as far as fuel cost goes.
Wouldn't give up the duramax though, the pulling power makes it worth it. Now with diesel at $1.99 here (finally) it's actually pretty economical to drive (for the time being) I wish it was that cheap last year. I'll be doing the same trip in the spring, hopefully these diesel prices hold.